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1
Cave, B. J. "Copper - Gold exploration in the Middleback Ranges; source(s) of fluids and metals." Thesis, 2010. http://hdl.handle.net/2440/98295.
Full textAbstract:
This item is only available electronically.The Moola Prospect of the Middleback Ranges, South Australia is an epigenetic, hypothermal copper-gold prospect that displays several clear genetic affinities with IOCG deposits/prospects in the Gawler Craton, although from this study alone classification of the mineralisation is imprudent. A broad study on the mineral paragenesis and geochemistry of the deposit was carried out on a single drill core provided by OneSteel, the holder of the tenement encompassing the Moola Prospect. The mineralisation, characterised by pyrite + chalcopyrite, hematite and magnetite, is hosted by the Palaeoproterozoic metavolcanic / volcaniclastic, Myola Volcanics and an unnamed, undated fine-grained microgranite that intrudes the Myola Volcanics. This unnamed, undated microgranite, displays geochemical and petrological similarities with the Myola Volcanics from which it‘s thought to be partial derived from its anatexis; likely being a Wertigo Granite equivalent. Four alteration assemblages were observed in the Moola Prospect drill core and placed into the following paragenic sequence; Na (Ca-Fe) characterised by the formation of albite; sericite replacing K-feldspar and plagioclase and alteration increasing towards sericite veining; chlorite with alteration increasing towards chlorite-mica±epidote veins; late stage quartz, quartz-carbonate, carbonate flooding, that hosts mineralisation. Ore mineral paragenesis occurs in an overlapping sequence; the first mineral precipitated was magnetite that was later extensively martitised, with hematite followed by pyrite and minor heamatite + pyrite, pyrite + chalcopyrite, then chalcopyrite. Later supergene alteration altered the chalcopyrite to native copper and malachite. Sphalerite precipitation couldn‘t be constrained from petrological evidence alone. Iron oxide and sulphide chemistry, and sulphur isotopes from the sulphides support this paragenesis, and constrains precipitation of sphalerite between the pyrite only and chalcopyrite only phases. Iron oxide chemistry also revealed the presence of illmentite in the core, however could only constrain illmentite precipitation as, coeval to after haematite precipitation. Sulphur isotopes revealed evidence for an additional late stage pyrite precipitation, after the chalcopyrite only phase. Bulk rock composition was quite variable with some altered samples showing strong enrichments of Fe2O3, SiO2, CaO, K2O, Na2O SO3, MnO, P2O5 and MgO. Strong enrichment of CaO and/or SiO2 in some of the altered samples, but not others, suggests that the quartz-carbonate alteration represented by this geochemical signature is sporadic in nature. Depletion in SiO2 in some of the altered samples could also represent the consumption of silica during the Na-Ca-Fe alteration event. Enrichment of SO3 in the altered samples likely directly represents alteration related to the precipitation of sulphide ore minerals. Trace element and rare earth element compositional changes from alteration shows enrichments of Cu, U, Pb, Li, B, Mn and V likely relating to alteration associated with mineralisation. εNd (1590Ma) values of the Moola Prospect together with εNd (1590Ma) versus whole rock Cu concentration and Co: Ni ratios of pyrite, indicates a crustal derived, with minor mantle input for the sources of metals. Sulphur isotopes and trace element whole rock geochemistry indicates a primitive/ magmatic fluid source is responsible for alteration and/ or mineralisation.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2010
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Jones, R. S. W. "Cu mineralisation in the Middleback Ranges: conditions of mineralisation." Thesis, 2010. http://hdl.handle.net/2440/101671.
Full textAbstract:
This item is only available electronically.The Moola Prospect situated within the Middleback Ranges on the northern Eyre Peninsula, South Australia, is comprised of potential IOCG-style, Cu mineralisation which appears to share some geological and mineralogical affinities with other IOCG deposits throughout the Gawler Craton. This recently identified mineralisation represents a new exploration region within the southern extent of the Olympic Cu-Au province which has proven to be highly lucrative with the recent discovery of the Hillside deposit in the neighbouring Yorke Peninsula. A broad investigation into host rock lithology, alteration and mineralisation paragenesis, as well as paleotemperature-pressure conditions of the deposit was carried out on drill core from OneSteel’s inaugural exploratory diamond drill hole. The mineralisation is hosted within the Paleoproterozoic Myola Volcanics, a package of rhyolites, rhyodacites and felsic gneisses which are intruded by amphibolite sills and granitic intrusives, assumed to be the neighbouring Wertigo granite. Prominently vein hosted, the mineralisation is localised around a north-northeast trending shear zone inferred to be an expression of the Kimban aged, Kalinjala shear zone which is located ~60 Km west of the Middleback Ranges. The alteration mineralogy present is divisible into two main assemblages, an early albite-epidote assemblage which has experienced extensive overprinting by the main mineralising phase associated with a quartz-carbonate-sericite± hematite-sulphide assemblage. Ore mineral paragenesis occurs as a transition of overlapping minerals that record coprecipiation. The first mineral to form was magnetite which was later extensively martitised during the transition to hematite precipitation which is preceded by a transition to pyrite, then finally chalcopyrite. A later phase of native copper mineralisation is recorded within the transecting shear zone which represents a supergene enrichment interpreted to have occurred as meteoric water gained access to depth via the structural weakness of the shear zone and remobilised any sulphides present, which were redeposited as native copper. The temperature of mineralisation was established by TitaniQ thermometry which provided a precise temperature range between 415-530 °C with the peak at ~475 °C, which represents the conditions at which the paragenically linked quartz and mineralisation formed. Chlorite thermometry was also performed to obtain a temperature of mineralisation, with a few samples corresponding with the conditions established by the TitaniQ thermometer; however a majority of the data overestimates the temperature range by an unacceptable amount. Pressure conditions were reconstructed using the much more reliable TitaniQ temperature range inconjuntion with fluid inclusion data to establish the pressure conditions of mineralisation which ranged between ~5-7 kbar, and indicated mineralisation occurred at a deep crustal setting. Fluid and mineralisation characteristics indicate a moderate salinity inferred from the fluid inclusions study, with NaCl ranging between 27.5-7.5 equiv wt%, along with a sulphur isotopic signature corresponding with magmatically derived fluids with the δ34S ranging between -10.5 and -1.2 ‰. Which corresponds with other IOCG style mineralisation present throughout the Craton, with the Moola Prospect also being spatially associated to the interpreted source of these fluids within the Galwer Craton, the Hiltaba Suite granitoids? Even though the Moola Prospect shares affinities with IOCG style mineralisation this study cannot definitively identify its model of genesis as it also comprises characteristics that contradict this model, indicating that further study is required to better understand the extent and nature of this mineralising system.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2010
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Barker, A. R. "The thermal properties, temperature structure and thermal evolution of the Eastern Ghats, India." Thesis, 2010. http://hdl.handle.net/2440/98285.
Full textAbstract:
This item is only available electronically.The role of the portable gamma ray spectrometer has become a fundamental addition for gathering heat production data to constrain stochastic thermal modelling of the crust. Numerous sensitivity and calibration analyses have been undertaken to verify the validity of the output, and to aid in more efficient and effective use for future users. When applied to a heat flow study of the Eastern Ghats, it was established that the predominantly granulite-facies rocks such as khondalites, Kfeldspar megacrystic granites and quartzo-feldspathic gneisses have high average heat production values of 3.76 ± 0.53μWm-3, 2.79 ± 0.53μWm-3 and 5.49 ± 0.69μWm-3 respectively, whereas the UHT granulites have a low heat production of 0.69 ±0.23 μWm-3. The contribution of uranium to the total heat production was considered low when compared to the input from thorium, which was almost four times higher. The average concentrations of thorium were also approximately fifteen times more than the concentrations of uranium. In this research, thermal conductivity testing was conducted to better constrain parameters for stochastic thermal modelling. Coupled with previous seismic studies, four crustal sections were analysed by one-dimensional steady-state finite difference models using the results of this project. Conclusions drawn from this study indicate that there is a possibility the Eastern Ghats is currently a UHT region, whereas burial of these high heat-producing rocks during orogenesis could have readily heated the crust to produce UHT granulite-facies metamorphism.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2010
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Grguric, B. "The petrology, geochemistry, and fluid history of calc-silicate rocks and associated primary Cu-Co mineralization in the Ethiudna Mines area, Olary Province, South Australia." Thesis, 1992. http://hdl.handle.net/2440/113058.
Full textAbstract:
This item is only available electronically.Textures in calc-silicate rocks of the Lower Proterozoic Bimba Suite in the Ethiudna mines area, Olary Province, South Australia, record multiple fluid infiltrational episodes associated with both prograde, amphibolite-facies, and retrograde, greenschist-facies metamorphism. Pervasive infiltration of H2O-rich fluids (XCO2<0.18) during prograde metamorphism, was associated with the large-scale development of wollastonite-rich lithologies within the Bimba Suite. Stable oxygen isotope evidence suggests these fluids were equilibrated with siliciclastic sequence(s) prior to infiltrating the Bimba Suite. A second, retrograde metamorphic (temperatures -300oC) infiltrational episode was associated with the development of a grossular-quartz assemblage. Fluid flow was channelized during this episode, the H2O-rich fluids being focussed along structurally-induced zones of high permeability. Large variations in fluid/rock ratios are recorded in the calc-silicates as large variations in the progress of the grossular-quartz producing reaction. The formation of cross-cutting quartz, calcite, and rare laumontite veins postdates both these infiltrational episodes. Fluid inclusion evidence suggests these veins were deposited by fluids at temperatures of less than 250°C. Fluid inclusion data and scapolite compositional data indicate fluids associated with all three episodes were highly saline, consistent with conclusions made by earlier workers that the Bimba Suite represents a meta-evaporite sequence. The microcline-rich rocks of the. Quartzofeldspathic Suite, which underlies the Bimba Suite, host stratiform and disseminated Cu-Co sulphide mineralization. Geochemical and petrological evidence suggests this mineralization is of the genetic type known as a red-bed-associated Cu deposit. The distribution, geochemistry, and textural characteristics of sulphides in the Bimba Suite, suggest this mineralization represents a metasomatic remobilization of pre-metamorphic Quartzofeldspathic Suite mineralization. The sulphide-silicate-carbonate textural relationship in the Bimba Suite suggests this remobilization took place during the high temperature, wollastonite-producing infiltrational episode, and that precipitation of ore metals was effected by a pH rise.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1992
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Guerin, R. J. "Petrography, mineralogy and trace element chemistry of Cu-Au-Mo mineralisation from Central Diorite, Boddington, W.A." Thesis, 2011. http://hdl.handle.net/2440/88640.
Full textAbstract:
This item is only available electronically.The world-class Boddington Cu-Au-Mo deposit has a complex genetic history. The relative importance of different ore-forming processes during the period 3.0 – 2.6 Ga is debated, particularly with respect to the role played by the 2611±3 Ma Wourahming granite. LA-ICP- MS analysis of trace element concentration in molybdenite represents a valuable new metallogenetic tool to track mineralising events in deposits with protracted geologic histories. The Re content and trace-element signatures in molybdenite from diorite and granite show three distinct populations, attributed to porphyry-style (hundreds of ppm) orogenic- and granite-related systems (<1 to a few ppm, respectively). Rhenium concentrations in molybdenite are highly variable on the deposit-scale. Economic concentrations of Re occur only at shallower levels in both Central Diorite and ABreccia. The Au content correlates with high-concentrations of chalcophile elements (CE). This is seen in the association of Au- minerals and Bi-(Pb)-tellurides present as inclusions in the molybdenite from diorite and is inferred from an LA-ICP-MS element map for molybdenite in granite. The FIB-SEM and TEM study show that visible telluride inclusions extend down to the nanoscale as coherent intergrowths with host molybdenite. Nanoporosity is accompanied by a whole range of structural defects and twinning. The telluride species identified include unnamed Bi4Pb7Te4S9. Analysis of stacking sequences show co-precipitation of Bi-tellurides and molybdenite under equilibrium conditions. In corroboration with EPMA data, this is the first confirmation that minerals from the aleksite series are characteristic components of the ore at Boddington. Molybdenite with high-concentration of chalcophile elements is present as the 2H polytype only, contrary to previous hypothesis that incorporation of trace elements is assisted by 3R structural modification. Instead, a new mechanism is presented in which coherent lattice-scale intergrowths between molybdenite and tellurides are reasons for the measured high CE concentrations. Knowing that Bi-(Pb)-tellurides are Au-carriers, this may also explain the observed, unusual Au-enrichment in molybdenite from Boddington. Nucleation of Au fine particles is inferred from element map correlations but further work is necessary to prove if Au nanoparticles are also present. Petrographic, mineralogical and geochemical evidence support a three-stage model for Boddington. An early porphyry event can account for the bulk of the Cu mineralisation, as well as some of the Au and Mo. A subsequent orogenic-Au event led to shearing and remobilisation of ore components. New constraints on metamorphic conditions are offered by chlorite and stannite-sphalerite geothermometry (200-420 °C) and the occurrence of two co- existing pyrrhotite species. The granite introduced some Au, Mo and other „granitic‟ elements, notably Bi leading to substantial upgrading of Au grades by Bi-melt scavenging. The study concludes however that hydrothermal activity associated with granite was not the most important concentrator of ore minerals.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2011
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Macintosh, J. N. "Age and basin evolution of the Cuddapah Supergroup, India." Thesis, 2010. http://hdl.handle.net/2440/103376.
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This item is only available electronically.U-Pb zircon geochronology indicates deposition of the Cuddapah Supergroup, Cuddapah Basin, India occurred for at least 986 million years. Deposition started after 2502±17 Ma with the deposition of the Gulcheru Formation and ended after 913±11 Ma with the deposition of the Cumbum Formation. Maximum depositional ages have been found for individual formations within the Cuddapah Supergroup; the Pulivendla Formation has a maximum deposition of 1899±19 Ma and the Bairenkonda Formation has a maximum depositional age of 1660±22 Ma. Thermal events during the Palaeoproterozoic present a possible cause of basin formation. At this early stage of the Cuddapah Basin’s evolution the provenance of sediments was the Dharwar Craton, which currently underlies the basin and borders it on the north, south and west sides. The uplift of the Eastern Ghats on the eastern margin affected the evolution of the Cuddapah Basin, changing the shape and the sediments of the basin. Uplift and deformation events in the Eastern Ghats folded the eastern side of the Cuddapah Basin and are responsible for its present crescent shape. The formation of the Eastern Ghats caused increased subsidence to the east, creating an asymmetry in the depth of the basin. The provenance of the sediments of the Cuddapah Supergroup changed to the Eastern Ghats for the deposition of the youngest stratigraphic group, the Nallamalai Group.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2010
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Saunders, P. J. "The structural evolution of the Bull Creek area, southern Adelaide fold belt, South Australia; through the integration of geological mapping and geophysical interpretation." Thesis, 1993. http://hdl.handle.net/2440/87598.
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This item is only available electronically.Integration of a high resolution aeromagnetic survey with detailed structural field data has been achieved in the Bull Creek area of the southern Adelaide Fold Belt, resulting in a comprehensive model for the structural evolution of this area. Aeromagnetic data has placed constraints upon structures mapped at the surface and has also revealed information concerning the nature of structures at depth. The successful interpretation of data is due to the good lithomagnetic marker horizons within the area. These horizons include the magnetic Barossa Complex basement and lithomagnetic units of the Adelaide Supergroup and Kanmantoo Group metasediments. The Brachina Formation, an important magnetic marker horizon of the Adelaide Supergroup, lies at depth (due to thrust related tear-faulting) beneath a magnetic cover of Backstairs Passage Formation of the Kanmantoo Group sediments. Geophysical images and contour maps reveal the location and intensity of important magnetic and radiometric anomalies which constrain the interpretation of mapped structures. Modelling of individual magnetic profiles places constraints on the depth to the top, the width, dip and susceptibility of magnetic bodies. Vertical gradient filtering enhances the edges of two dimensional sources and Automated Gains Control filtering amplifies the effects of small anomalies. A model suggesting multiple sequential thrusting has been devised for the Bull Creek area. This model incorporates a basal decollement located within the basement (4-5 km beneath the present erosion level) which has transported a sliver of basement complex to the surface where it forms a hanging wall anticline. An upper detachment has formed near the basement - cover contact within the basal unit of the Adelaidean sequence. High angle histric thrusts of an imbricate fan (or sigmoidal faults of a duplex system?) stem from this detachment fault.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1993
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Errock, C. H. "Hydrocarbon migration and mixing in four recently discovered oil fields of the southwestern Eromanga Basin." Thesis, 2005. http://hdl.handle.net/2440/93338.
Full textAbstract:
This item is only available electronically.The Cooper and Eromanga Basin is located in northeastern South Australia and southwestern Queensland. Nine samples from four fields within the SA sector of the Cooper-Eromanga Province along the southwestern Patchawarra Trough (Sellicks and Christies) and western Wooloo Trough (Worrior and Arwon) were analysed. The aromatic source and maturity cross plot of 1-MP/9-MP versus 2-MP/1-MP was used to determine the ratio of mixing between Permian- and Jurassic/Cretaceous-sourced hydrocarbon in oils. These oils from the Patchawarra Formation within the Sellicks Field has ~0.9% Rc and is a Family 2 Permian end-member, which has migrated a minimum distance of 23-24 km. This same oil contributes 60-70% of the input to the Birkhead and Hutton reservoirs in the Christies Field. The Jurassic input (~0.6% Rc) came from a Birkhead source located 15-30 km to the east. The Worrior and Arwon Fields contain mixed oils within Jurassic and Cretaceous reservoirs. Here the Permian input decreases up section (Hutton 70%, Birkhead 65%, McKinlay 60%) with the Permian Toolachee Formation and Jurassic Birkhead Formation being the likely source rocks. The minimum migration distance for the oil sourced within the Birkhead Formation is 4-5 km from the west and ~24 km from the east.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2005
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Ryan, S. J. "The geology and genesis of the polymetallic Wagga Tank prospect, Mount Hope, N.S.W." Thesis, 1987. http://hdl.handle.net/2440/105306.
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This item is only available electronically.The Wagga Tank Prospect is located in Central Western N.S. W, 125 km south of Cobar. The prospect is hosted by the Lower Devonian Mount Hope Group, a complex succession of sedimentary, felsic volcanic and comagmatic intrusive rocks representing the oldest division of the Cobar Supergroup in the Mount Hope area. The prospect is primarily a Pb and Zn deposit with minor Cu, Ag and significant Au. Gold values are highest within steeply dipping gossan shoots in the oxidised zone, while Pb and Zn values are highest in subvertical shoots of massive sulphide within the primary zone. Cu is concentrated as chalcocite, digenite and malachite at a zone of supergene enrichment. The primary mineralization occurs within a zone of intense tectonic brecciation and argillic alteration at a pronounced flexure along the steeply dipping contact between the volcaniclastic sequence and a siltstone - slate sequence. The mineralization can be divided into two categories on the basis of textural relationships, i.e. fine grained, crudely banded massive type sulphides and coarser grained vein type sulphides. The vein type sulphides are represented by varying proportions of pyrite, chalcopyrite, sphalerite and galena with rare inclusions of cubanite and pyrrhotite. The massive type sulphides show mineral abundances of pyrite>sphalerite>galena>>chalcopyri te. Fluid inclusion and chlorite data indicate that the mineralizing fluid reached temperatures of about 325°C. Sulphur isotope compositions of the sulphide minerals (delta 34S = 10 per mil) suggest that the sulphur originated from seawater SO4-2. Reduction of seawater SO4-2 to H2S was primarily by an inorganic process at elevated temperatures in a heated rock pile. Thermodynamic calculations suggest possible log f02 - pH constraints of about log f02 = -29. 5 to -31. 7 and pH = 3 to 4. 5 for the mineralizing fluid. The mineralization is considered to be of epigenetic hydrothermal origin. The hydrothermal fluid was probably derived from dewatering of the rock pile during metamorphism accompanying the major deformation. Sulphide precipitation occurred along a plane of high permeability produced by folding of adjacent beds with a contrasting competency. The prospect bears many similarities to the principal deposits in the Cobar area. Those deposits are typically narrow steeply plunging elongate bodies occurring along sheared or brecciated contacts between cleaved turbiditic siltstones and coarser clastic beds or felsic volcanics.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1987
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Jagodzinski, E. "The geology of the Gawler Range Volcanics in the Toondulya Bluff area and U-Pb dating of the Yardea Dacite at Lake Acraman." Thesis, 1985. http://hdl.handle.net/2440/86564.
Full textAbstract:
This item is only available electronically.At Toondulya Bluff a sequence of 'older' Gawler Range Volcanics dip in an easterly direction beneath the overlying Yardea Dacite, and are intruded by the comagmatic Hiltaba Granite. The volcanics occur as a series of tuffs and lava flows. Geochemical evidence suggests these volcanics are related to each other by fractional crystallisation, with plagioclase, clinopyroxene, K-feldspar and titan-magnetite, and accessory zircon and apatite controlling differentiation trends. The Si-rich Hiltaba Granite and Yardea Dacite formed from the final, highly fractionated melts. Geothermometry suggests the volcanic and granite crystallised at temperatures within the range 680deg-850degC. The initial magma from which the lithologies were derived, was formed by partial melting of a lower crustal source probably of granulitic composition. Lake Acraman is believed to have been a site of meteoritic impact in the late Proterozoic (~600 Ma ago). Fragments of dacitic ejecta have been identified within the Bunyeroo Formation, Flinders Ranges and dating of these fragments gives an age of c.1575 Ma using single zircon ion probe dating techniques (Gostin et al in prep.). U/Pb dating of the Yardea Dacite at Lake Acraman reveals it to be of comparable age to these fragments (1603-1631 Ma). The lower intercept of the discordia line reveals there has been no resetting of the U/Pb system in response to the postulated meteoritic impact.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1985
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Matthews, C. "The structural geometry of the Onkaparinga Gorge region, southern Adelaide Fold Belt, South Australia." Thesis, 1993. http://hdl.handle.net/2440/131121.
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This item is only available electronically.The Onkaparinga Gorge, situated on the Onkaparinga River southwest of Clarendon contains exposed middle Adelaidean rocks of the southern Adelaide Fold Belt. The structural geometry displayed exists as the result of a Cambro-Ordovician compressional deformation, the Delamarian Orogeny. Folds are gentle in competent strata and close to tight and west vergent in fine grained incompetent strata. The majority of faulting is thrusting oriented subparallel to bedding with one high angle thrust, the Onkaparinga Fault that crosscuts all other tectonic elements. Low angle thrusting caused the repetition of competent beds and the duplexing or imbrication of incompetent units. Total displacement calculated by the addition of all minimum displacements measured on individual thrusts is in the order of 1.8 kilometres. Strain patterns indicate that thickening of bedding has occurred in the Sturt Formation diamictite with considerable shortening and volume loss due to compaction. The style of deformation in the Belair Subgroup is one of stretching parallel to bedding. The difference in strain patterns in the two above mentioned formations suggests that there is a structural discontinuity between the Belair Subgroup and the Sturt Formation. Evidence from geological mapping and subsequent stereographic projections of field data indicates that thrusting subparallel to bedding has been the major deformational influence at the levels of the Sturt and Tapley Hill Formations with folding less influential. This evidence may support the existence of a roof thrust zone at this level but such features can also be attributed to other deformational models. Two models of tectonic evolution can explain the current structural geometry in the Onkaparinga Gorge. The first model associates the thrusting observed with fold development during compression. The second model proposes a two-part deformation of thrusting followed by folding of the thrusted strata during continued compression.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1993
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Pledge, S. J. "Tertiary and Plio-Pleistocene geomorphology and neotectonics of the Nilpena Area, western Flinders Ranges." Thesis, 2000. http://hdl.handle.net/2440/103500.
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This item is only available electronically.The Nilpena Hills are a small group of low hills extending south from the Ediacara Hills. They are detached from the main Flinders Ranges by an expansive of floodplain about twenty kilometres wide. They consist of uplifted and tilted Precambrian sediments of the Wilpena Group, in particular Pound Subgroup rocks that largely consist of quartzites and sandstones. Surfaces have been interpreted as remnant land surfaces that have been rotated due to the tilting of the Nilpena Hills. These surfaces consist of silcrete skinned cobbles and ironstone stained cobbles, as well as more recent calcrete and gypsum layers. Also in the area are lacustrine sediments. The lacustrine sediments consist of a basal limestone layer, the Nilpena Limestone, and subsequent gypsiferous clays. The age of these lacustrine sediments has been interpreted as Pleistocene and their extents has been mapped. X-ray diffraction analysis was performed on the clays to determine their composition and it was found that some of them contain glauconite. The surfaces also give an important indication of climate in the area and how it has varied from a predominantly warm and wet climate during the formation of the silcretes to a much drier climate during the formation of the ironstone stained cobbled surfaces. Faulting has also played an important part in what is a predominantly extensional area. Reactivation of ancient faults in the late Tertiary or early Quaternary has possibly served as a mechanism for the lake formation. The formation of numerous horsts and grabens in the southern region of the area has also promoted the formation of more armoured surfaces. Faulting in northern area allowed for the generation of a laterite which was subsequently overlain by sand dunes.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2000
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Wurst, T. M. "Investigation into high performance computing technologies for geophysics." Thesis, 2010. http://hdl.handle.net/2440/106283.
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This item is only available electronically.The processing of magnetotelluric (MT) data is typically carried out on a desktop computer and as a result suffers from a number of drawbacks. The time taken to process the data on the desktop computer is unacceptably long and can take approximately a month. The limited amount of random-access memory (RAM) in the desktop computer limits the length of the time series that can be used in the bounded influence remote referencing processing (BIRRP) program. Cloud computing is a new high performance computing (HPC) technology that can be accessed over the internet and has the potential to address the drawbacks presented by the desktop computer. Cloud computing reduces the cost of HPC by pooling computing resources on a large scale. Cloud computing offers on-demand resources allowing the user to use only what they need and to change the type of resources they require to suit an evolving need. To utilise the HPC capabilities of the cloud, a problem must exhibit a high degree of parallelisation. MT processing is particularly well suited to cloud computing because of its inherent ability to parallelise by the number of stations. To enable automatic utilisation of the cloud resources, workflow technology can be used in conjunction with the existing MT processing codes. This new approach to MT processing presents the opportunity to addresses other inefficiencies in the processing. As the cloud is accessible over the internet, this presents the opportunity to perform some processing in the field. The ability to process data in the field is advantageous because it allows for near instant feedback about the quality of the obtained data. This feedback can then be used by the survey team to change the survey to optimise the quality of the obtained data if required. However, to achieve this, a number of new processing techniques need to be introduced into the workflow.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2010
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Finlay, J. "Structural interpretation in the Mount Woods Inlier." Thesis, 1993. http://hdl.handle.net/2440/87305.
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This item is only available electronically.The Mount Woods Inlier (MWI) is an Early to Mid-Proterozoic terrane represented by numerous small scattered outcrops of metasediments and granitoids, located approximately 100 km southeast of Coober Pedy, north-central South Australia. Field mapping of three outcrops reveal the following deformation history: 1. D1/M1 was a high T, low P event that produced an S1 foliation defined by sillimanite, cordierite+/-almandine garnet (Flint and Benbow, 1977). 2. D2 produced folding on scales from microscopic crenulations of S1 to macroscopic folding of metasedimentary units over tens of km. Steep fold axes and variations in fold orientations throughout the MWI appeal to fold interference (i.e. re-folding), which probably occurred during the subsequent D3 shearing event. 3. D3 was a shearing (+ folding) event that produced discreet zones (100's m long) and a large scale shear zone (>7 km) in the Spire Hills-Skylark Hills area. Kinematic indicators such as Type I S-C mylonite fabrics suggest movement was predominantly strike-slip. The discrete shear zones appear to be the result of strain caused by dextral movement on the large scale shear zone. Dating of a foliated granitoid interpreted as syn-D1/M1 at ~1700 Ma and a granite interpreted as post-D2 and pre- to early-D3 at ~1580 Ma has constrained the timing of tectonism to within these dates. This deformation is synchronous with D3 of the Kimban Orogeny, The Olarian Orogeny, the Ernabellan deformation of the Musgrave Block, D1 of the Peake-Denison Inlier and deformation and metamorphism in the Karari Fault Zone.
Thesis (B.Sc.(Hons)) -- Monash University, Department of Earth Sciences, 1993
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Wurst, A. T. "Analyses of late stage, Mesoproterozoic, syn and post tectonic, magmatic events in the Moonta Sub-domain: Implications for Cu-Au mineralisation in the "Copper Triangle" of South Australia." Thesis, 1994. http://hdl.handle.net/2440/88299.
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This item is only available electronically.The Moonta-Wallaroo area has been of economic, historical and scientific importance in South Australia's history for over 130 years. The nature of mineralisation in the area has long been a point of conjecture. This study looks at the nature of ore deposition and specifically its relationship to granitoids and pegmatites in the Moonta Subdomain. Using various analytical techniques the study has shown that granitoids in the region have distinctly different petrological, textural, structural, geochemical and isotopic characteristics. Two main granitoids were·recognised as the Tickera Granite and the Arthurton Granite. Geochemical studies suggest that magmatism in the Moonta Subdomain was a continuous process in the Mesoproterozoic. The older Tickera Granite, displays syn-collisional, more I-type characteristics and syn-collisional S-type characteristics (represented by a monzonite and a tonalite respectively). The younger Arthurton Granite shows A-type, anorogenic characteristics. A temporal shift from syn-collisional to anorogenic granites suggests a tectonic control on magma generation and emplacement during this period. Trace element characteristics of the Arthurton Granite are homogeneous over a wide spatial range, is suggesting that it may be part of an extensive batholith. Geochemistry of pegmatites implies that they were late stage fractionation products, related to these granite intrusions. A study of the Tickera Granite (Point Riley-Nth Beach) revealed a dominant structural fabric which suggested the granite was intruded into a tectonic regime in which shearing was prominent. Sediments intruded by the granite suggested deposition in a shallow intracratonic rift setting, followed by polyphase deformation during orogenic activity and subsequent shearing possibly related to the enigmatic Wartakan Event. Isotopic studies highlighted differences in the petrogenetic source regions of the Tickera Granite and the Arthurton Granite. The Tickera Granite (represented by monzonite) displayed more mantle like characteristics while the Arthurton Granite (represented by granite from Arthurton and adamellite from Moonta) displayed more crustal features, highlighting its A-type nature. Studies also showed that a pegmatite from the Wheal Hughes was most like the later of these two granites. Tourmaline studies of Wheal Hughes samples implicated derivation from a metapelite and calcsilicate precursor, a common feature of most tourmaline studied in the area. This may indicate remobilisation of boron rich fluids and metals from these sediments The close association of tourmaline with the ore in the Moonta Mines region implied a common source region. A tectonic setting and model for ore deposition is proposed on the basis of the study findings. The model proposed the remobilisation of metals which were initially deposited in a ensialic rift type environment (common to other Palaeoproterozoic metalliferous terrains) by the intrusion of the Tickera Granite, during regional shearing. And further concentration of metals by subsequent intrusions of the Arthurton Granite batholith.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1994
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Nesbitt, C. D. "The structural evolution of the western frontal margin of the Adelaide Fold Belt in South Australia." Thesis, 1997. http://hdl.handle.net/2440/112939.
Full textAbstract:
This item is only available electronically.Sediments belonging to the western frontal margin of the Adelaide Fold Belt in the Southern Flinders Ranges have undergone deformation in the Delamerian Orogeny. Through continual E-W compression the, the sediments were folded and thrusted. A major decolloment was formed within the Callanna Beds at the base of the Adelaidean Sequence and a thin thrust sheet (approx. 5km) was produced. The decollement extends to the edge of the ranges, to the west of which are the relatively undeformed units of the Stuart Shelf. Within the thrust sheet, a high degree of subsidiary thrusting occurred leading to the generation of three distinct geometrical subdomains. These are a series of back thrusts near the leading edge of the thrust sheet, a series of forward thrusts to the east of the sections and a triangle zone between the two. Localised high strain areas occur along, or in the vicinity of thrusts in an otherwise low strain area. The amount of crustal shortening within this part of the fold belt is on average 4.4km. This has been largely accommodated by the thrust displacement and to a lesser extent fault bend folds, fault propagation folds and cleavage development.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1997
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Randabel, J. P. J. "The geology of the Snug Cove area, north west coast Kangaroo Island, South Australia." Thesis, 1992. http://hdl.handle.net/2440/87108.
Full textAbstract:
This item is only available electronically.On the north west coast of Kangaroo Island in the vicinity of Snug Cove a major shear - the Snug Cove Shear Zone (SCSZ) has been recognised. The Snug Cove Shear Zone trends east-west in the area but is believed to strike inland to the east. The lithologies in the area were highly foliated and recrystallised in the shear zone but are gently folded outside of it. The lithological descriptions of Daily & Milnes (1971, 1973) were used to determine the stratigraphic position of the Snug Cove rocks; they are most likely to be within the Tapanappa Formation. Flattening strains in the area were low and the strain ellipsoid was oblate to spherical - a result of high recrystallisation. Kinematic indicators indicate a top to the north sense of shear throughout the shear zone. Strain variations in the shear zone are illustrated by the presence of high strain mylonitic zones in between lenticular relatively less deformed zones and the anastomosing nature of the mylonitic foliation. The relationship between the SCSZ and the nearby West Bay Syncline is due to the reactivation of a preexisting fault such that the SCSZ is located on the normal limb of the fold and not on the overturned limb as expected. The localisation of stress to create a ductile to semi-ductile shear zone is attributed to the buttressing effect of the Gawler Craton. Regionally, more than one deformation can be proposed on the basis of foliation relationships in porphyroblast schist. D1 was folding and cleavage development; D2 was crenulation and metamorphism; D3 was shear zone development.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1992
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Gregory, C. T. "The geology and origin of sedimentary manganese from the Boolcunda, Etna and Muttabee deposits, central Flinders Ranges, South Australia." Thesis, 1988. http://hdl.handle.net/2440/105734.
Full textAbstract:
This item is only available electronically.The origin of small manganese deposits from the central Southern Flinders Ranges, has not previously been adequately discussed. The region comprising these sedimentary manganese accumulations incorporates a sinuous folded sequence of thick variegated clastic and carbonate sediments deposited within the Adelaide Geosyncline, the stratotype basin for the Adelaidean sediments delineated. Extended exposure of the craton to the west provided a dominant source of both sedimentary detritus and manganese ore constituent. Paragenesis involved leaching of manganese from this source region, transport into the aqueous system and subsequent precipitation in favourable shallow-marine environments meridionally within the Adelaide Geosyncline. Cyclic eustatic fluctuations increased potential ionic manganese concentration, with remobilization and concentration during transgressive oxygen deficient phases and oxidation and precipitation during alternate regressive more oxygenated phases. The precipitation of particulate manganese-oxides, from pre-existing particulate and dissolved manganese from an enriched reservoir, was controlled by the interactive responses of a number of features: estuarine circulation, anoxic-oxic water stratification, and sediment-water interface relationships, at specific geomorphological sites on a stable shallow-marine continental platform. Retention of the precipitated manganese resulted from rapid burial by regressive sands and silts, with little post-genetic supergene alteration of the deposit observed.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1988
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Taylor, A. D. "Structural mapping adjacent to the “Woman-in-White” amphibolite in the Olary Domain, South Australia." Thesis, 1999. http://hdl.handle.net/2440/119337.
Full textAbstract:
This item is only available electronically.A structural study of Palaeoproterozoic Willyama Supergroup rocks to the southeast of Old Boolcoomata approximately 20 kilometres north of Olary, South Australia, discloses a complex history of deformation. This includes an axial planar S1 schistosity and several intersecting locally developed subsequent planar fabrics. The main findings support previous unpublished company studies. Structural maps were produced at various scales in areas surrounding the ‘Woman-in-White’ amphibolite and all available observations were used to form a chronology of events and tectonic model for the geometric and kinematic evolution of the area. In a domain east of the 'Woman-in-White' amphibolite the S1 is parallel to the axial plane of a major isoclinal synform closing to the east. S2 is axial planar to tight to open class 2 and class 1c F2 folds that trend generally north to northeast. Regionally, and particularly in the vicinity of the 'Woman-in-White' amphibolite, a third deformation is very intensely developed generating two fabrics. The S3 schistosity is the axial planar fabric to tight to isoclinal F3 folds trending consistently east-west. The S3 fabric is also expressed as a crenulation of the S1 regional schistosity. These pre-Adelaidean structural elements are recognised as comprising the Olarian Deformation. Fold interference is present on all scales. Olarian deformation events two and three have given the flat lying western limb of the principal F1 synform a luniform, dome and basin morphology. Type 2 and type 3 interference patterns are the most common in the area mapped. The occurrence of the two interference patterns is due to the variable angle between OD2 and OD3 compressions, which is commonly approximately 40 in the west-southwest part of the mapped area. This work conforms closely in complexity to previous regional studies and has been supplemented by other new investigations of an important northeast-southwest trending shear zone corresponding to OD3, lying further to the north, and a geochemical investigation of the 'Woman-in-White' amphibolite indicating its probable mantle origin and possible emplacement before all deformations occurred.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1999
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Woodget, A. L. "The petrology, geochemistry and tectonic setting of basic volcanics on the Stuart Shelf and in the Adelaide Geosyncline, South Australia." Thesis, 1987. http://hdl.handle.net/2440/86641.
Full textAbstract:
This item is only available electronically.In 1980, von der Borch suggested that the Adelaide Geosyncline formed as a result of a rift initiated in the Late Proterozoic. In 1984, Gunn added further to the idea, and proposed that the Roopena Volcanics represented alkaline igneous activity associated with the initial doming phase. The basaltic lavas of Depot Creek, Port Pirie, Wooltana, the Adelaide Geosyncline, and the Beda Volcanics represent tholeiitic flood basalts from a later rifting stage, with the Gairdner Dyke Swarm acting as feeder dykes to the basalts. In hand specimen the volcanics look very similar, i.e. red-brown to green-grey fine vesicular basalts, but in thin section they are quite different. The Beda Volcanics are merocrystalline with an intersertal texture, the main mineral being plagioclase with small patches of subophitic augite (maximum 10%). The Gairdner Dyke Swarm rocks consist of either fine grained, curved branching augite with coarse laths of plagioclase and pehnocrysts of olivine set in an iron rich glass, or coarser grained holocrystalline ophitic rocks. The Depot Creek volvanics have a fine grained intersertal texture, consisting of potassium feldspar and recrystallised glass. The Port Pirie Volcanics are interbedded with both Calanna Group and Emeroo Subgroup sediments. The Emeroo Volcanics are intersertal fine grained rocks containing potassium feldspar and minor pyroxene set in an iron rich glassy ground mass. The Calanna Volcanics are subophitic in texture. Geochemically all the volcanics except the Port Pirie Volcanics are very similar, with the Beda Volcanics and Gairdner Dyke Swarm being the most fractionated. Magma chamber fractionation simulation studies suggest that the Gairdner Dykes were extruded from a crustal magma chamber of much greater depth, but the similar geochemistry suggests they may have stemmed from the same magma chamber as the other volcanics. Geochemical discrimination diagrams indicate the volcanics are tholeiitic continental flood basalts, and this is reinforced by using a spidergram plot developed by Pearce (1979). Comparison of these volcanics with volcanics from the central Karoo Province and northern Utah and southeastern Idaho on spidergrams show very similar trace element patterns. The basic volcanics of Depot Creek, Wooltana, and the Beda Volcanics, along with the Gairdner Dyke Swarm represent co-magmatic tholeiitic igneous activity associated with the Spencer Gulf rift. The more enriched Port Pirie volcanics were extruded at a later stage of the reactivation of the rift.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1987
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Bollenhagen, W. J. "The influence of bulk rock MnO on garnet development in metamorphic rocks of andalusite-staurolite grade; Kanmantoo, South Australia." Thesis, 1993. http://hdl.handle.net/2440/109466.
Full textAbstract:
This item is only available electronically.An outcrop of meta-pelitic schist from near the township of Kanmantoo, South Australia, was chosen to demonstrate the effect that increased bulk MnO content has on metamorphic assemblage development. From bulk composition and petrological analyses it is observed that the presence of small amounts of MnO in high XFe pelitic rocks correspond with the development of garnet. The incorporation of Mn into the KFMASH model system describes the existence of garnet with andalusite and staurolite that KFMASH does not predict. Furthermore it is shown that modal abundances of garnet are proportional to bulk MnO rock contents, enhancing the prediction that MnO causes an expansion of all garnet-bearing assemblages. This allows for the description of the numerous appearances of the garnet mineral in rocks that have calculated temperatures and pressures, for which it is not predicted to exist at.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1993
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Krneta, S. "Mineral paragenesis and alteration of the Mt. Carbine tungsten deposit far north Queensland: the late stage evolution of an S-type granite." Thesis, 2011. http://hdl.handle.net/2440/96680.
Full textAbstract:
This item is only available electronically.The Mt. Carbine tungsten deposit represents a good example of granite related sheeted vein mineralization recording the late stages of granite cooling volatile differentiation and subsequent expulsion. The presence of 3 distinct mineralizing stages has been recognized through the study of the alteration and mineral paragenesis. These observations coupled with geochemical analysis have culminated in unraveling some of the physiochemical conditions under which the deposit formed and their dynamic evolution through time. Along with gaining important insights into the formation of the deposit analyses were conducted on individual minerals from different parts of the deposit as an investigation into their possible use as geochemical vectors to mineralization through trends in trace and REE chemistry. The findings of the study indicate that the deposit formed as a result of fluid expulsions from a single magmatic event forming a distinctive high to low temperature and reduced to oxidized fluid evolution. The study also found the presence of 2 distinct alteration assemblages which although containing some lithologically induced heterogeneities appear as a alkaline distal and potassic proximal alteration. The use of mineral geochemistry as an exploration tool in many of the tested cases has proven to either be of little potential use whereas others have not been tested adequately. Wolframite Fe/Mn ratios have proven as being potentially useful as a means of delineating vertical displacement from the source of the mineralizing fluids due to the telescoped nature of the vein fill minerals.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2011
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Pewkliang, B. "The formation of opal in marine reptile bones and wood." Thesis, 2004. http://hdl.handle.net/2440/122447.
Full textAbstract:
This item is only available electronically.The age of precious opal and the mechanisms that result in formation as opposed to the ubiquitous common opal are poorly understood. Until now, there has been no research on the replacement of biominerals in vertebrate bones by opal. As the microtexture, mineralogy and chemistry of bones are well-known, they provide a unique opportunity to study the mechanism of precious opal deposition. In this article chemical and textural features of Andamooka opalised plesiosaur bones were compared with those in non-opalised ichthyosaur bones from Moon Plain and a recent dolphin bone. Opalised wood samples from Nevada and White Cliffs were also studied to compare with bone opalisation and different depositional environments (sedimentary vs volcanogenic). The cellular form of a continuous irregular framework of silica was retained in the wood samples. The mineralogy of the wood samples reflects their depositional environment, where opal-CT and opal-C is dominant in volcanic deposits (Nevada) and opal-A in sedimentary deposits (White Cliffs). Comparison of the Nevada wood to Post-Archean average shale (PAAS) shows that it is rich in most trace elements with the exception of Y and U. The high amount of trace elements is a reflection of its volcanic origin. In contrast, the opalised wood from White Cliffs is depleted in most trace elements with the exception of Co. Cracks were observed in both the opalised wood and bone samples which allowed the void space required to form precious opal. The opalised wood from White Cliffs and the opalised plesiosaur bones from Andamooka are chemically very similar and reflect similar compositions for the opalising fluids. The Haversian system was preserved in the non-opalised ichthyosaur bone but not in the opalised bones. The ichthyosaur bone is comprised mostly of carbonate-hydroxylapatite but in the opalised bones the major mineral is quartz. Modern dolphin bone consists of bioapatite with water and organic material: its trace element composition is broadly similar to the ichthyosaur bone from Moon Plain but is richer in Sr, Zn and Co. When normalized to PAAS, the ichthyosaur bone is depleted in all trace elements with the exception of Sr, which is likely a product of the carbonate-rich mineralogy. Like the ichthyosaur bones, the opalised bones are also depleted in trace elements, with the exception of Co and Zn. There is no evidence of remnant bioapatite in the opalised bone, a finding consistent with the chemical analyses that show only trace amounts of Ca and no P. The level of microstructural preservation in the opalised bone suggests that opalisation is not a closely coupled dissolution-reprecipitation reaction and that there was a fluid filled space between the reaction fronts which allowed the opal silica spheres to form and settle within a comparatively small space (100 µm). An alternative interpretation is that the fibrous quartz filled the osteon canals before opalisation and that the bioapatite was then dissolved away leaving a hollow cast that filled slowly with opal.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2004
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Fraser, G. L. "High T-low P metamorphism in the Kanappa Hill area of the Mount Lofty Ranges, S.A.; Implications for thermal evolution." Thesis, 1996. http://hdl.handle.net/2440/103515.
Full textAbstract:
This item is only available electronically.High T - low P metamorphic rocks in the Kanappa Hill area of the eastern Mt. Lofty Ranges preserve evidence for mineral equilibration during crustal thickening at temperatures marginally greater than 600°C and pressures of 3-5 kbars. Field and petrographic observations suggest that the high temperature portion of the P-T-t path experienced by these rocks was near-isobaric, with the implication that the thermal perturbation recorded by these rocks occurred in response to rapid advective heat transfer rather than to purely conductive processes. Estimation of the metamorphic fluid flux from a stable isotope study indicates that pervasive fluid flushing made no significant contribution to the thermal perturbation. Thermomechanical modelling of the response of the crust to magma emplacement predicts metamorphic conditions which closely match observations from the field, viz: (1) peak metamorphic temperatures reached during convergent orogenesis, (2) near isobaric P-T-t paths immediately before and after attainment of peak metamorphic conditions. Consequently high T - low P metamorphism in the Kanappa Hill Area is considered to have occurred in response to upper crustal emplacement of melts generated by subcrustal heat input.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1990
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Nokes, C. R. "Finite numerical modelling of stress deflections around salt diapirs in the Gulf of Mexico." Thesis, 2011. http://hdl.handle.net/2440/96686.
Full textAbstract:
This item is only available electronically.This research is focused on the Northern Gulf of Mexico Mississippi Fan Delta. Deltas have a maximum horizontal stress margin parallel (extensional stress regime) at the delta top and a margin normal maximum horizontal stress (compressional stress regime) at the delta toe (King et al., 2010). The area of the delta with intrusive salt diapirs has significantly deflected maximum horizontal stresses around the salt diapirs. This is due to the contrasting geomechanical rock properties between the salt and the deltaic sediments (Zhang, 1994). A 3D seismic survey of the area with vertical salt diapirs was provided by Western Geoco. The seismic data was interpreted for the top salt-sediment contact and diapir related deformation of the sedimentary overburden. The interpretation identified six salt diapirs: four piercing by active diapirism and two piercing by reactive diapirism. 2D finite numerical models were built from representative sections of each salt diapir to predict the principal stress deflections within the sedimentary overburden adjacent the salt. The models of the reactive diapirs deflected the maximum principal stress parallel to the salt-sediment contact of the salt diapirs. The models of the active diapirs deflected the maximum principal stress normal to the salt-sediment contact of the salt diapirs. The stress orientations allowed for borehole stability diagrams to be produced for the stress orientation above the diapir crests, over the diapir flank and over the base salt for each diapiric style.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2011
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Inkster, D. H. "Filtering aeromagnetic data to reduce the masking effect of near-surface basalt." Thesis, 1995. http://hdl.handle.net/2440/88300.
Full textAbstract:
This item is only available electronically.This project investigated two areas in northern Queensland where Tertiary basalt covers igneous and metamorphic rocks considered prospective for gold. The moderate to high magnetic susceptibility of the basalt, combined with variations in its thickness, give a high degree of variability to the aeromagnetic data which impedes interpretation of deeper structures. Low-pass filters of the Butterworth, averaging-window and median-window types were used initially, because the near-surface signals tends to be higher in spatial frequency. Upward continuation was also used. All were able to remove high frequencies but none showed a clear superiority at simultaneously resolving detail. The best results eventually were obtained from a differencing method in which the high-frequency signals were first emphasised by downward continuation and then subtracted from the original signal. This enabled identification of several features which had not been visible in either the original, or low-pass-filtered data. The differencing method is shown to be equivalent to subtracting the first vertical derivative (multiplied by a scaling factor) from the total magnetic intensity. The generality of this approach was then tested by applying it to another dataset with different sampling and geological parameters. The resolution available in the second case is limited by the 400m flight line spacing, instead of the 200m of the first dataset. The results were less successful but there is evidence that the approach is still valid.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1995
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Taylor, M. J. "The metamorphism, petrology and geochemistry of the Ooldea 2 drill core and the Lake Ifould area." Thesis, 1987. http://hdl.handle.net/2440/86565.
Full textAbstract:
This item is only available electronically.Comparison is made of petrological and geochemical features in the Ooldea 2 drill core with metasedimentary and meta-igneous outcrop at Lake Ifould, in the NW Gawler Cration. The predominant lithologies from the Lake Ifould area are granodiorite gneiss, granite gneiss and leucogneiss, all of which are intrusive in origin and Proterozoic in age. Calc-silicate outcrops as xenoliths within the leucogneiss and is possibly Archaean in age. The Lake Ifould area experienced a tight to isoclinal fold event followed by a regional deformation event which occurred after the intrusion of the granitic gneiss. The regional defamation is of variable intensity manifested by zones of low- and high-strain within the region. Geothermometry suggests temperatures of 400degC; pressures are indeterminate. Garnet gneiss outcropping 10 kilometres north of Lake Ifould indicates temperatures and pressures of 550degC and 2.5 kb from geothermometry and geobarometry estimations. Ooldea 2 drill core has peak assemblages indicating temperatures of 950-1000degC and pressures of 8-10 kb. Preservation of these high-pressure and high-temperature assemblages indicates isobaric cooling of the Ooldea 2 assemblages has occurred over an extensive period of time. Chemical similarity of the Lake Ifould meta-intrusives to the Donnington Granitoid Suite of the Lincoln Complex suggests tentative correlation. By contrast, the Ooldea 2 metasediments are most similar to the Mt Christie banded iron formation suggesting classification as Mulgathing Complex. The garnet gneiss is most geochemically similar to the Carnot Gneiss which also suggests correlation with the Mulgathing Complex. The garnet gneiss possibly represents the country rock of the Lake Ifould intrusives. The Archaean basement and the Proterozoic basement are most likely to be separated by a fault. This would explain the contrasting pressure-temperature conditions from the different areas; uplift from a relatively shallow depth in the Lake Ifould area and differential uplift of the Ooldea metasediments after isobaric cooling at great crustal depth.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1987
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Robertson, B. D. "The geology, petrology and geochemistry of the volcanics in the Kokatha Region, Gawler Ranges, South Australia." Thesis, 1989. http://hdl.handle.net/2440/128628.
Full textAbstract:
This item is only available electronically.Volcanics in the Kokatha region present a wider range of rock types than in other areas of the Gawler Ranges. High temperature Mg rich basalt flows through to rhyolite ignimbrites and air fall tuffs outcrop. Two magmatic cycles are observed with a cycle consisting of initial basalts, followed by voluminous dacites and rhyodacites. The final phase of the cycle following the rhydacites represents a period of more explosive activity resulting in the deposition of rhyolitic ignimbrites, air fall tuffs rhyolitic flows and pyroclastics. Geochemical data indicate both fractionation and mixing of fractionated components were active igneous processes resulting in the formation of layered magma chambers. The layering of the magma chambers being well illustrated in the stratigraphy of the volcanic pile. Further evidence for cyclic fractionation trends exists, with a relative depletion of incompatible elements in the second cycle when compared to the first cycle. Discrimination diagrams plot the rocks from Kokatha in the calc-alkaline field. Calc-alkaline series usually indicate subduction processes however volcanism at Kokatha is intracratonic. Rb-Sr data give an isochron age of 1588.4 ± 14 Ma suggesting the rocks from Kokatha are a part of the lower sequence of the Gawler Range Volcanics. Samples from both cycles produce the isochron indicating a melt from a homogeneous source. Neodymium data suggest a basaltic input from the mantle assimilating with lower crust is a likely source. A possible tectonic model for volcanism is presented. Initially a flux of mantle-derived basalt enters the lower crust. This provides heat for large scale melting. Assimilation of lower crustal melts and mantle-derived basalts may or may not occur however a homogeneous source is formed. Diapirism resulting in upper crustal magma chambers allows the formation of a layered magma chamber. Eruption of the magma results in the stratigraphic sequence of volcanic rock units.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1989
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Wittwer, P. D. "Geology and geochemistry of regolith carbonate accumulations of the southwestern Curnamona Province, SA: Implications for mineral exploration." Thesis, 2004. http://hdl.handle.net/2440/123526.
Full textAbstract:
This item is only available electronically.Although regolith carbonate accumulations (RCAs) have been extensively used in mineral exploration programs in the regolith-dominated terrains of the Yilgarn and Gawler Cratons, their use has so far been limited within the Curnamona Province, SA. This study shows how the detailed characterisation of RCAs in the southwestern Curnamona Province enhances their use in mineral exploration programs at the regional to prospect scales. A regional RCA distribution map for the study area shows that RCAs are generally widespread, although certain RCA morphological facies are dominant in different parts of the landscape, and in some areas RCAs are absent or at best a very minor component of the regolith. A dataset of whole rock geochemical assays of RCAs provides the basis of graphical presentations and geochemical maps that highlight the chemical characteristics of RCAs proximal to areas of known Au mineralisation in contrast to more distal samples. Several Au pathfinder elements in RCA assays were found to include As, W, Bi, and Mo, and greatly assist in further anomaly definition when used in conjunction with Au assays. Major element composition (e.g. Ca, Mg, Fe) showed little relationship to local landform setting, however, landscape setting appears to be a more important control on Au assay results both at the regional and prospect scales. Gold distribution in the area was independent of the presence of major elements such as calcium and magnesium. Microprobe analysis showed that Au was rare and invisible at the resolution of the analysis and existed in the calcium carbonate matrix as well as in detrital material. The composition of the underlying rock lithologies was also compared to the whole rock chemistry of the RCAs and showed the possibilities of this technique to aid geological mapping in regolith-dominated terrains and to assist in locating mineralised systems.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2004
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Barrett, L. "The structural geology of the Rapid BaySecond Valley area, Fleurieu Peninsula, South Australia." Thesis, 1995. http://hdl.handle.net/2440/128629.
Full textAbstract:
This item is only available electronically.Whilst the geology of the Rapid Bay-Second Valley area is known to be both structurally and stratigraphically complex, previous workers (Daily, 1963; Evans 1987; Drayton, 1963; Campana and Wilson, 1955) have been unable to agree on many aspects of the area. Neoproterozoic and Cambrian aged sediments were first deposited in an extensional basin, which was formed due to lithospheric thinning, and associated subsidence (Jenkins, 1986, 1990). These rocks have then been subjected to at least one phase of deformation, the Cambro-Ordovician Delamerian Orogeny (Offler & Fleming, 1968; Thompson, 1970). Listric extensional faults were formed both before and during sedimentation of the rocks, which has created narrow zones of weakness that the subsequent compressional event has exploited, creating thrust faults (Flottman et al., 1994). Structural mapping of the area has revealed that it is transected by two thrust faults and is intensely folded in places. Structural data has been collected during eight weeks of field work and has been compiled into a 1:10 000-scale geological map which accurately represents the area. A computer-generated three-dimensional model has been created for the area, based on this map, and cross and profile sections constructed from the data collected. The model was constructed using Vulcan™ software. Strain analysis has also been conducted on many of the folds in the area.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1995
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Macdonald, P. J. "The structural geology of the western margin of the Entia Dome, Harts Range, eastern Arunta Inlier." Thesis, 1986. http://hdl.handle.net/2440/131615.
Full textAbstract:
This item is only available electronically.The study area is located within the eastern Harts Ranges, approximately 150 km ENE of Alice Springs in the Proterozoic Arunta Inlier, central Australia. Detailed geological mapping at a scale of 1:12 500 has included lithologies of the Entia Gneiss Complex within the Entia Dome, the Irindina supracrustal assemblage and the Bruna Gneiss (terminology after Ding and James, 1985). The 'basement' lithologies of the Entia Gneiss Complex have undergone at least three repeated, generally isoclinal, recumbent folding events and peak (upper amphibolite facies) metamorphism prior to intrusion of the Bruna Gneiss. The metapelitic lithologies of the Irindina supracrustal assemblage ('cover') have been subject to at least one isoclinal folding event prior to its juxtaposition with the 'basement'. Emphasis is on the Bruna Gneiss, interpreted as a variably mylonitised orthogneiss that was emplaced along a wide ductile shear zone that separated the 'cover' and 'basement'. This study subdivides the Bruna Gneiss into two lithologies on the basis of field and microstructural observations and strain analysis: the structurally lower granitic gneiss and the overlying (much thinner) megacrystic gneiss. The megacrystic gneiss, previously described as mylonite derived from the granitic gneiss, is interpreted as having been intruded independently from the bulk of the Bruna (ie granitic) Gneiss, and has undergone less complex deformation relative to the granitic gneiss.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1986
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Oertel, A. G. "Magnetotelluric survey of the Central Australian Craton, with a focus on the structural history of the Warumpi and Musgrave Provinces and the Arunta Complex." Thesis, 2013. http://hdl.handle.net/2440/106295.
Full textAbstract:
This item is only available electronically.In spite of the continent of Australia being the oldest and most tectonically stable on Earth, its structural history is still the subject of much conjecture. The final closure of the South Australian Craton with the North Australian Craton at roughly 1080 million years ago deformed much of Central Australia into the lithospheric arrangement observed today. Structural constraints have been developed in the last 30 years on the history of the Musgrave Province, Amadeus Basin, Warumpi Province and Arunta Complex in the southern part of the Northern Territory. In this study the resistivity structure of these four provinces was assessed through the use of a long-period magnetotelluric survey along the Stuart Highway from the South Australia-Northern Territory border to 90 kilometres north of Alice Springs. A key focus was to determine whether the structural arrangement, identified in a magnetotelluric survey conducted 100 kilometres to the east of this profile in 2006, is laterally consistent between the four provinces. In the Stuart Highway profile model the major structures present exhibit a different arrangement, particularly in the northern part of the profile, resulting in the conclusion that the mechanism for the lithospheric closure of the region was a more complex nature than was previously thought.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2013
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Prohoroff, A. "Structural and Metamorphic Conditions of the Lower Burra Group and Callana Group at Arkaroola, Northern Flinders Ranges." Thesis, 2013. http://hdl.handle.net/2440/106297.
Full textAbstract:
This item is only available electronically.The lowermost Adelaidean sequences exposed to the immediate north of Arkaroola are unusual as they exhibit a localised complexity of deformation and elevated metamorphic grade that is not observed elsewhere in the Adelaide Fold Belt. Deformation and metamorphism in Arkaroola is thought to have formed as part of the Delamerian Orogen approximately 515-490 Ma. The timing of deformation and metamorphism however is poorly constrained in this area. This paper aims to discuss the structural and metamorphic conditions in the area to determine if there was a possibility of a pre or post-Delamerian structural and/or thermal event. A section was mapped to the North-East of the Arkaroola Homestead to gain an insight into the structural and metamorphic conditions of the area. Samples were collected from the field and used for microstructural analysis. An Electron Microprobe, Laser Ablation Inductively Coupled Plasma Mass Spectrometer and an XRF spectrometer were used for geochemical analysis on the samples. Structural and stratigraphic observations combined with microstructural analysis of samples from the field helped the author create an interpreted geological history of the area. Graben formation accommodated an initial period of sediment deposition followed by basalt extrusion. Several phases of localised rifting and deposition followed this initial deposition period due to changing fault geometries. A mineral fabric that occurs parallel to bedding is seen throughout the study area. This fabric is overgrown and included in prominent cordierite porphyroblasts that formed during peak metamorphism of ≥500 °C at a pressure of approximately ~1.30kbars. These pressure and temperature conditions were primarily due to the burial beneath a thick cover of sediments. A number of faults trending in a NE-SW direction have been identified as splays from the Paralana fault system. The strike-slip movement of the Paralana Fault along with the high heat producing basement of the Mount Painter Inlier has controlled the localised structural complexity and elevated metamorphic grade in the Arkaroola area.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2013
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Schneider, A. N. "Protolith age and role in tectonic significance of the Eastern Ghats Domain, east India." Thesis, 2010. http://hdl.handle.net/2440/106235.
Full textAbstract:
This item is only available electronically.U/Pb age analyses were conducted on detrital zircons from Khondalites in the Eastern Ghats Belt (EGB) in eastern peninsular India. This study was aimed at determining detrital ages to help understand the nature of the protolith to the metasedimentary rocks. These khondalite terrains make up the most extensive terrains in the EGB yet they are poorly understood. They are important because they help constrain timing of tectonism in the Mesoproterozoic and the formation of Rodinia and Eastern Gondwana. There were very few detrital zircons in the samples collected from the EGB and age analyses could not be made from them. Metamorphic ages were recorded from metamorphic/metamorphically recrystallised zircons. The age of metamorphism recorded in these zircons is approximately 900 Ma. This age agrees with metamorphic ages predicted from previous studies. This metamorphism is a result of the collisional orogeny that amalgamated eastern India with eastern Antarctica in the Mesoproterozoic. A Pan-African overprint has been recorded in the zircon ages which range from 660-560 Ma. These are predicted to be from lead loss due to metamorphism and can be seen on the concordia plots for U/Pb age data.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2010
35
Sanso, C. A. R. "Compositional controls on the thermal conductivity of metamorphic rocks." Thesis, 2019. https://hdl.handle.net/2440/137031.
Full textAbstract:
This item is only available electronically.Thermal conductivity is essential for determining heat flow within the Earth, which is necessary for geothermal investigations, accurately modelling tectonic and volcanic processes, and predicting petroleum maturation. Although, currently, conductivity can be measured on hand samples it can be impracticable to make regional and subsurface models due to time and expense required. In this study, an analysis of the compositional controls on thermal conductivity of metamorphic rocks is completed. Thermal conductivity was determined using an optical thermal scanner on 168 metamorphic samples for which there are prior major oxide element analyses. Density is determined through models, as well as measured using Archimedes’ principle. The results show that thermal conductivity varies between 1.698 to 5.226 W m−1 K−1. When observing the relationships there is no trend between thermal conductivity and the major oxides. However, anisotropy has a log normal distribution with a mean of -2.098 and a standard deviation of 1.346 and produces a weak negative correlation with conductivity of -0.566. A correlation exists between SiO2 and K2O where a maximum anisotropy potential peaks between 60% to 65%, and approximately 5%, respectively. The modelled density is successful in determining the measured density, allowing the density for future samples to be determined indirectly. From the results of the study, more consideration needs to be taken in the future when observing the compositional controls for metamorphic rocks. A narrower range of rock types or chemistry could be considered, along with the mineralogy of the samples. Singular provinces should also be considered to determine if conductivity for metamorphic rocks occurs regionally. Furthermore, a focused study on how the P-T conditions of a singular rock type change with thermal conductivity could be undertaken. Such analyses will improve estimates of subsurface conductivity and the ability to accurately estimate crustal temperatures.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2019
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Williams, T. "Mineralogy and trace element variations in Cu-(Fe) sulphides of the Munda Resource, Prominent Hill: application for mine scale exploration and ore genesis." Thesis, 2011. http://hdl.handle.net/2440/97939.
Full textAbstract:
This item is only available electronically.The Prominent Hill Iron-Oxide Copper-Gold deposit is situated on the southern margin of the Mount Woods Inlier, South Australia. The western Munda Au ± Cu resource is an extensional ore body governed by a subvertical, N-dipping, E-W-striking terrane-boundary. Since its discovery, debate has been focused on the distribution of principal ore components throughout the deposit, with Munda containing endowments of Au not present elsewhere at Prominent Hill. The present study attempts to unravel a complex history of source-fluid chemistry from trace/minor element concentrations in bornite-chalcocite determined by in situ laser-ablation ICP mass spectroscopy (LA-ICP-MS). One goal of the work was to establish if distinctions could be made between the mineralogy and textures present in the high-grade Munda gold resource with those elsewhere in the deposit. By integrating microscopy and electron probe microanalysis with the minor element geochemistry it has been determined that formation of purple bornite predates steely hematite alteration and thus represents stage I of mineralisation. The LA-ICP-MS data shows important concentrations of Au (up to 12 ppm) reside in purple bornite in solid solution or as submicroscopic inclusions. Experimental data also suggest gold saturation occurred at temperatures <400°C. Concentrations of >1 wt.% Se and Pb, 3208 ppm Te, 974 ppm Bi and 114 Ag have also been documented. Exsolution of clausthalite (PbSe) from purple bornite provides textural evidence for simultaneous deposition favouring a single fluid for the input of exotic elements (i.e. Pb and Se) and metal elements (Au and Ag). Two principal sequences are constrained by textural analysis. Sequence (1a) Type-A purple bornite to Type-B purple bornite to chalcopyrite illustrates the remobilisation of Cu and crystal lattice-bound Au from mineral-fluid interaction via dissolution. Alternatively sequence (2a) purple bornite to blue chalcocite to white chalcocite shows proximal-to-breccia Cu enrichment via coupled dissolution-reprecipitation reactions (stage II). Microprobe data show that significant fluorine concentrations (0.36 a.p.f.u; total negative charge of 22) are present in Munda sericite and suggest alkali-fluoride complexes have played a role in ore transportation and formation, as well as the development of pervasive sericitization in hydrothermal alteration profiles. Concentrations of Ag in chalcocite show promise for distal-to-source vectoring and suggest grey chalcocite formed during stage III. Investigations on gold mineralogy show two assemblages are present; native gold forms with chalcopyriteloellingite and occurs with various Co-Ni-Fe-arsenides, bismuth, Y-bearing coffinite and coffinite. In addition three phases in the system Au-Cu are identified; symplectic intergrowths of unnamed Au3Cu and Au9Cu form an assemblage with chalcocite and minor bornite, and tetra-auricupride (AuCu) forms homogeneous grains. All three phases rarely occur in nature and have implication for a S-deficient ore forming system.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2011
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Shearer, A. "The application of ground based and airborne radiometric methods to aid geological mapping in the Olary Province, South Australia." Thesis, 1999. http://hdl.handle.net/2440/112811.
Full textAbstract:
This item is only available electronically.The Late Palaeoproterozoic Olary Domain, in the east of South Australia, has been extensively surveyed using airborne geophysical methods, including 256 channel radiometries. This detailed data set over outcropping areas is potentially a valuable aid to geological mapping. Ground-based radiometric data was obtained along profiles through the eastern Weekeroo Inlier and Ninnerie Hill areas in order to relate radioelement concentrations to lithological units. The Weekeroo Inlier traverse sampled all stratigraphic units present in the Olary Domain. The Ninnerie Hill traverse sampled Early Mesoproterozoic granitoids, migmatites and host metasediments. Two acquisition styles were attempted when collecting the ground-based data, with continuous recording to provide results that better replicate the airborne data than discrete sampling. The discrete sampling method was found to be heavily influenced by single point anomalies and not representative of the lithological average. Relative peaks and troughs on all three channels and total count data correspond well between the ground and airborne data. Correlation between the airborne data and the ground-based data was best for the K channel. For the Th channel the ground-based data was similar to the airborne data in wavelength and amplitude but was bulk shifted below the airborne data. The U channel data from the ground-based data detected the same anomalies as the airborne data but was an order of magnitude higher. The differences between the airborne and ground-based data could be due to errors in the calibration process that was performed for part of this project or due to the time difference in acquisition of the ground based and airborne data. Comparison of ground-based data with the geology of the survey areas revealed that radiometric data can provide useful lithological discrimination. Within the survey area some differences between metasediments, intrusive lithologies, and alteration types are determinable. The radiometric data can successfully differentiate between potasic and sodic granites. The low levels in all three measured radioelement channels can reflect occurrences of amphibolites. The data discriminates between pelites and psammites in that the pelites contain significantly higher levels of K, the difference between levels of Th and U are less extreme but are still discernable. As well as providing a mapping tool on the lithology scale, the interpretation of radiometric data can resolve sub-lithology scale variations.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1999
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Sawley, P. "Supergene gold transformation: secondary and nano-particulate gold from northern Finland." Thesis, 2014. http://hdl.handle.net/2440/110562.
Full textAbstract:
This item is only available electronically.The transformation of gold (Au) in many supergene environments is driven by (bio)geochemical processes. This study assesses the link between surface morphologies of Au grains and supergene transformation processes in arctic settings. Gold grains were collected from nine sites across two localities in northern Finland, i.e., Ivalojoki and Lemmenjoki. Sites were chosen based on contrasting elevations and settings, from glacial till to alluvial. Gold grains were studied using field emission scanning electron microscopy (FEG-SEM), focused ion beam-scanning electron microscopy (FIB-SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDXS), and electron microprobe analyses (EPMA). Gold grains from all sites displayed supergene transformation features, i.e., morphotypes indicative of Au and Ag dissolution, as well as Au aggregation. The latter included a variety of secondary Au morphotypes, such as nano-particles and µ-crystals, sheet-like Au and branched Au networks. Dissolution features on grains from high organic matter environments suggest fulvic and humic acids are important contributors in the transformation of Au. Secondary Au occurs as part of the polymorphic layer. In addition to the secondary Au, the polymorphic layer consists of active microbial biofilms, organic matter and biominerals suggestive of remnant biofilms, as well as aluminosilicates, iron-sulfides and oxides. Bacterial cells and putative fungal hyphae were closely associated with Au nano-particles, suggesting that Au biomineralisation is an important factor in the transformation of Au. In conclusion, surface morphologies of Au grains from Finland are the result of supergene (bio)geochemical transformations occurring in the arctic environment.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2014
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Tylkowski, L. N. "Origin and genesis of calcrete in the Murray Basin." Thesis, 2004. http://hdl.handle.net/2440/123592.
Full textAbstract:
This item is only available electronically.Calcretes and other terrestrial carbonate accumulations have formed throughout the Murray Basin during the Quaternary, particularly in far western regions. Ooids and grain coatings of CaCO3 by infiltrating carbonate saturated solutions indicate calcrete has formed through pedogenic processes. Based on different morphologies and spatial relationships calcretes historically have been identified as either the younger Bakara or older Ripon Calcrete. The congruence of different stratigraphic calcretes, particularly the Bakara and Ripon Calcretes, was shown by clay mineralogy and the ratio of immobile elements. Three distinct sedimentological units were differentiated through zircon/rutile ratios of the heavy mineral fraction (>2.9 g/cm3); the underlying Blanchetown Clay and two differing aeolian units including the Woorinen Formation. The strontium isotope signature in all of the calcretes and carbonate material in the profile is believed to be due to an aeolian source from a marine environment. A model of calcrete development was constructed that incorporated illuviation of carbonate saturated solutions and other pedogenic processes synchronous with an aeolian deposition of highly calcareous material.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2004
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Rugari, J. "Monitoring of coal seam gas depressurisation using geophysical methods." Thesis, 2013. http://hdl.handle.net/2440/106457.
Full textAbstract:
This item is only available electronically.Coal seam gas has emerged as a major industry in Australia over little more than a decade. Resource production inevitably relies on the extraction of groundwater from coal seams to depressurise coal measures, and allow natural gas flow. Current groundwater monitoring of a coal seam gas project uses expensive borehole sampling programs that can only provide point information, and improved monitoring of water extraction is suggested for existing and future wells. This paper is a first stage feasibility study for surface magnetotelluric, and surface self-potential monitoring of a coal seam gas depressurisation event. The monitoring techniques used in this study directly measure fluid connectivity and dynamics to estimate the degree of porosity and permeability in a coal seam. In combination, the monitoring can provide both large scale and localised sub-surface fluid-flow modelling potential. The processes and its equipment are a practical, inexpensive and mobile solution for the expanding coal seam gas industry. In this study synthetic modelling has been used with coal seam conditions, prototype self-potential monitoring equipment is constructed, and various monitoring equipment are tested in the field. Synthetic modelling has provided encouraging results, showing that a depressurisation event based in a Surat Basin Walloon Measures, southern Queensland, Australia geological model could be successfully monitored using magnetotelluric and self-potential methods. The prototype self-potential logger operated with a high level of precision, successfully mapping localised electrodes change of electric field at an aquifer pump test site; and the E-Logger instrument successfully recorded electric field data for magnetotelluric monitoring. Overall, results present a great deal of potential for the combined effectiveness of magnetotelluric and self-potential monitoring methods in a coal seam gas depressurisation setting. Further studies, in particularly on-site depressurisation monitoring testing, is required to draw on more conclusive evidence.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2013
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Reid, B. A. "Structural, geochronological and tectonic evolution of the central Eastern Ghats Province, India: Araku-Anantagiri-Visakhapatnam." Thesis, 2010. http://hdl.handle.net/2440/102762.
Full textAbstract:
This item is only available electronically.The central Eastern Ghats Province is part of a series of terranes that collectively form the Eastern Ghats in India. The Eastern Ghats is a Mesoproterozoic to early Neoproterozoic orogen associated with the formation of the supercontinent Rodinia, c. 1.1 to 0.95 Ga. The central Eastern Ghats Province consists of metaquartzites and metapelites (khondalites) that are intruded by granitoids. The location of proto-India within Rodinia is disputed because of recently presented palaeomagnetic data. This has generated confusion about whether the protoliths to the Eastern Ghats Province metasedimentary rocks were deposited adjacent to proto-India or as an exotic terrane later accreted to India. U-Pb geochronology, in conjunction with Hf isotopes of zircons, constrain the maximum depositional age, determine provenance and identify the location of deposition. A maximum depositional age of 1.14 Ga on the protoliths to the khondalites has been determined from U-Pb zircon geochronology. The short period of time between deposition and the orogenesis related thermal event indicates that the sediments were deposited adjacent to the Bastar Craton. Provenance work identifies a number of sources within India and east Antarctica lending support to the theory that these continents were contiguous prior to the Eastern Ghats Orogeny. Structural transects and mapping reveals that shortening associated with the collision of east Antarctica and proto-India occurred along a NE-SW trending axis.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2010
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Pointon, V. J. "Structure and thermochronology of an E-W profile through the Mount Painter Province, Northern Flinders Ranges, South Australia: is this a southern example of deformation and exhumation driven by the Alice Springs Orogeny?" Thesis, 2010. http://hdl.handle.net/2440/88635.
Full textAbstract:
This item is only available electronically.The Mount Painter Province in the Northern Flinders Ranges, South Australia is composed of Palaeoproterozoic to Mesoproterozoic basement overlain by 7-12 kilometres of Neoproterozoic to Cambrian sedimentary rocks and is associated with high lateral geothermal gradients. During the Early Paleozoic, deformation and metamorphism reached greenschist to amphibolite facies during the ~500 Ma Delamerian Orogeny. This study focuses on the subsequent thermal history of the area by studying an E-W profile through the Mount Painter Province using the widely used techniques of structural mapping, micro-structural analysis and 40Ar/39Ar thermochronology to characterise and date deformation and cooling (as a proxy for exhumation). The E-W trending profile, known as the Hamilton Fault, is south dipping oblique slip with a normal and dextral component overprinted by younger brittle structures and brecciation which is seen in the structural and micro-structural analysis.. It is proposed to have a very active past and there is evidence of movement in the Adelaidean due to an apparent formation offset of ~600 m. The regional context of the Hamilton Fault having a dextral and normal component suggests an ε3 uplift, an ε2 extension SW to NE and ε1 NW-SE shortening. This is similar in character to the N-S shortening which is seen in the Alice Springs Orogeny (ASO). Results from the 40Ar/39Ar thermochronology show the basement metasedimentary rocks have cooling ages of around ~350 Ma between 300 to 400 °C and 312 Ma at 150 °C. Interestingly, the younger Adelaidean metasedimentary rocks have an older cooling age of 390 Ma between 300 to 400 °C. The thermochronology data suggests differential cooling has occurred. The observations suggest that exhumation is driven following the Delamerian folding event and forced the earlier cooling of shallower samples at a slower rate and later cooling of the deeper samples at a faster rate, a process caused by differential tilting. The cooling paths are well represented in this example as shown by converging cooling paths. Overall I attribute this subsequent thermal history and structural similarity to the ASO, a major widespread dramatic orogenic event which has not been widely recognized as a significant tectonic event in the Adelaide Fold Belt.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2010
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McDonald, G. D. "The petrology and timing of the Anabama Granite and associated igneous activity, Olary Region, SA." Thesis, 1992. http://hdl.handle.net/2440/122489.
Full textAbstract:
This item is only available electronically.Two ideologies of thought exist when models of granite genesis are considered. Do they represent the products of direct fractionation of a basaltic mantle melt, or, do they form in accordance with the restite model of White and Chappell (1977)? Assimilation and fractional crystallization (AFC) modelling of Nd - and Sr - isotopic data from the Anabama Granite, of this study, and data from the granites of the southern Adelaide Fold Belt, Antarctica and the Lachlan Fold Belt of New South Wales, all of approximately the same age, appears to reflect mixed sources with components derived both from an average Delamerian basalt composition and an average Archean crust composition. Results indicate that the Anabama Granite mostly represents primitive Delamerian basalt, contaminated by 12- 14 % Archean crustal material. Field relationships of the Anabama Granite indicate that it was the site of multiple magmatic intrusions, between approximately 490- 425 Ma. These intrusions are represented by several episodes of hydrothermal alteration and crosscutting dykes. A long-lived thermal source, not represented in the southern Adelaide Fold Belt, may be responsible for this ongoing magmatic activity. Examples of these dykes are the lamprophyre dyke, dated at 457 ± 18 Ma, which is similar in composition and appearance to the lamprophyres near Truro (South Australia) and the dacite porphyry dyke which crosscuts all other lithologies and was dated at 425 ± 13Ma. This age corresponds to the onset of thermal activity in the Lachlan Fold Belt, and therefore, leads to the suggestion that the region where the Anabama Granite outcrops may represent the western margin of the thermal perturbation responsible for the production of granitic melts in the Lachlan Fold Belt at around 400 Ma. Differences in source regions for the Anabama Granite, the granites of Antarctica and those of the Lachlan Fold Belt are recognized by the different Nd- and Sr - isotopic ratios, although all granites may represent the same process of formation, that being AFC. The dacite porphyry's isotopic signature indicates a more primitive source than that suggested for the Anabama Granite, and therefore its genesis does not represent a remelting of the Anabama Granite or of its source region. Geochemically, the Anabama Granite is similar to the Reedy Creek Granodiorite of the southern Adelaide Fold Belt and the Wanda Granodiorite of western Victoria. It can also be classified as an I-type granite using the criteria established by Chappell and White (1974). Geophysical gravity modelling of the Anabama Granite was carried out and it was found that the granite extends to a depth of approximately 15 km and dips uniformly to the north west. Thus giving an indication that fracture propagation, rather than plutonism, is the mechanism of granitic melt transport through the upper crust for the Anabama Granite and granites of the southern Adelaide Fold Belt.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1992
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Conway, D. J. "A numerical study on the distortion of magnetotelluric data from topography, near-surface conductors and basins." Thesis, 2013. http://hdl.handle.net/2440/100070.
Full textAbstract:
This item is only available electronically.Magnetotelluric (MT) data may be distorted by a variety of structures, including near-surface inhomogeneities, topographic gradients and large conductive bodies. A synthetic study is undertaken to analyse these three factors in the Curnamona Province, South Australia. Firstly, the effect of topography in the northern Flinders Ranges is investigated by the use of forward models. The results show both a galvanic and an inductive distortion concentrated at high topographic gradients. The effect of near-surface conductors is also investigated with forward models, using data from Lake Frome as input. The models show a small area of galvanic distortion around the circumference of the lake, but no regional effect. These results are compared with distortion analyses of real data. Finally, thin-sheet modelling is used to determine the effect of a synthetically calculated conductance using data from the eastern Arrowie Basin. Results from the thin-sheet model show that the Arrowie Basin has the potential to inductively distort MT data on a regional scale. Using this result as motivation, two three-dimensional (3-D) inversions are undertaken on the Geoscience Australia "08GA-C1 MT" line; one incorporating the Arrowie Basin as a prior model and the other starting from a homogeneous half-space. The results of these inversions are overlain with interpretations from seismic data collected along the same line. The best agreement between the seismic and MT data is achieved with the prior-model inversion, supporting the hypothesis that basin scale conductivity structures distorts MT data and showing that this effect is alleviated by incorporating basin structure as a prior model during inversion.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2013
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Meria, D. W. "Characterisation of gold mineralisation, Oberon prospect, Tanami region, N.T." Thesis, 2011. http://hdl.handle.net/2440/96685.
Full textAbstract:
This item is only available electronically.Oberon is a relatively recently discovered gold prospect in the Tanami district approximately 600 km NW of Alice Springs, N.T. Petrographic, mineralogical and mineral chemical analysis of the gold-bearing horizons in drillhole TID0065 has characterized the mineralisation with particular emphasis on gold distribution. Two mineralised horizons are identified. The ‘Upper’ zone contains semi-massive pyrite within a characteristic ‘Boudin Chert’ lithology and adjacent graphite schists. The ‘main’ mineralisation, towards the bottom of the drillhole, occurs within relatively low-sulphide calcareous turbidites of the ‘Puck’ sequence. The mineralogy of the gold mineralisation is simple. Arsenopyrite, pyrite and pyrrhotite are the dominant sulphides and occur both within multiple generations of quartz-carbonate veins and as disseminations in adjacent wallrock. There is widespread evidence for late sulphide recrystallization. Gold occurs as native gold. A population of fine-grained gold (1-10 microns) is seen within arsenopyrite, and more rarely in pyrite. ‘Exotic’ Au-bearing minerals such as Au-(Ag)-tellurides are not present. Laser-Ablation ICPMS analysis has established that invisible gold in sulphides plays a negligible role in terms of overall gold balance. ‘Residual’ gold concentrations in the central parts of arsenopyrite grains are no more than a few ppm; Au concentrations in pyrite are an order of magnitude lower still. There is, however, a marked enrichment in Au concentrations around the margins of arsenopyrite and in areas of intense fracturing and brecciation, with individual LA-ICPMS spot analyses giving up to several thousand ppm. This enrichment can be readily linked to grain-scale gold remobilization and reconcentration of lattice-bound gold during sulphide recrystallization. Using high-resolution Focussed Ion Beam-SEM imaging, this gold is revealed to occur as microfracture fillings and as fine particles and nanoparticles. This study is the first to demonstrate the presence of gold nanoparticles in an orogenic gold deposit. The Oberon deposit is metamorphosed at middle greenschist facies and displays both lithological and structural control. Mineralisation at Oberon shows broad similarities with that at Callie, but also a number of differences. Pyrite chemistry in the ‘Upper’ mineralisation is subtly different to that in the ‘Main’ mineralised level, leading to the conclusion that the former may represent authigenic (bacterially-mediated?) pyrite that formed in a euxenic or oxygen-starved environment. Such carbon- and iron-rich horizons provide a ready mechanism for gold precipitation from fluid via redox reaction. This contrasts with the clearly hydrothermal sulphide assemblage and associated chlorite alteration in the ‘main’ mineralised zone.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2011
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Blades, Morgan. "The age and origin of the western Ethiopian Shield." Thesis, 2013. http://hdl.handle.net/2440/83744.
Full textAbstract:
This item is only available electronically.Western Ethiopia is made up of a range of supra-crustal and plutonic rocks. The Precambrian exposures of the Western Ethiopian Shield are positioned within the juvenile Neoproterozoic crust of the Arabian Nubian Shield and the older, predominately gneissic Mozambique Belt (Woldemichael et al. 2010). The age and origin of the Western Ethiopian Shield are still largely unidentified. The aim of this paper is to constrain the age and origin of the sedimentary and igneous rocks within the Western Ethiopian Shield. This will be done using isotopic techniques. The detrital zircons have been analysed for U-Pb age (yielding maximum depositional ages and age provenance information) and Hf isotopes (to investigate the nature of zircons). Geochemical analysis on the Thermal Ionisation Mass Spectrometer (TIMS), Inductively Coupled Plasma Mass Spectromentry (ICP-MS) and microprobe has also been undertaken. One of the focuses is the examination of the volcanic and volcaniclastic successions, as well as, the geochemical nature of the ultra-mafic bodies in the Shield. The geochemistry of metavolcanic and meta-volcaniclastic data suggest that the origin of the volcanics formed in an arc-like setting. Relatively low niobium; however, suggest that the mantle source may have been more enriched than that seen in modern volcanic arcs. Detrital zircons, obtained from a meta-sandstone, yielded provenance age peaks at ~2499 Ma, ~1855 Ma and between 1100-800 Ma and a maximum depositional age of 838 ± 13 Ma. Hf Isotopes from the same zircons demonstrated that both the oldest and youngest populations have broadly juvenile Hf isotopic values however; ~1820 Ma age shows significantly evolved Hf isotopic values. A minimum age constraint on the deformation was provided by the U-Pb age of 572 .6 ± 7.6 Ma and yielded whole epsilon Nd values of 3.74 and epsilon Hf values of 6.79-7.98, demonstrating a juvenile origin. A significant aspect of the Arabian-Nubian Shield is the interpretation of the N-S oriented regional shear zones. Concentrically zoned mafic/ultramafic bodies, previously identified as remnants of the oceanic crust, are suggested to be Alaskan-type intrusions. Though chemically different to typical Alaskan-type intrusions these display a subduction affinity and have close associations to shear-zone hosted intrusions elsewhere in the Arabian Nubian Shield. Thus, they have been interpreted as being formed in similar supra subduction intrusive settings.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2013
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Virgo, G. M. "Was Earth really a snowball? Detailed facies analysis and 3D modelling of the Elatina Formation, Pichi Richi Pass, Flinders Ranges, South Australia." Thesis, 2017. http://hdl.handle.net/2440/128284.
Full textAbstract:
To access copy of the thesis please contact Structural Geology Course Co-ordinator in Earth SciencesThe Elatina Formation is exposed in outcrops throughout South Australia, most notably represented by distinct glaciogenic deposits in central and northern Flinders Ranges. As the formation reflects low latitude glaciation, it has previously been used as a benchmark study in the development of the Snowball Earth hypothesis. Pichi Richi Pass in the central Flinders Ranges is an excellent example of the Elatina Formation, however significant uncertainties exist regarding the local sequence stratigraphy and interpretation of the depositional environments. A detailed facies analysis and 3D model of the Elatina Formation at Pichi Richi Pass was established to demonstrate the variability and distribution of the depositional system. The Elatina Formation consists of four lithostratigraphic units, with eight facies identified within two of the units. The facies were established from lithological properties, and then associated based on descriptions and interpretation of their depositional processes. The results reflect thick non-glaciogenic layers interbedded with thin glaciogenic layers. The non-glaciogenic layers were deposited in coastal, deltaic and fluvial settings, while the glaciogenic units were deposited in a glaciofluvial environment. As most of the Elatina Formation in Pichi Richi Pass appears to be deposited under moving water, it suggests that the palaeoenvironment of the Elatina Formation is not consistent with prolonged glacial conditions like that of Snowball Earth. Rather, it denotes variable glacial periods characterised by glacial advance and retreat.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2017
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Simpson, C. A. "Constraints on Proterozoic crustal evolution from an isotopic and geochemical study of clastic sediments of the Gawler Craton, South Australia." Thesis, 1994. http://hdl.handle.net/2440/88297.
Full textAbstract:
This item is only available electronically.The Gawler Craton comprises tocks varying in age from Archaean to more recent Phanerozoic sediments. The rocks of greatest interest in defining processes of early crustal formation and evolution in the Australian continent, are the basement material older than approximately 1400 Ma (pre-cratonisation), comprising deformed and metamorphosed rocks suites of Archaean and Proterozoic metasediments and gneisses. These suites span an immense period of intense geological history, and as such are a topic of much past and present study. Detailed mapping in the Tumby Bay region of eastern Eyre Peninsula outlines stratigraphic and structural evolution of a sequence of Proterozoic rock suites, these are proposed to be related to other recognised deformation episodes elsewhere within the Gawler Craton, thus regional correlation is inferred. A new theory for development of two lineations within the map region is postulated by two movement directions along the Kalinjala Mylonite Zone. Geochemically the Proterozoic sediments of the Gawler Craton are similar to upper crustal average values of Taylor & McClennan (1985). However, characteristic depletions in Nb and Sr are recognised. Consistency in trace element compositions for Archaean and Proterozoic samples would suggest recycling of older Archaean crust into Proterozoic sediments and granitoids. Analysis of representative trace element ratios and indices of alteration and weathering suggest some change in geochemistry throughout the Proterozoic period. Selected Proterozoic elastic sedimentary suites were geochemicaly and isotopically (Sm-Nd) analysed, with the data being presented within this thesis. The most interesting of these being the Pandurra Formation, red-bed sediments deposited within the north-eastern Stuart Shelf region of the Gawler Craton. These sediments exhibit a change in measured isotopic values, with younger epsilon neodymium (ENd), and higher Sm/Nd ratios observed (ENd(O) = -14.67, Sm/Nd = 0.2441), than typical older Gawler Craton rocks (average Proterozoic sediments ENd(O) = -21.85, Sm/Nd = 0.1847). This isotopic shift is also recognised within the Adelaide Fold Belt to the east of the Gawler Craton (average shales ENd(O) = -16.20, Sm/Nd = 0.1942). A source for these younger signatures is not recognised within the Gawler Craton, and therefore more distal province sources, OR isotopic alteration in the originally considered 'robust' Sm-Nd isotopic system, are proposed.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1994
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Williamson, T. "Transgressions in the Gambier Limestone, Gambier Basin, S.A." Thesis, 2000. http://hdl.handle.net/2440/114263.
Full textAbstract:
This item is only available electronically.A detailed foraminiferal profile of the Late Eocene-Early Oligocene boundary in the Gambier Limestone was investigated by local and regional biostratigraphic correlations together with foraminiferal biofacies analysis. Occurrences of important planktonic species were used to produce chronostratigraphic charts to interpret the duration of the unconformable Eocene/Oligocene boundary. Deposition of the Early Oligocene basal Gambier Limestone is coeval with the Aldinga Transgression and is characteristic of an isochronous flooding event at sequence boundary Pr4/Ru1. The Late Eocene Narrawaturk Marl, where present, correlates to the Tuit regional biofacies member, and the Late/Middle Eocene sand unit is coeval to the Tortachilla unit. Hiatuses are represented by erosional surfaces at sequence boundaries. The maximum estimated duration of the hiatus ranges from Pr1 to Pr4/Ru1 indicating an age gap of approximately 3 Ma, with the majority of samples showing a hiatus between Pr3 to Pr4/Ru4, representing a time slice of approximately 2 Ma. The unconformable Eocene/Oligocene contact therefore parallels the Chinaman Gully downcut in the St Vincent Basin, indicating a regional event coeval with and in response to the oceanic-oxygen isotopic glaciation.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2000
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Klaebe, R. M. "Sedimentology and stable isotope geochemistry of the Trezona Formation; A local or global biogeochemical event?" Thesis, 2011. http://hdl.handle.net/2440/96233.
Full textAbstract:
This item is only available electronically.High magnitude δ13C shifts (>12‰) restricted to Neoproterozoic carbonate successions are widely interpreted to reflect a vastly different regime of carbon cycling that changed into the Phanerozoic. Despite isotopic values in the Neoproterozoic being anomalous, they are considered to reflect the δ13C composition of sea water because the values appear to be reproducible, change systematically, and occur in a similar stratigraphic interval relative to overlying glacial intervals within successions in different basins. The relation to a primary marine origin of the isotopic values in carbonates is key to these isotopic excursions providing constraints on the global carbon mass balance during the Neoproterozoic, that are central to present models of the ancient carbon cycle. The Trezona Formation in the Central Flinders Ranges in South Australia records a large (~9‰) pre-Marinoan glacial δ13C excursion widely correlated to basins globally and termed the ‘Trezona Anomaly’. This study examines the depositional setting of the Trezona Formation using outcrop exposures, petrographic studies, and stable isotope geochemical data and investigates the origin of δ13C values with respect to lithological and diagenetic controls. δ13C and δ18O data was collected using Isotope Ratio Mass Spectrometry. Field observations reported here are inconsistent with an open marine or tidal origin for the Trezona Formation. Sequence boundaries in the form of paleosols and fluvial deposits at the basal and upper contacts respectively indicate that it represents its own discrete depositional cycle. This is contrary to previous interpretations that the Trezona Formation records a broad shallowing upwards trend of widespread marine shales of the underlying Enorama Formation into the overlying glacial sediments of the Elatina Formation. Evidence of frequent desiccation throughout the basal half of the Formation and the limited spatial distribution of the Trezona Formation is suggestive of a consistently shallow, restricted marine or periodically lacustrine depositional setting. Covariant and diverging relationships between δ13C and δ18O values in stratigraphic profiles suggest a lithological relation to isotope values. Furthermore, petrographic data suggests that intervals of the Trezona Formation housing strongly negative δ13C values (<-5‰) may have undergone digenetic recrystalisation. A diagenetic origin for these values makes them typical of meteorically altered successions in the Phanerozoic, and removes the need for currently popular global biogeochemical models calling for dramatic differences in Precambrian carbon cycling. These observations also imply that the Trezona Formation is not a record homogeneous, open marine δ13C values and is therefore inappropriate as a correlation of chemostratigraphic events. Rather, it likely records the common alteration of coastal or lacustrine carbonates responding to exposure and alteration during sea-level fall coinciding with the Marinoan glaciation
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2011