Dissertations / Theses on the topic 'Geochemistry South Australia Gawler Craton'

Thesis (B. Sc.(Hons.))--University of Adelaide, Dept. of Geology and Geophysics, 1995.
Map sheets: Lincoln (SI 53-11) 1:250 000 Tumby Bay (SI 53-6129) 1:100 000. Includes bibliographical references.

"The seismic reflection method should find IOCG mineral deposits because of the relatively high density and hardness of these deposits compared to the host rocks. By simulating surveys with acoustic modelling and comparing the simulations to real data the thesis shows this to be true. The simulations and further inspection of existing data over known deposits indicate that most IOCG deposits can be detected by looking for the seismic signature of intrusions along prospective structures. "

Thesis (B. Sc.(Hons))--University of Adelaide, Dept. of Geology and Geophysics, 1998.
National Grid Reference 1:250 000 Geological Series Sheet SI 53-2 and Sheet SI 53-6. Includes bibliographical references (6 leaves ).

Le bouclier Est Antarctique est constitué de nombreux domaines géologiques accrétés autour de 530 Ma. Tous ces domaines enregistrent la trace des événements Grenvillien et Pan-Africain à l'exception d'un seul : le Craton de Terre Adélie.
Le Craton de Terre Adélie et son prolongement septentrional, le Craton du Gawler (en South Australia), font partie d'un même bloc : le Mawson Continent. Ils présentent donc une histoire géologique commune avant l'ouverture du domaine océanique Austral il y a environ 90 Ma. Ces cratons sont constitués d'un socle métamorphique polyphasé formé et structuré lors de deux événements géologiques majeurs datés au Néoarchéen (∼ 2.5 Ga) et au Paléoprotérozoïque (∼ 1.7 Ga).
Cette étude présente les mécanismes tectoniques à l'origine de la structuration de ce paléo-continent. Les campagnes de terrain et les travaux en laboratoire (pétrologie, géochronologie Ar–Ar et U–Th–Pb) réalisés sur des roches provenant des deux cratons ont permis (1) de préciser l'âge et l'origine de la déformation néoarchéenne ainsi que le comportement de la lithosphère continentale à cette époque et (2) de quantifier l'importance de la déformation paléoprotérozoïque au sein du noyau archéen et dans les domaines paléoprotérozoïques adjacents.
Ces travaux apportent de nouvelles contraintes sur la tectonique précambrienne.
Nos travaux ont permis de mettre en évidence et de modéliser numériquement en 3D l'évolution à l'échelle lithosphérique de la déformation lors de l'affaiblissement des contraintes tectoniques convergentes appliquées à une lithosphère archéenne chaude. Sous l'influence de la gravité, la lithosphère chaude va fluer dans une direction perpendiculaire à celle de convergence, principalement par des mécanismes de constriction horizontale. De plus, nous mettons en évidence une dualité rhéologique entre un noyau cratonique stable et sa couverture autochtone lors de processus tardifs de réactivation tectonique.

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The ‘Tomahawk’ Au-in-calcrete anomaly is a zone of peak Au-in-calcrete content within the Tunkillia prospect of the central Gawler Craton, South Australia. Exploration drilling of this area has failed to intersect significant underlying mineralisation, making this an important setting to investigate controls on linkages between Au-in-calcrete expression and possible mineralisation sources. This study is the first to consider the multi-element geochemical characteristics of calcretes at ‘Tomahawk’ rather than using the Au-only approach of previous geochemical exploration. This investigation also considers the potential for laterally dispersed geochemical signatures across the landscape recorded at the surface of Au and associated elements, and suggests that Au was, and may still be physically mobilised along old and contemporary alluvial drainage depressions. There is a low relief, but locally significant drainage divide to the south of ‘Tomahawk’, so the anomaly area is associated with a point of low, broad confluence of several north flowing palaeodrainage depressions. The interpretation of these palaeolandscape controls further builds on palaeodrainage channel identification from previous studies and supports hypotheses that ‘Tomahawk’ is in an upper catchment setting, relative to the ‘Area 191’ Au-in-calcrete anomaly. Primary Au mineralisation at Tunkillia is associated with pyrite, minor galena and sphalerite within quartz-sulphide veins, and has a geochemical association with Au, Ag, Pb and Zn. Supergene Au enrichment has been recognised within ferruginised saprock overlying mineralised bedrock, and this is largely considered Au-only mineralisation. The calcrete geochemistry here shows some distinction between possible primary and secondary Au occurrences based in the trace element characteristics. The Au-in-calcrete concentrations obtained in this study are up to 194 ppb within CHep and ISps2 regolith-landforms in the north of the study area, corresponding to the lower margins of topography and areas interpreted to be within palaeodrainage systems. Silver concentrations above detection were found in association with many of the elevated Au results, therefore identifying areas of interest and possible alteration halos surrounding primary Au mineralisation. Furthermore, small exposures of weathered in situ quartz veins support a possible source for the ‘Tomahawk’ Au-in-calcrete anomaly to the south, which is immediately upslope of the palaeodrainage system.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2009

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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

The Gawler Craton, South Australia, consists of late Archaean to early Mesoproterozoic igneous and supracrustal lithologies which preserve a deformation history lasting the duration of the Palaeoproterozoic. Understanding the evolution of the Gawler Craton is of significance in global supercontient reconstructions as it preserves evidence for earliest Palaeoproterozoic collisional orogenesis (c. 2460-2430 Ma) and, in conjunction with the North Australian Craton and Antarctica, has often been correlated to the western margin of Laurentia. In addition, the Gawler Craton is also host to the world-class Olympic Dam Fe-oxide-Cu-Au-U type-deposit (world's fourth largest Cu and largest U deposit) and related Fe-oxide-Cu-Au-U and Cu-Au mineralising systems. Despite the various geologically and economically important characteristics of the Gawler Craton there has traditionally been a poor understanding of the tectonothermal evolution of the Gawler Craton, in particular for the Palaeoproterozoic. This study addresses and refines the Palaeo-to Mesoproterozoic tectonothermal evolution of the Gawler Craton. This is done using geochemical, geochronological and isotopic analytical techniques to better understand selected supracrustal and igneous lithologies in the Gawler Craton and the orogenic events which have affected them. Largely unexposed metasedimentary lithologies of the northern Gawler Craton record multiple deformation events but have previously been virtually unconstrained with respect to their timing of protolith deposition and the age of deformation/metamorphism. New geochronological data demonstrate these metasedimentary lithologies were deposited during the time period -1750-1730 Ma before being metamorphosed and deformed during the Kimban (1730-1690 Ma) and Kararan (1570-1545 Ma) Orogenies. Detrital zircon geochronology and isotopic and geochemical characteristics of the sampled metasedimentary lithologies suggest a relatively similar protolith sedimentary succession was deposited across a large extent of the northern Gawler Craton. Detritus for the sedimentary protolith does not appear to have been sourced from the Gawler Craton. Instead the protolith it is more consistent with a North Australian Craton provenance suggesting a proximity between the northern Gawler Craton and North Australian Craton at the time of protolith deposition. The newly defined presence of the Palaeoproterozoic Kimban Orogeny in the northern Gawler Craton demonstrates the Kimban Orogeny to be a major, high-grade, craton-wide orogenic event. This finding contradicts previous suggestions that the northern Gawler Craton was accreted to the proto-Gawler Craton during the later Mesoproterozoic Kararan Orogeny. In addition, previous reconstruction models for the Palaeo-to early Mesoproterozoic often cite the felsic Tunkillia Suite (1690-1670 Ma), western and central Gawler Craton, as representing arc magmatism prior to the subsequent amalgamation of the Gawler Craton during the Kararan Orogeny. New geochemical and isotopic data for the Tunkillia Suite have allowed for re-examination of the tectonic setting for the petrogenesis of the Tunkillia Suite. Contrary to previous suggestions (based upon discrimination diagrams), the mineralogy, geochemistry and isotopic characteristics of the Tunkillia Suite are not consistent with arc-magmatism. Instead the Tunkillia Suite is interpreted to represent a late-to post-tectonic magmatic suite generated during the waning stages of the Kimban Orogeny. This petrogenesis further highlights the importance of the Kimban Orogeny as a fundamental tectonothermal event in the evolution of the Gawler Craton. Subsequent to the Kimban Orogeny, the Gawler Craton was thought to undergo a period of subduction-related magmatism (St Peter Suite) prior to the anorogenic magmatism of the voluminous felsic Gawler Range Volcanic (GRV) and Hiltaba Suite magmatism (1595-1575 Ma). New geochronological data for the ms-bi-gt-bearing peraluminous Munjeela Suite (1590-1580 Ma) have demonstrated the Hiltaba/GRV event was accompanied by significant crustal anatexis not associated with the Hiltaba/GRV magmatism. The Munjeela Suite and metasedimentary enclaves within it demonstrate that the Gawler Craton was likely to be undergoing compressive deformation and crustal thickening sometime during the petrogenesis of the Hiltaba/GRV magmatism. This suggests the Hiltaba/GRV magmatism did not occur in an anorogenic setting as previously proposed. The findings of this study are incorporated into a revised tectonothermal evolution of the Gawler Craton. This is used to discuss previous reconstruction models for Proterozoic Australia and provide a new reconstruction model of Australia and Antarctica during the Palaeoproterozoic. Important facets of the proposed model are links to the Archaean-Early Palaeoproterozoic Sask Craton in the Trans-Hudson Orogen, Laurentia, and the joint evolution of the North Australian and Gawler Cratons throughout the entire Palaeoproterozoic.
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1330862
Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2008

The Tarcoola Goldfield, central South Australia, is one of a number within the Central Gawler Gold Province (CGGP) spatially related to Hiltaba Suite granites. This study investigates the origin of mineralisation at Tarcoola, and the petrogenesis of granites at and around Tarcoola. ‘Hiltaba Suite’ granites in the Tarcoola region are assigned to two supersuites, which is expanded to four once granites from the rest of the Gawler Craton are considered. The term Hiltaba Association Granites (HAG) is introduced as the parental unit of the Jenners, Malbooma, Venus and Roxby Supersuites. These criteria are applied to the felsic parts of the comagmatic Gawler Range Volcanics (GRV). The HAG and GRV are grouped as the bimodal Gawler Ranges–Hiltaba Volcano–Plutonic (GRHVP) Association. The felsic components generally have high K, HFSE, LIL, are fractionated and evolved, have moderate to high Fe/Mg, are slightly alkaline, metaluminous to slightly peraluminous, slightly oxidised and high-temperature. The supersuites of the Tarcoola region are the Malbooma Supersuite, which is more strongly evolved and fractionated than the Jenners Supersuite. Both Supersuites are I-type and evolved from a granodiorite composition by fractional crystallisation. The Pegler and Ambrosia Granites (Jenners Supersuite), and are dated at 1591.7 ± 5.8 and 1575.4 ± 7.8 Ma. The Big Tank, Kychering and Partridge Granites (Malbooma Supersuite), and are dated at 1589.9 ± 7.4, 1574.7 ± 4.3 and 1577 ± 8.5 Ma. The Roxby and Venus Supersuites are A-type granites and volcanics, with higher HFSE, F, and zircon saturation temperatures than the I-types. Nd-isotope data indicate that the felsic GRHVP formed by mixing between evolved mantle and crust. Narrow dykes of the high-K Lady Jane Diorite intrude the Tarcoola Goldfield. This unit, and other basalts of the GRHVP, are interpreted to represent mixing between evolved lithospheric and primitive asthenospheric mantle melts. The Paxton Granite at the Tarcoola Goldfield was dated as older than the HAG at ~1720 Ma. The Tarcoola Formation was deposited in an ensialic basin directly onto the Paxton, with the basal Peela Conglomerate Member contains zircons of 1732.8 ± 5.1 Ma and 1714.6 ± 7.9 Ma, and the middle parts of the Tarcoola Formation being deposited at 1656 ± 7 Ma. Mineralisation at the Tarcoola Goldfield is quartz-vein hosted within the Tarcoola Formation, and comprises Au±Pb-Zn. The veins are structurally-controlled. 40Ar/39Ar geochronology and field relationships show that brittle veining, mineralisation, alteration and intrusion of the Lady Jane Diorite, occurred synchronously at ~1580 Ma. A Pb-Pb isotope study at the Tarcoola Goldfield is consistent with sourcing of Pb from the Paxton Granite, but does not exclude a mixed source. A shift in Nd during alteration may show an input from the relatively primitive Lady Jane Diorite. An atlas shows correlations between the four supersuites and the two defined mineral provinces of the Gawler Craton. Notably the Roxby Supersuite is associated nearly exclusive with iron-oxide copper-gold mineralisation in the Olympic Cu-Au Province in the eastern part of the Craton. The I-type Jenners and Malbooma Supersuites are mostly restricted to the CGGP. A position inboard of a subduction zone (hot continental back-arc) rather than anorogenic setting is proposed.

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The Gawler Craton (South Australia) records a complex thermal history during the Phanerozoic. Previous work has indicated that the central Gawler Craton was largely exhumed during the Carboniferous as a far-field effect of the Alice Springs Orogeny. Besides this widespread exhumation event, localised Mesozoic and Tertiary thermal events have been documented for the central Gawler Craton as well. The extent of these events into the northern Gawler Craton is not well understood as low-temperature thermochronological data is lacking for this region. For this study, granitoid samples along a roughly north-south transect through the northern and central Gawler Craton were analysed using the apatite fission track (AFT) and apatite (AHe) and zircon (ZHe) U-Th-Sm/He methods. Results from these low-temperature methods yield Neoproterozoic through to Cretaceous AFT, AHe and ZHe ages. Cumulative AFT age plots reveal a multi-phase Phanerozoic cooling history for the central and northern Gawler Craton. Significant AFT age peaks were found at ~480-450 Ma and ~350-300 Ma. The Ordovician age peak is thought to be related with the final stages of the Delamerian Orogeny, while the Carboniferous age peak is interpreted as being a far field response to the Alice Springs Orogeny. This is consistent with previous interpretations throughout South Australia. Additionally, localised Jurassic and Cretaceous AFT and ZHe ages were obtained which are thought to be related with rifting at the southern Australian margin and river incision respectively.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2014

Two folded coloured maps and 2 coloured overlays in back cover pocket.
Bibliography: p. 183-142.
x, 182 p. : ill. (some col.), maps (some col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Dept. of Geology, 1998?

Two folded coloured maps and 2 coloured overlays in back cover pocket.
Bibliography: p. 183-142.
x, 182 p. : ill. (some col.), maps (some col.) ; 30 cm.
Thesis (Ph.D.)--University of Adelaide, Dept. of Geology, 1998.

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Polymetamorphic signatures in rocks can be difficult to deconvolve, especially where events have similar metamorphic grade. In situ and erratic samples from the Terre Adélie Craton, Antarctica, and in situ samples from the formerly contiguous Gawler Craton, South Australia, are examined to deconvolve microstructural, pressure–temperature and geochronological evidence of terrane-scale polymetamorphism. In situ monazite U–Pb geochronology shows that coastal and erratic samples record c. 1700 Ma and c. 2420 Ma ages, consistent with known ages of the Kimban and Sleafordian events, respectively. In situ samples from the Antarctic coast record exclusively c. 2420 Ma ages whereas most erratic samples from the glacial moraines at Cape Denison record only c. 1700 Ma ages. Phase equilibria forward modelling for the c. 2000 Ma Redbanks Charnockite uniquely constrains peak metamorphic conditions of the c. 1700 Ma Kimban Orogeny to 5.0–7.2 kbar and 700–860 ºC. Peak metamorphic conditions of the c. 2420 Ma event are ~5–8.7 kbar and 690–1000 ºC, as constrained by in situ samples from the Terre Adélie coast. As the peak pressure–temperature conditions for the two events are similar and the record of polymetamorphism is cryptic and spatially variable in the rock record, Antarctic samples that only record Kimban ages are interpreted as reflecting either a record of complete overprinting of the older (c. 2420 Ma) event, or that the rocks are younger than the c. 2420 Ma event. In such a situation polymetamorphism at a terrane scale may only be detected by differences in geochronological data. This study serves to highlight the careful approach required when investigating polymetamorphic terranes and argues that a spatially variable record of overprinting metamorphism is possibly related to locations of retrogression occurring either in the waning/exhumation stages of the earlier event or between events.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2015

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The Gawler Range Volcanics (GRV) form part of a Mesoproterozoic Silicic Large Igneous Province (Gawler SLIP) within South Australia. The SLIP includes intrusive and extrusive rocks within the Gawler Craton and Curnamona Province that are dominantly felsic. Recent high precision dating of several GRV units has shown that they erupted between 1587 Ma and 1595 Ma allowing for geochemical comparisons with respect to a precise timeline. Trace element geochemistry has shown anomalies to be consistent through the lower and upper GRV demonstrating the main source in the GRV likely did not change. A mafic component is shown to have contributed to both the lower and upper GRV system. Eu anomalies and trace element geochemistry shows that there was a large change in magmatic evolution between the upper and lower GRV within a short time (<1 m.yr). This change is hypothesised to have occurred due to the tectonic regime during the SLIP emplacement. Hydrothermal alteration associated with the emplacement of the Gawler SLIP is known to have contributed to the formation of Iron-Oxide Copper-Gold (IOCG) and shear-hosted deposits in South Australia. More recent discoveries within the Southern Gawler Ranges display epithermal-porphyry characteristics associated with alteration in the lower GRV. Alteration within the GRV is hereby characterised in order to identify alteration associated with mineralisation. Alteration is shown to encompass a sericite – hematite dominated assemblage which has affected most of the GRV. Several other anomalous alteration assemblages exist in localised areas. Using direct evidence, it is suggested that epithermal-porphyry systems may be preserved within the upper GRV, which encompasses a larger outcrop area than the lower GRV which is underexplored.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2019

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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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The ca. 1600–1580 Ma time slice is recognised as a significant period of magmatism and deformation throughout eastern Proterozoic Australia. Within the northern Yorke Peninsula, this period was associated with the emplacement of multiple phases of the Tickera Granite; an intensely foliated orange granite, a white leucogranite and a red granite. These granites belong to the broader Hiltaba Suite that was emplaced at shallow crustal levels, throughout the Gawler Craton. Geochemical and isotopic analysis suggests these granite phases were derived from a heterogeneous source region. The orange and red granites were derived from the Donington Suite and/or the Wallaroo Group metasediments with slight contamination from an Archean basement. The white leucogranite is sourced from a similar but slightly more mafic/lower crustal source. Phases of the Tickera Granite were emplaced synchronously with deformation that resulted in development of a prominent northeast trending structural grain throughout the Yorke Peninsula region. This fabric is a composite of two fold generations; early isoclinal folds that were refolded by later open upright folds. Isoclinal folding may have occurred during the ca. 1730–1690 Ma Kimban Orogeny, or just prior to emplacement of the Tickera Granite at ca. 1597–1577 Ma. The upright fold generation was contemporaneous with the emplacement of the Tickera Granite. The Yorke Peninsula shares a common geological history with the Curnamona Province, which was deformed during the ca. 1600–1585 Ma Olarian Orogeny, and resulted in development of early isoclinal (recumbent) folds overprinted by an upright fold generation, a dominant northeast–trending structural grain and spatially and temporally related intrusions. This suggests an apparent correlation with the geological history of the Curnamona Province, and that the Olarian Orogeny may have also affected the southeastern Gawler Craton. Constraint on the timing of the earlier isoclinal fold generation in the Yorke Peninsula will allow further understanding of the similarities between the two regions.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2016

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The Cairn Hill Fe-(Cu-Au) deposit is located within the World-class 1.6 Ga Olympic iron oxide-copper-gold (IOCG) Province of the Gawler Craton, South Australia. Cairn Hill deposit formation was penecontemperaneous with regional orogenesis, and is interpreted as a deep-level, ‘magnetite-rich’ end-member IOCG system hosted by an upper-amphibolite quartzofeldspathic ortho-gneiss and Mesoproterozoic (1600 – 1575 Ma) Hiltaba-equivalent Balta-suite granites and granodiorites. U-Pb zircon SHRIMP dating of a representative host rock and cross-cutting foliated granitic dyke, constrains the timing of mineralisation between ~1587 Ma and ~1525 Ma, respectively; suggesting an affinity to Hiltaba-age granitoids. The deposit strikes E-W over a distance of 1.3 km and is up to 40 m wide. It is characterized by two mineralised zones: the North- and South- Lodes, coincident with subsidiary structures within the transpressional Cairn Hill Shear Zone (CHSZ), and concordant with the strike of the encompassing magnetic anomaly. Progressive exhumation resulted in temperature and pressure decreases under high-fluid pressure causing the CHSZ to cross the brittle-ductile transition. This occurred relatively late in the hydrothermal-metamorphic evolution, resulting in a contractional duplex in a restraining bend suggestive of a positive flower structure providing an optimal conduit for hydrothermal fluid-flow. Early Na-Ca alteration has affected the host rocks predominantly characterised by albite + scapolite + diopside ± actinolite/titanite. Extensive K-Fe metasomatism has affected the host rocks overprinted by localised zones of intense, texturally-destructive high-temperature magnetite-biotite alteration that is typical of a transitional-style IOCG system. Associated hypogene iron mineralisation predominantly consists of magnetite, with extensive zones of a superimposed texturally-complex sulphide assemblage (pyrite-pyrrhotite-chalcopyrite). Definition of the IOCG deposit clan remains a contentious issue, primarily due to mis-classification and poor understanding of some individual deposits. Nevertheless, the general consensus is that IOCG deposits sensu-stricto represent a spectrum between high-temperature, deeper magnetite-rich end-member systems, such as Cairn Hill, and lower-temperature, shallower hematite-rich end-members.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2014

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Multi-method thermochronology applied to the eastern Gawler Craton, beneath the Stuart Shelf cover (Olympic Dam Domain, South Australia), reveals multiple episodes of exhumation. Modelled data from Apatite Fission Track (AFT) analysis identifies four time periods where the eastern Gawler Craton basement experienced cooling into AFT closure temperatures (~60-120°C); at1050 ± 55 Ma (Mesoproterozoic), 439 ± 14 Ma (late Ordovician-Silurian), 304 ±36 Ma (mid-Carboniferous-mid Permian) and 245 ± 52 Ma (late Permian-early Jurassic). In addition, the Carboniferous and Jurassic peaks are supported by zircon (ZHe) and apatite (AHe) (U-Th-Sm)/ He results. The Ordovician peak is interpreted as resulting from the final pulses of the Delamerian Orogeny partially, mixed with the first pulses of the Alice Springs Orogeny. The Carboniferous-Permian event is linked with widespread exhumation likely due to the final pulses of the Alice Springs Orogeny (~300Ma). The preserved Mesoproterozoic event presents new AFT data in the area and coincides with some recent studies. However, it occurs only in samples obtained from the Gawler Range Volcanics and more prominent in core depth shallower than 500m. The late Permian-early Jurassic event is comparable to events believed have to stemmed from hydrothermal events. This event compliments AFT studies in the northern Flinders Ranges. The Late Ordovician-Silurian and Carboniferous-early Permian AFT pulses confirm events seen in studies of surrounding regions. Other geochronological studies around the Olympic Dam area indicate that this pulse either results from a localised hydrothermal event or distal effects of the Musgravian Orogeny. The Jurassic event suggests that the hydrothermal effect on AFT ages may be a more widespread event and not just localised to the northern Flinders Ranges as previously thought. The Ordovician event represents mixing between Delamerian and Alice Springs Orogenies. The Carboniferous-Permian event represents late distal effects of the Alice Springs Orogeny. These events match those of surrounding regions.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2015

The thesis presents the application of the magnetotelluric (MT) sounding method to image Earth’s crust in Oman and South Australia. The aim of these MT surveys is to provide constraints on the geological interpretation of emplacement scenarios and the tectonic evolution of the geological domain. The thesis concentrates on the methodological aspects of the MT technique, e.g. the data analysis and modelling of electromagnetic fields. The phase tensor approach by Caldwell et al. (2004) is applied to the data and provides insights into the dimensionality of the MT data in even complex and electrically distorted terranes. Modelling and inversion of the MT data is performed with various 2-D and 3-D codes to show how the interpretation of the data can benefit from multiple modelling approaches. Data collected in a 2-D survey across the Oman ophiolite mountains show complex behaviour and 2-D inversion and 3-D forward modelling resolve ambiguities in the emplacement scenario of the Oman ophiolite. It is believed that initial underthrusting of the Jurassic-Cretaceous oceanic lithosphere was followed by exhumation. Further oceanic thrusting subsequently led to rising of lower-plate eclogites and eventually gravitational collapse of the ophiolite onto the margin (Gray et al., 2000). The 3-D inversion code by (Siripunvaraporn et al., 2005a) was expanded to incorporate static shift corrections and inversion model misfits have therefore improved significantly compared to inversion models without static shift correction. 2-D and 3-D surveys across the South Australian Gawler Craton reveal deep crustal conductors which are connected to near surface mineralisation systems of the IOCG Olympic Dam deposit in the north-eastern part of the craton and the Au-dominated central Gawler Craton provinces.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008