Academic literature on the topic 'Geology Queensland Mount Isa Region'

AbstractThe earliest of four distinct phases of deformation recognized in the central part of the Proterozoic Mount Isa inlier involved brittle extensional faulting at shallow crustal levels. Extensional faulting produced stacks of imbricate fault slices, listric normal faults and characteristic tourmalinerich breccias. Structures belonging to this phase occur over a large part of the inlier and indicate an important phase of basin-forming crustal or lithospheric extension at 1750–1730 Ma. Late intense ductile deformation and tight folding of the imbricate systems destroyed part of these older structures, and obscures their existence in many parts of the inlier.

An airborne survey was undertaken on the Mount Isa inlier in 1990–1992. During this survey, both airborne magnetic and gamma‐ray spectrometric data were recorded over 639 170 line-km. Because of perceived value of the radiometric data, stringent calibration procedures, including the creation of a test range, were adopted. In addition to the data from the newly‐flown areas, 76 760 line‐km of existing data were acquired from other companies, and were reprocessed and merged with the Mount Isa survey. The total area covered by the Mount Isa airborne survey was 151 300 km2. Over the last five years, several studies have been undertaken that seek to exploit the Mount Isa region gamma‐ray database and maximise the use of radiometrics for mineral exploration. This paper highlights the results of these studies by focussing on radiometric signatures of major mines in the Mount Isa Inlier, radioelement contour maps, geomagnetic/radiometric interpretation maps, lithological mapping, regolith mapping, geochemical sampling, and spatial modeling using geographical information systems (GIS). Due to the recent introduction of GIS technology and better techniques for handling high quality digital data, there has been a revived interest in making more use of image data sets. The integration of raster and vector data sets for both spectral and spatial modeling has maximized the potential of this approach.

As part of the Strategic Resources Exploration Program and to complement surveys acquired under Geoscience Australia’s Exploring for the Future (EFTF) initiative, the Geological Survey of Queensland acquired the Camooweal 2D seismic survey in 2019. This survey was designed to support exploration for hydrocarbons in the Georgina and South Nicholson Basins and Isa Superbasin in Northwest Queensland (NWQ) by providing precompetitive sub-surface data to enable interpretation of basin and basement architecture and to examine structures interpreted in the 2018 North West Queensland SEEBASE Study. The Camooweal 2D seismic survey extends Geoscience Australia’s L210 South Nicholson Seismic Survey into an underexplored region of NWQ. It also ties into and complements the 1994 and 2004 Mount Isa seismic surveys, and the 2019 L212 Barkly Seismic Survey in the Northern Territory. The South Nicholson survey highlighted a significant thickness of sedimentary strata and identified a new depocenter of probable Proterozoic age, now referred to as the Carrara Sub-basin. The Camooweal and Barkly surveys extended the seismic coverage in this region and possibly increase the Carrara Sub-basin’s extent underneath the Georgina Basin. This work will present an interpretation of the basin architecture of the Camooweal 2D seismic in light of the recent drilling at NDI Cararra 1 and tie into interpretation of the Barkly Seismic Survey to provide a regional interpretation of NWQ’s Proterozoic basins in the region.

The Mount Isa Basin is a new concept used to describe the area of Palaeo- to Mesoproterozoic rocks south of the Murphy Inlier and inappropriately described presently as the Mount Isa Inlier. The new basin concept presented in this thesis allows for the characterisation of basin-wide structural deformation, correlation of mineralisation with particular lithostratigraphic and seismic stratigraphic packages, and the recognition of areas with petroleum exploration potential. The northern depositional margin of the Mount Isa Basin is the metamorphic, intrusive and volcanic complex here referred to as the Murphy Inlier (not the "Murphy Tectonic Ridge"). The eastern, southern and western boundaries of the basin are obscured by younger basins (Carpentaria, Eromanga and Georgina Basins). The Murphy Inlier rocks comprise the seismic basement to the Mount Isa Basin sequence. Evidence for the continuity of the Mount Isa Basin with the McArthur Basin to the northwest and the Willyama Block (Basin) at Broken Hill to the south is presented. These areas combined with several other areas of similar age are believed to have comprised the Carpentarian Superbasin (new term). The application of seismic exploration within Authority to Prospect (ATP) 423P at the northern margin of the basin was critical to the recognition and definition of the Mount Isa Basin. The Mount Isa Basin is structurally analogous to the Palaeozoic Arkoma Basin of Illinois and Arkansas in southern USA but, as with all basins it contains unique characteristics, a function of its individual development history. The Mount Isa Basin evolved in a manner similar to many well described, Phanerozoic plate tectonic driven basins. A full Wilson Cycle is recognised and a plate tectonic model proposed. The northern Mount Isa Basin is defined as the Proterozoic basin area northwest of the Mount Gordon Fault. Deposition in the northern Mount Isa Basin began with a rift sequence of volcaniclastic sediments followed by a passive margin drift phase comprising mostly carbonate rocks. Following the rift and drift phases, major north-south compression produced east-west thrusting in the south of the basin inverting the older sequences. This compression produced an asymmetric epi- or intra-cratonic clastic dominated peripheral foreland basin provenanced in the south and thinning markedly to a stable platform area (the Murphy Inlier) in the north. The fmal major deformation comprised east-west compression producing north-south aligned faults that are particularly prominent at Mount Isa. Potential field studies of the northern Mount Isa Basin, principally using magnetic data (and to a lesser extent gravity data, satellite images and aerial photographs) exhibit remarkable correlation with the reflection seismic data. The potential field data contributed significantly to the unravelling of the northern Mount Isa Basin architecture and deformation. Structurally, the Mount Isa Basin consists of three distinct regions. From the north to the south they are the Bowthorn Block, the Riversleigh Fold Zone and the Cloncurry Orogen (new names). The Bowthom Block, which is located between the Elizabeth Creek Thrust Zone and the Murphy Inlier, consists of an asymmetric wedge of volcanic, carbonate and clastic rocks. It ranges from over 10 000 m stratigraphic thickness in the south to less than 2000 min the north. The Bowthorn Block is relatively undeformed: however, it contains a series of reverse faults trending east-west that are interpreted from seismic data to be down-to-the-north normal faults that have been reactivated as thrusts. The Riversleigh Fold Zone is a folded and faulted region south of the Bowthorn Block, comprising much of the area formerly referred to as the Lawn Hill Platform. The Cloncurry Orogen consists of the area and sequences equivalent to the former Mount Isa Orogen. The name Cloncurry Orogen clearly distinguishes this area from the wider concept of the Mount Isa Basin. The South Nicholson Group and its probable correlatives, the Pilpah Sandstone and Quamby Conglomerate, comprise a later phase of now largely eroded deposits within the Mount Isa Basin. The name South Nicholson Basin is now outmoded as this terminology only applied to the South Nicholson Group unlike the original broader definition in Brown et al. (1968). Cored slimhole stratigraphic and mineral wells drilled by Amoco, Esso, Elf Aquitaine and Carpentaria Exploration prior to 1986, penetrated much of the stratigraphy and intersected both minor oil and gas shows plus excellent potential source rocks. The raw data were reinterpreted and augmented with seismic stratigraphy and source rock data from resampled mineral and petroleum stratigraphic exploration wells for this study. Since 1986, Comalco Aluminium Limited, as operator of a joint venture with Monument Resources Australia Limited and Bridge Oil Limited, recorded approximately 1000 km of reflection seismic data within the basin and drilled one conventional stratigraphic petroleum well, Beamesbrook-1. This work was the first reflection seismic and first conventional petroleum test of the northern Mount Isa Basin. When incorporated into the newly developed foreland basin and maturity models, a grass roots petroleum exploration play was recognised and this led to the present thesis. The Mount Isa Basin was seen to contain excellent source rocks coupled with potential reservoirs and all of the other essential aspects of a conventional petroleum exploration play. This play, although high risk, was commensurate with the enormous and totally untested petroleum potential of the basin. The basin was assessed for hydrocarbons in 1992 with three conventional exploration wells, Desert Creek-1, Argyle Creek-1 and Egilabria-1. These wells also tested and confrrmed the proposed basin model. No commercially viable oil or gas was encountered although evidence of its former existence was found. In addition to the petroleum exploration, indeed as a consequence of it, the association of the extensive base metal and other mineralisation in the Mount Isa Basin with hydrocarbons could not be overlooked. A comprehensive analysis of the available data suggests a link between the migration and possible generation or destruction of hydrocarbons and metal bearing fluids. Consequently, base metal exploration based on hydrocarbon exploration concepts is probably. the most effective technique in such basins. The metal-hydrocarbon-sedimentary basin-plate tectonic association (analogous to Phanerozoic models) is a compelling outcome of this work on the Palaeo- to Mesoproterozoic Mount lsa Basin. Petroleum within the Bowthom Block was apparently destroyed by hot brines that produced many ore deposits elsewhere in the basin.

Thesis (B. Sc.(Hons.))--University of Adelaide, Dept. of Geology and Geophysics, 1997?
National Grid reference SF53-14 (Alice Springs), SF54-1 (Mount Isa) (1:250 000). Includes bibliographical references (leaves [32-36]).

The study involved investigating the use of ASTER and HyMap datasets from the Tick Hill area, Mount Isa region in Queensland, to make mineral maps and validate them, and subsequently to use the mineral maps to map and study the regolith-landforms. The processing techniques used on the multispectral and hyperspectral data were relative band depth (RBD) and Spectral Indices, and a sequence of masking procedures to minimize spectral overlap effects from other materials such as vegetation, atmospheric particles and minerals. The ASTER datasets allowed mapping of mineral groups such as Al-OH, Mg-OH and iron oxides rather than individual mineral maps. HyMap data, due to its better spectral resolution was able to map kaolinite, kaolinite crystallinity, iron oxides (hematite and goethite), white mica, Mg-OH + carbonate minerals, and to an extent silica and Al-smectite.The application of the mineral maps applied to map regolith-landforms allowed better characterization of regolith materials as compared to traditional band combination methods. Surface mineralogy could be linked to specific surface regolith materials such as kaolinite and iron oxides representing ferruginous materials (duricrusts, soils or mottled zones), abundance of well crystalline kaolinite equated to saprolite and mottled saprolite and high Mg-OH equated to slightly weathered (saprock) exposures of Pre-Mesozoic basement rocks. Spatial variation in mineralogy permitted interpreting changes in surface regolith and refining regolith-landform units as mapped from simple Red-Green-Blue band combinations. Kaolinite crystallinity maps were effective in highlighting in situ regolith from transported regolith, and allowing interpretation of the presence of deep weathering profiles being capped by ferruginous materials (duricrusts) or saprolite exposures on the hills, rises and erosional plain landforms of the regions.

Includes copies of articles co-authored by author during the preparation of this thesis in back pocket.
Includes bibliographical references (leaves 113-124).
viii, 172 leaves : ill. (some col.), maps ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Focuses on the impact of change in the distribution of heat producing elements on lithospheric thermal regimes and on temperature dependent processes such as metamorphism, magmatism and deformation, with application to Proteozoic Australia (Mount Isa and Mount Painter inliers).
Thesis (Ph.D.)--Adelaide University, Dept. of Geology and Geophysics, 2001

Includes copies of articles co-authored by author during the preparation of this thesis in back pocket.
Includes bibliographical references (leaves 113-124).
viii, 172 leaves : ill. (some col.), maps ; 30 cm.
Focuses on the impact of change in the distribution of heat producing elements on lithospheric thermal regimes and on temperature dependent processes such as metamorphism, magmatism and deformation, with application to Proteozoic Australia (Mount Isa and Mount Painter inliers).
Thesis (Ph.D.)--Adelaide University, Dept. of Geology and Geophysics, 2001

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The Mount Cuthbert mine is situated ~100km NE of Mt Isa near the eastern edge of the Kalkadoon Leichhardt Belt (KLB); a Proterozioc block of the Mt Isa Inlier that divides the world class mineral regions of the IOCG-style Eastern Fold Belt (EFB) and the Mount Isa style copper deposits of the Western Fold Belt (WFB). KLB hosted deposits display characteristics related to both the EFB and WFB style of mineralisation; however mineralisation at Mount Cuthbert is indicative of a genesis for KLB hosted deposits related to metasomatic and tectonic events responsible for mineralisation in the EFB. The Mount Cuthbert mine is a low tonnage-high grade, shear controlled, retrograde chalcopyrite-pyrite-pyrrhotite deposit hosted within silica-dolomite and biotite-chlorite altered schists and felsic volcanic units of the Leichhardt Volcanics. The paragenetic alteration sequence is composed of 5 alteration stages: Stage 1) sodic alteration (albite + quartz); Stage 2) K-Fe-Ca alteration (siderite + calcite + dolomite+ quartz + biotite ± magnetite ± ilmenite ± apatite ± pyrite); Stage 3) mineralisation (chalcopyrite + quartz ± pyrite ± pyrrhotite ± calcite ± chlorite); Stage 4) major chloritisation; Stage 5) oxidation and localised enrichment to chalcocite. The alteration halo within the deposit is characterised by a proximal alteration envelope (<50m) consisting of chalcopyrite, pyrite, quartz, dolomite and chlorite, an intermediate alteration envelope (50-500m) described by quartz-carbonate veining with minor chalcopyrite, pyrite and pyrrhotite, in addition to extensive biotite and chlorite alteration and minor magnetite alteration. A distal alteration envelope (>500m) is identified tentatively as albite dominant. The trace geochemistry of the main chalcopyrite ± pyrite ore phase reveals elevated Ni, Zn, Cd and Hg in pyrite and elevated Sn, Pb, Se, V, Cr, Te, Ga, As, Cd, Mo, Ga, Bi and Sb in chalcopyrite. Differing elemental trends within the ore minerals supports paragenetic evidence suggesting several phases of sulphide growth. The characteristics and features of the Mount Cuthbert deposit outlined in this study show the greatest number of similarities to other low tonnage-high grade, shear hosted deposits present in the KLB (i.e. Mighty Atom, Orphan). This suggests that despite having a genesis related to that of the EFB, KLB deposits are uniquely their own style of mineralisation. This supports a shear-zone associated exploration model that is specific to the KLB.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2015

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Copper mineralisation within the Mount Isa Mines deposit is associated with variable talc alteration. An understanding of the mineralogy and distribution of talc alteration associated with the northern 3500 orebody is important for future mining processes and could potentially be used for exploration targets around the Mount Isa area. Mineralogical and geochemical investigations have shown one major type of talc mineralogy throughout the entire 3500 orebody. Variations in colour and texture are visible macroscopically and microscopically but there are no distinctive differences in mineralogy. The talc has minor iron (~4 wt% FeO), probably due to the moderate iron within the Mount Isa system. The same type of moderately Fe-rich talc is found within the 1100 oreobody (Waring, 1990), suggesting a similar style of talc alteration extends beyond the 3500 orebody. The distribution of talc is reliant on the fluid pathway. The altering fluids have used selected faults within the 3500 orebody as pathways. The NSFW fault which roughly defines the eastern limit of mineralisation in the 3500 orebody is typically a strong wide shear zone with talc fill and is recognised as being a possible pathway for the fluids. Talc is dominant on the footwall of the 3500 orebody from south of 6700mN and dominant on the hangingwall, north of 6700mN. Within the siliceous core where mineralisation is at its greatest concentrations, talc is only located within faults. Outside the siliceous core where copper mineralisation is lower, talc alteration is present within the rocks and varies in quantity. The talc alteration has occurred after the formation of dolomite and pyrite. However, the timing of the talc alteration in relation to the copper mineralisation remains unknown. Four methods of determining the most accurate and cost effective method for talc abundance estimates within the 3500 orebody are evaluated. The most effective method is through the calculation of stoichiometric equations from XRF assay data. These calculations can be used to create an accurate talc 3D numerical model that enables the distribution and numerical quantity of the talc to be viewed throughout the copper mine.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2004

This item is only available electronically.
The Ernest Henry Iron-oxide Copper Gold (IOCG) deposit is by far the largest in the Eastern Succession of the Mount Isa Inlier. In the current genetic model, the release of CO2 from fluids sourced from enriched mantle was critical to brecciation and mineralisation. However, a weakly mineralised and brecciated shear zone within the orebody named the ‘Inter-lens’ separates the orebody into two distinct lenses. The Inter-lens was not well reported early in the life of the mine and has not been taken into account in the current ore deposit models. Establishing the relative timing of the Inter-lens structure provides strong geological constraints for the formation of the orebody. In this study, optical petrographic investigations, Scanning Electron Microscopy (SEM) and Mineral Liberation Analysis (MLA) were used to investigate the protolith. Key mineral relationships and textures were assessed to reveal the paragenesis of the Inter-lens. Structural observations in oriented drill core complemented underground mapping of exposures of the Inter-lens to reveal the deformational history of the Inter-lens with respect to the Ernest Henry orebody. The protolith was revealed to be Mount Fort Constantine Metavolcanics that have undergone intense deformation with a metasomatic evolution broadly consistent with the main orebody. Mineralisation stages overprinted tectonic fabrics via veining, replacement and infill, providing direct evidence that the Inter-lens is a pre-mineralisation structure. Preservation of the Inter-lens during brecciation and mineralisation of the Ernest Henry deposit requires that the currently accepted ‘explosive’ breccia model must be revised.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2016

Mount Dore-style breccia-hosted copper-gold deposits define a 70 kilometre-long, north-trending lineament from Kuridala (65 kilometres south of Cloncurry), southwards. The type deposit lies 130 kilometres south of Cloncurry, and a detailed study of it was undertaken to produce a metallogenic model applicable (with suitable modifications) to all deposits having this style. Regional geology results from a combination of (i) at least two cycles of ensialic rift sedimentation, (ii) later compressional tectonics and associated metamorphism to a maximum middle amphibolite grade, and (iii) intrusion of late-tectonic granitoids (Beardsmore et al., 1988 and Newbery et al., in prep.). Mount Dore-style deposits are largely restricted to rocks of the upper part of the Middle Proterozoic Maronan Supergroup, a newly-recognized package of rift-basin sediments. The precise age of this unit is presently unknown; it could belong to either rift episode, or be older or younger. The Mount Dore deposit occurs within steeply east-dipping quartz-muscovite schists and carbonaceous slates of the uppermost Maronan Supergroup structurally overlying meta-calcarenites, calcilutites, marbles and metabasalts of the Staveley Formation. The structural history includes early, subhorizontal (D1) detachment of the Staveley Formation from older units, followed by upright, northtrending, tight to isoclinal folding (D2), accompanied by peak metamorphism in the lower to middle amphibolite facies (Jaques et al., 1982). The events are tentatively dated at 1545 Ma, by analogy with D2 and metamorphic history derived for the western part of the Mount Isa Inlier (Page and Bell, 1986). Northwest-trending corridors of open, upright folds belonging to the D3 deformation event are scattered across the region, and one of these passes through the Mount Dore orebody. Latest tectonism produced the Mount Dore Fault Zone, a moderately- to steeply east-dipping reverse fault-zone about 250 metres wide, which passes through Mount Dore and reactivates the D1 structure. The fault zone contains a thin sliver of uppermost Maronan Supergroup, sandwiched between footwall Staveley Formation and hangingwall (truncated) Mount Dore Granite. The granite is dated at 1510 Ma (Nisbet et al., 1983). Mount Dore displays a complex history of brecciation and alteration. Both are related to movement along the Mount Dore Fault Zone and to associated hydrothermal activity. Brecciation was a continuum process, with any particular "event" first producing angular, commonly tabular, crenulated schistose fragments. The crenulation is identified with S3, but is randomly orientated from clast to clast, arguing for post-D3 brecciation. Subsequent reworking of the early fragments involved tectonic and hydrothermal milling. Replacement and infill in the breccias are extensive. Early alteration produced Kfeldspar (or biotite), tourmaline, sericite and quartz. Later alteration produced carbonate (dolomite and calcite), apatite and chlorite. All phases are associated with all brecciation styles, but the most pervasive alteration is associated with the intensively milled breccias. Sulphide mineralization is associated temporally with carbonate alteration, and occurs late in the history of development of the Mount Dore deposit. Primary sulphide mineralization comprises pyrite and chalcopyrite, with minor sphalerite and galena. Pyrite is early, and is replaced by the other phases. Chalcocite also clearly replaces earlier pyrite, but is restricted to shallow depths, and probably formed by deep leaching of the deposit during Recent weathering. Alteration, fluid inclusion and stable isotope geochemistry identify a primary deep-seated, hot (>500oC?), oxidized, CO2-bearing, highly-saline (65-70 wt% salt) metamorphic or magmatic fluid containing K+, Na+, Fe2+, Ca2+, B, SiO2, H+, Cl- and possibly SO2. After initial separation and loss of an immiscible CO2-rich phase, the residual aqueous fluid became more dilute with time, probably by mixing with cooler, lower salinity (<20 wt% salt), low-CO2 fluid, possibly also of metamorphic origin. A model accounting for mineralization at Mount Dore invokes dilation and hydraulic brecciation during movement along the Mount Dore Fault Zone, where the fault intersects D3 "corridors" of shallowly-dipping bedding and S2 foliation. Early potassic and silicic alteration released ore metals (Cu, Pb, Zn, Ag, Co, U, Au) to the fluid from the host rocks at this time. Sulphide precipitation was controlled by sulphate reduction with carbon released from host. Pyrite scavenged most of this, and later Cu-, Pb- and Zn-sulphides formed by scavenging of S from pyrite. Data concerning other Mount Dore-style deposits (Mount Elliott, S.W.A.N., Hampden) are limited, but suggest they may have formed by similar processes, with superficial differences arising from variations in geological setting. These deposits apparently all formed during a single metallogenic event related to late tectonism in the eastern part of the Mount Isa Inlier. A speculative regional model proposes emplacement of at least one large allochthonous slab of Maronan Supergroup over the carbonate-evaporite successions of the Mary Kathleen Group. The latter passed highly saline, CO2-bearing connate and prograde metamorphic fluids upwards into and along the decollement. Subsequent upright to inclined F2 antiforms may have ponded these fluids, allowing them to "stew" for some time in contact with relatively metal-rich rocks in the overriding plate. Alternatively, or additionally, the fluid may have migrated dissolved in Williams Batholith magmas, which were produced by partial melting of deep crustal material probably at the peak of regional metamorphism. Eventual release of hydrothermal fluid to higher crustal levels occurred only when vapour separation occurred in the rising plutons, and when permeable, latetectonic reverse faults, which also controlled the solid-state emplacement of at least some of the plutons, breached F2 structures. Passing rapidly upwards along the faults, the fluids encountered local dilatant zones, where high fluid fluxes and rapidly changing physical and chemical conditions instigated extensive alteration and sulphide precipitation. Low salinity fluids of meteoric, or more likely upper-plate metamorphic derivation also migrated into the dilatant zones when the deeply penetrating fault structures became available, and subsequently mixed with the saline fluids, perhaps initiating some styles of mineralization in the process. Epigenetic mineralization across the Cloncurry Fold Belt (and perhaps the entire Mount Isa Inlier) appears to be the result of large-scale devolatilization of the crust during the waning stages of regional deformation and metamorphism. The characteristics of individual deposits depends on the combination of local factors such as structure and rock types available adjacent to these structures for leaching of metals.