Thông tin tài liệu
AUSTRALIA/Proterozoic 221 the Palaeozoic Lachlan Orogen Extensive eruption of continental flood basalts (Kalkarinji large igneous province) of the $510-My-old Antrim Plateau Volcanics and the Table Hill Volcanics in northern and western Australia may reflect further mantle plume activity coincident with this collision Mineral Deposits The Proterozoic rocks of Australia are endowed with substantial mineral resources, containing significant deposits of iron ore, manganese, uranium, gold, copper, lead, zinc, silver, nickel, and diamond (Figure 8) (see Mineral Deposits and Their Genesis) World-class hematite deposits (Mount Whaleback, Tom Price) have been produced by enrichment of the banded iron formations of the Hamersley Basin during the Palaeoproterozoic The highest grade lowP deposits (62–69% Fe), have been interpreted as the product of burial metamorphism of original supergene enrichment prior to $1840 Ma More recently, they have been reinterpreted as the product of hypogene processes related to the expulsion of fluids into the foreland of the Ophthalmian Orogeny ($2200 Ma) Proterozoic iron ore deposits have also been mined in the Palaeoproterozoic iron formations of the Hutchison Group in the Gawler Craton, and from enrichment of ferruginous placer deposits in the upper Kimberley Group in the Kimberley Basin (Koolan Island) Manganese has been mined from supergene deposits (Woodie Woodie) associated with Palaeoproterozoic karst developed on dolomites in the eastern Hamersley Basin ‘Unconformity-related’ uranium (Ỉ Au Ỉ platinum group elements) deposits (Rum Jungle, Alligator River) are found in Palaeoproterozoic sedimentary successions overlying predominantly Archaean basement rocks in northern Australia, and may be related to interaction of highly oxidized, acidic and Ca-rich meteoric brine with reduced basement fluids Similar deposits have been found elsewhere in the Australian Proterozoic, including Kintyre, where Neoproterozoic metasedimentary rocks overlie Palaeoproterozoic basement Metasomatic U deposits and the metamorphic-related Mary Kathleen deposit occur in Palaeoproterozoic rocks of the Mount Isa Inlier Gold is found in a number of settings throughout the Proterozoic, and historic production is related to generally small lode-gold occurrences and associated alluvial deposits Major gold (Cu) mines have been developed at Telfer in the Yeneena Basin, and at The Granites in the Granites–Tanami Complex Mineralization is centred on metasedimentary rocks in structural domes and is hypogene, related to the emplacement of granitic pluton(s) near a periodically reactivated, regional-scale, fluid-focusing structure, often a strike–slip fault ‘Proterozoic Cu–Au deposits’ are found associated with iron oxide in the Tennant Creek Inlier, at Olympic Dam in the northern Gawler Craton, and in the Mount Isa Inlier (Ernest Henry) There is usually a spatial and temporal relationship between this style of deposit and granite intrusion (e.g., Olympic Dam and the $1590-My-old Hiltaba Suite) Cu mineralization at Mount Isa is regarded as syn-deformational, late metamorphic, and is a separate event from Pb–Zn–Ag mineralization The Mount Isa orebody is a world-class example of stratiform sediment-hosted Pb–Zn–Ag mineralization, produced by oxidized fluids moving through the sediment pile and being deposited either by seafloor exhalative processes or within the sediments A similar orebody is present at McArthur River The Broken Hill orebody is generally regarded as a metamorphosed example of stratiform sediment-hosted mineralization, although syn-metamorphic, skarn-type processes may have modified it Volcanic-hosted massive sulphide (VHMS) Pb–Zn mineralization has been found at Koongie Park in the Halls Creek Orogen Nickel mineralization in the Proterozoic, together with platinum group elements, Cu, and V, is generally associated with layered mafic–ultramafic intrusions such as those in the Halls Creek Orogen (Sally Malay) Large, layered intrusions are also present in the Musgrave Complex (Giles Complex–Nebo and Babel deposits), the Albany–Fraser Orogen (Fraser Complex), and the Arunta Inlier The Argyle diamond mine, which is the world’s largest, is developed on the $1200-My-old AK1 lamproite pipe intruded into the Halls Creek Orogen Proterozoic diamondiferous kimberlites from $815 Ma are present in the Kimberley Basin (see Igneous Rocks: Kimberlite) See Also Igneous Processes Igneous Rocks: Kimberlite Large Igneous Provinces Mantle Plumes and Hot Spots Metamorphic Rocks: Classification, Nomenclature and Formation Mineral Deposits and Their Genesis Mining Geology: Exploration; Hydrothermal Ores Plate Tectonics Sedimentary Environments: Depositional Systems and Facies Sedimentary Rocks: Mineralogy and Classification; Banded Iron Formations Tectonics: Mountain Building and Orogeny Time Scale Further Reading Australian Geological Survey Organisation (1998) Geology and mineral potential of major Australian mineral pro vinces AGSO Journal of Australian Geology and Geophysics 17(3): 260
Ngày đăng: 26/10/2022, 10:54
Xem thêm:
