Research Article| March 01, 2005 Major orogenic gold episode associated with Cordilleran-style tectonics related to the assembly of Paleoproterozoic Australia? A. Kerim Şener; A. Kerim Şener 1Centre for Global Metallogeny, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Search for other works by this author on: GSW Google Scholar Carl Young; Carl Young 1Centre for Global Metallogeny, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Search for other works by this author on: GSW Google Scholar David I. Groves; David I. Groves 1Centre for Global Metallogeny, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Search for other works by this author on: GSW Google Scholar Bryan Krapež; Bryan Krapež 1Centre for Global Metallogeny, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Search for other works by this author on: GSW Google Scholar Ian R. Fletcher Ian R. Fletcher 1Centre for Global Metallogeny, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information A. Kerim Şener 1Centre for Global Metallogeny, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Carl Young 1Centre for Global Metallogeny, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia David I. Groves 1Centre for Global Metallogeny, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Bryan Krapež 1Centre for Global Metallogeny, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Ian R. Fletcher 1Centre for Global Metallogeny, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Publisher: Geological Society of America Received: 14 Jul 2004 Revision Received: 18 Nov 2004 Accepted: 26 Nov 2004 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2005) 33 (3): 225–228. https://doi.org/10.1130/G21017.1 Article history Received: 14 Jul 2004 Revision Received: 18 Nov 2004 Accepted: 26 Nov 2004 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation A. Kerim Şener, Carl Young, David I. Groves, Bryan Krapež, Ian R. Fletcher; Major orogenic gold episode associated with Cordilleran-style tectonics related to the assembly of Paleoproterozoic Australia?. Geology 2005;; 33 (3): 225–228. doi: https://doi.org/10.1130/G21017.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract New in situ sensitive high-resolution ion-microprobe (SHRIMP) U-Pb analyses of hydrothermal phosphates associated with orogenic gold mineralization in the Paleoproterozoic Ashburton and Pine Creek gold provinces of northern Australia provide ages of ca. 1740 and ca. 1730 Ma, respectively. Argon-argon analyses of gold-related hydrothermal mica from the Tanami gold province of northern Australia provide ages ca. 1730 Ma. It is important to note that late orogenic events across the western half of Australia coincide with gold metallogenesis across this time interval, in several widely separated provinces. Thus, this orogenic gold episode is interpreted to relate to tectonic events during the amalgamation of various continental blocks to form Paleoproterozoic Australia. It is potentially Earth's best-preserved record of orogenic gold formation during a major early Precambrian continental assembly event. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Many gold deposits in the Laverton greenstone belt, in the northeast of the Eastern Goldfields province of the Yilgarn craton, are located adjacent to, or hosted by, granitoids. This has led to controversy over whether the granitoids provided the auriferous fluids from which the deposits formed or were structural traps controlling the siting of the gold deposits. New regional-scale stable isotope data, combined with robust geochronology on several deposits, resolves this controversy in the Laverton greenstone belt. The median S, C, and O isotope compositions of ore and gangue minerals from nine different gold deposits in the Laverton greenstone belt fall in a very narrow range. The only exceptions to this are the more negative δ 34 S values of ore sulfides at the Jupiter gold deposit, which were most likely caused by preexisting highly oxidized host rocks and the more negative δ 13 C values of ore carbonate at deposits with reduced black shale host rocks. Redox conditions and mineralization temperatures for all gold deposits in the Laverton greenstone belt are broadly similar. Therefore, the lack of variation in the isotopic compositions of ore and gangue minerals is consistent with their deposition from a similar ore fluid. There is no convincing evidence to indicate that more than one ore fluid was involved in deposition of gold deposits within the Laverton greenstone belt, although the data do not uniquely define the source of the ore fluid (e.g., whether it was proximal or distal). SHRIMP U-Pb dating of gold-related monazite and xenotime provides a temporal framework for gold mineralization in the Laverton greenstone belt. Synmineralization phosphates have ages of 2650 ± 7 Ma at Mount Morgans, 2649 ± 11 Ma at Jubilee, 2657 ± 21 Ma at Jupiter, and probably 2653 ± 6 Ma at Granny Smith. The similarity in age of these four deposits, as well as previously published ages for the Wallaby (2650 ± 5 Ma) and Sunrise Dam and/or Cleo deposits (2654 ± 8 Ma), places three major constraints on the source of auriferous fluids in the Laverton greenstone belt. First, the Wallaby and, most likely, the Granny Smith gold deposits are not the same age as adjacent granitoids, ruling out the exposed granitic rocks as a proximal magmatic fluid source. Second, the broadly synchronous timing of gold mineralization on a camp scale provides evidence that the deposits have a similar genesis. Third, the range of ages of the gold deposits is not as great as that of the granitoids postulated to be their source. Magmatic activity that has been invoked as the source of ore fluids by various workers is related to several geochemically distinctive granitoid suites that are diachronous over several tens of millions of years in the Laverton greenstone belt and the wider Eastern Goldfields province. In contrast, the consistent age of gold mineralization in the Laverton greenstone belt supports a single fluid source, as implied by the isotope geochemistry. It is concluded that all studied deposits are orogenic gold deposits with a distal and deep source.
The Tombstone, Mayo and Tungsten plutonic suites of granitic intrusions, collectively termed the Tombstone-Tungsten Belt, form three geographically, mineralogically, geochemically and metallogenically distinct plutonic suites. The granites (sensu lato) intruded the ancient North American continental margin of the northern Canadian Cordillera as part of a single magmatic episode in the mid-Cretaceous (96-90 Ma). The Tombstone Suite is alkalic, variably fractionated, slightly oxidised, contains magnetite and titanite, and has primary, but no xenocrystic, zircon. The Mayo Suite is sub-alkalic, metaluminous to weakly peraluminous, fractionated, but with early felsic and late mafic phases, moderately reduced with titanite dominant, and has xenocrystic zircon. The Tungsten Suite is peraluminous, entirely felsic, more highly fractionated, reduced with ilmenite dominant, and has abundant xenocrystic zircon. Each suite has a distinctive petrogenesis. The Tombstone Suite was derived from an enriched, previously depleted lithospheric mantle, the Tungsten Suite is from the continental crust including, but not dominated by, carbonaceous pelitic rocks, and the Mayo Suite is from a similar sedimentary crustal source, but is mixed with a distinct mafic component from an enriched mantle source.
Giant,and to a lesser extent world-class,mineral deposits are the ultimate exploration targets,with discovery changing the financial bottom line of junior exploration companies and providing long-term resources and reserves for major mining companies.Despite this,there have been few volumes specifically devoted to giant mineral deposits,with most research papers
The Early Archean Bamboo Creek gold deposit contrasts with most other orogenic deposits because of its relatively early timing in the tectonic evolution of the Pilbara granitoid-greenstone terrane. The Bamboo Creek deposit is situated in a bedding-parallel, brittle-ductile shear zone (the Bamboo Creek shear zone) within a komatiite sequence. The laminated quartz-carbonate gold lodes occur in carbonate-altered boudins within the Bamboo Creek shear zone and are associated with early sinistral, northeast-up deformation in the shear zone, whereas dextral reactivation of the zone postdates gold deposition. Gold-related alteration zones reflect an increase in X CO 2 toward the mineralized zone. Variations in original host-rock composition give rise to asymmetric alteration zoning, with a fuchsite-carbonate zone in the more Mg- and Cr-rich cumulate-textured footwall and a chlorite-quartz zone in the more aluminous spinifex-textured hanging wall. The alteration envelope is enriched in Na 2 O, K 2 O, Rb, Pb, As, and Sb. Whereas pyrite and minor chalcopyrite occur in all alteration zones, tetrahedrite, galena, and sphalerite are strongly associated with gold in the lodes. The alteration and metal enrichment of the Bamboo Creek gold deposit are indistinguishable from those of other orogenic (mesothermal) lode gold deposits in Archean terranes. Carbonate δ 13 C (PDB) and δ 18 O (SMOW) isotope signatures are consistent throughout the alteration envelope at 0.2 ± 0.6 and 14.6 ± 0.6 per mil, respectively. The δ 13 C value, in particular, is higher than typical values for orogenic gold deposits, implying interaction of auriferous fluids with preexisting marine carbonates that formed during an early sea-floor alteration event. The temperature of deposition, estimated from chlorite thermometry and alteration assemblages, is about 250°C, which is within the lower part of the range for orogenic gold deposits. Lead-lead model ages for galena, together with the relationships between the Bamboo Creek shear zone and dated granites, indicate a relatively early age of gold deposition of ca. 3400 Ma. Correlation of structures associated with gold deposition and regional structural phases shows that gold deposition was most likely related to an extensional tectonic phase. The early timing and association with extension is unlike the tectonic setting of other Archean gold deposits, which tend to form during the final, compressional or strike-slip stages of orogenesis. The Bamboo Creek gold mineralization may have been related to an Early Archean lower crustal delamination event. This may explain the anomalous timing and the low gold endowment of the Pilbara relative to Late Archean greenstones.
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