Sheree Armistead , Sebastien Meffre , Ralph Bottrill , Andrew Cross , David Huston , Grace Cumming
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引用次数: 0
Abstract
Plate tectonic reconstructions place Laurentia and eastern Australia together during the Mesoproterozoic. Specifically, the Belt-Purcell Basin in the USA and Canada has been linked to the Rocky Cape Group in northwest Tasmania based on detrital zircon studies. The Belt-Purcell Basin is highly endowed in economic deposits of Cu, Pb, Zn, Ag and critical metals such as Co, formed during the Mesoproterozoic. The Rocky Cape Group of northwest Tasmania hosts several sediment-hosted Cu-Pb-Zn ± Co prospects, however they were previously thought to be Devonian in age. New laser ablation inductively-couple plasma mass spectroscopy (LA-ICP-MS) in situ U-Pb monazite, xenotime and apatite data, sensitive high resolution ion microprobe (SHRIMP) in-situ U-Pb monazite data, and LA-ICP-MS galena Pb isotope data were collected from these prospects. By using multiple minerals with different U–Pb closure temperatures, we have unravelled a complex and protracted history of thermal pulses in the Rocky Cape region associated with Cu-Pb-Zn ± Co mineralisation. These data indicate that primary sulphide mineralisation formed at c. 1350 Ma, with several resetting or remobilisation events recorded at c. 1250 Ma, c. 1100 Ma and c. 950 Ma. These ages are contemporaneous with previously published authigenic monazite and metamorphic monazite ages from the Rocky Cape Group. This suggests that mineralisation is broadly syn-sedimentary and related to the development of the basin into which the Rocky Cape Group was deposited. These new ages are similar to those of sediment-hosted ore deposits in the Belt-Purcell Basin in the USA and Canada, further supporting the proposed link between northwest Tasmania and North America during the Mesoproterozoic. The high metal endowment of age-equivalent rocks in the Belt-Purcell Basin, highlight the potential for new discoveries of base and critical metals in southeastern Australia.
期刊介绍:
Precambrian Research publishes studies on all aspects of the early stages of the composition, structure and evolution of the Earth and its planetary neighbours. With a focus on process-oriented and comparative studies, it covers, but is not restricted to, subjects such as:
(1) Chemical, biological, biochemical and cosmochemical evolution; the origin of life; the evolution of the oceans and atmosphere; the early fossil record; palaeobiology;
(2) Geochronology and isotope and elemental geochemistry;
(3) Precambrian mineral deposits;
(4) Geophysical aspects of the early Earth and Precambrian terrains;
(5) Nature, formation and evolution of the Precambrian lithosphere and mantle including magmatic, depositional, metamorphic and tectonic processes.
In addition, the editors particularly welcome integrated process-oriented studies that involve a combination of the above fields and comparative studies that demonstrate the effect of Precambrian evolution on Phanerozoic earth system processes.
Regional and localised studies of Precambrian phenomena are considered appropriate only when the detail and quality allow illustration of a wider process, or when significant gaps in basic knowledge of a particular area can be filled.