Unconformity-style rare earth element mineralisation along the Watts Rise-Castella Trend, Tanami Region, Western Australia.
Date
2022
Authors
Rowland, J. R.
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Abstract
Unprecedented demand for rare earth elements (REEs), driven by the development of new ‘green energy’ technologies, is driving significant exploration activity globally. Traditionally, REE production has been controlled by unique igneous rocks (e.g., peralkaline volcanics and plutonics) considered relatively minor in the geological record; however, to address demand, new mineralisation styles are being explored.
Newly recognised unconformity-style hydrothermal REE (+ Au) mineralisation along the Watts Rise-Castella Trend by PVW Resources Ltd in the Tanami Region of north-western Australia comprises HREE-dominant mineralisation along a regional unconformity, hosted within hematised conglomeratic units of the Paleoproterozoic Pargee Sandstone. Detailed ore mineralogy, petrography, and mineral chemistry (via LA-ICP-MS) of samples from two currently-identified prospects within the exploration area provide insights into REE distribution. Geochronological ages via LA-ICP-MS U-Pb dating for both xenotime and zircon in the Pargee Sandstone constrain both the timing of ore mineralisation and the maximum depositional age of the host rock.
Two main REE-bearing minerals are identified: xenotime [(Y,HREE)PO4] and florencite (LREEAl3(PO4)2(OH)6). Xenotime is the major host of HREEs, and occurs in different textural phases. In-situ U-Pb dating of xenotime yielded an age range of mineralisation between ca. 1.65 to 1.60 Ga; this timeframe is absent in local magmatic or orogenic events and is comparable to the timing of other REE occurrences in the region, suggesting a regional scale hydrothermal event in northern Australia. Detrital zircon U-Pb geochronology for the Pargee Sandstone produced a wide range of ages primarily between ca. 2.6 to 1.8 Ga, and a maximum depositional age between 1811 ± 5 Ma and 1832 ± 8 Ma. There is significant potential for discovery of further orebodies of this style, especially in the vicinity of regional unconformities, and given the current surge in exploration for REEs, this investigation will assist in the development of exploration models for equivalent terranes.
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School of Physical Sciences
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Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, YEAR
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