VCMSM Report 2 - An evaluation of rare earth elements, phosphorus, vanadium and rhenium in sediment starved stratigraphy in Victoria.
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Product description:Executive Summary:As part of the Developing Victoria’s Critical Minerals Initiative, new pre-competitive geoscience was acquired to characterise the presence and form of a select number of Victoria’s known critical mineral occurrences. Sedimentary phosphate deposits in Australia and elsewhere in the world can contain elevated rare earth elements. Geochemical processes in sediment starved environments allow the rocks to become enriched in other critical minerals including vanadium and rhenium. Sediment starved rocks occur in late Cambrian to early Ordovician stratigraphy across central and eastern Victoria and contain historical phosphate production and small phosphate occurrences. This study investigated sedimentary phosphate mineralisation from the Phosphate Hill Mine in Mansfield, Victoria’s largest known phosphate deposit, and the Romsey Phosphate Mine to understand the potential for critical minerals in these deposits. These sites were selected to test the influence of two different, albeit widespread, early Palaeozoic palaeogeographic settings in Victoria – submarine continental plateau and/ or shelf settings and submarine abyssal plain settings - on the potential of critical mineral enrichment within phosphatic sediments. Two drill holes from beneath the Phosphate Hill Mine, in stratigraphy deposited on a submarine plateau, were sampled along their entire length and analysed for multielement geochemistry. Results confirmed the down dip continuation of the phosphate horizon mined near surface, which was 20 to 30 metres wide (downhole width). The new geochemistry data show low level heavy rare earth element enrichment within the phosphate interval. Several carbonaceous shale horizons (up to 5 metres downhole width) contain narrow (less than 1 metre) intervals of elevated vanadium (up to 0.17 % V2O5) and rhenium (up to 0.55 ppm Re). Trace element geochemistry of the phosphatic interval suggests that it contains airfall volcanic detritus sourced from the coeval Ordovician Macquarie Arc. Samples of stockpiled iron and phosphorus rich accretionary nodules from the former Romsey Phosphate Mine, in stratigraphy deposited in a submarine abyssal plain setting, are not elevated in rare earth elements but do contain elevated base metal values (including up to 63% Fe2O3 and 0.33% Zn). Palaeogeographic considerations indicate that prospectivity for rare earth elements, vanadium and rhenium may be higher elsewhere based on known stratigraphy. For example, sediment starved stratigraphy that has been exposed to above wave base conditions necessary for the mechanical concentration of phosphate and its contained rare earth elements in the southern Melbourne Zone. These rocks remain unsampled and warrant further work to characterise the stratigraphy and critical mineral potential. Bibliographic Reference: Andrews, T.M. & Cayley, R.A. 2024. An evaluation of rare earth elements, phosphorus, vanadium and rhenium in sediment starved stratigraphy in Victoria. Victoria’s Critical Minerals and Strategic Materials, Report 2. Geological Survey of Victoria. Department of Energy, Environment and Climate Action, Melbourne. 63 pp. Download: The downloadable version of this report is supplied as (PDF 21 MB), Attachment A1 data (XLSX/ODS 134 KB) & Attachment A2 data (PDF 91 KB). Related products:
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