Mineralogy study of sandstone-type rhenium deposit:A case study of Tieshangeng rhenium deposit in Sichuan basin
Rhenium is a strategic mineral resource that plays a crucial role in national defense and aerospace industry.In the sandstone of the Jurassic Shaximiao Formation in the Muchuan area of southwestern Sichuan Basin,there are multiple rhenium abnormally enriched layers with synsedimentary characteristics.The rhenium mineralization features here are significantly different from those in porphyry copper deposits,characterized by high rhenium grade and large resource volume.To determine the mineral composition and characteristics of rhenium-rich min-erals in the rhenium abnormally enriched layer,this paper selects the Tieshangeng rhenium deposit,which is the most representative of the rhenium abnormally enriched layers in the Muchuan area,as the research object and systematically conducts tests such as polycrystalline X-ray diffraction(XRD),scanning electron microscopy(SEM),and electron probe microanalysis(EPMA).The results show that there are three types of mineral assem-blages of jordisite-chalcopyrite,clausthalite-anilite,and powellite-wulfenite-selenium-malachite in the metallo-genic period of the Tieshangeng rhenium deposit,indicating that the ore-forming fluid gradually changes from medium-low temperature acidic reducing sulfur-rich conditions to medium-low temperature weakly alkaline oxi-dizing sulfur-poor conditions.The main rhenium-rich minerals in the deposit are jordisite(with a Re content of 0.01％～1.85％,averaging 0.35％),powellite(with a ReO2 content of 1.02％～1.14％,averaging 1.08％),and wul-fenite(with a ReO2 content of 0.49％～0.58％,averaging 0.53％).Among them,jordisite is the most important rhe-nium-rich mineral,according to its morphology,it can be divided into oolitic jordisite,block-like jordisite,veinlet jordisite,foggy jordisite,and annular jordisite.Among them,the Re content in oolitic jordisite is the highest(up to 1.85％),and in terms of quantity,foggy jordisite and veinlet jordisite are the main ones.Comprehensive re-search suggests that the extraordinarily enriched rhenium ores in the Jurassic Shaximiao Formation in Muchuan area,southwestern Sichuan Basin is a kind of sandstone-type rhenium deposit produced in siliceous clastic rocks and closely related to jordisite.
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