Geochemical Characteristics and Geological Significance of Pyrite and Calcite in the Puke Gold Prospect Area,Guizhou Province
The Puke gold prospecting area is located 3 km southwest of the famous Nibao gold deposit,sharing the same regional geological background,similar stratigraphic characteristics,tectonic style,and ideal geolo-gical conditions for gold mineralization.Based on field observations of the calcite veins(limonitization)deve-loped on the surface and in drill holes,we conducted mineralogical analysis of calcite and pyrite,rare earth ele-ment(REE)analysis of calcite,electron probe micro-analysis(EPMA),and LA-ICP-MS analysis of pyrite to constrain the origin of the ore-forming fluids and materials in the Puke gold prospecting area.The results show that most of the calcite veins in the Puke gold prospect area have similar characteristics to those in the Nibao gold deposit;however,the latter does not contain ore-bearing calcite veins.Most calcite veins in the Puke gold prospect area exhibit REE patterns similar to those of the Nibao gold deposit,and a few calcite samples show positive Eu anomalies,similar to the calcite from the mineralization period of Carlin-type gold deposits in South-eastern Guizhou.However,the Au content of pyrite in these calcite veins is several orders of magnitude higher than that of the average crustal abundance and sedimentary pyrite,with Au existing in pyrite in the form of Au+.This suggests that these pyrite veins are of hydrothermal origin.The gold-bearing calcite exhibits an en-richment pattern of medium REE and positive Eu anomalies.This suggests that the gold-forming fluids are reducing,possibly controlled by acidic ore-forming fluids as in the case of the Nibao gold deposit.There are fewer calcite veins exposed on the surface in the Puke gold prospect area,possibly because the favorable ore-forming strata of the Puke gold are deeper.There is less ore-forming hydrothermal fluid transported to the pre-sent-day surface strata,implying that ideal gold mineralization developed at deeper levels.
geochemistryhydrothermal calcitepyritemedium REE enrichmentthe Puke gold prospect area
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