首页|The gold-telluride connection:Evidence for multiple fluid pulses in the Jinqingding telluride-rich gold deposit of Jiaodong Peninsula,Eastern China
The gold-telluride connection:Evidence for multiple fluid pulses in the Jinqingding telluride-rich gold deposit of Jiaodong Peninsula,Eastern China
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The mechanism of gold migration,enrichment,and precipitation in forming world-class gold deposits has been a topic of wide interest,particularly where these deposits are abundant in tellurides.The Jiaodong Peninsula in eastern China hosts some of the world-class gold deposits among which the Jinqingding deposit is one of the best examples with substantial telluride mineralization and thus provides opportu-nity to investigate the genetic connection between tellurium and gold mineralization.The orebody in this deposit is hosted in the NE-NNE-trending Jiangjunshi-Quhezhuang fault with the Jurassic Kunyushan granitic pluton as wall rock.The deposit involved three mineralization stages as inferred from assem-blages and crosscutting relationships between veins.These stages are:(Ⅰ)pre-ore gold-poor quartz-pyrite veins,(Ⅱ)main ore auriferous quartz-pyrite-Te/Bi-minerals±sphalerite±chalcopyrite±barite±marc asite veins,and(Ⅲ)post-ore quartz-calcite veins.We present here the textural,isotopic,and geochemical variations of different stages/generations of pyrite based on scanning electron microscopy-energy disper-sive spectroscopy(SEM-EDS),electron probe microanalysis(EPMA),and laser ablation inductively cou-pled plasma mass spectrometry(LA-ICP-MS).Pyrite in the Jinqingding deposit displays distinct characteristics.Py1a shows a porous and dissolution-reprecipitation texture in the core,whereas Py1b exhibits a smooth and flat rim.Geochemical analysis reveals contrasting elemental compositions,with Py1a characterized by low Au(avg.0.14 ppm),As(avg.15.57 ppm),Ag(avg.17.71 ppm),and Te(avg.19.22 ppm)contents,but elevated Co(avg.1068.10 ppm)and Ni(224.12 ppm)concentrations,and variable sulfur isotopic composition(δ34SV-CDT=9.54‰-12.12‰).Conversely,Py1b displays increased concentrations of these elements and a more concentrated δ34SV-CDT value(11.99‰-12.23‰),possibly associated with weak coupled dissolution-reprecipitation(CDR)processes.In Stage Ⅱ,pyrite can be further categorized into two generations:the porous core(Py2a)and the smooth periphery(Py2b).Notably,Stage Ⅱ exhibits increased contents of Au(Py2a:avg.0.47 ppm;Py2b:avg.5.57 ppm),As(Py2a:avg.1265.20 ppm;Py2b:1049.46 ppm),Ag(Py2a:avg.5.43 ppm;Py2b:avg.65.23),and Te(Py2a:avg.21.47 ppm;Py2b:avg.51.66 ppm),δ34SV-CDT value exhibits minor changes(Py2a:11.48‰-1 3.05‰;Py2b:11.79‰-12.80‰).These changes poten-tially indicate the involvement of a fluid pulse characterized by low fO2:-34.9 to-30.2,medium fTe2:-14.7 to-10.9 and fS2:-11.4 to-6.9.Despite the dissolution-reprecipitation textures present in the ores,gold did not undergo remobilization,except for a possible weak contribution in Stage Ⅱ.The pres-ence of abundant Bi/Te-minerals underscores the significant role of low-melting point chalcophile ele-ments in gold migration and enrichment.By compiling and analyzing sulfur isotopic composition of gold deposits across the entire Jiaodong Peninsula,which shows the reduction of marine sulfates as a cru-cial mechanism for sulfur enrichment.We conclude that the Jinqingding gold deposit,characterized by abundant tellurium,along with episodic pulses of ore-forming fluids,and exhibit subtle distinctions com-pared to other gold deposits within the Jiaodong Peninsula.
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