The characteristics of wall-rock alteration and the trace element migration in Dajishan U-(Mo)deposit,Youjiang basin:Implications for genetic relationship between the uranium and gold mineralization
Located in the southwest margin of the Yangtze Block,Youjiang basin is the second largest cluster area of Carlin-type gold deposits(associated with Sb,Hg,Tl anomaly and mineralization)in the world,is also known as"Golden Triangle"of Dian-Qian-Gui.Beside the gold deposit,a large number of U deposits(occurrences)with similar ore-hosting lithology and ore-controlling structure are also developed in this area.However,previous research were mostly focused on the gold,a few was on uranium.The genetic relationship between U and Au is still unclear.In this paper,Dajishan U-(Mo)deposit in the Youjiang basin was studied as a case of a large number of U and Au deposits(or ore occurrences)discovered in the region.In space,uranium and gold mineralization are closely related which provided an ideal research object for understanding the regional mineralization process and the relationship between Au and U mineralization.In this paper,petrography,mineragraphy and geochemistry was used to study the alteration mineral in the Dajishan U-(Mo)deposit,sulfides,bitumen,goyazite,quartz and illite were examined,and the relative enrichment of Re,Tl,Mo,U,Cd,Ni,Co,As,Sb and MREE was discovered during the mineralization process.The alterated mineral assemblage and trace element migration constrain that the ore-forming materials of Dajishan U-(Mo)deposit probably came from Niutitang Formation,and the ore-forming fluid should be a mixture of reductive organic fluid and surface to near surface acidic and oxydic fluid,and the mineralization occurred in low temperature,acidic and reductive environment.Comprehensive analysis suggests that there is significant differences in the distribution characteristic and genesis of U and Au deposits in the Youjiang basin,and U and Au deposits should be products of different mineralization events.
wall-rock alterationtrace element migrationDajishan U-(Mo)depositgenetic relationship between the uranium and gold mineralizationYoujiang basin
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