Geochemical Background And Distribution Of Gold And Associated Elements In The Carlin-Type Gold Districts Of Yunnan-Guizhou-Guangxi Region,China

The Yunnan-Guizhou-Guangxi region is an important locality of Carlin-type gold deposit.In this paper,we collected the stream sediments geochemical data from the 1:200000 Regional Geochemistry-National Reconnaissance project(RGNR),rock and soil geochemical data from the China Geochemical Baselines project(CGB)to investigated the geochemical background and temporal-spatial distribution of gold and its associated elements.The results were compared with the regional geochemical characteristics in soils of Nevada,USA.The following conclusions can be drawn:(1)Factor analysis of 20 elements in stream sediments indicates four main associations:Factor 1(Co,Cr,Cu,Nb,Ni,Ti,V)represents the geological processes related to the basic magmatic rock activities and Cu,Ti metallogenesis in the study area;factor 2(B,F,Li,U)represents carbonate sedimentary construction in the shallow marine platform environment of the Youjiang basin and U metallogenesis;factor 3(Ag,Bi,Cd,Pd,Zn)represents various medium-low temperature hydrothermal metallogenic processes;factor 4(As,Au,Hg,Sb)represents the typical Carlin-type gold and hydrothermal mercury-antimony metallogenesis in the study area.(2)The Yunnan-Guizhou-Guangxi region is an important enrichment area of gold,arsenic,antimony and mercury in China,and the distribution characteristics of those elements were consistent in the regional faults and secondary landscape areas.Five gold geochemical provinces,one giant geochemical province and one geochemical province of arsenic,seven antimony geochemical provinces,and six mercury geochemical provinces were delineated over the anomaly threshold in this area.Most of these geochemical anomalies were consistent with the spatial distribution of corresponding metallogenic districts.(3)The Youjiang basin and Triassic strata owned the highest background values of Au,As,Sb and Hg in the study area,where was the mudstone,shale,sandstone,and siliceous rocks with the highest background values of above elements.These areas with high background values were also the regions where Carlin-type gold deposits and hydrothermal mercury-antimony deposits located.The concentrations of Au,As,Sb and Hg were obviously enriched in the process of secondary weathering from rocks to stream sediments,but the of elements had some inheritance from stream sediments to rocks,but the rocks with high background values was not the only factor that determines the formation of geochemical anomalies in stream sediments.(4)The background values of As,Sb and Hg of soils in China were higher than that in USA.And Nevada,the world's largest Carlin-type gold ore districts,owned the lower background values of As,Sb and Hg than that in the Yunnan-Guizhou-Guangxi region implied two possibilities:1)the concentrations of As,Sb and Hg in Yunnan-Guizhou-Guangxi region were significantly enriched in soils;2)the Yunnan-Guizhou-Guangxi region of China still has great potential for further exploration.