Geological And Geochemical Characteristics And Regional Metallogenic Prospective Evaluation Of The Sanchahe-Xiongbi Area,Yunnan Province

The Sanchahe-Xiongbi area is located in the eastern part of Yunnan province.It's tectonic position mainly belongs to the eastern Yunnan passive continental margin fold-thrust belt in the southern part of the Upper Yangtze block.It is sandwiched between the Xiaojiang Fault and the Mile-Shizong large fault.The tectonic zone is an important gold,copper,lead and zinc mineral prospecting area in Yunnan Province characterized with sedimentary and stratabound type mineralization.This paper focuses on the geochemical characteristics of the Emeishan basalts and stream sediments,and discusses the metallogenic geological conditions and the metallogenic element combination.On the basis of comprehensive geological,geochemical anomalies,remote sensing interpretation and other prospecting information,the metallogenic prospect of the study area was systematically evaluated,and the metallogenic prospect area was delineated.The volcanic rocks in the study area are high-Ti basalt of subalkaline tholeiitic series,formed in an extensional environment of intraplate.Geochemical data show that basalt magma is formed by partial melting of the garnet lherzolite enriched mantle.During the evolution of magma,the fractional crystallization has been occurred with no crustal contamination.The major elements and trace elements characteristics show that the basalt has obvious characteristics of the OIB,which has the genesis characteristics of the mantle plume,and provides advantage condition for regional mineralization.The geochemical characteristics of the study area geochemical characteristics are further identified by carrying out 1:50000 stream sediment survey and statistical analysis of 16 kinds of elements.The work has greatly enriched large scale regional geochemical data.The geochemical characteristics of the stream sediments indicate that all elements in the study area are higher than the background value of Yiliang area.The enrichment of these elements in the study area provides favorable conditions for mineralization.Through multivariate statistical analysis,two types of metallogenic element combination were identified,which are Au-HgSb(-As-Pb-Zn-Bi-W)and Cu-Fe(-Co-Cr-V).The main metallogenic elements are Au,Hg,Sb,Cu and Fe.In the study area,465 single element anomalies and 5 composite anomalies have been delineated,providing a powerful evidence for delineation and evaluation of metallogenic prospective area.By use of geostatistical methods for analyzing and counting geological metallogenic information,geochemistry anomaly,remote sensing interpretation information,five metallogenic regions have been quantitatively delineated.The high information value in the metallogenic prospective area is mainly distributed in the northeast direction,which is consistent with the regional stratigraphic,structure and magmatic rock distribution characteristics.The geochemical abnormal distribution and remote sensing interpretation are matched well with the high value of information.It has a good relationship with each metallogenic geological factor,and provides an important evidence for the further prospecting work in the study area.