Enrichment Regularity Of Dispersed Elements And The Geochemical Charateristics Of Lawu Cu-Zn Deposit In Tibet

The Lawu Cu-Zn deposit is a skarn deposit,which is located in Xainza-Poindo Cu-Ag-Pb-Zn-Au mineralization subzone in Gangdese magmatic-tectonic metallogenic belt.The geologists have done numerous researchs in the area and accumulated a large amount of data since 1995.In order to understand the enrichment regularity of dispersed elements in the deposit,the author studies the geochemical characteristics of the deposit and the enrichment characteristics of dispersed elements with field geological survey,data collection,systematic sampling and analysis.Through contrast with the representative Pb-Zn deposit in Tibet and other places in China,the paper discusses the enrichment characteristics of dispersed elements Cd in different deposit types,different mineralization backgrounds and different regions.After a detail study,the main results obtained are as follows:?1?The hydrothermal alteration gradually reduce from near ore to far wall rock in the deposit.It is difficult to dissolution and migration for Si O₂,which indicates that the ore-forming fluid is alkaline in the Lawu Cu-Zn deposit.Due to some rare earth elements of wall rock near the ore got into the ore-forming fluid,and migrated with the fluid.Hence the?REE of wall rock near the ore is far lower than rock.?2?The dispersed elements mainly occur as isomorphism instead of independent minerals.Geochemistry study shows that the ores and minerals have little Ge and Tl,whereas large amount of Cd and In exist,especially in sphalerite.The maximum concentrations of Cd and In element in sphalerite is 6400 ppm and 75 ppm,seperately.The main mineral containing element Ge is galena,the sphalerite have a large number of Cd.?3?Evidences from the reaserch implies that the mineralization of Skar deposit is conducive to enrich the dispersed element Cd.Geological survey shows that the enrichment of Cd gradually decreased from north to south in Tibet,the Cd is more easily isomorphism with Zn-containing mineral in the Gangdese belt.The concentrations of Cd are related to rock mass,and the concentrations of Zn are related to host rock.The mineralization of Pb-Zn deposit in southwest china is more conducive to enrich the dispersed element Cd.The wall rock containing limestone in the deposit usually has a large amount of Cd.