The Genesis And Metallogenic Model Of Lead-Zinc Deposits In The Middle Part Of Dadu River Valley

A number of conformable stratiform Lead-Zinc deposits and occurrences have been discovered in recent years along the Dadu River valley on westem margin of the Yangze Craton. The sulfide-bearing blackish siliceous rocks are interbedded in top of dolomite of Lower Cambrian Maidiping Formation. The author names these deposits as Dadu River Valley Style Lead-Zinc deposits.Based on detail field and microscope observation and ore geochemical analyses, the author regard that these deposits are belong to MTV Lead-Zinc deposits and build up the metallogenic model of Dadu River Valley Style Lead-Zinc deposits.Their geological characters include these follows. They are apparently controlled by faults and distributed along deep faults, such as Ganluo-Xiaojiang, Ebian-Jinyang, Shimian-Ebian. Some minerals in the ore are very fine, such as sphalerite, galenite, pyrite, quartz dolomite and so on. Brecciform, stratiform and block structures are their major types. Silicificative, baritive and carbonative mineralization developed. The ores were formed at low temperature (160-200 degrees). Although there are lots of ores of stratiform structure, most of them are lean ore. The rich ores are brecciform and block structures, which were formed by rebuilding of hot brine in the later.The course of deposits-forming is analyzed: Hot Brine was depressed by Emeishan basalt and drenched basement strata and sedimentary cover, then formed material situation brine, that raised along the faults. When these material situation brine moved to Lower Cambrian Maidiping Formation stratum, PbS, ZnS sedimentated and formed Lead-Zinc deposits because of a shelter--Qiongzhusi Formation stratum which is built up by clay rock.