Study On Geological Characteristics Of Pb-Zn Deposits In Mayuan, Nanzheng County

Dengying formation of Sinian distributed around the margin of Yangtze platform is importantformation which Pb-Zn ore deposits occur in. Now, a number of Pb-Zn deposits was discovered in Hunan,Guizhou,Guanxi,Yunnan,Shaanxi province on Yangtze platform, and MaYuan Pb-Zn ore deposits is alarge Pb-Zn ore deposits discovered on the north margin of Yangtze platform these years, the ore body isstrata-controlled, occurred in the breccias of Dengying formation.Based on the research of the geological characteristics, This text focuses on the geochemicalcharacteristics of Pb-Zn ore deposits.Through the research on geochemical characteristics of host rocks, geochemical comparison betweenhost rocks and vein, and also between vein and ore deposits, the research on inclusion geochemistry of oredeposits. It shows that the host rocks dolomites are normally carboniferous rock of marine sediments,probably influenced by hydrothermal fluidl. Dolomite, calcite, quartz vein have close relations to host rocks,it was the result of interaction between diagenetic fluid and host rocks. Barite vien, zinc blende and geleniteis the result of mixing of hydrothermal fluid circled in deep earthcrust and sea water. Metallic elements arederived from base rocks but sulphur derived from marine sulphate of Dengying stage or Early Cambrianreduced by organic fluid. Characteristics of Inclusion geochemistry shows that the temperature ofmineralization is between150~250℃, the pressure of mineralization is between24.9~31.7MPa, therelevant depth of mineralization is between900~1198m, belonging to epithermal deposit.Research on the pattern of Pb-Zn ore deposit shows that: the Nanzheng uplift made the Beiba domeaggravated, the stress of uplift not only made the Dengying formation fractured along brittleness part, but italso made the hydrothermal fluid which circled in deep earthcrust migrated up and Cambrian geologicalfluid migrated down, meeting in the breccias zone, organic fluid reduced the sulphate to sulphur whichcombined with metallic elements, converting to ore deposits. Other components also deposited due to thevariation of conditions of fluid and grown together with ore deposits, filled and distributed in the space ofbreccias.