Geological And Geochemical Characteristics Of Mayuan Pb-Zn Ore Deposit On Northern Margin Of Yangtze Landmass

Mayuan Pb-Zn deposit is a newly discovered and has good resources prospects, whichoccurs in bedded and stratoid forms and lies in a structural zone of dolomite breccias in theSinian Dengying Formation on the northern margin of Yangtze landmass. At present, theresearch works of MaYuan lead-zinc deposit are not enough comprehensive and still havemany blank. On the basis of understanding clearly tectonic background and ore geologicfeatures, this paper mainly explore the mechanism of Pb-Zn ore deposit and enrichore-forming theory through studying geochemical characteristics (including temperature andcomponent of fluid inclusions、REE、trace element and C、H、O、S、Pb、Sr isotope)ofhydrothermal minerals and ore-controlling brecciated dolostone and Combining analysis datasfrom predecessors.Researches show that:1. Carbonatite is the main ore-bearing rock in Mayuan Pb-Zn deposit with obviousepigenesist characteristic.The ore body is bedded and stratoid in form and lies in a structuralzone of dolomite breccias along the stratification, and the wall-rock alteration is weak. Themajor ore mineral is sphalerite and galena; gangue mineral is dolomite and calcite.2. The analysis of the REE element and C、O、S、Pb、Sr isotope suggest that metallogenicmaterials is mainly derived from Sinian-Siluric strata and basement rocks.3. The analysis of the S isotope suggests that sulfur should be derived from the in suitthermochemical reduction of sulfates from the sedimentary strata.4. The analysis of the fluid inclusions suggests that the ore-forming fluids are mainly ofthe saltwater and are characterized by medium-high salinity，medium-low temperature andrich in CH4. These suggest that the ore-forming fluid may be originated from seawater withthe participation of atmospheric precipitation, and organic matter may be involved in themineralization process.5. The analysis of the H、O isotope indicates that the ore fluid was likely meteoricwater,and might have experienced an water–organic matter reaction.6. On the basis of analysis datas of metallogenetic age from predecessors, and combiningtectonic background, the author regards that the Mayuan Pb-Zn deposit is likely to be formedin Early Cambrian-Middle Ordovician or slightly later than this time.7. By compared the research area with the classic MVT deposits，the author regards thatthe Mayuan Pb-Zn deposit has obvious metallogenetic characters of MVT deposits and is belong to MVT Pb-Zn deposits.8. The mineralization of this area may be the common result of reaction of organic matterwith mixed fluid from seawater and meteoric water.