| The southwest margin of Yunnan metallogenic zone is located in the Yangtze block,its location is surrounded by several faults,wan factory factory-Baotaichang-Hongmenchang faults to the North,the Red River fault to the south,Xiaojiang Fault to east,Luzhijiang fault to the west,in the upper Yangtze lead-zinc metallogenic belt,the magmatic activity is strong leading that the crustal structure in this region is more complex.This research work is a typical deposit which occurs in the Cambrian meishucun formation under the guidance of my tutor' s selection.on the basis of Lulu lead-zinc deposit in the geological field work(including detailed geological mapping,sampling and some out of work),we research on the geological background,the geological characteristics of deposit(including the shape of ore body,ore texture,composition and so on),trace elements and REE geochemistry,fluid inclusion geochemistry,isotope geochemistry,isotope chronology and geochemical features.We combined with previous geological data and do the work to summarize.Then we conclude the ore bearing strata,the source of ore-forming materials and ore-forming age of LuLu lead-zinc deposit,the main conclusions are as follows:1.Ore bearing strata of Lu Lu lead-zinc deposit are mainly as follows:Cambrian meishucun formation strata.Ore is by strata control.the ore bearing strata lithology is carbonate rock,the lithology characteristics of concrete is gray to gray thin and medium thick bedded dolomite,sandy dolomite containing phosphate rock bottom.At the top of the dolomite layer,there are some lead and zinc deposits.The macroscopic characteristics of the ore deposits show that the ore bodies are basically layered.2.Microscopic characteristics show that the main ore structure is in fine crystalline euhedral to his shaped,crushing structure,metasomatic dissolution structure and metasomatic relict structure and so on;the ore structures are mainly:stockwork structure and vein structure,massive structure,the banded stripe structure,disseminated structure.Ore minerals are native to the metallic minerals in galena,sphalerite and pyrite,pyrite and arsenopyrite is also white;and the non-metallic mineral is barite,quartz and calcite.It is further proved that the mineralization is epithermal mineralization.3.The wall rock alteration of LuLu lead-zinc deposit are mainly pyritization,silicification,carbonatization and baritization,has been previously described,here is not repeated.4.The geochemical characteristics of fluid inclusions indicate that the ore-forming fluid is a low temperature,low salinity and low density NaCLL-H20 system.5.By studying the distribution characteristics of sulfur isotope,lead isotope,trace element and rare earth element.LuLu lead-zinc deposit show that the characteristics of the ore materials of the deposit with multiple sources,the ore-forming ore of LuLu lead-zinc deposit are from carbonate rock or basement strata,and may have deep involvement with fluid mineralization,Mount Emei basalt may also provide a source of minerals.Lu Lu lead-zinc deposit metallogenic epoch is for late Indosinian and early Yanshan.6.Zinc isotope studies indicate that the basement strata is the main mineral source,and ore formation may also provide some sources of zinc,Mount Emei basalt 66Zn isotope value falls into the middle position of the isotopic composition of zinc deposit.Mount Emei basalt may also provide some material for mineralization.Study on magnesium isotopes show that the source of magnesium might mainly come from the surrounding rock,there is an indirect link basalt and lead-zinc deposit.7.Integrating the geological characteristics of the deposit,geochemical characteristics and characteristics of the isotope,preliminary,the genetic types of lulu lead-zinc deposits in central Yunnan is Deposition-Mixed hydrothermal lead-zinc deposits. |
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