| Siding Pb-Zn deposit is one of important large Pb-Zn deposits in the northern Guangxi metallogenic area,which is located in Rong'an county.On basis of previous research work and geological data,metallogenic geological background,geological features and geochemical characteristics are studied for Siding deposit.Furthermore,the ore controlling factors and sources of ore forming materials are analyzed,and the genesis of deposit are discussed.The major results and understandings are obtained as following:1.The deposit is controlled by the formation,lithology and structure,mainly manifested in which the deposit is located in the upper Devonian Rongxian group,the wall rock of the orebody is dolomitic limestone,and the distribution of the ore body are controlled by structure.2.Pb-Zn ores and the wall rocks have similar REE characteristics,such as LREE enrichment,HREE depletion,moderate negative Eu anomaly and no obvious Ce anomaly.The total of REE??REE?decreasing from wall rocks to ores.The deep ores show more intense LREE enrichment and more obvious negative Ce anomaly than the upper ores.It is considered that Siding Pb-Zn deposit is a middle-low temperature hydrothermal deposit and REE in ore-forming fluid comes from the ore-host strata,and the deposit was reformed by groundwater at the late stage of metallogenic epoch.3.206Pb/204Pb,207Pb/204Pb,208Pb/204Pb of metal sulfide minerals are 18.1019.22,15.4516.51 and 18.7218.77,average value is 18.526,15.814 and 18.74.Limestone from ore-hosting strata are 18.7218.77,15.8515.91 and 39.5139.59,average value is18.74,15.88 and3 9.54.It is considered that most Pb in metallogenic hydrothermal fluid was derived from the ore-hosting strata,meanwhile little from the deepness of fault.4.?34S value of ore is-17.1‰5.1‰,average is-2.6‰.It is considered that metallogenic hydrothermal fluid is a mixture of two different type of fluid,and S in metallogenic hydrothermal fluid was derived from the ore-hosting strata.5.?13CPDB value of Calcite is-5.0‰-1.1‰,average is-2.6‰,as well as?18OSMOW value is 13.2‰18.4‰,and average is 16.4‰.?13CPDB value of Carbonate minerals is-1.63‰0.83‰,and average is-0.34‰,as well as?18OSMOW value is 19.02‰22.00‰,and average is 20.90‰.It is considered that C in metallogenic hydrothermal fluid was derived from the ore-hosting strata.6.The formation of Siding Pb-Zn deposit experienced 4 stages:?1?the sedimentary formation stage of the ore source layer;?2?the evolution stage of the hydrothermal fluid;?3?the stage of mixing of hydrothermal fluids and mineralization;?4?the groundwater reformation stage of deposit. |
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