The Organic Matter And Its Re-Os Dating In The Jinding Zn-Pb Deposit, Northwestern Yunnan

The oil-gas reservoirs and the metal deposits often co-exist in many sedimentarybasins and their formation relations have been paid much attention. The Jinding Zn-Pbdeposit, Yunnan, China, is so far the largest Zn-Pb deposit in China, it is also one of17zinc—lead deposits whose metal reserves are more than10Mt．the youngest andonly giant Zn-Pb deposit hosted in the continental sedimentary rocks in the world.The showing of oil-gas and old oil-pool traces are evident in the finding ore district.Various kinds of organic matter, such as the kerogen,, heavy oil and bitumen withdifferent forms in the rocks and ores. Although the J historical research of the JindingZn-Pb deposit have been taken for more than twenty years,. It has been a debate on ifthe bitumen formed earlier or later than the Zn-Pb mineralization, and therelationships between the bitumen and the Zn-Pb ores in the Jinding could not be wellunderstood.The bitumen in the Jinding Zn-Pb ores hosted in the breccia-bearing sandstonesand sandy breccias of Pleocene Yunlong Formation has been dated by Re-Os methodin this paper, and the isochron age is68±5Ma (MSWD=9.2，n=6). The oil-gasreservoir in the Jinding ore district formed in Paleocene Epoch, and earlier than theZn-Pb mineralization. The organic matter could provide the reduction sulfur for theZn-Pb mineralization by the thermal chemical reduction of the sulfate; The bitumenand the heavy oil in the Jinding Zn-Pb ores hosted in the breccia-bearing sandstonesand sandy breccias of Pleocene Yunlong Formation has been analyzed by the traceelements geochemistry method, the REE patterns in organic matter are characterizedby strong LREE enrichment, with weak (negative and positive) Ce and remarkednegative Eu anomalies, it is similar to the metal sulfides REE patterns whichApparent to the mantle source, maybe the mantle fluid play a part during themineralization..The formations of the oil-gas reservoir and the Zn-Pb deposit might be acontinuous geological processes token place one after the other,the organic fluidreduction the sulphate of the layer,and trap condition is the basic of Jinding oil-gasreservoir,because it made the possible to collect enough H2S to react with metals. theoil-gas reservoir was the basic condition of the Zn-Pb mineralization and the brokenduring the Zn-Pb mineralization in the Jinding ore district and the Jinding giant Zn-Pbdeposit came into being.