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岩石学报 2012
Re-Os dating of bitumen in the giant Jinding Zn-Pb deposit, Yunnan and its geological significance
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Abstract:
Oil-gas reservoirs and metal deposits often co-exist in many sedimentary basins, and their genetic relations have been paid much attention. The Jinding Zn-Pb deposit, Yunnan, China, is so far the largest Zn-Pb deposit in China, the youngest and only giant Zn-Pb deposit hosted in continental sedimentary rocks in the world. Bitumen and heavy oil were often observed in the Jinding Zn-Pb deposit. It has been a subject of debate whether the bitumen formed before or after the Zn-Pb mineralization, making it difficult to evaluate and the genetic relationship between the bitumen and Zn-Pb mineralization. The bitumen in the Jinding Zn-Pb ores hosted in the breccia-bearing sandstones and sandy breccias of the Paleocene Yunlong Formation has been dated by the Re-Os method in this paper, and an isochron age of 68±5Ma (MSWD=9.2, n=6) has been obtained. Therefore, the oil-gas reservoir in the Jinding ore district was formed earlier than the Zn-Pb mineralization. The hydrocarbons in the reservoirs may have provided the condition for the production of reduced sulfur required for Zn-Pb mineralization through thermal chemical reduction of sulfates. The formation of the oil-gas reservoir and the Zn-Pb deposit may have been a continuous geologic process, and the oil-gas reservoir was one of the basic conditions of Zn-Pb mineralization in the Jinding ore district. The oil-gas reservoir was destructed by the mineralization process.
