Reconsideration of the Relationship between Organic Reef and Lead-Zinc Deposits in West Qinling
西秦岭地区生物礁与铅锌矿关系的再认识

Based on previous studies of stratigraphy,lithofaces and organic geochemistry in combination with data obtained by the authors,this paper deals with the association relationship and genetic connection of organic reef with lead-zinc deposits in West Qinling region.In geological formation,the lead-zinc ore-bearing strata are characterized by well-developed limestone and biogenic limestone;in space,the organic reef generally acted as the baffle of the ore-forming depression;in sequences,the association relationship between organic reef and sedimentary lead-zinc deposits is different from that between organic reef and reformation deposits,i.e.,the former occur in limestone or clastic rocks,whereas the latter often occur in the transitional position between limestone and argillite.The organic matter related to hermatypic organism was likely to participate in such processes as thermal sulfate reduction,extraction of lead-zinc from rocks,transportation and accumulation before sedimentary mineralization or reformation mineralization.The injection of fluids from the depth during the intraplate stretching and that from the depth or magma during intracontinental subduction into epithermal to mesothermal organism-rich brine led to sedimentary mineralization and reformation mineralization respectively.The hydrothermal sedimentation and mineralization along the growing faults facilitated the formation of organic reef or baffle of depressions in the low latitude area.The role of organic reef in reformation mineralization lies primarily in the formation of metallogenic structures favorable for reformation mineralization.