西大别白垩纪两阶段花岗岩成岩及钼成矿作用的讨论
Two Stages of the Cretaceous Granitic Magmatisms and Mo Mineralizations in Western Dabie Orogenic Belt

系统总结西大别白垩纪赋钼花岗岩的岩石成因，并结合这些岩体的岩石地球化学特征对西大别钼矿床形成条件进行探讨，对认识西大别钼成矿带的地球化学动力学背景具有重要意义.在白垩纪时期，西大别含钼花岗岩成岩作用与东大别地区相似，可分为早、晚两个阶段.早阶段岩体(早于132 Ma)形成于加厚地壳环境，晚阶段岩体(晚于130 Ma)形成于非加厚地壳环境.这种岩石成因上的差别是导致该地区钼矿成矿条件差异的根本原因.结合钼元素的地球化学属性和中央造山带的演化特征，认为晚古生代时期位于造山带南侧的古秦岭洋可能为地壳中Mo元素在表生风化过程中提供有利的沉积环境，并且在三叠纪时期伴随扬子板块一起俯冲到华北板块之下，富钼沉积物与扬子地壳一起部分熔融形成富钼的岩浆，最终形成西大别白垩纪时期大规模的含钼成岩作用.
This paper investigates the petrogenesis of the Cretaceous Mo-bearing granites in West Dabie orogenic belt. Utilizing the rock geological chemistry of these granites, the formation condition of the Mo deposits in West Dabie orogen is discussed, which is significant to recognize the geochemical dynamics background of West Dabie Mo metallogenic belt. Similar to the Cretaceous granites in East Dabie orogen, the magmatisms of Mo-bearing granites in West Dabie orogen could be divided into two stages. The early stage was formed under thickened crustal environment, and the late stage was formed under nonthickened crustal environment. This is fundamental reason to decide the differences of the Mo metallization in West Dabie orogen. Combining with the geochemical characteristics of the Mo and the evolutionary process of central orogenic belt, the Qinling paleo-oceanic basin probably offered a favorable environment for the supergene weathering crustal Mo element, and then the Mo enriched sediment was carried by the Yangtze block and subducted underneath the North China block. Together with the Yangtze block, the Mo enriched sediment was partial melted, forming the large-scale Mo-bearing magmatism in West Dabie orogen