Large-scale tungsten-tin mineralization in the Nanling region,South China:Metallogenic ages and corresponding geodynamic processes. 论文

摘要

The Nanling region,located in the central part of South China,is the most important W-Sn metallogenic province in China and even over the world.Based on the latest highly precise radiometric dating of the ores and related granites and new progress in the study of geodynamic processes we propose that large-scale W-Sn mineralization occurred in the Nanling region in the Mid-Late Jurassic(165 to 150 Ma)and that its corresponding tectonic setting could be a back-arc region of the continental margin.When the Paleo-Pacific plate was subducted beneath the Eurasian continent,a number of paralleling NE-trending extensional belts developed in a back-arc region where the mantle-crust interaction was strong.The intersection sites between these extensional belts and long-lived previous E-W-trending faults were the central areas of magmatism and mineralization,and the largest W-Sn-Mo-Bi-Be mineralization clusters in southern Hunan is located in the intersection site between the Shihang NE-trending fault belt and the E-W-trending deep fault in the middle ridge zone of the Nanling region.In the Mid-Late Cretaceous,because the Paleo-Pacific plate or Izalagi plate strike- shift to NNE-direction the Eurasian continent started to extension.In this geodynamic setting,the large-scale volcanic eruption mainly took place east of the Wuyi Mountains whereas range-basin tectonics appeared extensively in South China including the Nanling region, NNE-trending Cretaceous red bed-volcanic basins alternate with uplifts represented by granite,and some granite stocks emplaced at 130～90 Ma and their related tin mineralization can be found in some basins.For instance,the Yanbei and Taoxiba in Jinagxi province, Yinyan in Guangdong province and the Jiepailing in the Hunan province occurred in this period as porphyry or porphyry-skarn ores.