中国东部大规模成矿时限及其动力学背景的初步探讨

A PRELIMINARY STUDY ON TIME LIMITS AND GEODYNAMIC SETTING OF LARGE-SCALE METALLOGENY IN EAST CHINA

通过对以往金属矿床同位素年龄数据的收集、整理和分析 ,初步厘定中国东部大规模成矿作用发生的时限为 1 60× 1 0 6～ 1 1 0× 1 0 6 a。提出西秦岭地区金矿床出现于中国两大古陆后碰撞的伸展环境 ;与花岗岩有关的铜钼矿床发育于早中侏罗世由挤压向伸展环境过渡时期 ,钨锡铅锌银锑汞金铀出现于晚侏罗世—早中白垩世岩石圈大规模拆沉或减薄期间。尽管不同类型矿床形成过程有所不同 ,都与大规模构造圈热侵蚀密切相关。

As a part of Circum Pacific megametallogenic belt, East China seems to be the most important metallogenic province in China. There exist in East China decades of world class tungsten, tin, bismuth, beryllium, copper, molybdenum, REE, antimony, uranium and lead zinc deposits together with numerous large clusters of other metallic deposits, mostly formed in Mesozoic. Based on the collection, discrimination and analysis of the radiometric data available, it is prelminarily considered that the large scale metallolgeny in East China occurred from 160×10 6 to 110×10 6 a. Based on tectonic evolution, the authors propose that the gold deposits in west Qinling were developed in the extensional post collision setting between North China craton and Yantze craton. The granite related copper molybdenum deposits were formed in Early to Middle Jurassic transitional period from compression to extension, whereas W Sn Pb Zn Sb Hg Au Ag U mineralization took place in Late Jurassic and Early to Middle Cretaceous, corresponding to the period of large scale delamination of the lithosphere. Though occurring in different genetic types and mineralization associations, these deposits are closely related to tectosphere thermal erosion.