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    华南燕山早期晚阶段两类花岗质岩体与成矿作用:以赣南—闽西南地区为例

    Metallogenesis of two types of late Early Yanshanian granitoids in South China: Case studies of south Jiangxi and southwest Fujian

    • 摘要: 提要:华南燕山早期晚阶段花岗岩(170~150 Ma)分布广泛,且与成矿关系密切。该时期的花岗岩具有两种不同的分布格局:在南岭东段地区以东西向分布,在武夷山地区呈北东向分布,这些花岗质岩石具有不同的地球化学特征。赣南地区出露的小岩株与钨锡成矿关系密切,具有钨锡找矿潜力,在地球化学特征上明显不同于同时代出露的大岩基。东西向展布的小岩株与同时代的大岩基可能是由时代相当于元古宙中等成熟度的陆壳富泥砂质变质沉积岩部分熔融形成,小岩株在岩浆演化过程中经历了流体相参与的高程度的分异作用,是岩浆演化到晚期阶段的产物;而北东向分布的岩体可能是由中元古代泥质变质沉积岩部分熔融所形成。该时期南岭及邻区大陆岩石圈以伸展背景为主,而整体上中国东南部大部分地区已处于东亚活动大陆边缘构造体制作用下,古太平洋板块朝东亚陆缘的北西向碰撞挤压作用已经显现。

       

      Abstract: Abstract:Late-stage Early Yanshanian granitoids are widely distributed in South China and closely related to metallogenesis. They have two different distribution patterns, being EW-trending in Nanling and NE-trending in Wuyi area. Granitic rocks formed in two different tectonic settings have different geochemical characteristics. The little stocks in southern Jiangxi Province are closely related to W and Sn mineralization, quite different from things of big batholiths. The little stocks and big batholiths might have been formed by partial melting of the crust-derived argillaceous-arenaceous metasedimentary rocks related to Proterozoic crust; nevertheless, fluid was present during magmatic evolution and experienced highly differentiation and evolution in the formation of little stocks, whereas NE-extending granitoids were probably formed by partial melting of argillaceous metasedimentary rocks related to Mesoproterozoic crust. During that period, the mainland lithosphere of Nanling and adjacent regions belonged to an extensional setting, southeast China was mostly under the tectonic framework of East Asia active continental margin, and the collision and compressional role of the Pacific plate toward East Asian continental margin began to emerge.

       

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