个旧老厂矿田花岗岩地球化学特征及其形成构造背景

个旧老厂矿田是中国著名的铜锡多金属矿产地而倍受关注,本文以个旧老厂矿田花岗岩体为研究对象,结合岩体产出的地质条件,在岩石学研究的基础上,运用主量元素及微量元素地球化学方法对老厂花岗岩的地球化学特征、源区及其形成的构造背景进行了系统研究。结果表明,老厂花岗岩体为一复式岩体,来源于陆壳岩石的部分熔融,但其具有不同的源区性质。构造环境判别图显示,老厂花岗岩体不同单元形成于不同的构造环境,与成矿作用有关的花岗岩则主要形成于后碰撞造山向板内环境的转换阶段,这种特殊的构造环境是区内超大型矿床形成的有利条件。

Geochemical Characteristics and Tectonic Setting of Laochang Granite in Gejiu

Laochang ore field of Gejiu, as a famous tin-copper polymetallic ore producing area in China has received great attention. The paper aimed at the granite in the ore field, and mainly studied geochemical characteristics of the granite, source area and tectonic settings. Combined with the geological background and lithological features of the granite body, the research indicated that the Laochang granite is a compound massif, resulted from partial melting of the crust rock, and of the features of different source area. The diagram of tectonic discrimination shows that different granite units of the Laochang compound massif formed at different structural environments and the granite related to metallogenesis formed at the transitional stage from the post-collisional orogeny to intraplate environment, which is most favorable condition for the formation of super-large deposit in the Laochang ore field.