湖南锡矿山地区云斜煌斑岩及其花岗岩包体的意义

湖南锡矿山地区云斜煌斑岩是属碱钙性系列的基性岩脉,其在上侵时捕获了石灰岩包体而发生局部同化混杂,致使煌斑岩褪色蚀变。同时,对岩石包体特征、黑云母与锆石年代,Pb同位素与稀土元素的研究表明,锡矿山深部有隐伏花岗岩体存在,而云斜煌斑岩是在花岗岩浆尚未完全固结时上侵,形成于成矿期末或成矿后;该煌斑岩不是地幔岩浆分异产物,而是中元古代地壳重熔形成的。据推断,在中生代该地区深部有一次较大地质热事件,并对成岩、成矿发生了直接影响。

XIKUANGSHAN MICA-PLAGIOCLASE LAMPROPHYRE AND ITS GRANITE INCLUSIONS, HUNAN PROVINCE

Mica-plagioclase lamprophyre is the only outcropping igneous rock in the Xikuangshan area, belongingto the calc-alkaline series. According to the mineralogy, petrology and isotope geochemistry of the lamprophyre and granite inclusions, it is suggested that there is a concealed intrusive mass in Xikuangshan; themica-plagioclase lamprophyre intruded after granite intrusion. Residual zircon is from the basement rockMiddle Proterozoic Banxi Group and Lingjiaxi Group. It isn' t the product of mantle magma differentiation.So it is inferred that there occurred a Mesozoic geological heat event in the Xikuangshan area.