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在西藏冈底斯山以北、唐古拉山以南地区,分布着侏罗纪到白垩纪的基性和中性火山岩。它们与本区的超基性岩空间上接近,或者呈断层接触。对这些岩石组合的成因有不同的解释。有人认为是大陆碰撞缝合带的蛇绿岩(常承法与郑锡澜,1974),有人认为是岛弧与边缘海的产物。近来,张旗(1983)在丁青发现了比较连续的蛇绿岩组合。要正确地对这些岩石的构造环境进行解释,必须进行详细的岩石学、岩石化学和微量元素地球化学研究。本文对采自拉弄沟、罗布中(图1)两地的玄武岩和采自切里湖的安山岩的岩石化学和微量元素地球化学做了初步研究,这里将初步结果及讨论作一报道。
In the area north of the Gangdise Mountain in Tibet and south of the Tanggula Mountain, basic and neutral volcanic rocks of the Jurassic to Cretaceous are distributed. They are close to the ultramafic rocks in this area or are in fault contact. There are different explanations for the causes of these rock assemblages. Some people think that the continent suture ophiolite ophiolite (Chang Chengfa and Zheng Xilan, 1974), some people think that is the product of the island arc and the edge of the sea. Recently, Zhang Qi (1983) found a relatively continuous ophiolite assemblage in Dingqing. To properly interpret the tectonic setting of these rocks, detailed petrology, petrochemistry, and trace element geochemical studies must be conducted. In this paper, a preliminary study on petrochemistry and trace element geochemistry of basalts collected from Laononggou and LuoBuZhong (Fig. 1) and andesite taken from Lake Cheri Lake is presented here. Preliminary results and discussions are reported here.