摘要
在中国东南部中－新生代玄武质岩石中陆续找到了来自下地壳的辉长岩质麻粒岩／辉长岩深源捕掳体。本文着重研究了沿海地区广东麒麟新生代玄武质角砾岩筒中的辉长岩质麻粒岩捕掳体，并与内陆湖南道县早中生代玄武质角砾岩筒中的辉长岩、花岗片麻岩捕掳体作了比较。研究表明，辉长岩质麻粒岩是底侵作用形成的基性岩浆底垫于下地壳，并经变质作用的产物。底侵作用是重要的壳－幔作用过程，也是中国东南大陆边缘陆壳演化的重要过程。Ｓｍ－Ｎｄ同位素定年显示，中国东南大陆边缘底侵作用物质在地壳底部的结晶年龄约为１１２．３±１７．８Ｍａ，属晚中生代时期。此外，底侵作用在不同大地构造域的发育程度是不一致的，底侵作用发育强弱的标志是基性火山岩是否发育。
A group of gabbroic granulite/gabbro deep seated xenoliths have been found from Mesozoic-Cenozoic basaltic rocks in southeast China. The gabbroic granulite xenoliths from Qilin Cenozoic basaltic pipe in the coastal area are studied.A comparison study is also made with the gabbro, granitic gneiss xenoliths from Daoxian Mesozoic basaltic pipe. These studies indicate that gabbroic granulite was formed by underplating of basaltic magma at the bottom of the crust, and experienced metamorphism. Underplating is an important process of crust/mantle interaction, and an essential process in the crustal evolution of the continental margin of southeast China. The Sm Nd isotope dating shows that the crystallization age of underplating material in the continental margin of southeast China is 112 3±17 8Ma. In addition, the extent of underplating in different tectonic area may be different, which depends on the development of basaltic volcanism, wide distribution of crust mantle type granitoids.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1999年第2期217-223,共7页
Acta Petrologica Sinica
基金
国家自然科学基金
国家教委博士点基金
