内蒙古迪彦庙蛇绿岩辉长岩岩石学特征

LITHOLOGY OF GABBRO OF THE DIYANMIAO OPHIOLITE IN INNER MONGOLIA

迪彦庙蛇绿岩位于中朝古板块与西伯利亚古板块之间的兴蒙造山带,主要由蛇纹石化斜辉辉橄岩、辉长岩、玄武岩、细碧角斑岩组成.岩相学研究表明,迪彦庙辉长岩分为层状辉长岩(具堆晶结构)和均质辉长岩(具辉长结构)两类,且均经历了低—中级变质改造.在详细的野外工作基础上,通过对迪彦庙辉长岩的地质特征、岩相学特征和岩石化学研究,认为其为活动大陆边缘或岛弧环境下小规模单旋回封闭系统内形成的.

The Diyanmiao ophiolite, consisting of serpentinized enstenite pyrolite, gabbro, basalt and spilite-keratophyre, is situated in the Daxinganling-Mongolia orogenic belt between Sino-Korean paleo-plate and Siberia paleo-plate. Petrographical study shows that the Diyanmiao gabbro can be classified into bedded gabbro （with cumulatic texture）and isotropic gabbro （with gabbro texture）, both of which experienced low-medium metamorphic reformation. On the basis of field survey and study of geology, petrography and lithochemistry, the Diyanmiao gabbro is believed to form in a small- scaled monocycle closed system under the active continental margin or island arc.