汉诺坝玄武岩中麻粒岩捕虏体的发现

The Discovery of Granulite Xenolithes in Hannuoba Basalt, North Hebei, China

近十余年来,中外地质学家对我国河北西北部的汉诺坝玄武岩及其深源包体进行了广泛深入的研究,发现了种类繁多的上地幔岩石捕虏体,发表了不少专著和论文,但有关麻粒岩捕虏体的报导,迄今为止尚未见到。本文作者经过三年的努力,在汉诺坝玄武岩中发现了五类八种麻粒岩捕虏体,其中包括石榴辉石麻粒岩、斜长石榴辉石麻粒岩、斜长单辉麻粒岩、斜长二辉麻粒岩、石榴钾长石英麻粒岩、石榴斜长石英麻粒岩、辉石二长麻粒岩、辉石钾长麻粒岩。初步研究表明这些麻粒岩大部分是在下地壳环境下形成的,它们具有麻粒岩矿物组合和结构构造特征,但又不完全类同于古老高级变质地体中的麻粒岩。

In recent decade the geologists of China and foreign countries have Profoundly researched Hannuoba basalt and deep-seated xenolithes from north-west Hebei, China, discovered many kinds of xenoliths of upper mantle source rocks, and pub- lished a lots of academic theses and works. However, there is no report on the granulite xenolithes as yet. As a result of hard work in three years we discover five types and eight sorts of granulite xenolithes from Hannuoba basalt. The lithology of these xenolithes are garnet-pyroxene granulite, plagioclase-garnet-clinopyroxene granulite, plagioclase- orthopyroxene granulite, plagioclase-pyroxene granulite, garnet-potash feldspar-quartz granulite, garnet-plagioclase-quartz granulite, clinopyroxene-feldspar granulite and clinopyroxene-potash feldspar grnulite. Prelimnary researches show most of the granulite xenolithes form in lower crust-conditions. They have the characteristics of mineral assem blage and fabric of granulite in ancient high-grade metamorohic terrain, but they arc not entirely alike to the granulite in ancient high-grade metamorphic terrain.