大麻坪二道沟二辉橄榄岩岩体成因研究

大麻坪超镁铁岩主要以两种产状产出,一是以包体形式寄生在碧玄岩、碱性橄榄玄武岩中,二是地幔底辟体侵位至近地表形成二辉橄榄岩岩体.二道沟二辉橄榄岩体相对规模大,露头较好,岩石新鲜,其中橄榄石颗粒粗大,色泽鲜艳,现被当作宝石矿加以开采利用.同时也吸引了不少专家、学者在此作了大量研究工作.关于它的成因问题,多数学者认为它是包体堆积成因.通过近两年野外和室内工作,笔者认为二道沟二辉橄榄岩岩体并非包体堆积,而是二辉橄榄岩固态侵入体.

PETROGENESIS OF DAMAPIN- ERDAUGOU LHERZOLITE, WANGQUAN, HEBEI

Field geological observation, petrographic investigation, chemical analysis and thermodynamic calculation on Damapin-Erdaugou spinel-lhexzolite and the coexisting dike-like basalt suggest that this spinel-lhexzolite is a diapir of fragments of the upper mantle emplaced near the surface along a deep fracture zone, rather than an accumulation of ultramafic nodules carried by alkali basalt on the surface.