摘要
中国东部新生代玄武岩和大别-苏鲁超高压变质带中的含石榴石相橄榄岩,带来了发生在上地幔的尖晶石→石榴石相转变和铝辉石→贫铝辉石+石榴石的重要信息,为中国东部上地幔岩石结构分层奠定了重要基础.通过岩石学与实验岩石学的研究,推导出发生相转变的P-T条件,为建立中国东部大陆上地幔岩石分层结构提供了重要约束.尖晶石二辉橄榄岩向石榴石二辉橄榄岩相转变发生在55～70km,随着深度增加,石榴石二辉橄榄岩从富铝石榴石二辉橄榄岩(70～120km)转变为贫铝石榴石二辉橄榄岩(>120～150km).
The rare samples of garnet bearing peridotites （GBPs）, either from alkaline volcanics or from orogenic belt, provide important information of the evolution of subcontinental lithospheric upper mantle. Cenozoic volcanic rocks widely spread in eastern China, and GBPs occur in the volcanic fields of Mingxi, Xilong, Hebi, Ntishan, Hannuoba and Chaoerhe. According to the occurrence of spinel, the mantle xenoliths from above volcanic fields can be divided into two groups as Gt peridotite and Gt/ Sp peridotite. Electronic probe data reveal the P-T conditions of these xenoiths as （1） Gt peridotite from depths over 70 km, and （2） Gt/Sp peridotite from 55--70 km. Meanwhile, orogenic garnets from Dabie-Sulu UHP belt also facilitate the under-standing of the subcontinental lithospheric upper mantle of eastern China. Variations of garnets in the Gt lherzolite from the UHP belt record the evolution of subduction from Al-rich Gt （70--120 km） to Al-poor Gt （〉120-- 150 km）. Garnets and their metamorphic reactions reveal the mantle compositions and evolution in eastern China.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2009年第3期387-391,共5页
Earth Science-Journal of China University of Geosciences
基金
国家自然科学基金项目(No.40772038)
