Mineral chemistry and reaction textures in metabasites from the Eastern Ghats belt, India and their implications
Mineral chemistry and reaction textures in metabasites from the Eastern Ghats belt, India and their implications
复制标题
印度东高止山脉变碱岩的矿物化学和反应结构及其意义
DOI：
10.1180/minmag.1993.057.386.11
复制
发表时间：
1993
影响因子：
2.7
通讯作者：
M. Fukuoka
中科院分区：
文献类型：
--
作者：
S. Dasgupta;P. Sengupta;A. Mondal;M. Fukuoka
摘要在印度东高山带Sunkarimetta，暴露出2种辉石斜长花岗岩（MG）、2种辉石斜长石榴石麻粒岩（GMG）和尖晶石-橄榄石斜长- 2辉石麻粒岩（SMG） 3种基性麻粒岩。麻粒岩的叶理特征与伴生麻粒岩相石英辉长片麻岩一致。结构特征和矿物化学数据表明：橄榄石+斜长石=尖晶石+正辉石+斜辉石（SMG），正辉石+斜长石=石榴石+石英（GMG），斜辉石+斜长石=石榴石+石英（GMG），斜长石+铁铁矿+石英=石榴石+钛铁矿+ 02 （GMG）。地温测量表明，最大P-T变质条件为摄氏8.5 kbar, 950°c，玛丽麻粒岩后来经历了近等压冷却至摄氏7.5 kbar, 750°c。侵位深度约32 km的基性麻粒岩原岩可能是造成包裹岩麻粒岩相变质的热扰动的原因。
Abstract Three types of mafic granulites, namely two pyroxene-plagioclase granutite (MG), two pyroxeneplagioclase-garnet granulite (GMG) and spinel-olivine-plagioclase-two pyroxene granulite (SMG) are exposed at Sunkarimetta, Eastern Ghats belt, India. The marie granulites exhibit a foliation concordant with that in associated granulite facies quartzofeldspathic gneisses. Textural characteristics and mineral chemical data suggest the following mineral reactions: olivine + plagioclase = spinel + orthopyroxene + clinopyroxene (SMG), orthopyroxene + plagioclase = garnet + quartz (GMG), clinopyroxene + plagioclase = garnet + quartz (GMG) and plagioclase + hemoilmenite + quartz = garnet + ilmenite + 02 (GMG). Geothermobarometry indicates maximum P-T conditions of metamorphism at c. 8.5 kbar, 950°C The marie granulites later suffered nearly isobaric cooling to c. 7.5 kbar, 750°C Bulk compositional characteristics suggest that SMG is of cumulate origin. The protoliths of the mafic granulites, emplaced at c. 32 km depth, are probably responsible for thermal perturbation causing granulite facies metamorphism of the enclosing rocks.