滇西勐库退变质榴辉岩的P-T-t轨迹及地质意义

发布时间：2018-05-13 21:06

  本文选题：退变质榴辉岩 + PT视剖面图　； 参考：《岩石学报》2017年07期

【摘要】：滇西双江县勐库地区的退变质榴辉岩经历了多期退变质作用的改造,早期的平衡共生矿物组合难觅踪迹。应用传统的石榴石-单斜辉石(GC)温度计、石榴石-单斜辉石-多硅白云母(GCP)压力计进行变质作用的PT条件估算存在许多不确定性。本文应用魏春景等(2009)依据MORB成分计算的PT视剖面图上多硅白云母、石榴石、绿辉石的成分随体系中PT条件的变化情况,估算了进变质的P=2.00~2.30GPa,T=420~460℃,相当于硬柱石蓝片岩相—硬柱石-蓝闪石榴辉岩相;峰期变质的P=3.35~4.46GPa,T=530~610℃,相当于硬柱石榴辉岩相;早期退变质的P=2.00~2.50GPa,T=470~540℃,相当于硬柱石-蓝闪石榴辉岩相;中期退变质的P=0.95~1.43GPa,T=700~750℃,相当于角闪石榴辉岩相-高压麻粒岩相。晚期退变质作用以出现大量的闪石类矿物为特征,可划分为3个阶段,并显示了持续的降温、降压过程。结合区域地壳演化进程,本文详细讨论了上述P-T-t轨迹的地质意义。
[Abstract]:The retrograde metamorphic eclogite in Mengku area, Shuangjiang County, western Yunnan has undergone many retrograde metamorphic processes, and the early balanced symbiotic mineral assemblage is difficult to find. There are many uncertainties in the estimation of PT conditions for metamorphism by using the traditional garnet-clinopyroxene GC- thermometer and garnet-clinopyroxene-polysilicon Muscovite pressure gauge. Using Wei Chunjing et al. 2009) according to the change of composition of Muscovite, garnet and omphacite in the PT profile calculated by MORB with PT conditions in the system, the authors estimate the temperature of the retrograde metamorphic P _ (2.00) ~ 2.30GPA _ T _ (420C) ~ (460) 鈩，

本文编号：1884794