Long-lived high-temperature granulite-facies metamorphism in the Eastern Himalayan orogen, south Tibet
Long-lived high-temperature granulite-facies metamorphism in the Eastern Himalayan orogen, south Tibet
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DOI：
10.1016/j.lithos.2014.10.009
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发表时间：
2015
期刊：
影响因子：
3.5
通讯作者：
Zeming Zhang;H. Xiang;Xin Dong;H. Ding;Zhenyu He
中科院分区：
文献类型：
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作者：
Zeming Zhang;H. Xiang;Xin Dong;H. Ding;Zhenyu He
藏南南喜马拉雅构造结东段南车-巴尔瓦杂岩经历了高压-高温麻粒岩相变质作用和深熔作用。高压泥质麻粒岩主要由石榴子石、蓝晶石、硅线石、堇青石、黑云母、石英、斜长石、钾长石、尖晶石、钛铁矿和石墨组成。这些矿物具有复合反应结构和不同的化学成分，形成四个连续的矿物组合。相平衡模拟的P-T条件为：变质阶段为10-12 kbar，温度550-700 °C;峰变质阶段为13-16 kbar，温度840-880 °C;退变质晚期为5-6 kbar，温度830-870 °C。表明HP麻粒岩记录了顺时针P-其成因机制为早期的加热埋藏和白云母、黑云母脱水熔融的深熔作用，晚期的等温减压和高温麻粒岩相条件下的逐步熔融结晶作用。锆石U-Pb定年结果表明，HT麻粒岩相变质作用可能开始于约1000年。40马，并持续到约。八马。因此，本研究提供了强有力的证据，在深埋的印度大陆的长期HT变质和相关的深熔作用和重要的约束淡色花岗岩的生成和构造演化的喜马拉雅造山带。
The Namche Barwa Complex exposed in the Eastern Himalayan Syntaxis, south Tibet, underwent high-pressure (HP) and high-temperature (HT) granulite-facies metamorphism and associated anatexis. The HP pelitic granulites contain garnet, kyanite, sillimanite, cordierite, biotite, quartz, plagioclase, K-feldspar, spinel, ilmenite and graphite. These minerals show composite reaction texture and varying chemical compositions and form four successive mineral assemblages. Phase equilibrium modeling constrains theP–Tconditions of 10–12 kbar and 550–700 °C for the prograde stage, 13–16 kbar and 840–880 °C for the peak-metamorphic stage, and 5–6 kbar and 830–870 °C for the late retrograde stage, indicating that the HP granulites recorded a clockwiseP–Tpath involving the early heating burial and anatexis through dehydration melting of both muscovite and biotite, and the late isothermal decompression and gradual melt crystallization under HT granulite-facies conditions. The zircon U–Pb dating reveals that the HT granulite-facies metamorphism probably initiated at ca. 40 Ma, and lasted to ca. 8 Ma. Therefore, the present study provides robust evidence for a long-lived HT metamorphism and associated anatexis in the deeply buried Indian continent and important constraints on the leucogranite generation and tectonic evolution of the Himalayan orogen.