Five generations of monazite in Langtang gneisses: implications for chronology of the Himalayan metamorphic core
Five generations of monazite in Langtang gneisses: implications for chronology of the Himalayan metamorphic core
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DOI：
10.1111/j.1525-1314.2005.00584.x
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发表时间：
2004-05
影响因子：
3.4
通讯作者：
M. J. Kohn;M. Wieland;C. D. Parkinson;B. Upreti
中科院分区：
文献类型：
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作者：
M. J. Kohn;M. Wieland;C. D. Parkinson;B. Upreti
对尼泊尔Langtang河谷大喜马拉雅序列片麻岩中的独居石颗粒进行了化学制图，然后通过Th-Pb离子微探针分析进行了原位定年。年龄和化学成分的相关性揭示了至少五个不同世代的独居石，从c。9至300 Ma。独居石化学的岩石学模型提供了这些世代和这些岩石的热演化之间的联系，产生了主中央冲断层片（c. 16 Ma），以及逆冲岩席就位的时间比通常看到的要年轻。独居石的化学表征是至关重要的年代学微分析之前，许多年龄以前报道的独居石从大喜马拉雅序列解释模糊。
Monazite grains from Greater Himalayan Sequence gneisses, Langtang valley, Nepal, were chemically mapped and then dated in situ via Th–Pb ion‐microprobe analysis. Correlation of ages and chemistry reveals at least five different generations of monazite, ranging from c. 9 to >300 Ma. Petrological models of monazite chemistry provide a link between these generations and the thermal evolution of these rocks, yielding an age for the melting of Greater Himalayan rocks within the Main Central Thrust sheet (c. 16 Ma), and for the timing of thrust sheet emplacement that are younger than commonly viewed. Chemical characterization of monazite is vital prior to chronological microanalysis, and many ages previously reported for monazite from the Greater Himalayan Sequence are interpretationally ambiguous.