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对产于喜马拉雅造山带中段片麻岩和石英岩中的透镜状高压基性麻粒岩内锆石进行离子探针(SHRIMP)U-Pb测年,14个锆石颗粒15个测点中有13个点集中分布在谐和线上,其206Pb/238U年龄平均值为17.6±0.3 Ma,反映了麻粒岩从地壳深部快速上升的绝热降压变质事件,形成于印度板块与欧亚板块碰撞后的构造隆升环境,与喜马拉雅造山带大规模的逆冲推覆作用、伸展拆离作用和淡色花岗岩侵位同步.还有1颗锆石206Pb/238U年龄为29.5±0.4 Ma,与新特提斯的最终关闭有关;另一粒锆石206Pb/238U年龄为1991±26 Ma,代表了麻粒岩原岩的年龄.总之,定年结果反映该区麻粒岩经历了多期变质和复杂的地质演化过程.
Ion-probe (SHRIMP) U-Pb dating of zircons in lenticular and granodioritic granulites produced in the middle gneisses and quartzites of the Himalayan orogenic belt has been reported. Of the 14 zircons, 15 The points are concentrated on the harmonic line, and the average age of 206Pb / 238U is 17.6 ± 0.3 Ma, which reflects the adiabatic step-down metamorphic event of granulite rapidly rising from the deep crust, formed after the collision between Indian plate and Eurasian plate Tectonic uplift environment with large-scale thrust-nappe, extensional detachment and pale-granite emplacement in the Himalayan orogenic belt.An other zircon 206Pb / 238U age of 29.5 ± 0.4 Ma, The final zircon 206Pb / 238U age is 1991 ± 26 Ma, which represents the age of the granulite source rock.In conclusion, the dating results show that the granulite in the area experienced multi-metamorphic and complicated geological evolution process.