Miocene exhumation of the Pamir revealed by detrital geothermochronology of Tajik rivers
Miocene exhumation of the Pamir revealed by detrital geothermochronology of Tajik rivers
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DOI：
10.1029/2011tc003040
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发表时间：
2012-04
期刊：
影响因子：
4.2
通讯作者：
C. Lukens;B. Carrapa;B. Singer;G. Gehrels
中科院分区：
文献类型：
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作者：
C. Lukens;B. Carrapa;B. Singer;G. Gehrels
帕米尔山脉是西藏-喜马拉雅系统的西部延续，该系统是地球上最大和最高的造山系统。碎屑热年代学应用于塔吉克斯坦帕米尔西部现代河砂记录了沉积物源结晶、冷却和折返的历史。这提供了重要的信息的时间构造过程中，浮雕的形成，并在造山作用的侵蚀。来自帕米尔西部五条不同构造碎屑河流的碎屑锆石U-Pb年代学和白色云母40 Ar/39 Ar热年代学记录了古生代至新生代的结晶年龄和中新世（13-21 Ma）的冷却信号。碎屑锆石U-Pb年龄显示其时代为元古代至新生代，与西藏的亚洲岩石有密切关系。碎屑40 Ar/39 Ar数据集记录了印度-亚洲碰撞后帕米尔山脉超过3000万年的深度和区域折返，这可以用变质圆顶的广泛侵蚀来解释。这个折返信号与邻近前陆超过6公里的砾岩沉积相吻合，记录了该地区的高沉降、沉积和区域折返。我们的数据与高起伏景观和造山带范围内的折返在1013 -21 Ma一致，并与帕米尔片麻岩穹隆折返的时间相关。帕米尔高原的折返比邻近西藏的折返要年轻，这与新生代造山系统这一部分的变形和缩短幅度更大是一致的。
The Pamir mountains are the western continuation of the Tibetan‐Himalayan system, the largest and highest orogenic system on Earth. Detrital geothermochronology applied to modern river sands from the western Pamir of Tajikistan records the history of sediment source crystallization, cooling, and exhumation. This provides important information on the timing of tectonic processes, relief formation, and erosion during orogenesis. U‐Pb geochronology of detrital zircons and 40Ar/39Ar thermochronology of white micas from five rivers draining distinct tectonic terranes in the western Pamir document Paleozoic through Cenozoic crystallization ages and a Miocene (13–21 Ma) cooling signal. Detrital zircon U‐Pb ages show Proterozoic through Cenozoic ages and affinity with Asian rocks in Tibet. The detrital 40Ar/39Ar data set documents deep and regional exhumation of the Pamir mountains >30 Myr after Indo‐Asia collision, which is best explained with widespread erosion of metamorphic domes. This exhumation signal coincides with deposition of over 6 km of conglomerates in the adjacent foreland, documenting high subsidence, sedimentation, and regional exhumation in the region. Our data are consistent with a high relief landscape and orogen‐wide exhumation at ∼13–21 Ma and correlate with the timing of exhumation of the Pamir gneiss domes. This exhumation is younger in the Pamir than that observed in neighboring Tibet and is consistent with higher magnitude Cenozoic deformation and shortening in this part of the orogenic system.