Sedimentology of the Indus Group, Ladakh, northern India: implications for the timing of initiation of the palaeo-Indus River
Sedimentology of the Indus Group, Ladakh, northern India: implications for the timing of initiation of the palaeo-Indus River
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DOI：
10.1144/jgs.158.1.151
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发表时间：
2001-01
影响因子：
2.7
通讯作者：
H. Sinclair;N. Jaffey
中科院分区：
文献类型：
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作者：
H. Sinclair;N. Jaffey
印度河的上游形成了一个纵向网络，排出了喜马拉雅西部的大部分地区。它作为一个重要的沉积物输送系统，为印度河三角洲和海底扇提供补给，并在喜马拉雅西部的剥蚀历史中起着控制作用。鉴于河流的长期重要性，其启动时间仍然缺乏限制。沿着现代印度河上游保存的后早始新世印度河群的相、古水流和物源揭示了一个以内部水系为主的山间盆地的河流/三角洲和深水沉积历史。因此，印度群岛群并不像以前认为的那样代表古印度河的沉积。印度岩群的伊利石结晶度值和磷灰石裂变径迹测年表明，该序列被埋在155 - 280 ° C的温度下，而去顶开始于中新世早期，并以0.1 - 0.4 mm a − 1的速度进行到现在。最年轻的沉积岩保存沿着印度河盆地早中新世的年龄从周围的卡尔吉尔研究区西部的构造地层学等效存款。早中新世时期从沉积物堆积到侵蚀去顶的过渡与南部高喜马拉雅山脉的加速区域去顶以及西部印度河三角洲/海底扇的形成相一致。向北逆冲的Zanskar和印度河的沉积序列对未变形的拉达克岩石之间的差异隆起提供了一个机制后早中新世启动的主要纵向河流。因此，早中新世时代被认为是古印度河沿着这条路线开始的最早可能年龄。
The upper reaches of the Indus River form a longitudinal network that drains a large portion of the western Himalaya. It plays an important role as a sediment routing system, feeding the Indus Delta and submarine fan, and has played a controlling role in the denudational history of the western Himalaya. Given the rivers long-term significance, its timing of initiation remains poorly constrained. The facies, palaeocurrents and provenance of the post-early Eocene Indus Group preserved along the upper reaches of the modern Indus reveal a history of fluvial/deltaic and deep-water sedimentation in an intermontane basin dominated by internal drainage. Hence, the Indus Group is not considered to represent the deposits of a palaeo-Indus River as previously thought. Illite crystallinity values and apatite fission track dating of the Indus Group suggest that the succession was buried to temperatures of 155–280°C, and that unroofing started in early Miocene times and proceeded at 0.1–0.4 mm a−1 to the present. The youngest sedimentary rocks preserved along the Indus Basin are early Miocene in age from the tectonostratigraphically equivalent deposits around Kargil to the west of the study area. The transition from sediment accumulation to erosional unroofing in early Miocene times coincides with accelerated regional unroofing of the High Himalayas to the south, and the initiation of the Indus Delta/submarine fan to the west. Differential uplift between the northward thrusting of the Zanskar and Indus sedimentary succession against the undeformed Ladakh Batholith provides a mechanism for post-early Miocene initiation of a major longitudinal river. Hence, early Miocene times is believed to represent the earliest possible age of initiation of the palaeo-Indus river following this course.