Subsidence history of the Tethys Himalaya
Subsidence history of the Tethys Himalaya
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DOI：
10.1016/j.earscirev.2011.11.007
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发表时间：
2012-02
影响因子：
12.1
通讯作者：
D. Sciunnach;E. Garzanti
中科院分区：
文献类型：
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作者：
D. Sciunnach;E. Garzanti
本文重建了印度半岛面向新特提斯的被动北方边缘从石炭纪最早的裂陷阶段到始新世早期与亚洲主动南缘碰撞的演化过程。将盆地分析的经典技术应用于广泛而连贯的地层数据库。通过对8个主要复合剖面的10 km厚的沉积序列进行相分析、生物地层定年和古环境解释，绘制了精确的沉积和回剥沉降曲线，并对从沉积记录中推断的古构造情景进行了定量约束。在每一个调查的复合部分，三个主要的地层缺口一致地承认在裂谷序列：“裂谷不整合”（密西西比），“石炭纪/二叠纪间断”（主要是卡西莫瓦至Asselian），和“破裂不整合”（中期Sakmarian）。两个或甚至所有三个间隙可能合并成一个单一的间隙，总跨度高达70 Ma。间隙与裂谷肩隆起有关，在计算回剥沉降后，至少在三个调查段中总计达600 m。中二叠世至中三叠世的漂移序列记录了热沉降和低沉积速率，这些漂移序列是在冈瓦纳北方和分离的冈瓦纳周边地块之间的新特提斯扩张时沉积的。一个显着增加的积累率记录在卡尼安-诺利安，但计算均匀的岩石圈拉伸表明，延伸是轻微的，并与构造过程影响冈瓦纳遥远的部分。特提斯喜马拉雅边缘在侏罗纪/白垩纪边界附近隆起，在一个主要的火山事件的开始。最后，地层柱最上面的单元记录了超过以往所有事件的隆升幅度，这些单元是在古新世末至始新世初印度和亚洲之间碰撞的最早阶段沉积的。
This article reconstructs the evolution of the passive northern margin of peninsular India facing the Neotethys, from the earliest rifting stages in the Carboniferous to final collision with the active southern margin of Asia in the Early Eocene. Classical techniques of basin analysis were applied to an extensive and coherent stratigraphic data base. Facies analysis, biostratigraphic dating, and palaeoenvironmental interpretation of an over 10km-thick sedimentary succession from eight main composite sections allowed us to draw accurate sedimentation and backstripped subsidence curves, and to place quantitative constraints on the palaeotectonic scenario inferred from the sedimentary record. In each of the investigated composite sections, three major stratigraphic gaps are consistently recognised in the rift sequence: the “rift unconformity” (Mississippian), the “Carboniferous/Permian hiatus” (largely Kasimovian to Asselian), and the “break-up unconformity” (mid-Sakmarian). Two or even all three gaps may merge into a single hiatus, spanning up to 70Ma overall. Gaps are associated with rift-shoulder uplift, which after calculation of backstripped subsidence sums up to 600m at least in three of the investigated sections. Thermal subsidence and low sedimentation rates are documented by the mid-Permian to Middle Triassic drift sequence, deposited while the Neotethys was expanding between northern Gondwana and the detached Peri-Gondwanan blocks. A marked increase in accumulation rates is recorded in the Carnian–Norian, but calculations of uniform lithospheric stretching suggest that extension was minor and associated with tectonic processes affecting distant parts of Gondwana. The Tethys Himalayan margin was uplifted around the Jurassic/Cretaceous boundary, at the onset of a major volcanic episode. Finally, uplift exceeding in magnitude all previous events is documented by the uppermost units of the stratigraphic column, deposited during the earliest stages of collision between India and Asia in the latest Paleocene to Early Eocene.