Initial India-Asia Continental Collision and Foreland Basin Evolution in the Tethyan Himalaya of Tibet: Evidence from Stratigraphy and Paleontology
Initial India-Asia Continental Collision and Foreland Basin Evolution in the Tethyan Himalaya of Tibet: Evidence from Stratigraphy and Paleontology
复制标题
DOI：
10.1086/663876
复制
发表时间：
2012-03
期刊：
影响因子：
--
通讯作者：
Qinghai Zhang;H. Willems;L. Ding;K. Gräfe;E. Appel
中科院分区：
文献类型：
--
作者：
Qinghai Zhang;H. Willems;L. Ding;K. Gräfe;E. Appel
印度-亚洲大陆-大陆碰撞在西藏的开始伴随着洋壳的消减和俯冲陆壳上周缘前陆盆地的发育。然而，由于这个前陆盆地的逐步向南迁移，弯曲隆起（前隆）的出现早于弯曲沉降（前渊）在远端的位置，如在Gamba和Tingri在南部特提斯喜马拉雅。因此，对该前隆的追踪和定年，可能会对印度-亚洲碰撞提供更好的约束。在岗巴和定日，我们对地层、古生物和古环境的研究表明，灰岩的沉积停止发生在岗巴地区的第7浅水底栖带（SBZ 7，距今54-55 Ma）和定日地区的SBZ 10底部（距今52.8 Ma）。在岗巴，上宗普组中的砾岩层代表了前陆盆地开始时前隆的形成，砾岩层与碳同位素漂移（CIE）的一致性为可能的初始印度-亚洲大陆碰撞提供了精确的156 Ma（古新世/始新世界线）的年龄。我们的结果不仅提供了一个可靠的和精确的年龄的印度-亚洲碰撞，但第一次，报告之间的时间等价的印度-亚洲碰撞和CIE在西藏。
The onset of the India-Asia continent-continent collision in Tibet was accompanied by the elimination of oceanic crust and the development of a peripheral foreland basin on the subducting continental crust. However, owing to the progressively southward migration of this foreland basin, the appearance of flexural uplift (forebulge) predated flexural subsidence (foredeep) at the distal location, such as at Gamba and Tingri in the southern Tethyan Himalaya. Consequently, to trace and date this forebulge may provide a better constraint on the India-Asia collision. At Gamba and Tingri, our studies on the stratigraphy, paleontology, and paleoenvironment show that depositional cessation of the limestones occurred at Shallow Benthic Zone 7 (SBZ 7, ∼54–55 Ma) in the Gamba area and at the base of SBZ 10 (∼52.8 Ma) in the Tingri area. At Gamba, a conglomerate layer within the upper Zongpu Formation is suggested to represent the formation of the forebulge at the onset of the foreland basin, and the coincidence of the conglomerate layer with the Carbon Isotope Excursion (CIE) provides a precise age of ∼56 Ma (the Paleocene/Eocene boundary) for the possible initial India-Asia continental collision. Our results not only provide a reliable and precise age for the India-Asia collision but, for the first time, report time equivalence between the India-Asia collision and the CIE in Tibet.