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Volume 32 Issue 1 (January 2022)

GSA Today

Article, pp. 4-9 | Full Text | PDF

Discovery of an Entrapped Early Permian (ca. 299 Ma) Peri-Gondwanic Sliver in the Cretaceous Shyok Suture of Northern Ladakh, India: Diverse Implications

Rajeev Upadhyay

Dept. of Geology (CAS), Kumaun University, Nainital-263001 (Uttarakhand), India, rajeevntl1@gmail.com

Saurabh Gautam

Birbal Sahni Institute of Palaeosciences, 53 University Road, Lucknow-226007, India

Ram Awatar

7/464 A, Vikas Nagar, Lucknow-226022, India

Abstract

In a significant breakthrough, we report the first discovery of twenty-six genera and thirty-five species of Early Permian (Asselian–Sakmarian and Artinskian; 299 Ma to 276 Ma) Gondwanic palynomorphs from a tectonically emplaced metasedimentary sliver of Shyok Ophiolitic Mélange of the India-Asia Collision zone of Northern Ladakh, India. These palynofloral assemblages are of peri-Gondwanian (Cimmerian) origin and have a strong affinity with the Gondwana assemblage of peninsular India. Similar palynofloral assemblages are also known from Extra-Peninsular India, Salt Range, Karakoram, Antarctica, Australia, South Africa, and South America. The occurrence of Gondwanic sliver within the Shyok Suture is interpreted as a thin flake of active continental margin of peri-Gondwanic microcontinent/Kshiroda plate, which was sliced off during the subduction/collision process, between Ladakh block and Karakoram–Qiangtang-Lhasa terrane and amalgamated with obducted remnants of the accretionary prism of the nascent Shyok Suture. The Shyok Suture closed during the mid- to Late Cretaceous period. Subsequent syn- and post-collision synkinematic episodes tectonically juxtaposed the peri-Gondwanic sliver in the tectonized zone of Shyok Ophiolitic Mélange. The India-Asia collision, which took place ca. 60–50 Ma with the demise of Neo-Tethys Ocean, along the Indus Tsangpo Suture Zone, modified the geometry of accreted ophiolitic stack of the Shyok Suture.

Manuscript received 16 Aug. 2020. Revised manuscript received 23 Sept. 2021. Manuscript accepted 27 Oct. 2021. Posted 19 Nov. 2021.

© The Geological Society of America, 2021. CC-BY-NC.

https://doi.org/10.1130/GSATG481A.1

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