MI2021 - 07 Craig Martin: Paleocene latitude of the Kohistan-Ladakh arc
Channel: MagNetZ
Date: 2021-02-18

Paleocene latitude of the Kohistan-Ladakh arc indicates multi-stage India-Eurasia collision

Craig R. Martin, Massachusetts Institute of Technology, USA

We report paleomagnetic data showing that an intraoceanic Trans-Tethyan subduction zone existed south of the Eurasian continent and north of the Indian subcontinent until at least Paleocene time. This system was active between 66 and 62 Ma at a paleolatitude of 8.1 ± 5.6 °N, placing it 600–2,300 km south of the contemporaneous Eurasian margin. The first ophiolite obductions onto the northern Indian margin also occurred at this time, demonstrating that collision was a multistage process involving at least two subduction systems. Collisional events began with collision of India and the Trans-Tethyan subduction zone in Late Cretaceous to Early Paleocene time, followed by the collision of India (plus Trans-Tethyan ophiolites) with Eurasia in mid-Eocene time. These data constrain the total postcollisional convergence across the India– Eurasia convergent zone to 1,350–2,150 km and limit the north–south extent of northwestern Greater India to less than 900 km.