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Edited by B. Clark Burchfiel, Massachusetts Institute of Technology, Cambridge, MA, and approved October 5, 2020 (received for review May 6, 2020)
Significance
We present paleomagnetic constraints on the latitude of an intraoceanic subduction system that is now sutured between India and Eurasia in the western Himalaya. Our results demonstrate that the India–Eurasia collision was a multistage process involving at least two subduction systems rather than a single-stage event. This resolves the discrepancy between the amount of convergence and the observed crustal shortening in the India–Eurasia collision system, as well as the 10–15 Ma time lag between collision onset in India and the initiation of collision-related deformation and metamorphism in Eurasia. The presence of an additional subduction system in the Neotethys ocean explains the rapid India–Eurasia convergence rates in the Cretaceous and global climate variations in the Cenozoic.
Abstract
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 <900 km. These results have broad implications for how collisional processes may affect plate reconfigurations, global climate, and biodiversity.
Footnotes
- ↵1To whom correspondence may be addressed. Email: crm7{at}mit.edu.
Author contributions: O.J., L.H.R., and B.P.W. designed research; C.R.M., O.J., R.U., L.H.R., and B.P.W. performed research; C.R.M., M.P.E., E.B., C.I.O.N., and B.P.W. analyzed data; and C.R.M., O.J., R.U., L.H.R., M.P.E., E.B., C.I.O.N., and B.P.W. wrote the paper.
The authors declare no competing interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2009039117/-/DCSupplemental.
Published under the PNAS license.
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Paleocene latitude of the Kohistan–Ladakh arc indicates multistage India–Eurasia collision
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- Physical Sciences
- Earth, Atmospheric, and Planetary Sciences
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