Structure of the deep lithosphere between Pamir and Tarim

The Pamir protrudes ~300-km between the Tajik and Tarim lithosphere of central Asia. It overlies a Wadati-Benioff earthquake zone connected to a low velocity zone interpreted as crustal rocks. Together with the mantle lithosphere it constitutes the arc-shaped Asian slab. We use new seismic data to better constrain the lithospheric architecture of the Pamir where it abuts the Tarim block and test competing models of its formation. With complemented local-seismicity and focal-mechanism catalogs and a P-wave velocity model that spans the Pamir and the western Tarim lithosphere, we infer the presence of a high velocity zone, interpreted as an Indian mantle lithosphere indenter, delaminating the Asian slab and overturning it in the eastern Pamir. The indenter bends down in the east under the northwestern Kunlun, where it terminates. The indenter–Tarim lithosphere interface is a compressive transform zone lined by a slice of Pamir Plateau crust. As the largest principal stress at depth parallels surface motion and both are highly oblique to the western Tarim margin, this crustal slice is likely dragged with the indenter and downward underneath the Tarim lithosphere.