Bangong suture

The geology of the suture includes Jurassic marine shale and conglomeratic strata, melange and ophiolites and volcanic rocks from multiple pulses of magmatism.

[6] Each of these lithologies can be tied to specific terranes, either island arcs[7] or microcontinents, that were gathered in front of the Indian subcontinent as it drifted northward during the Mesozoic.

During the Jurassic-Cretaceous collision[8] of the Lhasa and Qiangtang terranes, the ancient Tethys ocean closed,[1][8] creating the Bangong suture zone.

[8] Geology of the Amdo records Mesozoic metamorphism, magmatism, and exhumation and is composed of orthogneisses and metasediments which are intruded by undeformed granitoids.

The "soft Tibet" model suggests that a series of small multiple faults along the suture zone would occur, due to the ductile nature of the lithosphere.

[10] Crustal extrusion (in the form of sinistral strike-slip faults) should also be present and would be caused by oblique subduction at the edges of the suture zone.

General map of central and southern Tibet depicting the Bangong suture (located between the BSZ and Qiangtang terrane) and Bangong suture zone (BSZ) and surrounding terranes . Map is modified from Guynn et al., 2011. [ 1 ]
Cross section depicting the tectonic evolution of the Bangong suture zone. 1. An oceanic backarc basin forms separating the Amdo basement from the Qiangtang terrane. Slab rollback is a possible explanation for this extension. 2. Continued subduction of oceanic crust in the early-middle Jurassic. Closure of the oceanic back arc basin causes ophiolite obduction and a period of metamorphism in the Amdo basement. 3. In the early Cretaceous, the Lhasa and Qiangtang terranes collide creating the Bangong suture. A foreland basin also forms at this time. Cross section is modified from Guynn et al., 2006. [ 8 ]