Low-Temperature Thermochronology of the Tibetan Plateau - a Review and New Results from the Interior

The Tibetan Plateau is the largest mass of uplifted rock on earth, yet the mechanism of uplift and the denudation history are poorly known. The formation of the plateau is generally assumed to be related to the Cenozoic Indo-Asian collision, though it has been known for some time that Tertiary contractional deformation is limited in the plateau interior. A review of work along the edges of the plateau reveals both Cenozoic tectonic activity and Cenozoic exhumation, the youngest and greatest being the Himalayan mountain range on the southern boundary. However, in the northern and eastern margins, Mesozoic exhumation signatures are preserved. More recent work on the interior of the plateau has revealed that the tectonic history is dominated by Paleocene and older events and confirms only sparse Tertiary contractional deformation. Preliminary low-temperature thermochronology from the interior does not show any significant exhumation attributable to the Indo-Asian collision. Instead, Cretaceous-Paleocene cooling ages are dominant and similar to the older ages along the margins. Sparse younger shortening and exhumation is typically younger than ~55 Ma (mid-Tertiary or younger), the typically cited age for the India's collision with Asia. The low-temperature thermochronologic data indicate less than ~3 km of denudation since the Paleocene, consistent with other estimates of Cenozoic erosion rates for the Plateau. Late Cretaceous – early Tertiary contraction in Tibet likely produced a significantly thickened crust and the exhumation history suggests that it maintained that thickened crust before and during the Indo-Asian collision.