Quantifying the rise of the Himalaya orogen and implications for the South Asian monsoon

Abstract

We reconstruct the rise of a segment of the southern flank of the Himalaya-Tibet orogen to the south of the Lhasa terrane, using a paleoaltimeter based on paleoenthalpy encoded in fossil leaves from two new assemblages in southern Tibet (Liuqu and Qiabulin) and four pre viously known floras from the Himalaya foreland basin. U-Pb dating of zircons constrains the Liuqu flora to the latest Paleocene (ca. 56 Ma) and the Qiabulin flora to the earliest Miocene (21-19 Ma). The proto-Himalaya grew slowly against a high (~4 km) proto-Tibetan Plateau from ~1 km in the late Paleocene to ~2.3 km at the beginning of the Miocene, and achieved at least ~5.5 km by ca. 15 Ma. Contrasting precipitation patterns between the Himalaya-Tibet edifice and the Himalaya foreland basin for the past ~56 m.y. show progressive drying across southern Tibet, seemingly linked to the uplift of the Himalaya orogen.