Oblique Stepwise Rise and Growth of the Tibet Plateau

Abstract

Two end member models of how the high elevations in Tibet formed are (i) continuous thickening and widespread viscous flow of the crust and mantle of the entire plateau and (ii) time-dependent, localized shear between coherent lithospheric blocks. Recent studies of Cenozoic deformation, magmatism, and seismic structure lend support to the latter. Since India collided with Asia approximately 55 million years ago, the rise of the high Tibetan plateau likely occurred in three main steps, by successive growth and uplift of 300- to 500-kilometer-wide crustal thrust-wedges. The crust thickened, while the mantle, decoupled beneath gently dipping shear zones, did not. Sediment infilling, bathtub-like, of dammed intermontane basins formed flat high plains at each step. The existence of magmatic belts younging northward implies that slabs of Asian mantle subducted one after another under ranges north of the Himalayas. Subduction was oblique and accompanied by extrusion along the left lateral strike-slip faults that slice Tibet's east side. These mechanisms, akin to plate tectonics hidden by thickening crust, with slip-partitioning, account for the dominant growth of the Tibet Plateau toward the east and northeast.

Phylogeny and biogeographic diversification of Maianthemum (Ruscaceae: Polygonatae)

“…Geologic uplift of this region began about 50 mya, and the last significant increase in altitudes of the Tibetan plateau was hypothesized at about 10-8 mya ago (Harrison et al, 1992). Although the final major uplift of the Tibet plateau is still controversial (Li and Fang, 1999;Tapponnier et al, 2001), the region likely…”

“…Geologic uplift of this region began about 50 mya, and the last significant increase in altitudes of the Tibetan plateau was hypothesized at about 10-8 mya ago (Harrison et al, 1992). Although the final major uplift of the Tibet plateau is still controversial (Li and Fang, 1999;Tapponnier et al, 2001), the region likely ACCEPTED MANUSCRIPT reached the present elevation no later than about 3.6 mya (Cui et al, 1996;Shi et al, 1998;An et al, 2001). The diversification of Maianthemum likely occurred shortly after the uplift and formation of the Himalayas and the Tibet Plateau.…”

Evolutionary events in Lilium (including Nomocharis, Liliaceae) are temporally correlated with orogenies of the Q–T plateau and the Hengduan Mountains

“…4 and 5). Though the eastern margin of the Q-T Plateau may have undergone continuous uplift beginning 20 Mya and lasting until approximately 7 Mya, it is widely accepted that phases of more rapid uplift have occurred (e.g., Harrison et al, 1992;An et al, 2001;Tapponnier et al, 2001;Song et al, 2001). For example, rapid uplift may have occurred approximately 8-7 Mya and is evident from sedimentary layers indicative of increased aridification (i.e., loess) that accumulated within the rainshadow of the plateau during that time (Guo et al, 2002).…”

Uplift of the Tibetan plateau: Evidence from divergence times of glyptosternoid catfishes

“…Much of the elevation of the plateau derives from the collision of India and Eurasia around 50-45 million years (Ma) ago. The Cenozoic uplift processes of the Tibetan plateau and its environmental eVects are of considerable scientiWc interest, but the mechanism, amplitude, and timing of the uplift are still controversial (Li and Fang, 1999;Tapponnier et al, 2001). Studies of molecular phylogeny and biogeography of organisms endemic to the plateau oVer an alternative approach for investigating the historical processes of the geological events and the concomitant ecological changes.…”