Extensional tectonics in central and eastern Asia: a brief summary

Abstract

Although most of the neotectonics of eastern and central Asia seems to be due to the collision and continued convergence between India and Eurasia, extensional tectonics prevails in four portions of this region: Tibet, the Baikal rift system, the Shansi graben and Yunnan. We think that the convergence between India and Eurasia is responsible for crustal extension in all four regions, but the physical mechanisms responsible for the extension are not the same in all of these cases. Fault plane solutions of earthquakes, and clearly defined escarpments and adjacent basins seen on the Landsat imagery, indicate widespread normal faulting in Tibet (Molnar & Tapponnier 1975, 1978; Ni & York 1978). The direction of extension appears to be east-west, but the poorly determined fault plane solutions and the lack of field studies allow some variation in the direction of extension. The normal faulting seems to be confined to the areas of highest elevation and some of the normal faults cross the Indus-Zangbu suture into the high Himalaya.