Differential crustal deformation across the Cona-Oiga rift, southern Tibetan Plateau

Abstract

The Cona-Oiga rift (COR) is the easternmost member of a series of ∼N-S trending Cenozoic rifts in the southern Tibetan Plateau. The Yarlung River flows from west to east, across the COR and exhibits diverse river morphology along strike. We analyze tributary fluvial longitudinal profiles in the Yarlung drainage and the published strain rate field on both sides of the rift in order to gain knowledge about its development and crustal deformation patterns within the plateau interior. Tributaries on the western side of the rift have relatively low normalized steepness index (ksn). Concave curves in χ-elevation plots and cross-divide contrasts in χ, mean relief, and mean gradient, indicate ongoing river reorganization in this region. In contrast, high topographic relief and steep stream channels developed on the eastern side. In addition, spatial variations in negative dilatational strain rates indicate diverse crustal shortening and regional uplift across the COR. We suggest that the Cona-Oiga rift plays an important role in accommodating deformation associated with the continuing indentation of the eastern Himalayan syntaxis. Tectonic forcing might be the dominant factor controlling landscape evolution across the COR.