Tectonic topography and Late Pleistocene activity of the West Qinling Fault, northeastern Tibetan Plateau

Abstract

A precise measurement of the slip rate of active faults within and around the Tibetan Plateau will provide definite and explicit knowledge of continental dynamics and present-day active tectonic processes. The WNW-trending West Qinling Fault (WQLF), the target of this study, is one of the major active strike-slip faults developed in the northeastern Tibetan Plateau. The interpretation of three dimension (3D) perspective topographic maps, field investigations, and 14C-dating results reveal that (i) the drainage systems, mountain ridges, alluvial fans, and terrace risers have been systematically left-lateral deflected or offset by ∼6 m up to hundreds of meters during the Late Pleistocene–Holocene along the WQLF in the northeastern marginal zone of the Tibetan Plateau; (ii) the left-lateral strike-slip rate is estimated to be ∼2.5–2.9 mm/yr with an average value of ∼2.7 mm/yr since the Late Pleistocene; (iii) compared to the well-studied strike-slip active faults developed in the northern and northwestern Tibetan Plateau such as the Altyn Tagh Fault and the Kunlun Fault with high slip rate of >10–20 mm/yr, the WQLF displays a characteristically low strike-slip rate of <3 mm/yr. We interpret that the low slip rate of the WQLF is related to the limited convergence transfer and that most of the strain energy was probably absorbed and partitioned by continuous crustal deformation in the northeastern marginal zone of the Tibetan Plateau, rather than only the localized deformation along active faults.