First Discovery of North-South Striking Normal Faults near the Potential Eastern End of Altyn Tagh Fault

Abstract

The Altyn Tagh fault is the northern boundary of Tibetan Plateau. As one of the most well-known strike-slip fault in the world, great achievements on tectonic deformation and Late Quaternary slip rate have been made. However, there is a long-lasting debate on whether the Altyn Tagh fault extends into the Jinta Basin or even eastward. In this paper, we use satellite image interpretation, field investigation, trench excavation, and optical stimulated luminescence dating to study newly found NS striking scarps in the eastern end of Jinta Nan Shan. The results are as follows: firstly, a group of normal faults develop on terrace T2 of Heihe River, the total length amounts to ∼40 km, total scarp height is 30±5 m; secondly, four paleoseismic events have been interpreted from three trenches, approximate ages of events are 79.97±19.14 ka BP, 62.55±13.10∼55.41±10.77 ka BP, before 16.89±2.08 ka BP, 8.52±1.49 ka BP, respectively; thirdly, just like NS normal faults in the western end of Altyn Tagh fault, the newly found NS extensional faults are likely the terminating tectonics of the eastern end of Altyn Tagh fault, the large Altyn Tagh fault may end in the eastern end of Jinta Nan Shan.