New paleomagnetic results of the early Permian in the Xainza area, Tibetan Plateau and their paleogeographical implications

Abstract

The characteristic remanent magnetizations (ChRMs) of the late Paleozoic in the Lhasa Terrane reported previously were not widely used for paleogeographical reconstructions because the rocks have been obliterated significantly by multiphase orogeny. This study reports the paleomagnetic data of 131 samples collected from 17 sites in the Permian and the late Triassic rocks from the Zhakang section of the Xainza area, where the relative undeformed Paleozoic strata were preserved. Consequently, the ChRMs of high temperature with the different paleomagnetic directions were isolated from the Permian sandstones, limestones, dolomites and the late Triassic silicalites. Without the constraints with the spatial and temporal limitation of the chemical remagnetization derived from the fluids driven by the Neogene strike-slip faults and the Paleogene thrusting faults in the study area, the ChRMs carried by hematite in early Permian sandstones away the faults have potentially preserved a primary magnetization, which has a paleomagnetic direction of D=46.6°, I=−31.2°, κ=69.0, α95=9.3°, N=5 sites after tilt correction, corresponding to a pole at 24.5°N, 219.3°E with A95=7.8°. The new corresponding paleomagnetic pole with the former Carboniferous poles shows the Lhasa Terrane drifted into the middle-lower latitude and isolated in the Paleo-Tethys Ocean rather than adjacent to the northern margin of Gondwanaland during the early Permian after being rifted from the Australian continent in the late Carboniferous.