Magnetostratigraphic Construct of Awate Section in the North Tarim Basin: the Impulse Uplift of Tianshan Range

Abstract

AbstractMagnetostratigraphic results of Awate Section from 1606 horizons in Neogene strata between the upper Jidike Formation and the base of the Xiyu Formation in the Kuche Depression of the Tarim Basin, are used to evaluate the tectonic evolution of Tianshan Range. Progressive thermal demagnetization successfully isolated a linear characteristic remanent magnetization of dual polarity between 450 and 680°C, from which a magnetic polarity sequence is constructed. Twenty‐six reversed and twenty‐six normal polarity chrons can be identified from the composite magnetostratigraphy, which correlate between ~1.7 and ~15.1 Ma with the geomagnetic polarity time scale of Cande and Kent. Sedimentation rates from magnetostratigraphic age versus height show a decrease from ~22 to ~7 cm/ka at ~11 Ma, and around 6.5 Ma there was another abrupt increase from ~7 to ~68 cm/ka. These episodic changes can be connected with Late Cenozoic impulse uplift of Tianshan Range.