Crustal thickness and lithospheric thermal state beneath the Junggar Basin and adjacent Mountain Ranges, northwest China

摘要

In this paper, data of gravimetry, aeromagnetic survey, and surface heat flow are utilized in a combined manner to investigate the crustal thickness, Curie surface, and lithospheric thermal state beneath the Junggar Basin and adjacent Mountain Ranges. The Moho depth, Curie depth, and thermal lithospheric thickness are found to be 38-52 km, 32-50 km, and 120-260 km, respectively. The Moho and Curie surface present a rough inverse correspondence between each other. In the Tianshan and Altai Mountain Ranges, Moho interface is deep but Curie surface is shallow. In the Junggar Basin, Turpan Basin, and Yili Basin, the situation is in reverse. The uppermost mantle in the Central Depression and Eastern Uplift of the Junggar Basin, the Turpan Basin, the Yili Basin, as well as the north-west area off Fuhai is investigated to have been magnetized. The aeromagnetic anomalies and the Curie surface in the Junggar Basin surprisingly reveal that the northward subduction of the north Tarim block/slab under the Junggar Basin accompanied by the uplift of the Tianshan Mountain Range. Also, in response to the northward movement, the rigid Central Depression of the Junggar Basin extruded from its east and west sides. The westward extrusion is manifested by the West Uplift of the western Junggar Mountain Range.