158 / 2015-09-03 19:29:16

Provenance Analysis and Structure Significance of Mesozoic Sedimentary Rocks in Moqinwula Mountain in Xinjiang

7745,7746,7743,7747,7748

Abstract: Moqinwula Mountain, located in the east edge of Bogda Peak, is a branch range of East Tianshan Mountain, the south and north of which are respectively surrounded by Balikun and Santanghu Basin. This article focuses on researching on the Jurassic sedimentary stratums of conglomerate mixed up with sandstone in Moqinwula Mountain. By counting the occurrences of biggest flat surface of gravels and flake identification to add up the percentage of quartz, feldspar and debris of the rocks in study area and analyzing detrital zircon, combining with mineralogy characteristics of zircon, CL images and surrounding regional geological data, following conclusions can be drawn: (1) This suite of stratum is a continental deposit. Lithological combination is conglomerate mixed up with grit stone to fine sandstone, narrow shed coal partly included. (2) The lowest zircon age of sandstone in research area is 242±6Ma, which illustrates that this suite of stratum is not older than Middle Triassic stratum. Combining with regional geological data, this suite of sedimentary rocks is assumed to deposit in Late Triassic to Early Jurassic. (3) Major detrital components are siltstone and feldspar debris sandstone, including some granite and volcanic rocks, which conforms to the lithology of Haerlike Mountain in south. Meanwhile, it’s proved by counting the occurrences of biggest flat surface of gravels. In addition, two peak value of detrital zircon between 290-320 Ma and 440-500 Ma also can demonstrate this conclusion. (4) The lowest age of the detrital zircon of Moqinwula Mountain, as an east branch range of Bogda Peak, is 242±6 Ma. The mountain lifting motion should happen later than that. Combining with regional background data, it’s assumed that lifting motion happened after Early Jurassic.