| PDF: | |
| Time: | 2016 |
| Journal: | Earth Science |
| Volumn: | 41 |
| Issue: | 8 |
| Pages: | 1259-1274 |
| Type: | EI |
| Author: | Chongyang Chen,Youfeng Gao,Haibo Wu,Xuejiao Qu,Zhiwen Liu,Xuefeng Bai,Pujun Wang |
Abstract: | LA-ICP-MS zircon U-Pb dating for 4 volcanic rock samples from coring well in the Hailaer Basin (HB) were presented in this paper. Their formation time and tectonic setting were discussed with emphasizing on the intra-/inter-basinal stratigraphic correlation, which can provide a basis for the structural evolution of the Great Xing\'an Range. Zircon minerals from the 4 representative samples are euhedral-subhedral in shape and display striped absorption or oscillatory zoning in CL images as well as high Th/U ratios (0.22～1.5), implying their magmatic origin. The authors discovered with the dating results that volcanic rocks with ages of Late Triassic-early Early Jurassic (214.4±4.3 Ma) do exist in the HB. And the whole volcanic successions in the region can be subdivied into 4 stages of eruption, i.e., Middle-Late Carboniferous (320～290 Ma), Late Triassic-early Early Jurassic (224～197 Ma), Late Jurassic-early Early Cretaceous (152～138 Ma), late Early Cretaceous (128～117 Ma). Combined with geochemical characteristics, temporal and spatial distribution characteristics of the magma in the Great Xing\'an Range area, as well as the characteristics of the seismic profile of the basin, it is suggested that the Middle-Late Carboniferous magmatic rocks (320～290 Ma) were probably formed in a post-collision extensional setting related to the collision and merging of the Songnen and Ergun-Xing\'an blocks. The Late Triassic-early Early Jurassic volcanic rocks (224～197 Ma) were probably formed in a post-collision extensional setting related to the closure of Paleo-Asian Ocean, which indicate Paleo-Asian Ocean tectonic domain affects the Great Xing\'an Range area extended to the early Early Jurassic at least and the collision of the Mongolia Okhotsk Ocean possible start in the early Jurassic at the earliest. The Late Jurassic-early Early Cretaceous (152～138 Ma)and the late Early Cretaceous (128～117 Ma) volcanic rocks were probably formed in a post-collision extensional setting related to the closure of Mongolia Okhotsk Ocean. We also got some ages of Paleoproterozoic-Neoproterozoic zircon dating which were preferably explained to be captured from some crystal rocks of Proterozoic crystalline basement in the blocks underneath the HB. |