Late-Cretaceous And Cenozoic Uplifting Process Of Xuefeng Mountain And Its Adjacent Area

Xuefeng Mountain(Xuefengshan), located on the southeast margin of Yangtze Block, is between Mayang-Zhijiang Basin(Yuanma Basin) and Xiangzhong Basin(Hengyang Basin). And these units are separated from central Yangtze Block by Fanjingshan Dome, which on the west of Xuefeng mountain. About the formation of this range-basin tectonics on the margin of Yangzte Block, previous studies suggested that the Xuefeng Mountain uplifted in Paleozoic or early-Mesozoic time, and the basins deposited separately. But the sedimentary provenance of Mayang-Zhijiang Basin and Xiangzhong Basin are identical base on the Zircon U-Pb ages, what’s more, the Cretaceous can be found on the Mountain. These evidences may indicate that the basins on the southeast margin of Yangtze Block were a integrate basin.Therefore, inorder to reconstuct this range-basin tectonics formation process, we combined field observation of sedimentary evidences, previous studies and apatite fission track ages to study. The average central ages are: Fanjingshan Dome 64±5Ma, Mayang-Zhijiang Basin 49.4±3.7Ma, Xuefeng Mountain 45.3±3Ma. The time-temperature paths reversed from apatite fission track data indicate: Fanjingshan uplifted during 92-72Ma and 14-0Ma; Mayang-Zhijiang Basin did not uplifted as a integrated unit, and the main uplifting period were 78-60Ma and 15-0Ma; Xuefeng Mountain uplifted during 82-49Ma and 12-0Ma.Therefore, the results indicate that Fanjingshan was a highland since Late-Cretaceous and block the west side of Mayang-Zhijiang Basin; Mayang-Zhijiang Basin and Xuefeng Mountain was a integrated basin in Late-Cretaceous; Xuefeng Mountain uplifted and disintegrated the form Cretaceous basin in Paleocene and Eocene time; all these three belts uplifted slowly in Oligocene and Early-Miocene; all these three belts uplifted and river terrace developed since Late-Miocene.