Cenozoic sedimentation rate of Xunhua, Linxia and Guide basins responding to the uplift of the Tibetan Plateau

Based on sedimentary facies and sedimentation rate analysis of Neogene sedimentary basins in Xunhua, Linxia and Guide in northeastern Tibetan Plateau, the authors divided the sedimentary evolution responding to tectonic uplift into four processes: ①In the Late Oligocene-Early Miocene period (25-20Ma), the changes of sedimentary facies and sedimentation rate in the three basins showed that the NE-trending accretion arrived in the north margin of West Qingling in Oligocene. At 22Ma, the uplift of Laji Mountain was strong. ② During Middle Miocene (17-13Ma), with the interaction of the basin-mountain coupling of the northeastern plateau, the lake expanded further. The growth of the Jishi Mountain and the continued uplift of the West Qingling and the Laji Mountain at 13Ma turned the study area into basin-margin type. ③ In Late Miocene (11-6Ma), the transition of sedimentary facies, the acceleration of sedimentation rate and the existence of unconformity indicated that the plateau was subjected to strong tectonic uplift activities at this time. Besides, the tectonic uplift reflected by fission track thermochronologic evidence was also consistent with sedimentary response. ④ In Pliocene (5Ma-), the sedimentation rate continued to increase, the differences of terrain were enhanced, and the lakes died out gradually.