Sedimentary evolution of the foreland basin in the NE Tibetan Plateau and the growth of the Qilian Shan since 7 Ma

Abstract

We studied the magnetostratigraphy and sedimentary facies of a 550-m-long drill core from the Jiudong Basin in the NE Tibetan Plateau. Our aims were to reconstruct the late Cenozoic sedimentary evolution of this foreland basin, and to determine the spatiotemporal pattern of growth of the Qilian Shan. The magnetostratigraphy indicates that the sedimentary sequence was deposited during ca. 7–0 Ma. From ca. 6.7–3.0 Ma, the sediment accumulation rate increased gradually from ∼30 mm/k.y. to 120 mm/k.y., which was associated with the gradual evolution of sedimentary facies from a shallow lake/delta front to braided rivers. The progradation of the depositional system from 7 Ma to 3 Ma probably reflects the growth of the relief of the Qilian Shan caused by tectonic uplift. The occurrence of a continuous braided river environment from 3 Ma to the present suggests that the high relief of the Qilian Shan developed before 3 Ma. An abrupt decrease of the sedimentation rate to ∼46 mm/k.y. during 3.0–1.8 Ma, and the deposition of coarse-grained sediments, indicates the uplift of the basin center. We interpret this to reflect the propagation of the thrust system of the Qilian Shan into the basin along a southward-dipping décollement from ca. 3 Ma. Climatic changes may have influenced the sedimentary sequence by introducing long-distance-transported thin coarse sand/gravel layers which are sandwiched within the sequence, and likely were a response to cooling events or climatic transitions. The widespread occurrence of deformation within the basin region in the NE Tibetan Plateau at ca. 3 Ma indicates that this date marks the basinward growth of the deformation system.

Three‐Dimensional Crustal Structures of the Shanxi Rift Constructed by Rayleigh Wave Dispersion Curves and Ellipticity: Implication for Sedimentation, Intraplate Volcanism, and Seismicity

“…Journal of Geophysical Research: Solid Earth orogenic erosion processes and the deposition rate of fault basins (e.g., Ding et al, 2009;Hu et al, 2019;Huang et al, 2013). Our observation of much thicker sedimentary layers in the Datong Basin supports the notion that the formation of Datong Basin is contributed by both the passive rifting and active rifting.…”

The interplay between climate and tectonics during the upward and outward growth of the Qilian Shan orogenic wedge, northern Tibetan Plateau

“…8. The suggested onset time of deformation along these faults is based on the previous low-temperature thermochronology and provenance studies (Bovet et al, 2009;Chen et al, 2006a;Fang et al, 2005;Hetzel et al, 2004;Hu et al, 2019;Palumbo et al, 2009;Song et al, 2001;Wang et al, 2018;Yuan et al, 2013;Zhao et al, 2001;Zheng et al, 2010;Zheng et al, 2017;Zheng et al, 2013c;Zhuang et al, 2011b)…”

Late Miocene to Quaternary Development of the Jiujing Basin, Southern Beishan Block, China: Implications for the Kinematics and Timing of Crustal Reactivation North of Tibet

“…This low sedimentation rate is not 11 Lithosphere consistent with a fast sediment burial system, suggesting that the postburial production may increase the concentration of the nuclides and underestimate the burial ages [34,38,42]. Magnetostratigraphy and borehole drilling in the Jiudong Basin, 250 km SE of the Beishan, constrain a sedimentation rate of 60 m/Ma during the last 6-5 Ma [48]. Assuming similar climate conditions between the Beishan and the Qilian Shan during the late Miocene, and applying the Jiudong sedimentation rate of~60 m/Ma, the burial ages of Jiujing Basin samples B3B-1 and B3B-2 are~5.78 Ma and~5.67 Ma, respectively.…”