Cenozoic basin-filling evolution of the SW Tarim Basin and its implications for the uplift of western Kunlun: Insights from (seismo)stratigraphy

Abstract

The western Kunlun Mountains and the adjacent southwestern Tarim Basin define the northwestern boundary of the intensely deformed Cenozoic Tibetan Plateau, and thus should bear important information on the growth processes of the NW Tibetan Plateau. In this study, the integration of a stratigraphic investigation of the Cenozoic Keliyang succession section and a seismostratigraphic analysis on the seismic reflection profile reveal the sedimentary evolution and basin-filling processes of the southwestern Tarim Basin. Our results suggest a significant depositional shift from marine facies during the depositional periods of the Aertashi to Bashibulake Formations to continental facies during the depositional periods of the Keziluoyi to Xiyu Formations. This shift, which corresponds to southward depositional thickening, has been attributed to the uplift of South Kunlun and the onset of foreland basin subsidence along the southwestern Tarim Basin. Strata from the Keziluoyi to Xiyu Formations form an upward-coarsening sequence that is interrupted by a subordinate upward-thinning sequence in the Anjuan Formation. These results, in combination with the northward migration of the depocenter by at least ~56 km since the depositional period of the Artux Formation and previous studies on basinward deformation propagation, demonstrate that the tectonic loading of the western Kunlun has propagated northward to North Kunlun, which suggest expansion of the NW Tibetan Plateau since this period. We posit that the upper-crustal boundary between western Kunlun along the NW Tibetan Plateau and the Tarim Basin is a northward movable feature. This would support the hypothesis that the substantial lower Tarim Plate (>~56 km if calculated from the magnitude of the northward depocenter migration) has underthrusted southward beneath western Kunlun.