Sedimentary environment of the early Pleistocene Baitushan Formation strata in the western Songliao Basin, NE China: Implications for regional tectonic and drainage development

Abstract

The Songliao Basin plays a key role in determining the basin-mountain evolution history of the China, which is closely related to uplift dynamics, paleoenvironment changes, and landform evolution. Whereas, knowledge of basin-mountain evolution history of landforms in NE China since Quaternary remains limited, due to a lack of high-quality sedimentary records. The Baitushan Formation strata in the western Songliao Basin, are of great significance because they record a series of regional tectonic uplift, volcanism and drainage evolution events. However, the sedimentary environment and age of the strata are still highly controversial, which limits our understanding of the evolutionary history of the basin-orogenic belt systems in the NE China. Here, we present a multidisciplinary approach, e.g., geochronology, sedimentology, petrography, mineralogy and geochemistry, for an investigation of the stratotype section of the Baitushan Formation. The Baitushan Formation sediments are characterized by a moderate-to-strong degree of chemical weathering, textural immaturity and low recycling sedimentation history. The geochemical composition and detrital zircon U-Pb ages indicate the felsic igneous parent rocks eroded from the central Great Xing’an Range. The sedimentological characteristics indicate a braided river origin under the warm and semi-arid climate. The 26Al/10Be burial dating does not give a conclusive stratigraphic age, but the integrated paleomagnetic and electron spin resonance (ESR) dating strategies constrain the stratigraphic age of the Baitushan Formation to be ∼ 1.1 Ma. The geomorphological and sedimentological evidence suggests the significant Quaternary uplift of the Great Xing’an Range before at least ∼ 1.1 Ma. The zircon U-Pb ages of the Baitushan Formation record the multi-phase volcanism in the central Great Xing’an Range during the Mesozoic. The closure of Mongol-Okhotsk Ocean and the rollback of the paleo-Pacific plate played a decisive role in the asthenospheric mantle upwelling, crustal uplift and extension, and volcanic activity. The geomorphical and detrital zircon age evidence indicates that the Baitushan Formation is the paleo-channel accumulation of the Yalu River, which implies the birth of the Yalu River no later than 1.1 Ma. This study contributes to deepening our present understanding of the Great Xing’an Range uplift and drainage evolution history in NE China.