Identification of three stages of paleochannels and main source analysis beginning in the middle Pleistocene in the western Bohai sea in north China

Abstract

Significant global sea transgressions–regressions have occurred under the influence of glacial–interglacial climatic change during the Quaternary period. Various types of paleochannels developed on the continental shelf of the western Bohai Sea as a result of sea level decline. Currently, the source of the paleochannels and the sedimentary environment and evolutionary pattern of the paleochannels are disputed. This study interprets high-resolution single-channel seismic data using a chronological framework based on accelerator mass spectrometry 14C (AMS14C) dating and optically stimulated luminescence (OSL) dating of core DZQ01. Furthermore, this research correlates this data with the cores of TJC-1 and H6 in the Western Bohai Sea and analyzes sedimentological characteristics based on grain size and clay mineral analyses. The results indicate that (1) three stages of paleochannels, namely Seismic Unit 6 (SU6), SU4, and SU2 are identified from bottom to top during Marine Isotope Stage 8 (MIS 8), MIS 6, and MIS 4, respectively; (2) from 300 to 243 cal. ka B.P., the SU6 paleochannel has four pathways, with the Yellow River serving as a primary source; from 191 to 130 cal ka B.P., the SU4 paleochannel has three pathways, and the main sources are the Yellow River, the Liao River, and the Luan River; from 74 to 14 cal. ka B.P., the SU2 paleochannels have two large tributaries, with the principal sources being the Yellow River and the Luan River. We, therefore, it can be inferred that the uplift of the Tibetan Plateau and glacial–interglacial climatic change constitute the formation mechanism for the paleochannels.