New evidence on the spatial-temporal distribution of superlobes in the Yellow River Delta Complex

Abstract

Unraveling the spatial-temporal distribution of delta superlobes precisely is particularly important and challenging in the Yellow River Delta Complex (YRDC). Previous research on this issue can be dated back to the early 1990s, when the paleoenvironmental reconstructions mainly hinged on the historical documents and geomorphologic analysis of well-developed cheniers from the west coast of Bohai Bay, and only few drilled cores with scant radiocarbon dates were available. To build a refined model of the Holocene stratigraphic architecture and reconstruct the sedimentary evolution of the YRDC, detailed sedimentological investigation of 12 boreholes, including 59 new AMS 14C radiocarbon dates, was combined with other published 25 cores and 174 AMS 14C dates therein. Age-depth curves were grouped by stratigraphic positions and facies characteristics of these 233 radiocarbon dated samples across different sectors of the YRDC, exhibiting consistent patterns that can be used to identify distinct phases of delta superlobe activities. Eight new superlobes with relatively accurate dating spans were, therefore, proposed in the YRDC. Our results demonstrate that very high aggradation rates almost invariably correlate with the onset of deltaic deposition. Age-depth patterns, thus, may be very useful to elucidate the complex sedimentary evolution of delta systems with multiple lobes.