Sediment routing systems in the second member of the Eocene Shahejie Formation in the Liaoxi Sag, offshore Bohai Bay Basin: A synthesis from tectono-sedimentary and detrital zircon geochronological constraints

Integration of three-dimensional (3D) seismic reflection data, well, core, and detrital zircon geochronological data from the second member of the Eocene Shahejie Formation in the Liaoxi Sag of the offshore Bohai Bay Basin offers a new insight of transportation and deposition of regional sediment delivery systems as well as tectonic influence of sediment routing, accumulation and distribution. Sequence stratigraphic work shows that the study interval generally corresponds to a complete third-order sequence, while well- and seismic-based tectono-stratigraphic and sedimentological signatures have demonstrated that several braided-river deltas sourced from the Yanshan Mountain and associated distal delta-lobes are shaped by the development of the F1 fault. Furthermore, the age distribution of detrital zircons sampled from subsurface cores and cuttings mainly represent two different age populations, virtually corresponding to two independent paleodrainages from the Yanshan Mountain. The correlation between the bedrock lithology and detrital zircon geochronological dataset as well as tectono-sedimentary evidences of regional sediment delivery systems have provided us with a general understanding of specific hypothetical sediment routes from the source domain with the high lithological diversity to the sink area under the control of extensional and strike-slip movement. This study also shows how to define and differentiate specific sedimentary delivery systems in a small oilfield scale from a source-to-sink perspective.