Sedimentology And Provenance Analysis Of Paleogeneneogene Strata In The Eastern Bohai Bay Basin

The Bohai Bay Basin experienced tectonic transition from rifting to post-rifting during Cenozoic.Knowing how the sedimentary process and provenance responded to this tectonic transition played a central role in the Bohai Bay Basin analysis and petroleum exploration.In this study,we report new petrology,heavy mineral assemblages and zircon U-Pb data from the Paleogene(Shahejie Formation and Dongying Formation)and Neogene(Guantao Formation and Minghuazhen Formation)strata in Shijiutuo-Yellow River Mouth area to explore the possible link between the sedimentaion-provenance and the tectonic evolution of Bohai Bay Basin.The Shahejie Formation is mainly fan-delta facies in the Shijiutuo area and braided river delta facies in the Yellow River Mouth Depression.The Dongying Formation developed meandering river delta sediments.Fluvial facies deposits is dominant in the Guantao Formation.The provenance changed from the neighboring Shijiutuo uplift to the Yanshan-Liaoxi during the Dongying Formation in the Shijiutuo area.In the Yellow River Mouth Depression,the provenance changed from Luxi Bulge to Yanshan-Liaoxi belt during the deposition of Guantao Formation.The Liaodong uplift began to supply the northeast part of the Yellow River Mouth Depression in the Minghuazhen Formation.Comparing our data with the thermal subsidence of Bohai Bay Basin suggests the tectonics controled the sedimentary system and provenance change in the ShijiutuoYellow River Mouth area.During the strong rifting time,near-source fan deltas and braided river delta developed with the adjacent uplifts(e.g.Shijiutuo Uplift)being the provenance.After the Dongying movement,far-source fluvial-shallow water delta facies developed and provenance is from outside the basin.Combining our youngest detrital zircon dating from the Guantao Formation with the previous cyclostratigraphy age,we suggest the tectonic transition of rifting to post-rifting in the Bohai Bay Basin is at ~21-23 Ma.