SEISMIC SEQUENCE AND SEDIMENTARY CHARACTERISTICS OF THE NEOGENE IN THE OFFSHORE AREA OF SOUTH SHANDONG PENINSULA

This study aims to revealing the sedimentary sequence since Neogene in the coastal waters off the southern Shandong Peninsula, China. Detailed processing and interpretation are performed for shallow stratigraphic sections and recently acquired single-channel seismic data for the study area. Results show that the study area is mainly located on the Qianliyan Uplift, with the Quaternary and Neogene strata directly overlying the Indosinian metamorphic rock series. Since the bottom boundary of the Neogene strata is gently dipping to the southeast (SE), and transgressive beds since Neogene have a continuous overlapping pattern towards northwest (NW) direction, the strata of different ages all show a wedge shape pattern thinner in NW and thicker in SE in isopach maps. Holocene strata are widely distributed throughout the study area with a maximum thickness up to 22.5m. They also show a wedge shape in general, representing the marine strata formed by latest transgression. The distribution of Upper Pleistocene strata is strongly affected by underground structures. They pinch out in the waters to the east of Rushan. This set of strata as a whole is relatively thick in the southeast of the study area and gets thinner offshore, with a mean thickness of approximately 60 m. The Middle Pleistocene deposits are still under the control of regional tectonic settings, which become increasingly thicker towards the sag in the northern South Yellow Sea Basin and become thinner until pinching out. The depositional pattern of the Lower Pleistocene strata is similar to the Middle Pleistocene under the control of regional tectonics. However, the former is smaller and more localized in distribution. During Pliocene, the Yellow Sea area continued to subside steadily and remained stable tectonically; a layer of flat strata was deposited in rather uniform thickness in a NW-thinning wedge shape, with relatively moderate changes in thickness. The Miocene strata, as the first deposits of post-rift depression deposits, present a similar thickness distribution pattern with the depth of the Neogene bottom boundary.