Seismic stratigraphy and buried special geomorphological features in shallow strata off middle and south Fujian Province, China

High-resolution shallow-seismic profiles using boomer in inshore area off Meizhou Bay and Quanzhou Bay, the middle of the western Taiwan Strait were analyzed. The survey grids are 1 km×5 km in the southern area and about 5 km×8 km in the northern. The seismic profiles reveal two regional strong reflectors: T0 (sea bottom) and SB (subaerial erosion surface); and three locally recognizable: TS (transgressive surface), MFS (maximum flooding surface), and TR (rock surface). Apart from paleo-negative topography, such as river channels of MIS 2, SB coincides with TS. In addition, the seismic profiles can be divided at SB into upper sequence (USQ) and lower sequence (LSQ). The USQ is subdivided at TS into unit U1 (marine Holocene) and U2 (infillings of paleo-channel of MIS 2). During the last low sea level, the south and north channels of paleo-Jinjiang River were developed in the southern study area in 7~8 km and 2 km, the widest width, respectively. In the northern study area were developed quite dense gullies, about 1 km wide, which might be related to complicated paleo-ground and streams from Meizhou Bay region varying strongly in season. Considering sea level curves, as sea level rising, the south channels were gradually submerged landward about 12.0~9.6 kaBP. In addition, 19 buried linear tidal sand ridges in NE-SW direction within unit U1 in the southernmost part of the study area were recognized. The sand ridges are about 1~7 m high, 1.5–10 km long, and usually in intervals of several-hundred meters to about 1 km. They were mainly formed at about 10 kaBP. In terms of the profile shapes and internal structures, they could be divided into single-crest sand ridges and multiple-crests sand ridges. The former ones are in turn subdivided into isolated single-crest ridges and single-crest ridges of multiple-lines, while the latter ones, into simple multiple-crests ridges and overlapped multiple-crests ridges. A small river channel and a subaqueous delta were mainly buried inside U1 just outside Quanzhou Bay mouth. They were formed during the Holocene. The development of all these buried special geomorphological features, but gullies in the northern area, were related with sand and water discharges of paleo-Jinjiang River.