Sandy and mixed beach-bar, which has good exploration potential, are widely developed in the upper fourth member of Shahejie Formation(Es4U) to the lower third member of Shahejie Formation (Es3L) of the Laizhou Bay Sag in the Bohai Bay Basin. At present, the sedimentary characteristics, genesis mechanism and evolution model of the beach-bar are still poorly understood, which seriously restricts the exploration and prediction of this type of sedimentation. Therefore, this study makes comprehensive use of drilling, logging, and seismic data to finely recover the micro-paleogeomorphology of the study area, clarifies the controlling role of geomorphology of the multi-stage gentle slope on the development of the beach-bar in the study area, sums up the depositional characteristics and the main controlling factors of the sand bodies of the beach-bar at different locations, and constructs the depositional model. The results show that: (1) sandy beach-bar are mainly developed in the front flanks of the braided river delta of the Es4U, which are mainly controlled by the windward geomorphic features of the first-stage gentle slope, strong sediment supply and paleo-wind direction. (2) The thick-layered mixed beach-bar are mainly developed in the windward zone of the secondary gentle slope of the Es4U, which is jointly influenced by paleogeomorphology, medium sediment supply and strong coastal currents. (3) The thin-layered mixed beach-bar are developed in the windward zone of the first-stage gentle slope of the Es3L, which is influenced by the combination of paleogeomorphology, weak sediment supply, paleo-wind direction and littoral current. By dividing the multi-stage gentle slope geomorphology, the establishment of the depositional model can help to predict the distribution of the sand body of the beach-bar and provide a reference for the exploration of the sand body of the beach-bar in the Bohai Bay Basin.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |