Sedimentary Characteristics of Near-shore Subaqueous Fans of the Lower Cretaceous in the Honghaoershute Depression

Key words: 
• near-shore subaqueous fan /
• sedimentary characteristics /
• controlling factors /
• Lower Cretaceous /
• Honghaoershute depression

Abstract: The sedimentary characteristics, distribution characteristics, evolution laws and the controlling factors of the development of the Lower Cretaceous near-shore subaqueous fan, located in the steep slope of the Eastern Honghaoershute depression, were defined clearly based on the integrated information including cores, well-logging, logging and seismic data. The results show that three kinds of sub-facies, including upper fan, mid-fan and lower fan, can be identified in the nearshore subaqueous fan in the study area, the glutenite deposition is the most important deposition, including massive or grading middle-fine clast-supported conglomerate, turbidite bearing Bouma Sequence and slumps with slump structures. Besides, we also can find some seismite deposition. In the study area, the subaqueous fan began to develop from the upper part of the Aershan Formation, and it became the largest and shifted towards the north-east at the lower part of Tengger Formation by 3.5 km, however, the scale of the fan in the upper part of the Tengger Formation began to reduce with the weak of the tectonic activities and the shrink age of the basin and then the subaqueous fan became gradually changing into fan-delta deposition. The sedimentary characteristics, distribution and evolution laws were controlled by the multiple-staged tectonic activities and the palaeo-climates, which was hot and humid. The plate type boundary fault which is steep and active provides the favorable tectonic setting for the development of the near-shore subaqueous fans in the steep slope.