Depositional model for lacustrine nearshore subaqueous fans in a rift basin: The Eocene Shahejie Formation, Dongying Sag, Bohai Bay Basin, China
A B S T R A C T
The origin of the fourth member of the Eocene Shahejie Formation in the northern steep slopes of the Minfeng Sub-sag, Dongying Sag, China, was investigated by integrating core studies and flume tank depositional simulations. A non-channelized depositional model is proposed in this paper for nearshore subaqueous fans in steep fault-controlled slopes of lacustrine rift basins. The deposits of nearshore subaqueous fans along the base of steep border-fault slopes of rift basins are typically composed of deep-water coarse-grained sediment gravity-flow deposits directly sourced from adjacent footwalls. Sedimentation processes of nearshore subaqueous fans respond to tectonic activities of boundary faults and to seasonal rainfall. During tectonically active stages, subaqueous debris flows triggered by episodic movements of border-faults dominate the sedimentation.
A B S T R A C T
The origin of the fourth member of the Eocene Shahejie Formation in the northern steep slopes of the Minfeng Sub-sag, Dongying Sag, China, was investigated by integrating core studies and flume tank depositional simulations. A non-channelized depositional model is proposed in this paper for nearshore subaqueous fans in steep fault-controlled slopes of lacustrine rift basins. The deposits of nearshore subaqueous fans along the base of steep border-fault slopes of rift basins are typically composed of deep-water coarse-grained sediment gravity-flow deposits directly sourced from adjacent footwalls. Sedimentation processes of nearshore subaqueous fans respond to tectonic activities of boundary faults and to seasonal rainfall. During tectonically active stages, subaqueous debris flows triggered by episodic movements of border-faults dominate the sedimentation.
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