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Cyclic Evolution Pattern of Submarine Channel Geomorphology in the Levant Basin: its link to Paleoenvironmental Conditions and Implications for Hydrocarbon Exploration

Abstract

Submarine channels are considered as a crucial component of deep water sedimentary system that transfers sediment from continental shelves to the deep sea. They can form important hydrocarbon reservoirs when filled with sand-prone deposits and are, therefore, one of the most important hydrocarbon prospects on deep basins around the world. Based on an integrated study of high resolution 3D seismic data and well-log data, by describing seismic facies and geomorphological statistics, this research shows significant cyclic variations and in morphology and internal architecture of the submarine channels in Pliocene succession of the Levant Basin. This channelized interval is bordered on top and bottom by undeformed basin series, indicating a distinctive depositional condition during the formation of the channel that predates the salt related deformations in the basin. Morphologically, the channels, incising <50 m, with ~50 m to 350 m width, are trending in a north to northwest direction. This incised interval is further separated by a unique draping face, into two typical channelized subunits, based on number of channels and seismic facies. Interestingly, the lower part of each subunit, showing cleaning-up trend in GR log, is dominated by about ca.10, coarser grained, narrow V-shaped straight channels (average width <120 m and low sinuosity, <1.06). In contrast, the upper part of each subunit, demonstrating dirtying-up trend in GR log, is governed by more than ca.20, fine-grained and U-shaped, wider sinuous channels (average width >230 m and higher sinuosity, >1.1). Estimated age of this channelized interval based on previous studies and the cyclic geomorphological evolution pattern of the channels, enable us to correlate the long term channel evolution to lower order sea level fall and increased sediment supply associated with rapid uplift of the Ethiopian plateau and increased African Monsoon rainfall during the Pliocene, while the short term evolution to higher order sea level fluctuations. Therefore, our work implies that lower sea level and increased sedimentation are beneficial for development of coarse grained submarine channels. The seismic geomorphological analysis of the channels in the study area has wider applications for understanding the different mechanisms behind source-to-sink processes, reservoir distribution and petroleum prospectivity in basins worldwide.