Makran continental margin sedimentation during the Late Holocene

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Sedimentation in the Makran active margin is governed by a complex interaction of atmospheric, tectonics, and hydrodynamic setting of the northern flank of the Gulf of Oman. The mixed clastic carbonate sediments in the tectonically and hydrodynamically active environment have complicated the distribution pattern. The region is suffering from basic sedimentological data, and specifically, the sedimentation history of the Holocene deposits has been rarely studied in the Iranian coast. To deal with this deficiency, surface and core sediment samples from the Iranian continental shelf and upper slope of the Gulf of Oman have been studied using standard sedimentological techniques. The overall sediment distribution pattern demonstrates that the grain size gradually decreases from the shoreline to the deeper zones. However, some medium- to coarse-grained sand patches can be found in the deeper parts, especially in the middle part of the studied area that can be related to sediment supply of ephemeral rivers discharging into the sea in rainy seasons and (or) high-energy events (i.e., turbidites and tsunamis during the Holocene). Several horizons of the coarse-grained detrital sediments are detectable in the upper slope sediment cores. The coarse-grained materials are received from the hinterland during flash floods and could be accumulated due to mass wasting events. The elevated amount of organic materials in the upper slope indicates a deficit of dissolved oxygen that leads to preservation of organic materials in the bottom sediments.