The Principal Environmental Factors Influencing Holocene Sedimentation and Diagenesis in the Persian Gulf
The Persian Gulf is a marginal sea with an average depth of 35 m, and a maximum depth of 100 m near its narrow entrance. Its elongate bathymetric axis separates two major geological provinces — the stable Arabian Foreland and the unstable Iranian Fold Belt — which are reflected in the constrasting coastal and bathymetric morphologies of Arabia and Iran. The Persian Gulf has a gently inclined sea floor lacking “shelf edges” comparable with those of modern Caribbean carbonate provinces.
The arid, sub-tropical climate with summer temperatures attaining 50° C, and frequent winds, stimulate the formation of evaporitic minerals and the delivery of aeolian dust to the basin. Fluviatile influx is limited to the Tigris-Euphrates-Karun delta and to the mountainous Iranian coast where terrigenous sediments contrast with the relatively pure carbonates forming in the shallow seas in front of the low deserts of Arabia.
Excessive evaporation and partial isolation from the adjacent Indian Ocean provoke abnormal salinities throughout most of the basin, which attain a maximum of ca 70 ‰ in remote Arabian lagoons. Because the prevailing “shamal” wind blows down the axis of the gulf from the NW, most coastal environments are swept by waves and surface currents which favour the formation and dispersal of carbonate sands on the Arabian side and terrigenous material on the Iranian. Tidal currents influence sediment textures, even in the deepest parts of the gulf, while extensive rock bottoms influence the biota and skeletal composition of Holocene sediments. These are mixed with significant amounts of relict sediment, especially in the deeper parts of the basin.
KeywordsBlow Down Shelf Edge Aeolian Dust Carbonate Sand Iranian Coast
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