SUBMARINE LITHIFICATION OF HOLOCENE CARBONATE SEDIMENTS IN THE PERSIAN GULF

Abstract

SUMMARY: Large areas of the sea floor in the Persian Gulf are composed of lithified carbonate sediment. That this cementation is contemporaneous and occurs within the present submarine environment has been proven by carbon dating, the presence of pottery and other artifacts within the lithified sediments, and other methods. Although the chemistry of the processes resulting in lithification is unknown it would seem not to require any special conditions other than carbonate‐saturated sea water. The process seems to be operating in areas of relatively normal salinity and temperatures in depths ranging down to 30 m. It is deduced that the principal physical factors involved are relatively low rates of sedimentation, sediment stability, and high initial permeability of the sediments. The principal types of cement filling the intergranular spaces and locally replacing grains are aragonite (in several growth forms) and microcrystalline magnesium calcite. The aragonite cement seems to be unstable and has inverted locally to more stable calcite within the marine environment. Lithification results indirectly in the production of several characteristic macro‐structures, including superimposed bored surfaces, fine sediment overlying drusy cement, and several other features all of which in the past have been regarded as criteria for unconformity.