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The AAPG/Datapages Combined Publications Database
AAPG Bulletin
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Examination of modern saline lakes, solar ponds, and lagoons shows that the evaporitic environment can be very productive of organic matter. Few species survive in the brines, but those that do survive commonly exist in abundance. In a model evaporitic embayment, the flow of surface currents is persistently toward regions of highest salinity, so that there is a continual supply and concentration of those nutrients being brought into the saline environment. Prolific growth of phytoplankton may occur, analogous to phytoplankton blooms in areas of upwelling in modern oceans. Only carbonates precipitate in the "mesosaline" part (4 to 12% salinity) of the marine evaporitic environment and no great dilution of organic matter by clastic or biogenic sediments occurs. Because of s ratification of the brine and the chemically reducing conditions associated with brines, much of the organic matter produced is preserved. The result may be a potentially rich carbonate source rock, frequently unrecognized in the geologic column. In the Middle East, mesosaline conditions have occurred many times from Triassic to Cretaceous and may be responsible for the vast reserves of petroleum in the area. Evaporitic conditions may also have played a part in the petroleum productivity of many other basins, including the Michigan, Paradox, Williston, and Devonian of western Canada.
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