Distribution of sediments and sedimentary structures in the Gulf of Mexico
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Results of three types of investigations are described and combined to obtain a better understanding of transport and deposition characteristics that played a role during the accumulation of at least the upper 7 meters of the sediment column. The 4D sediment map presents average data from piston cores on clay, silt, sand, and carbonate percentages, total thickness of silt intercalations and thickness of the top Globigerina ooze. Separate plots of these parameters reveal their distribution. Analyses of type, distribution and cyclic patterns of minor sedimentary structures shed light on transport and deposition media. Heavy mineral analyses determine provenance areas and distribution of mineral provinces. The Mississippi Fan and major portions of the abyssal plain and continental rise contain sediments that were transported in part by turbidity currents and in part deposited pelagically. Sediments in these areas have been derived from the northern and western shelves and slopes; however, the bulk has been derived from the Mississippi Delta. The midwestern and southwestern Gulf have sediments that are more pelagic in origin. Their carbonate content is high and is made up in major part by foraminifera tests. A low accumulation rate is assumed for this area based on the high degree of bioturbation. The Alaminos, Old Mississippi and DeSoto canyons are inactive canyons in which the upper part of the sediment column does not reveal typical submarine canyon characteristics but a rather homogeneous ooze type sediment as filling.