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Analyses of grain-size parameters, carbonate content, and heavy-mineral content of foreshore and dune sediment samples collected along the Texas coast indicate that five textural zones exist. The characteristics of these zones are controlled by sediment supply, nearshore hydrography, and shoreline stability. In general, Texas coast sediments are fine to very-fine grained, well-sorted sands. Dune and foreshore subfacies can be distinguished from one another by mean standard deviations, skewness values, and carbonate content.
Variations in dune geometry and size are controlled by climate, coastal orientation, and wind direction and velocity. Measurements of the foredune cross-stratifications show that polymodal distributions of the dip angles and azimuths are typical along the Texas coast. Pyramidal dune forms, which are produced by seasonal variations of wind direction, result in bimodal distributions of cross-bedding azimuths; the two direction modes are bisected by the prevailing winds from the southeast. Offshore-directed winds from the north and west produce a significant number of offshore-dipping beds at each sample station.
Analysis of the internal structure of the Texas coast dunes demonstrates the variability of cross-stratification dip angles and azimuth values that is possible in an eolian environment. The information from this study may be used to help define relict coastal orientations and eolian processes that acted within an ancient depositional setting. Depending upon diagenetic processes, the well-sorted character of the dune sediments may provide porosity values that are suitable for hydrocarbon accumulation. Therefore, it is important to recognize and understand these eolian deposits.
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