Late Quaternary Evolution of the Wave–Storm-Dominated Central Texas Shelf
Brenda J. Eckles, Michelle L. Fassell, John B. Anderson, 2004. "Late Quaternary Evolution of the Wave–Storm-Dominated Central Texas Shelf", Late Quaternary Stratigraphic Evolution of the Northern Gulf of Mexico Margin, John B. Anderson, Richard H. Fillon
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The central Texas shelf is mainly an interdeltaic region with little fluvial influence and a ramp-like profile. Prograding shoreline and shoreface deposits and offshore marine muds are the dominant highstand strata. These deposits prograded across the inner shelf during the early phases of falling sea level (during Stage 5 and Stage 3). Lowstand deposits are virtually absent, by comparison to shelf areas to the north and south, where large fluvial deltas exist. Lowstand fluvial valleys of smaller rivers are confined mainly to the inner shelf, owing to steeper outer-shelf gradients. The offshore parts of these valleys were removed by transgressive ravinement. In the northern part of the study area, where shelf gradients are relatively low, lowstand fluvial valleys extend farther seaward. Transgressive muds blanket the shelf. Sandy deposits occur only in early highstand strata and within incised fluvial valleys and are confined to the inner shelf. There is considerable facies variability within the highstand shoreline and shoreface deposits. This facies variability is attributed to irregular topography on which these deposits prograded, fifth-order sea-level fluctuations, and changes in sediment supply.
Strong correlation of stratigraphic units to the late Quaternary glacio-eustatic sea-level curve indicates that fourth-order (100,000 yr) cycles are the primary mechanism controlling deposition on the central Texas shelf. This is in contrast to shelf areas north and south, where autocyclic influences on stratal architecture are far more pronounced.
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The northern Gulf of Mexico margin encompasses a variety of depositional settings characterized by different drainage basin size, physiography, fluvial morphology, climatic setting, and structural and diapiric activity. This, plus the abundance of long sediment cores and platform borings from oil industry activities, make it an unparalleled natural laboratory for sedimentological and stratigraphic studies and for testing sequence stratigraphic concepts. This volume contains twelve papers describing results from high-resolution stratigraphic studies of late Quaternary strata of the northern Gulf of Mexico, from the mouth of the Apalachicola River to the Rio Grande. These papers focus on fluvial response to climate and base-level change, variations in delta growth and evolution across the shelf, lowstand delta-fan evolution, the evolution of transgressive deposits on the shelf, the preservation of these deposits. The robust chronostratigraphic frameworks developed for the different study areas allows comparison of stratal geometries produced by contemporaneous depositional systems operating under identical eustatic conditions. This volume will appeal to sedimentologists and stratigraphers interested in source to sink issues, such as how various forcing mechanisms influence strata formation on continental margins.