Stratigraphic Interpretation of a Possible Paleostream Channel of the Ancient Nueces River, South Texas
The Nueces River in South Texas flows in a southeasterly direction toward the Texas Gulf Coast. In southeastern Lasalle County, the Nueces River makes an abrupt 90° turn and flows northeast for 56 miles. The Nueces River joins with the Frio and Atascosa Rivers to flow southeasterly, debouching in Co...
Summary: | The Nueces River in South Texas flows in a southeasterly direction toward the Texas Gulf Coast. In southeastern Lasalle County, the Nueces River makes an abrupt 90° turn and flows northeast for 56 miles. The Nueces River joins with the Frio and Atascosa Rivers to flow southeasterly, debouching in Corpus Christi Bay. It has been theorized that the Nueces River once flowed southeasterly crossing northeast Webb and central Duval Counties and then into Baffin Bay. The paleo-Nueces River is thought to have occupied the Las Animas and/or Parilla streams in Duval County. This study attempts to locate this ancient paleo-stream channel of the Nueces River. A ground investigation including topographic maps, multispectral aerial photographs at various scales, along with Skylab photographs, and Landsat imagery, revealed no positive surficial expression of the paleo-system. A lineament study failed to depict any definitive structural control of the present course of the Nueces River. Termination of most electric well logs near the surface, resulted in a lack of data on Pleistocene or Holocene deposits to determine if a fluvial system did exist in the uppermost portion of the stratigraphic section. As a result, a lower stratigraphic sequence, upward from the Catahoula (Miocene) through the Goliad (Pliocene) was examined with emphasis on the Catahoula and Oakville Formations. If stacked bar and channel sequences beneath the proposed former course of the Nueces River exist in these older sediments, they will lend credence to the theory that the course of the paleo-Nueces River crossed Duval County. Electric log data including the construction of five cross sections provided no definitive evidence of the Las Animas and/or Parilla streams superposing a paleo-Nueces River. Construction of a sand dispersal system of the Oakville and Catahoula Formations included maximum sand, net sand, and percent sand lithofacies maps. These lithofacies maps depicted a sandy fluvial system, during Catahoula time (only) superposed by the Las Animas ... |
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