College of Arts and Sciences
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Browsing College of Arts and Sciences by Author "Ainsworth, Ryan, 1980-"
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Item Seismic Vp & Vs tomography of Texas and Oklahoma with a focus on the Gulf Coast margin.(2013-09-24) Evanzia, Dominic A. D.; Pulliam, Robert Jay.; Geology.; Ainsworth, Ryan, 1980-; Pratt, Kevin; Gurrola, Harold; Baylor University. Dept. of Geology.We present new 3D seismic tomography velocity models with data from 326 stations, located in Texas, Oklahoma and New Mexico, which utilized 537 seismic events. Tomography results on the North American (NA) craton show a fast anomaly outlining the southern extent. Around the Southern Oklahoma Aulacogen there is a slow anomaly, which indicates there is abundant heat present. In the Gulf Coast Plains, the NA craton shallows, allowing the ascendance of the asthenosphere. Below the craton the velocity models so a slow anomaly associated with the LAB shear zone. The slow velocity along the coast is attributed to the sediment packages. There is also a high velocity body in central/southeast Texas that has begun to delaminate from the upper crust in the region. The upper mantle structures of the Gulf Coast region suggest that the opening of the Gulf of Mexico was due to a volcanically active rifting event.Item Sp receiver function imaging of a passive margin : transect across Texas’s Gulf Coastal Plain.(2013-09-24) Ainsworth, Ryan, 1980-; Pulliam, Robert Jay.; Geology.; Gurrola, Harold; Evanzia, Dominic A. D.; Baylor University. Dept. of Geology.A Sp receiver function common conversion point (CCP) stacked image beneath Texas Gulf Coast Plain (GCP) reveals anomalies that may be detached lower crust sinking into the mantle. The detached crust may have resulted from distinct episodes of delamination as the lower crust peeled away from the upper crust. The apparent presence of delaminated crust in the mantle indirectly points to a thermal anomaly in the mantle that may have initiated the rifting episode that created the Gulf of Mexico. The CCP stacked image also reveals a significant structure with negative polarity ~110 km beneath the array. Discontinuities of this polarity at this depth have been interpreted elsewhere as the lithosphere-asthenosphere boundary (LAB) and this interpretation is consistent with previous results for this region. The observed variations in amplitudes of Sp conversions at this “LAB” discontinuity may be produced by large contrasts in seismic anisotropy created by a shear zone.