Geophysical investigation of the post Grenville Orogen lithosphere: Texas Gulf Coast

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2013-05

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Abstract

Receiver function and Pn tomography were used in conjunction to characterize the seismic velocity structure of the lower crust and upper mantle of the Laurentian Margin of Texas. The velocity interfaces modeled are the Mohoroviçiç Discontinuity (Moho), and the Hales Discontinuity. Observations resulted in crustal thicknesses from 26 to46 kilometers, and a Hales Discontinuity depth from 60to 88 kilometers. Pn tomography provided differential velocity variations of ±0.24 km/s, with the average velocity approximately 8.1 km/s. The Sabine and San Marcos Arches were not imaged in the upper mantle indicating they are crustal features only. A northwest-southeast trending anomaly was observed in observed in receiver function shallow Moho depths, Pn tomography low Moho velocity, and low aeromagnetic data was interpreted to be a relic of strike-slip motion attributed to the Ouachita Rift System. The anomaly crosses the Ouachita Orogenic Front without truncation or offset, inferring that the younger Ouachita Front was a, “thin-skinned,” collision along the Laurentian Margin

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Keywords

Laurentian margin, Grenville, Pn tomography, Receiver function, Passive margin, Mohoroviçiç Discontinuity (moho)

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