Investigation of the crust and uppermost mantle in the Carolina Terrane and Blue Ridge, southern Appalachians, using receiver function analysis of broadband earthquake data
Baker, Michael Scott
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This study provides new estimates of crustal thickness and average crustal composition in the area surrounding two broadband seismic stations located in Murphy, NC in the Blue Ridge mountains and Godfrey, GA in the Carolina Terrane. Lateral variations around each station are investigated by grouping teleseismic wave arrivals into separate azimuthal ranges and finding the corresponding estimates of thickness and average VP/VS using receiver function analysis.The thickness of the crust beneath station MYNC is approximately 48 52 km with a decrease in thickness from the NW to SE, and approximately 39 42 km beneath station GOGA with a similar decrease in thickness from the NW to the SE. VP/VS ratios for MYNC vary between 1.742 and 1.852 and suggest the presence of rocks of granitic to intermediate average composition. For GOGA, VP/VS was slightly lower (1.720 to 1.777, suggesting a slightly more granitic average crustal composition. The crustal thickness differences between the two stations are consistent with results from previous reflection and refraction profiles which suggest westward crustal thickening beneath the Blue Ridge Mountains and portions of the Valley and Ridge.