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Free keywords:
Upper-lower Crust; Receiver Function; Borborema Province
DDC:
550 - Earth sciences
Abstract:
The thickness estimates of the upper-crust and the Vp/Vs ratios are essential in order to detail the structures and geologic features. They also corroborate the regional tectonic evolution models. The crust study using the Receiver Function is performed with teleseismic P-waves that reaches the interface, under the station, with an almost vertical angle. The Receiver Function is obtained through the deconvolution of the horizontal component from the vertical one. The synthetic seismogram of the Receiver function has a higher peak of direct P-waves, followed by minor peaks of Psc waves, where P converted into S in the upper-lower crust limit and multiple reflections. It was used the phase weighted slant-stacked method for the estimate of upper-crustal thickness and mb ratio. The best estimates are correctly stacked. The Normal Moveout correction for the Psc phase was used for the upper-crust thickness, simulating a vertical incidence. A total of 8 stations on the Borborema Province in the Brazilian Northeast was analyzed. The results show that there is an upper-lower crust limit in all the analyzed signs. The thickness estimates showed two thickness regions. The first one in Coast Region, that indicates of the thin upper-crust and the second, continental regions characterized by uniform thicker upper-crust. East station data suggests undeplating of mafic bodies.
