Using the receiver function for studying earth deep structure in the Southern Borborema Province

Abstract

The Borborema Province is characterized by a succession of tectonic events, including compressive periods associated with amalgamation of lithospheric blocks during the Brasiliano orogeny in the Neoproterozoic, superimposed by extension events related to the breaking of the continents and the South Atlantic formation in the Cretaceous. Ten seismographic broadband stations belonging to the Geoterm Network were installed in the Transversal Zone and South Domains to collect the data used in this work in the southern Borborema Province, northeastern Brazil. Thus, this study aims to determine the thickness of the Moho and Mid-Crustal (“Conrad”) discontinuities and estimate the Vp/Vs ratios to define rock composition using the receiver function over a time window, using the HK-stacking method. The station in the Alto Moxotó Terrain determined a crustal thickness of 35.4 km. The two stations in the Pernambuco-Alagoas Terrain estimated thickness of approximately 37 km and no thinning trend in the geotectonic context. The four stations in the Sergipano Folding Belt indicated thickness ranging between 34.6 and 37.2 km, and a South-North crustal thickening. Mid-crustal discontinuity depth estimates ranged between 10 and 19 km, indicating a WNW-ESE thinning of the upper crust in the middle of the area. The P and S wave velocity ratios appeared to have no geological or tectonic correlation and ranged between 1.68 and 1.77, indicating that the crustal composition is predominantly felsic.