Crustal thickness estimates in the Potiguar Basin (NE Brazil) using receiver functions
Potiguar Basin; Receiver function; Rift system
The opening of the South and Equatorial Atlantic during the Jurassic/Cretaceous originated several inner marginal and interior basins which compose the NE Brazil rift system. The Potiguar Basin, located at the easternmost portion of the Equatorial margin is a product of this complex rifting system. Therefore, via the analysis of crustal thickness and seismic wave velocity profile we are able to identify structural and/or lithological contrasts in the crust which may have influenced the deformation processes during the formation of the onshore Potiguar Basin and its surroundings. Additionally, we may also investigate the viability of the McKenzie model for the onshore rift system. The estimates of crustal thikness (H) and the VP/VS ratio (k) were obtained from the computtion of receiver functions and their stacking at 15 seismographic stations located on the onshore portion of the Potiguar basin. Our results indicate a crustal thinning (H=25 km) under station PCMA, located close to the Umbuzeiro graben. This thinning is expected from the MacKenzie model, as it shows a thinning beneath the basin depocenter. Another crustal thinning is observed under stations MOSS and MCAU, located next the Mulungu Fault and the Guamaré Graben, respectively. These results emphasizes that the thermal subsidence phase has exceeded the limits of the rift system. The remaining stations reveal a slight crustal thinning (30 km < H < 32 km) in other parts of the basin, and the H ranging between 32 and 35 km elsewhere