Extruding the Borborema Province (NE-Brazil): a two-stage Neoproterozoic collision process

摘要

We propose that the development of the Borborema Province from 620 to 570 Ma resulted from two discrete collisional events. Collision I, along the West Gondwana Orogen on the west side of the Province, took place at c. 620-610 Ma as the result of collision between the Parnaíba Block, as the forefront of the much larger Amazonian-West Africa Craton, and the old basement of the Borborema Province. The suture zone related to this collision was reactivated by a dextral transform zone (the Transbrasiliano Lineament), allowing the Borborema Province to approach and collide against the S?o Francisco Craton in the south at c. 590-580 Ma marking collision II along the Sergipano Orogen. The combined stresses related to eastward push from collision I and northward push from the cratonic indentation into a thickened lithosphere gave rise to an extensive network of strike-slip shear zones across the Province, forcing its northeastward extrusion.