A tectono-magmatic model for the Abrolhos Volcanic Complex region

Abstract

The Abrolhos Volcanic Complex is an important igneous basaltic province formed during Paleogene times at the Eastern Brazilian Continental Margin enclosing Espírito Santo, Cumuruxatiba and Mucuri basins. The exploratory potential of that region has been traditionally underrated mainly due to insuffi-cient geological knowledge. According to the most traditional regional perspective (though more simplis-tic and generic too), the Abrolhos Volcanic Complex is represented as a province characterized by the extensive occurrence of volcanic rocks, which would extend continuously from near the shore line up to the vicinity of the continental shelf break. As an attempt to better understand the general framework of the Abrolhos region, an alternative tectono-magmatic model was proposed by integrating geophysical and geological data. This model suggests a rather non uniform distribution pattern for the prevailing volcanic rocks, as well as the location of former magmatic chambers, where thermal flow would have focused through. Adjacently to this zone of main occurrence of volcanic rocks, deposition would have been dominated by younger sedimentary and vol-caniclastic rocks. Due to less severe overload effects, this inner region would be the locus where the nucle-ation of salt domes and even late intrusions (dykes) have taken place, which could have been important to create hydrocarbon traps. 
The regional model proposed herein for the Abrolhos region has positive implications for issues related to hydrocarbon generation, migration and trap, and thus, to the exploratory potential of the region as a whole, as opposed to the commonplace expectation of a typical igneous province.