Ametista Block - An Unusual Prospect in Santos Basin - Albian Atoll Upon Exhumed Mantle

The authors present a new, distinctive prospect in the southern Santos Basin, constituted of a possible Albian atoll developed upon exhumed mantle. The prospect was identified due to the acquisition of new high-quality 3D with the latest processing techniques. The prospect shows great petroleum potential and has excellent analogs in the present Pacific atolls and on an island in the Red Sea. A large buildup composed of stratified seismic facies exhibiting basin-edge offlaps/clinoforms, and capped by a massive structureless construction, is developed upon a protrusion of exhumed mantle. This four-way closed structure is surrounded by Aptian salt bodies that onlap its flanks and by the lowermost strata of the Drift Sequence of the Santos Basin, known to be the ACT source rocks. Considering the nearby geology, this buildup is interpreted as an Albian carbonate platform capped by a reef (rudist?). An adjacent on-trend structure is constituted by volcanos developed upon the exhumed mantle. The overall structure resembles the well-known atolls of the Pacific Ocean.