Along-Strike Continuity of Caribbean Tectonic Terranes and Their Controls on Source and Reservoir Rocks Offshore Colombia and Venezuela

Vence, Eleine Melisa¹, Alejandro Escalona¹, Paul Mann¹, Hamed El-Mowafy¹ (1) Jackson School of Geosciences, The University of Texas at Austin, Austin, TX

Satellite gravity maps and seismic data reveal a remarkable continuity of elongate basement terranes extending in an arcuate belt from offshore Venezuela to offshore Colombia. Our hypothesis - constrained by seismic, outcrop, and limited well data from both offshore Venezuela and Colombia - predicts that four main basement terranes control overlying source and reservoir rocks of specific ages and types: 1) South American continental passive margin of late Jurassic-early Cretaceous age occupies the most inboard position; this section contains the Turonian-Cenomanian platform limestone and shale of the La Luna Formation, the source for most of the onland oil and gas in Venezuela and Colombia; 2) a late Eocene-Miocene intra-arc basin formed during the collision of the Caribbean arc and the passive margin contains Turonian marine source rocks known from DSDP wells, isolated outcrops, and a proven petroleum system in the northern part of San Jacinto belt of northwestern Colombia; the geochemistry of this source rock varies along the length of the intra-arc terrane; 3) domal and acoustically inpenetrable, early Cretaceous-Eocene volcanic arc is present from the Caribbean coast of Colombia to the Leeward Antilles north of Venezuela and the Aves Ridge of the eastern Caribbean; this terrane contains no obvious source potential; and 4) South Caribbean deformed belt is an accretionary prism of Eocene to Recent age produced by the underthrusting and imbrication of Colombian and Venezuelan basin sedimentary rocks against the arc terrane; source rocks may include Turonian marine shale that has been incorporated into the prism.