AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Crustal Structure, Sequence Stratigraphy and Petroleum Potential of the Western Colombian Basin Adjacent to Costa Rica and Nicaragua
(1) Institute for Geophysics, The University of Texas at Austin, Austin, TX.
(2) Department of Geology and Geophysics, University of Wyoming, Laramie, WY.
(3) Woods Hole Oceanographic Institution, Woods Hole Oceanographic Institution, Woods Hole, MA.
(4) Universidad de Costa Rica, San Jose, Costa Rica.
Maps showing the location and thickness of the late Cretaceous Caribbean Large Igneous Province vary widely from a small plateau centered on the Beata Ridge in the central Caribbean Sea to an extensive plateau covering the entire Caribbean Sea and southern Nicaraguan Rise along with fringing land areas in southern Central America and the Greater Antilles. Seismic reflection and OBS refraction data collected in 2008 on the RV Marcus Langseth have revealed that the westernmost Colombian basin near Costa Rica and Nicaragua is underlain by thick crust with velocities consistent with a more extensive Caribbean oceanic plateau. Lower crustal velocities are consistent with high-temperature, mantle-derived picritic basalts of late Cretaceous age that are widespread in southern Central America and have been previously linked to a late Cretaceous mantle plume head formed at the Galapagos hotspot. Seismic reflection data and ODP wells show that the late Cretaceous plateau crust is overlain by up to 500 m of late Cretaceous carbonate and shale with TOC up to 33%. These organic-rich deposits have been linked to an anoxic event previously linked to the formation of the Caribbean oceanic plateau and described from ODP wells and from outcrops in surrounding onland regions. We illustrate the distribution of this organic-rich horizon using two, newly-processed MCS reflection lines in the Colombia Basin that are correlated with existing MCS and well data. A possible petroleum play includes this late Cretaceous source with traps in overlying deepsea, turbiditic sandstone derived from the erosion of mountains in Costa Rica and the northern Andes.