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Three-Dimensional Relationships between Synchronous Normal Faulting, Folding and Sedimentation in the Columbus Basin, Offshore Southern Trinidad

Alvarez, Tricia 1; Mann, Paul 1; Wood, Lesli 1
1 Jackson School of Geosciences, The University of Texas at Austin, Austin, TX.

Analysis of 9000 km2 of 3D seismic data combined with eight wells in the Columbus Basin shows the three-dimensional relationships between synchronous listric normal faults, folds, and sedimentary infilling during the late Quaternary (last 500,000 yrs). Previous tectonic models have emphasized either convergent structures related to the active Columbus foreland basin or the extensional structures produced by gravitational sliding or strike-slip faulting and pull-apart basin formation. 3D seismic data shows that normal faults are gravitationally-driven and synchronous with orthogonal to broad open folding of the Columbus Basin shelf.

Northwest-to-southeast-striking normal listric faults and the northeast-to-southwest striking anticlines created structural traps which contain the 3 billion barrels of proven oil and 22 trillion feet of gas stored in vertically-stacked reservoirs. Within this complex tectonic framework, 12-15 km of Plio-Pleistocene sediments were deposited on the shelf and slope at extremely high sedimentation rates of ~ 3 mm/yr. Synclines are parallel to the direction of shelfal sediment transport and contain thickened sections along their synclinal axes. Margin-parallel listric normal faults were formed during oversteepening of the shelf and slope margin at the southeastern margin of the Columbus foreland basin. Prograding sediments of the Orinoco Delta combined with eustatic lowstands leads to pulses of activity for the listric normal faults.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009