HR: 0830h
AN: T31F-0894    [PDF]
TI: Basement blocks and basin inversion structures mapped using reprocessed Gulfrex 2D seismic data, Caribbean-South American oblique collisional zone
AU: * Escalona, A
EM: escalonaa@mail.utexas.edu
AF: University of Texas at Austin, Department of Geological Sciences, John A. and Katherine G. Jackson School of Geosciences, 1 University Station C1100, Austin, TX 78712 United States
AU: * Escalona, A
EM: escalonaa@mail.utexas.edu
AF: University of Texas Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, 4412 Spicewood Springs Road, Bldg. 600, Austin, TX 78759-8500 United States
AU: Sena, A
AF: University of Texas at Austin, Department of Geological Sciences, John A. and Katherine G. Jackson School of Geosciences, 1 University Station C1100, Austin, TX 78712 United States
AU: Sena, A
AF: University of Texas Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, 4412 Spicewood Springs Road, Bldg. 600, Austin, TX 78759-8500 United States
AU: Mann, P
AF: University of Texas Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, 4412 Spicewood Springs Road, Bldg. 600, Austin, TX 78759-8500 United States
AB: We have reprocessed and reinterpreted more than 10,000 km of "Gulfrex" multi-channel 2D seismic reflection lines collected by Gulf Oil Corporation in 1972 along the northern margin of South America (offshore Venezuela and Trinidad). These digital data were donated to the University of Texas Institute for Geophysics and represent the largest single, digital reflection survey of the region. Reprocessing of these data included: format correction, filtering, post-stack multiple suppression, and fk migration. Reprocessed data were loaded and interpreted on a workstation. The data straddle a 2,000,000 km2 zone of Paleocene-Recent, time-transgressive, oblique collision between the Caribbean arc system and the passive continental margin of northern South America. Free-air, satellite gravity data shows the remarkable 1000-km-scale continuity of four basement ridges between the uncollided part of the Caribbean arc system (NS-trending Lesser Antilles arc) and the EW-trending collisional area north of Venezuela. The basement ridges involved in the Venezuelan collisional zone include: 1) Aruba-Bonaire-Curacao ridge that can be traced as a continuous feature to the Aves ridge remnant arc of the Lesser Antilles; 2) the partially inverted Blanquilla-Bonaire basin that can be traced into the Grenada back-arc basin; 3) Margarita-Los Testigos platform that can be traced to the Lesser Antilles volcanic arc; and 4) foreland basins and fold-thrust belts of eastern Venezuela (Serrania del Interior and Maturin basin) that can be traced to the Tobago forearc basin and Barbados accretionary prism. Gulfrex data document the progressive change of basinal fault systems from NS-striking normal faults formed in extensional, Lesser Antilles intra-arc settings to rotated and inverted, NE and EW-striking normal faults deformed in the collisional area north of Venezuela. Age of initial shortening of basinal areas and inversion of normal faults setting does not follow the simple, expected pattern of west-to-east younging; instead important, regional pulses of regional shortening and normal fault inversion occurred during the Eocene and Middle Miocene. ESE-striking lateral ramp faults related to differential convergence across the region disrupt the lateral continuity of the arc-related basement ridges
DE: 8102 Continental contractional orogenic belts
DE: 8105 Continental margins and sedimentary basins
DE: 8150 Plate boundary--general (3040)
SC: Tectonophysics [T]
MN: 2003 Fall Meeting