HR: 1340h
AN: T33B-1376    [Abstracts]
TI: Tectonic Evolution of the Central Venezuela Margin From Integration of BOLIVAR and GULFREX MCS Data, Venezuelan Margin
AU: * Kroehler, M E
EM: mekroe@wm.edu
AF: College of William and Mary, Dept. of Geology, P.O. Box 8795, Williamsburg, VA 23187 United States
AU: Mann, P
EM: paulm@utig.ig.utexas.edu
AF: University of Texas Institute for Geophysics, 4412 Spicewood Springs Rd., Bldg 600, Austin, TX 78759 United States
AU: Escalona, A
EM: escalona@ig.utexas.edu
AF: University of Texas Institute for Geophysics, 4412 Spicewood Springs Rd., Bldg 600, Austin, TX 78759 United States
AU: Christeson, G L
EM: gail@utig.ig.utexas.edu
AF: University of Texas Institute for Geophysics, 4412 Spicewood Springs Rd., Bldg 600, Austin, TX 78759 United States
AB: The Lesser Antilles arc obliquely collided with the passive margin of central Venezuela in Miocene and younger time. The offshore basement arc high now trends directly into outcropping arc and passive margin rocks of the 2-km-high Cordillera de la Costa. We combine a newly acquired, deep-penetration BOLIVAR MCS line with GULFREX lines and published data to constrain the following tectonic features of the area: 1) Paleogene back-arc basin opening northwest of the arc basement high is shown by half-grabens filled by sedimentary wedges; these features are contemporaneous with similar half-grabens observed to the west in the Bonaire basin and to the east in the Grenada basin; the degree of fault inversion is much less in this area than in the western and eastern areas 2) the strong basement reflector of the extinct arc is known from published well data to correspond to Late Cretaceous andesite, basalt, and diorite formed in the Lesser Antilles volcanic arc; 3) the NW-striking Margarita fault zone is an active right-lateral strike-slip fault connecting dying thrust faults at the eastern end of the South Caribbean deformed belt with active, EW-striking right-lateral strike-slip faults of the El Pilar fault system; the Tuy basin, a Miocene-recent depocenter may have formed at a stepover in this fault system; and 4) the Cariaco basin is a large, active pull-apart basin formed at a stepover in the San Sebastian-El Pilar fault system; on BOLIVAR line 19, the basin-controlling El Pilar fault is downthrown to the south and controls an asymmetric wedge of Plio-Pleistocene sediment.
DE: 9360 South America
DE: 8105 Continental margins and sedimentary basins
DE: 8150 Plate boundary--general (3040)
DE: 3025 Marine seismics (0935)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting