HR: 1340h
AN: T33B-1368 [Abstracts]
TI: Chronology of Tectonic Events in Western Venezuela Based on Integration of BOLIVAR MCS Data with Wells
and Onland Geology
AU: * Gorney, D L
EM: gorneydl@mail.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78759
United States
AU: Mann, P
EM: paulm@ig.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78759
United States
AU: Escalona, A
EM: escalona@ig.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78759
United States
AB:
Newly acquired BOLIVAR MCS lines combined with existing GULFREX lines collected in 1975 document a complex chronology of
tectonic events affecting the Paraguana Peninsula, Falcon coast of Venezuela, and the offshore Bonaire basin. Three basin
phases can be identified: 1) Paleogene backarc opening of the 3 km-thick Bonaire-Grenada basin occurred along low-angle
normal fault systems that have locally been inverted by later tectonic phases. Normal faults trend EW and parallel the trend
of the Bonaire basin; 2) WNW to NW-striking normal faults crosscut this older trend and form deep offshore rifts with up to
4 km of fill that separate the islands of the Dutch Antilles. One EW-trending rift with 4 km of fill continues onshore to
the northern Paraguana Peninsula. Offshore well data and the age of onland sediments indicate that rifting occurred in
Oligocene through middle or late Miocene. GPS data from Falcon and the Paraguana Peninsula indicate east-west extension of
the area is occurring at rates of 10-15 mm/yr; and 3) A Miocene-recent accretionary prism parallels the coast of Falcon for
about 175 km, forming a boundary between the Falcon and Bonaire basins. Restoration of imbricate thrusts seen on seismic
lines indicate that a minimum of 7 km of shortening has occurred. Onland wells show that detachment occurs at the level of
Oligocene shale units. Shortening between the Falcon coast of Venezuela and the offshore Bonaire basin is related to the NE
displacement of the Maracaibo block along the Bocono fault.
DE: 9360 South America
DE: 8105 Continental margins and sedimentary basins
DE: 8110 Continental tectonics--general (0905)
DE: 8150 Plate boundary--general (3040)
DE: 3025 Marine seismics (0935)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting