HR: 1340h
AN: T33B-1381    [Abstracts]
TI: Tectonics Of Eastern Offshore Trinidad Based On Integration Of BOLIVAR 2D Seismic Lines With Industry 3D Seismic Surveys
AU: * Soto, M D
EM: sotomd@mail.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712 United States
AU: Mann, P
EM: paulm@utig.ig.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712 United States
AU: Wood, L J
EM: lesli.wood@beg.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712 United States
AB: New MCS lines in the eastern offshore area of Trinidad augmented by existing 3D seismic surveys by industry provide new insights into complex, strain partitioning produced along this segment of the South America-Caribbean plate boundary. Two major tectonosequences are imaged separated by a Middle Miocene angular unconformity known from wells and mapping in Trinidad. A thick section of deep-marine carbonate and clastic rocks are cleanly truncated by the Middle Miocene unconformity and are chaotically deformed along vertical to northwest-dipping thrust faults. This shortening event reflects a major pulse of pre-Middle Miocene southeastward overthrusting of the Caribbean arc over the passive margin of South America. An upper 2-7-km-thick tectonosequence consisting of late Miocene-Quaternary shelf-related sandstone and shale was deposited by the nearby Orinoco delta. This section is folded to lesser degree and deformed by the sub-vertical, right-lateral Central Range fault zone (CRFZ), known from GPS studies to accommodate 12 mm/yr, of the total 20 mm/yr of interplate motion. Deep, continuous reflec-tors are observed at a depth of 12-17 km beneath eastern Trinidad are correlated with authochthonous, late Cretaceous-early Tertiary carbonate and clastic rocks of the South American passive margin. The Darien fault southeast of the CRFZ accommodates active shortening, elevates passive margin rocks to the surface in Trinidad, and forms the northeastern limit of a large, 12-km-thick foreland basin (Columbus basin) that extends onshore.
DE: 9360 South America
DE: 8105 Continental margins and sedimentary basins
DE: 8150 Plate boundary--general (3040)
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3025 Marine seismics (0935)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting