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1 Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Road, Building 600, Austin, Texas 78759; escalona{at}ig.utexas.edu
2 Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Road, Building 600, Austin, Texas 78759; paulm{at}utig.ig.utexas.edu
Alejandro Escalona is a postdoctoral researcher at the Institute for Geophysics, University of Texas at Austin. He received his Ph.D. in geology at the University of Texas at Austin in 2003, where he focused on stratigraphic and structural evolution of the Maracaibo Basin, Venezuela. He is currently interpreting regional seismic and well data from offshore Venezuela to link offshore and on-land Cenozoic depocenters.
Paul Mann is a senior research scientist at the Institute for Geophysics, University of Texas at Austin. He received his Ph.D. in geology at the State University of New York in 1983 and has published widely on the tectonics of strike-slip, rift, and collision-related sedimentary basins. His current focus area of research is the interplay of tectonics, sedimentation, and hydrocarbon occurrence in Venezuela and Trinidad.
The northeastern Maracaibo Basin in western Venezuela was deformed by Paleogene thrusting and an associated tear fault (Burro Negro right-lateral strike-slip fault zone), related to Paleogene oblique collision between the Caribbean and South American plates. Two different tectonic models have been previously proposed for the thick Paleogene depocenter located along the northeastern margin of the Maracaibo Basin. The first model proposes that the depocenter is a foreland basin controlled by southwestward-directed overthrusting during a late Paleocene–middle Eocene oblique collision between the Caribbean and South American plates. The second model, supported by data presented in this study, proposes that the asymmetric Paleogene Maracaibo sedimentary wedge was controlled by strike-slip displacement along a right-lateral tear fault, separating southeast-directed thrust sheets to the east (Lara nappes) from a more stable platform area to the west (Maracaibo Basin).
Regional seismic lines recorded to 5 s two-way traveltime reveal the structure of the asymmetric Paleogene depocenter in the northeastern part of the Maracaibo Basin. The approximately 100-km (62-mi)-long Burro Negro fault is a right-lateral strike-slip fault separating less deformed, inner- to outer-shelf rocks of the western Maracaibo Basin from highly deformed, deep-marine rocks of the eastern Maracaibo Basin. Seismic lines northeast of the Burro Negro fault zone show elongate, subsurface basins bounded by partially inverted reverse and strike-slip faults filled with about 3 km (1.8 mi) of Oligocene and Miocene clastic marine sedimentary rocks. Structural highs of Eocene rocks are characterized at depth on seismic reflection lines by chaotic seismic reflections that underlie the more coherently stratified Oligocene and Miocene subbasins. We interpret these structural highs as steeply dipping fault zones and shale diapirs activated during Eocene–Oligocene oblique plate convergence.
The geology and overall structural configuration of the northeastern Maracaibo Basin and the Burro Negro fault zone support its origin as a right-lateral tear fault. In our model, the Burro Negro fault zone accommodated southeastward migration of the thrust front in the deep-water area east of the fault in the present-day Falcón region. The Paleogene clastic wedge of the Maracaibo Basin exhibits many common features of a classic foreland basin, including onlap onto an arch or forebulge located near the center of the present-day Lake Maracaibo. This paleogeographic coincidence of the Burro Negro fault zone and the Maracaibo shelf edge suggests that the paleotrend of the South American passive margin prior to collision was serrated in map view. West-to-east migration of the Caribbean–South America oblique collision formed progressively younger, parallel tear faults to the east of the Maracaibo Basin that may have formed by the same tectonic process as the Burro Negro fault zone.
This article has been cited by other articles:
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  D. Gorney, A. Escalona, P. Mann, M. B. Magnani, and BOLIVAR Study Group Chronology of Cenozoic tectonic events in western Venezuela and the Leeward Antilles based on integration of offshore seismic reflection data and on-land geology AAPG Bulletin, May 1, 2007; 91(5): 653 - 684. [Abstract] [Full Text] [PDF]
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 P. Mann Global catalogue, classification and tectonic origins of restraining- and releasing bends on active and ancient strike-slip fault systems Geological Society, London, Special Publications, January 1, 2007; 290(1): 13 - 142. [Abstract] [Full Text] [PDF]
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P. Mann, A. Escalona, and M. V. Castillo Regional geologic and tectonic setting of the Maracaibo supergiant basin, western Venezuela AAPG Bulletin, April 1, 2006; 90(4): 445 - 477. [Abstract] [Full Text] [PDF]
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L. Duerto, A. Escalona, and P. Mann Deep structure of the Merida Andes and Sierra de Perija mountain fronts, Maracaibo Basin, Venezuela AAPG Bulletin, April 1, 2006; 90(4): 505 - 528. [Abstract] [Full Text] [PDF]
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M. V. Castillo and P. Mann Cretaceous to Holocene structural and stratigraphic development in south Lake Maracaibo, Venezuela, inferred from well and three-dimensional seismic data AAPG Bulletin, April 1, 2006; 90(4): 529 - 565. [Abstract] [Full Text] [PDF]
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M. V. Castillo and P. Mann Deeply buried, Early Cretaceous paleokarst terrane, southern Maracaibo Basin, Venezuela AAPG Bulletin, April 1, 2006; 90(4): 567 - 579. [Abstract] [Full Text] [PDF]
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A. Escalona and P. Mann Sequence-stratigraphic analysis of Eocene clastic foreland basin deposits in central Lake Maracaibo using high-resolution well correlation and 3-D seismic data AAPG Bulletin, April 1, 2006; 90(4): 581 - 623. [Abstract] [Full Text] [PDF]
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J. I. Guzman and W. L. Fisher Early and middle Miocene depositional history of the Maracaibo Basin, western Venezuela AAPG Bulletin, April 1, 2006; 90(4): 625 - 655. [Abstract] [Full Text] [PDF]
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A. Escalona and P. Mann An overview of the petroleum system of Maracaibo Basin AAPG Bulletin, April 1, 2006; 90(4): 657 - 678. [Abstract] [Full Text] [PDF]
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