Three-dimensional Structure and Kinematics of the Piedras-Girardot Fold Belt: Surface Expression of Transpressional Deformation in the Northern Andes
Camilo Montes, Pedro A. Restrepo-Pace, Robert D. Hatcher, Jr., 2003. "Three-dimensional Structure and Kinematics of the Piedras-Girardot Fold Belt: Surface Expression of Transpressional Deformation in the Northern Andes", The Circum-Gulf of Mexico and the Caribbean: Hydrocarbon Habitats, Basin Formation and Plate Tectonics, Claudio Bartolini, Richard T. Buffler, Jon F. Blickwede
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This paper presents a new kinematic model for the structure and tectonic evolution of part of the northern Andes of Colombia based on detailed geologic mapping, strain analysis, seismic interpretation, and 3-D forward modeling. This model indicates that the oblique convergence vector imposed by the Caribbean Plate is not fully partitioned in space, but instead must be distributed in a diffuse zone of transpressional deformation spanning the Cordilleras Oriental and Central. The Piedras-Girardot fold belt, located between the two cordilleras, contains the termination of two regional scale structures of the northern Andes: the Ibagué fault and the Guaduas syncline. The Ibagué fault, with a minimum dextral displacement of 30 km, is the southern boundary of a rigid indenter that was inserted to the east-northeast, causing contrasting deformation styles in the Mesozoic sedimentary sequence to the east and to the south of it. South of the rigid indenter, a complex array of diverging north- to northeast-trending faults and folds delineate a sigmoidal stepover to the left with faults verging outwardly in opposite directions that define the Piedras-Girardot fold belt. The kinematics of deformation indicate that this fold belt is a dextral transpressional system where oblique contraction is accommodated along north-and northwest-trending segments of faults, dextral strike-slip along their northeast-trending segments, and extension along the east-trending faults. This doubly vergent system has northwest-verging thrust faults with oblique displacements approximately parallel to the Ibagué fault (17-km Cambao fault; 7-km Camaito fault), as well as a southeast-verging roof thrust with approximately 8 km of oblique displacement to the east-northeast (Cotomal fault). A geometric fit constrained with a stratigraphic piercing point also requires counterclockwise rotation of the easternmost two thrust sheets by 7° and 138. A three-dimensionally admissible and valid palinspastic restoration of this fold belt requires approximately 52% east-northeast contraction (about 32 km), which is consistent with the minimum displacement of the Ibagué fault and other estimates of shortening in the eastern margin of the Cordillera Oriental. This component of deformation had not been previously identified and quantified in the northern Andes.
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The Circum-Gulf of Mexico and the Caribbean: Hydrocarbon Habitats, Basin Formation and Plate Tectonics
The Circum-Gulf of Mexico and the Caribbean has long been one of the world's most important petroleum provinces, as well as one of the world's most geologically complex regions. These two characteristics have resulted in an extensive amount of ongoing research by both industry and academia. AAPG Memoir 79, The Circum-Gulf of Mexico and the Caribbean, is the first volume in more than a decade to document such a wide range of research on the geology of this vast area. Of the total 44 papers, roughly two-thirds pertain to the Gulf of Mexico, with an emphasis on the Mexican portion of the basin, and to the petroliferous areas of the southern Caribbean, including Colombia, Venezuela, Cuba, and Trinidad and Tobago. The remaining papers relate to the Antilles and Central America, as well as a series of papers that address region-wide topics such as plate tectonic evolution. A significant number of papers were contributed by authors from national oil companies and universities from within the region.