@article{MoraGaonaKleyetal.2009, author = {Mora, Andr{\´e}s and Gaona, Tatiana and Kley, Jonas and Montoya, Diana and Parra, Mauricio and Quiroz, Luis Ignacio and Reyes, German and Strecker, Manfred}, title = {The role of inherited extensional fault segmentation and linkage in contractional orogenesis : a reconstruction of Lower Cretaceous inverted rift basins in the Eastern Cordillera of Colombia}, issn = {0950-091X}, doi = {10.1111/j.1365-2117.2008.00367.x}, year = {2009}, abstract = {Lower Cretaceous early syn-rift facies along the eastern flank of the Eastern Cordillera of Colombia, their provenance, and structural context, reveal the complex interactions between Cretaceous extension, spatio-temporal trends in associated sedimentation, and subsequent inversion of the Cretaceous Guatiquia paleo-rift. South of 4 degrees 30'N lat, early syn-rift alluvial sequences in former extensional footwall areas were contemporaneous with fan- delta deposits in shallow marine environments in adjacent hanging-wall areas. In general, footwall erosion was more pronounced in the southern part of the paleorift. In contrast, early syn-rift sequences in former footwall areas in the northern rift sectors mainly comprise shallow marine supratidal sabkha to intertidal strata, whereas hanging-wall units display rapid transitions to open-sea shales. In comparison with the southern paleo-rift sector, fan-delta deposits in the north are scarce, and provenance suggests negligible footwall erosion. The southern graben segment had longer, and less numerous normal faults, whereas the northern graben segment was characterized by shorter, rectilinear faults. To the east, the graben system was bounded by major basin-margin faults with protracted activity and greater throw as compared with intrabasinal faults to the west. Intrabasinal structures grew through segment linkage and probably interacted kinematically with basin-margin faults. Basin-margin faults constitute a coherent fault system that was conditioned by pre-existing basement fabrics. Structural mapping, analysis of present-day topography, and balanced cross sections indicate that positive inversion of extensional structures was focused along basin-bounding faults, whereas intrabasinal faults remained unaffected and were passively transported by motion along the basin-bounding faults. Thus, zones of maximum subsidence in extension accommodated maximum elevation in contraction, and former topographic highs remained as elevated areas. This documents the role of basin-bounding faults as multiphased, long-lived features conditioned by basement discontinuities. Inversion of basin-bounding faults was more efficient in the southern than in the northern graben segment, possibly documenting the inheritance and pivotal role of fault-displacement gradients. Our observations highlight similarities between inversion features in orogenic belts and intra-plate basins, emphasizing the importance of the observed phenomena as predictive tools in the spatiotemporal analysis of inversion histories in orogens, as well as in hydrocarbon and mineral deposits exploration.}, language = {en} } @article{ParraMoraJaramilloetal.2009, author = {Parra, Mauricio and Mora, Andr{\´e}s and Jaramillo, Carlos and Strecker, Manfred and Sobel, Edward and Quiroz, Luis and Rueda, Milton and Torres, Vladimir}, title = {Orogenic wedge advance in the northern Andes : evidence from the Oligocene-Miocene sedimentary record of the Medina Basin, Eastern Cordillera, Colombia}, issn = {0016-7606}, doi = {10.1130/B26257.1}, year = {2009}, abstract = {Foreland basin development in the Andes of central Colombia has been suggested to have started in the Late Cretaceous through tectonic loading of the Central Cordillera. Eastward migration of the Cenozoic orogenic front has also been inferred from the foreland basin record west of the Eastern Cordillera. However, farther east, limited data provided by foreland basin strata and the adjacent Eastern Cordillera complicate any correlation among mountain building, exhumation, and foreland basin sedimentation. In this study, we present new data from the Medina Basin in the eastern foothills of the Eastern Cordillera of Colombia. We report sedimentological data and palynological ages that link an eastward-thinning early Oligocene to early Miocene syntectonic wedge containing rapid facies changes with an episode of fast tectonic subsidence starting at ca. 31 Ma. This record may represent the first evidence of topographic loading generated by slip along the principal basement-bounding thrusts in the Eastern Cordillera to the southwest of the basin. Zircon fission-track ages and paleo-current analysis reveal the location of these thrust loads and illustrate a time lag between the sedimentary signal of topographic loading and the timing of exhumation (ca. 18 Ma). This lag may reflect the period between the onset of range uplift and significant removal of overburden. Vitrinite reflectance data document northward along-strike propagation of the deformation front and folding of the Oligocene syntectonic wedge. This deformation was coupled with a nonuniform incorporation of the basin into the wedge-top depozone. Thus, our data set constitutes unique evidence for the early growth and propagation of the deformation front in the Eastern Cordillera, which may also improve our understanding of spatiotemporal patterns of foreland evolution in other mountain belts.}, language = {en} } @article{GomezJaramilloParraetal.2009, author = {Gomez, Andreas A. and Jaramillo, Carlos A. and Parra, Mauricio and Mora, Andres}, title = {Huesser Horizon : a lake and a marine incursion in northwestern South America during the early Miocene}, issn = {0883-1351}, doi = {10.2110/palo.2007.p07-074r}, year = {2009}, abstract = {The Cenozoic stratigraphic sequence in the foothills of the Eastern Cordillera of Colombia is mostly fluvial in nature and very thick (similar to 8000 m), but it contains very few mollusk-bearing horizons. Recent fieldwork discovered a well-preserved molluscan assemblage that occurs near the top of the Carbonera Formation (lower Miocene) in the central foothills of the Eastern Cordillera. This level, named the Huesser horizon, is laterally extensive and can be followed for tens of kilometers. The horizon is 10 m thick and was divided into eight levels, five of them highly fossiliferous. Most of the levels are dominated by the freshwater gastropod Sheppardiconcha, with lower abundances of the bivalves Anodondiles and Mytilopsis. The top level is dominated by specimens from the bivalve family Arcidae. The taxonomic composition of the assemblage is similar to that of the Magdalena and Amazonas Basins during the early-to- middle Miocene. Paleoecologic, taphonomic, and palynological analyses indicate that the Huesser accumulated in a freshwater lake system, capped by a marine incursion. The development of a large lake and the subsequent marine event could be related to increasing subsidence coincident with eustatic sea-level rise that has been identified for the basin during the early Miocene.}, language = {en} } @article{ParraMoraSobeletal.2009, author = {Parra, Mauricio and Mora, Andr{\´e}s and Sobel, Edward and Strecker, Manfred and Gonz{\´a}lez, Rom{\´a}n}, title = {Episodic orogenic front migration in the northern Andes : constraints from low-temperature thermochronology in the Eastern Cordillera, Colombia}, issn = {0278-7407}, doi = {10.1029/2008tc002423}, year = {2009}, abstract = {New thermochronometric data from the Eastern Cordillera of the Colombian Andes reveal diachronous exhumation associated with Cenozoic contractional deformation in this sector of the northern Andes. We present a comprehensive account of exhumation patterns along a 150-km-long, across-strike transect between similar to 4 degrees and 6 degrees N by integrating 29 new apatite fission track (AFT) ages and 17 new zircon fission track (ZFT) ages with sparse published thermochronological data from this area. Our data reveal episodic eastward migration of the orogenic front at an average rate of 2.5-2.7 mm/a during the Late Cretaceous-Cenozoic. We identify three major stages of orogen propagation: (1) slow propagation (0.5-3.1 mm/a) until early Eocene; (2) rapid orogenic advance (4.0-18.0 mm/a) during middle-late Eocene, which accounts for similar to 86\% of the orogen's present width; and (3) slow orogen propagation (1.2-2.1 mm/a) from Oligocene to Holocene times. Our data demonstrate that in the course of changes in plate kinematics, the presence of inherited crustal anisotropies, such as the former rift-bounding faults of the Eastern Cordillera, favor a nonsystematic progression of foreland basin deformation through time by preferentially concentrating accommodation of slip and thrust loading along these zones of weakness.}, language = {en} }