Villagomez D.,University of Geneva |
Spikings R.,University of Geneva |
Mora A.,Instituto Colombiano Del Petroleo |
Guzman G.,Invemar |
And 3 more authors.
Tectonics | Year: 2011
The topographically prominent Sierra Nevada de Santa Marta forms part of a faulted block of continental crust located along the northern boundary of the South American Plate, hosts the highest elevation in the world (∼5.75 km) whose local base is at sea level, and juxtaposes oceanic plateau rocks of the Caribbean Plate. Quantification of the amount and timing of exhumation constrains interpretations of the history of the plate boundary, and the driving forces of rock uplift along the active margin. The Sierra Nevada Province of the southernmost Sierra Nevada de Santa Marta exhumed at elevated rates (0.2 Km/My) during 65-58 Ma in response to the collision of the Caribbean Plateau with northwestern South America. A second pulse of exhumation (≥0.32 Km/My) during 50-40 Ma was driven by underthrusting of the Caribbean Plate beneath northern South America. Subsequent exhumation at 40-25 Ma (≥0.15 Km/My) is recorded proximal to the Santa Marta-Bucaramanga Fault. More northerly regions of the Sierra Nevada Province exhumed rapidly during 26-29 Ma (∼0.7 Km/My). Further northward, the Santa Marta Province exhumed at elevated rates during 30-25 Ma and 25-16 Ma. The highest exhumation rates within the Sierra Nevada de Santa Marta progressed toward the northwest via the propagation of NW verging thrusts. Exhumation is not recorded after ∼16 Ma, which is unexpected given the high elevation and high erosive power of the climate, implying that rock and surface uplift that gave rise to the current topography was very recent (i.e., ≤1 Ma?), and there has been insufficient time to expose the fossil apatite partial annealing zone. Copyright 2011 by the American Geophysical Union.
Montes C.,Smithsonian Tropical Research Institute |
Guzman G.,Invemar |
Bayona G.,Corporacion Geologica Ares |
Cardona A.,Smithsonian Tropical Research Institute |
And 2 more authors.
Journal of South American Earth Sciences | Year: 2010
A moderate amount of vertical-axis clockwise rotation of the Santa Marta massif (30°) explains as much as 115. km of extension (stretching of 1.75) along its trailing edge (Plato-San Jorge basin) and up to 56. km of simultaneous shortening with an angular shear of 0.57 along its leading edge (Perijá range). Extensional deformation is recorded in the 260. km-wide, fan-shaped Plato-San Jorge basin by a 2-8. km thick, shallowing-upward and almost entirely fine-grained, upper Eocene and younger sedimentary sequence. The simultaneous initiation of shortening in the Cesar-Ranchería basin is documented by Mesozoic strata placed on to lower Eocene syntectonic strata (Tabaco Formation and equivalents) along the northwest-verging, shallow dipping (9-12° to the southeast) and discrete Cerrejón thrust. First-order subsidence analysis in the Plato-San Jorge basin is consistent with crustal stretching values between 1.5 and 2, also predicted by the rigid-body rotation of the Santa Marta massif. The model predicts about 100. km of right-lateral displacement along the Oca fault and 45. km of left-lateral displacement along the Santa Marta-Bucaramanga fault. Clockwise rotation of a rigid Santa Marta massif, and simultaneous Paleogene opening of the Plato-San Jorge basin and emplacement of the Cerrejón thrust sheet would have resulted in the fragmentation of the Cordillera Central-Santa Marta massif province. New U/Pb ages (241 ± 3. Ma) on granitoid rocks from industry boreholes in the Plato-San Jorge basin confirm the presence of fragments of a now segmented, Late Permian to Early Triassic age, two-mica, granitic province that once spanned the Santa Marta massif to the northernmost Cordillera Central. © 2009 Elsevier Ltd.
Roderstein M.,Justus Liebig University |
Perdomo L.,INVEMAR |
Villamil C.,INVEMAR |
Hauffe T.,Justus Liebig University |
Schnetter M.-L.,Justus Liebig University
Aquatic Botany | Year: 2014
Over a period of 44 years, we observed the vegetation changes in the western part of the lagoon system of the Ciénaga Grande de Santa Marta, which is situated on the Caribbean coast of Colombia and is separated from the sea by a sandy barrier. Since the construction of the Barranquilla-Ciénaga Road between 1956 and 1960, the lagoon system has been exposed to different interventions in its hydrological make-up, as well as changes to the vegetation. During the time of our investigations, four periods with different plant cover were distinguished. In 1965, the road was bordered by dense mangrove forests. The low surface water salinity and the presence of freshwater plants indicated the influence of the Magdalena River. At the beginning of the seventies, the second period was marked by a decrease in the freshwater in-flow from the river, which led to an increase in salinity and a gradual decay of vegetation. In 1988, the areas formerly covered by mangroves had converted into salt flats. The third period began with the reconstruction of several channels (1995-1998) which renewed the freshwater in-flow from the river to the lagoons. The subsequent vegetation development was characterized by the establishment of Typha domingensis Pers. In 1999, a year with an unusually high amount of rainfall, this species covered most of the former mangrove area in the western part of the lagoon system. The very low surface water salinity favored its spread. The last period began in 2001/2002, when growth conditions for T. domingensis became unfavorable due to an increase in salinity. Instead, conditions for mangrove regeneration improved. This process was slower than expected and is still ongoing. The striking vegetation changes indicate the sensitivity of the coastal lagoon system to hydrological variability. © 2013 Elsevier B.V.