HR: 15:15h
AN: T23A-06    [Abstracts]
TI: Uplift of continental crustal blocks adjacent to the Rancheria Basin-Guasare area: the effects of Maastrichtian-Paleocene collision along the southern Caribbean plate boundary
AU: * Bayona, G
EM: gbayona@cgares.org
AF: Smithsonian Tropical Research Institute, Balboa, Ancon, Panama
AU: * Bayona, G
EM: gbayona@cgares.org
AF: Corporacion Geologica ARES, Calle 57 N. 23-09, Bogota, Colombia
AU: Montes, C
EM: camilo.montes@cerrejoncoal.com.co
AF: Carbones de Cerrejon, Calle 100 # 21-64, Piso 12, Bogota, Colombia
AU: Jaramillo, C
EM: jaramilloc@si.edu
AF: Smithsonian Tropical Research Institute, Balboa, Ancon, Panama
AU: Ojeda, G
EM: german.ojeda@ecopetrol.com.co
AF: Instituto Colombiano del Petroleo, Km 7 via a Piedecuesta, Bucaramanga, Colombia
AU: Cardona, A
EM: cardonaa@si.edu
AF: Smithsonian Tropical Research Institute, Balboa, Ancon, Panama
AU: Pardo, A
EM: andres.pardo@ucaldas.edu.co
AF: Universidad de Caldas, Calle 65 N. 26-10, Manizales, Colombia
AU: Pardo, A
EM: andres.pardo@ucaldas.edu.co
AF: Agencia Nacional de Hidrocarburos, Calle 99 N. 9A-54 Piso 14, Bogota, Colombia
AU: Lamus, F
EM: flamusochoa@yahoo.com
AF: Corporacion Geologica ARES, Calle 57 N. 23-09, Bogota, Colombia
AB: In the Rancheria basin (RB) and Guasare area (GA), Maastrichtian-Paleocene synorogenic strata overlie the Aptian-Campanian carbonate platform. Nowadays, RB is bounded to the west by metamorphic-and-igneous cored Santa Marta massif, where Upper Cretaceous strata overlie unconformably pre-Cretaceous rocks. The eastern boundary of the RB is the Perija range that includes volcaniclastic and sedimentary rocks of Jurassic and Cretaceous age in the hanging-wall of a NW-verging, low-angle dipping thrust belt. The GA is on the eastern foothills of the Perija range and corresponds to the western boundary of the Maracaibo basin. Strata architecture, seismic reflectors, gravity, provenance, and paleocurrent analyses carried out in those basins constrain the timing and style of uplift of Santa Marta massif and Perija range, which are linked with tectonism along the southern Caribbean plate. Maastrichtian-Paleocene strata thicken eastward up to 2.2 km in the RB, and this succession includes (in stratigraphic order): foram-rich calcareous mudstone, oyster-pelecypod rich carbonate-siliciclastic strata, coal- bearing mudstones and feldspar-lithic-rich fluvial sandstones. Internal disconformities and truncations of seismic reflectors are identified to the west of the RB, but there are not major thrust faults at this part of the basin to explain such unconformities and truncations. In Early Paleocene, carbonates developed better to the west of the RB, whereas mixed carbonate-siliciclastic deposition continued toward the east of the RB. In early Late Paleocene, influx of terrigenous material (key grains=metamorphic, microcline and garnet fragments) derived from the Santa Marta massif increased to the west, but to the east of the RB and GA carbonate-siliciclastic and carbonate deposition continued, respectively. In mid-Late Paleocene, diachronous eastward advance of paralic/deltaic environments, tropical humid climate, and high subsidence rates favored production and preservation of peat in RB and GA. In the late Late Paleocene, inversion along a buried graben system under the Perija range explain supply toward RB and GA of micritic, volcanic, and sedimentary rock fragments, and the record of a thinner Upper Paleocene strata in the GA than in the RB. Tectonic subsidence in the RB was mainly related to pivoting of the Santa Marta massif as result of collision of the Maracaibo continental sub-plate with the southern margin of the Caribbean oceanic plate. This model explains the generation of accommodation space in the RB without faulting, denudation of upper crustal material of the Santa Marta massif, early capture of terrigenous detritus in the RB that favored carbonate deposition in the GA, the mechanism of initial inversion of the Perija range, and the present positive gravity anomaly under the Santa Marta massif.
DE: 8011 Kinematics of crustal and mantle deformation
DE: 8100 TECTONOPHYSICS
DE: 8108 Continental tectonics: compressional
DE: 8138 Lithospheric flexure
DE: 8169 Sedimentary basin processes
SC: Tectonophysics [T]
MN: 2007 Joint Assembly