Print this pageMud Diapirism Associated to Neotectonic Transcurrent Leaky Faults in the Colombian Caribe — A Pass Way to Hydrocarbon Migration
The north Colombian continental edge tectonic framework is related to the Nazca/South American/Caribbean Plates triple junction. The seismological records and the geology of the Cartagena city and neighborhoods have been interpreted as a result of the deformation and sedimentary processes caused by NW direction regional compressive tectonics. The stratigraphical scenario of this area is characterized by a typical Pliocene-Pleistocene carbonate inner-shelf overlaying continental clastic sediments that cover a thick Miocene deep sea mud sequence. Major structures of the Sinu and San Jacinto Deformation Belts (SSJDB) characterize the area and are represented by anticline and synclinal folds, NE-SW high angle thrust-faults, NW-SE left-lateral strike-slip faults and E-W right-lateral strike-slip faults. Locally, there are diapiric features like mud volcanoes, sometimes associated to gas/oil seeps, previously attributed to fold structures orthogonal to regional compression based on geophysical data.
In this case study, we identified a close relationship between diapiric features and morphostructural lineaments on the land area as well as on the continental shelf, mainly denoted by E-W and WNW-ESE direction structures. Seismic information allowed too the identification of a relationship between the lower mud level underlying the Tertiary sedimentary sequence and Pliocene-Pleistocene diapiric features. The inversion stress analysis indicates that the E-W / NW-SE structures are related to a WNW-ESE regional compressional stress, so implying that the E-W structures are right-lateral strike-slip faults and the NW-SE structures are reactivated left-lateral strike-slip faults. In both cases, a normal component was detected and that suggests a transtractive character to these structures. The presence of mud volcanoes indicates that the lower mud levels submitted to overpressurization help to generate or/and reactivate secondary fractures and faults associated to the NW compression related to the E-W dextral transcurrent binary.
The E-W and WNW-ESE dextral transcurrent faults and the NW-SE sinistral transcurrent faults, which control the mud diapirism, act as fluid-conducting surfaces - or leaky faults - that must be taken into account on the studies aiming the characterization of hydrocarbon migration processes in the SSJDB.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil