Abstract

COLON-USECHE, Sirel et al. Northern offshore margin of Venezuela: High-resolution marine seismic survey between Golfo Triste and Cabo Codera. Bol. Soc. Geol. Mex [online]. 2021, vol.73, n.2, 00005.  Epub Jan 31, 2022. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2021v73n2a060121.

The continental shelf north of Central Venezuela is partially or completely structurally controlled by major right lateral strike slip active faults (e.g. San Sebastián fault), comprising three physiographic provinces, from west to east: The Golfo Triste Platform, the Choroní Basin and the La Guaira Platform. The two mentioned platforms are of erosional type while the Choroní basin is a deep depression, which is incised by submarine canyons. These canyons seem to be related to turbidity currents with greater flows during the Pleistocene wetter periods. Following several authors, these submarine canyons are partially or completely structurally controlled by major structures present in the north-central coastal range of Venezuela. Five major regional unconformities and/or seismostratigraphic limits have been identified. We propose to correlate the most recent to MIS 2 (Last Glacial Maximum ~ 20 ka) lowstand. The chronological significance of the deepest detected major uncomformity (strong erosion) is tentatively attributed to MIS 6 (~130 ka) lowstand. Based on the present-day position of the later one, we propose an estimation of ~1.2 mm.y-1 of the mean subsidence rate in the La Guaira Shelf, considering that the obtained value may locally represent a minor vertical component of the dominantly horizontal displacement along the San Sebastián Fault. The San Sebastián fault shows a linear deformation in the eastern profiles. In contrast to the west, we observe in some profiles an intense deformation zone.

Keywords : seismestratigraphy; neotectonique; San Sebastián fault; La Tortuga fault.

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