MORFOLOGÍA Y ARQUITECTURA INTERNA DE UNA PLATAFORMA CONTINENTAL CAMBIANTE: GOLFO DE MORROSQUILLO
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Universidad Industrial de Santander
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La adquisición de 50 perfles batimétricos con sus correspondientes transectos de alta resolución (ecosonda de transductores de 200 y 12 kHz) colectados en el marco del proyecto Eaft-Colciencias: "Geomorfología de la plataforma somera del Departamento de Córdoba y del Golfo de Morrosquillo", permitió mapear la morfología (batimetría, pendiente, aspecto y relieve) y arquitectura estratigráfca del subfondo de la plataforma continental interna (profundidades < 10m) del Golfo de Morrosquillo. Visualizada a partir de un mapa batimétrico elaborado con base en registros digitales de 200 kHz, la morfología de la plataforma interna del Golfo se presenta en su mayor extensión como una superfcie cóncava hacia arriba, predominantemente erosional, que alcanza las profundidades de 10 m a distancias entre 2 y 3.5 km de la línea de costa actual. En algunas zonas localizadas (por ejemplo en el sector noreste del área de estudio), los registros disponibles evidencian importantes anomalías positivas de relieve, aparentemente correspondientes a volcanes de lodo recientes con cúspides bien conservadas y diámetros del orden de las decenas de metros; estas anomalías podrían corresponder también a escarpes asociados a fallas con actividad reciente. Los registros de ecosonda de 12 kHz ofrecen una resolución vertical entre 30 y 80 cm y penetraron en muchos sectores hasta 5m por debajo de la superfcie del fondo, evidenciando numerosos rasgos erosionales y depositacionales cubiertos, incluyendo escarpes, discordancias angulares y paleocanales colmatados. Estas geoformas del fondo y subfondo evidencian una dinámica Holocena activa en extremo, con componentes tectónica y eustática importantes.
Palabras Clave: Plataforma continental, geofísica de alta resolución, Holoceno, Geomorfología de costas.
Acquisition of 50 bathymetry and high resolution profles (echosounder transducers of 200 and 12 Khz respectively) col-lected under the EAFIT-COLCIENCIAS project "Geomorphology of the shallow shelf of Departamento de Cordoba and Golfo de Morrosquillo" allowed mapping the morphology and stratigraphic architecture of the inner shelf (depths < 10 m) seafoor and sub-seafoor under Gulf of Morrosquillo. The morphology of the inner shelf, as depicted on a bathymetry map based on 200 kHz soundings, appears broadly as a concave up, largely erosive surface that reaches the 10 m isobath at distances of 2 and 3.5 km from the shoreline. At several localized sites (such as in the NE of the study area), echosounder data provide evidence of positive terrain anomalies, apparently corresponding to recent mud volcanoes of well preserved tops tens of meters across, or recently faulted. The 12 kHz records, which offer a vertical resolution of 30 to 80 cm, were able to penetrate 5 m below the seafoor at various places, and allowed recognition of several buried erosional and deposi-tional features including scarps, angular unconformities, and flled paleochannels. These seafoor and subseafoor features are evidence of an extremely active Holocene dynamics, with important eustatic and tectonic components. Keywords: Continental shelf, high resolution Geophysics, Holocene, coastal geomorphology.
Acquisition of 50 bathymetry and high resolution profles (echosounder transducers of 200 and 12 Khz respectively) col-lected under the EAFIT-COLCIENCIAS project "Geomorphology of the shallow shelf of Departamento de Cordoba and Golfo de Morrosquillo" allowed mapping the morphology and stratigraphic architecture of the inner shelf (depths < 10 m) seafoor and sub-seafoor under Gulf of Morrosquillo. The morphology of the inner shelf, as depicted on a bathymetry map based on 200 kHz soundings, appears broadly as a concave up, largely erosive surface that reaches the 10 m isobath at distances of 2 and 3.5 km from the shoreline. At several localized sites (such as in the NE of the study area), echosounder data provide evidence of positive terrain anomalies, apparently corresponding to recent mud volcanoes of well preserved tops tens of meters across, or recently faulted. The 12 kHz records, which offer a vertical resolution of 30 to 80 cm, were able to penetrate 5 m below the seafoor at various places, and allowed recognition of several buried erosional and deposi-tional features including scarps, angular unconformities, and flled paleochannels. These seafoor and subseafoor features are evidence of an extremely active Holocene dynamics, with important eustatic and tectonic components. Keywords: Continental shelf, high resolution Geophysics, Holocene, coastal geomorphology.