|Evolución morfológica y estratigráfica plio-cuaternaria del umbral de camarinal (Estrecho de Gibraltar) basada en sondeos marinos|
Esteras, M.; Izquierdo, J.; Sandoval, N.G.; Bahmad, A. (1999). Evolución morfológica y estratigráfica plio-cuaternaria del umbral de camarinal (Estrecho de Gibraltar) basada en sondeos marinos. Revista de la Sociedad Geologica de España 13(3-4): 539-550
In: Revista de la Sociedad Geologica de España. Sociedad Geologica de España: Madrid & Salamanca. ISSN 0214-2708, more
Gibraltar Strait, paleo-channels, submarine slumps, breccia, Plio-Quaternary
|Authors|| || Top |
- Esteras, M.
- Izquierdo, J.
- Sandoval, N.G.
- Bahmad, A.
Boreholes drilled in the Strait of Gibraltar down to 222 m allow us to carry out a new interpretation of its Main Sill (Camarinal Sill). The Main Sill has been hitherto interpreted as a N-S range of flysch units resistant to marine erosion. The results now acquired show that it consists of two E-W paleo-channels, eroded until 650 m deep and separated by a central flysch outcrop (Monte Tartesos). The ages of the main events involved in the erosion of the channels are not yet fixed. The first stages could be contemporaneous with the opening of the Strait during the lower Pliocene or result of a later marine currents erosion. The infilling of the channels was initially due to the deposition of clay breccias result of the gravitational collapse of unstable areas placed in the surroundings. These breccias were partly eroded in the southern channel during a new erosional stage, which was followed by deposition of bio-lithoclastic sands transported by the intense Strait currents. Afterwards, but limited to certain areas, a conglomerate made of lithic and bioclastic pebbles of a clear coastal and platform origin was deposited. The last unit is constituted by a well cemented mounds of bioclasthic limestone (lithoherms) favoured by the high biogenic productivity associated to the current regime. The samples dated with U/Th in the first upper meter show an age of 150-180 ka.