Análisis sísmico-secuencial del relleno sedimentario de la Ría de Pontevedra (Galicia, NO de España)

Resumo

/\ sequence stratigraphy analysis of high resolution seismic reflection profiles reveals that the latePleistocene- Holocene deposits in the Ría de Pontevedra comprise a 5th order (20 kyr) sequence consisting of a set of units interpreted as Transgressive and Highstand System Tract deposits. These deposits appear overlaying an irregular surface that truncates older sedimentary strata, interpreted as a result of the Last Glacial Maximum sea level fall (García-Gil et al., 2002; Durán et al., 2003; Ferrin et al., 2003). Lowstand System Tract deposits have not been identified in the study area. The Transgressive System Tract is characterized by a succession of retrogradational deposition systems that vary both in lateral extension and facies association. They are limited at their top by boundary surfaces reflecting episodic sea-level rises occurred during the postglacial transgression. The uppermost bounding surface on the Transgressive System Tract corresponds with the Maximum Flooding Surface. The Highstand System Tract is represented by the deposition of fine sediments in the central part of the ría and by the development of recent delta deposits along the coast and between Ons and Onza islands.