Estructura del prodelta de la Tordera (costa del Maresme, NO Mediterráneo) a partir del análisis sísmico de alta resolución

Abstract

Tordera delta is feeded by sediments from the granitic Catalan Coastal Range System giving a coarse grain and arkosic sedimentar y facies. Sediment input to the coastal system was up to 200.000 m3/y as deduced from shelf Holocene relict bodies, presently is less than 50.000 m 3/y. The fluvial regime is pluvio-torrential, with two or three annual avenues. Only higher avenues and dominant drift to the SW nourished delta front system and Maresme coastal sedimentary cell wich extends 60 Km up to Barcelona. Continuous presence of sand along this coast result on high reflective beaches. Present Tordera delta had built up from the maximum transgressive sea level; some delta relict bodies were constructed during last sea level rise controlled by previous morphology and river dynamics from the lowstand level (Blanes Canyon head at – 110m). At least two intermediate relict deltas can be distinguished from present morphology and are described for the first time by seismic profiles (Uniboom). Modern delta system has prograded and overpass previous relict deltas increasing its base level up to – 60 m. Recently a sand spit has developed from delta mouth to the south, feeded with the main volume of Tordera run off. High resolution seismic profiles (Uniboom) of the prodelta zone show internal structure of the previous deduced delta bodies. Foresets of progradding delta bodies of three different units have been deduced and correlated with eustatic curve