Resumen de La transgresión holocena en la Ría de Vigo (Rías Baíxas, Galicia): registro sedimentario en la zona costera

Marta Pérez Arlucea, Irene Alejo Flores, Guillermo Francés Pedraz, D. González, Miguel Angel Nombela Castaño, Gonzalo Méndez Martínez, F. Clemente

• Four sedimentary areas were selected to study vertical sediment distribution. 6 cores were obtained. Sediment thicknesses range between 4.0m and 26.0 m. Vertical sediment distributions show 6 different lithologic units from basal fluvial (A), estuarine (B), tidal flat and peat fens (C), muddy subti-dal bay (D), estuarine-shallow embayment (E) and beach barrier (F). 5 14C age determinations wereobtained from the longest core (Ladeira N), 5 in the suction corers, 1 in Patos Beach and 1 in Moaña.The oldest sample located at 22 m yields an age of 8,177 y. BP in unit (B) allowing to constrain mostof sediment evolution in the holocene transgressive context. The lower unit (A) composed mainly offluvial gravels, and deposited in a palaeovalley, is attributed to the Younger Dryas although the LSTcould be also represented in these deposits. Units B, C and D configure the TST showing an initialrapid increase in water depth at 8,177 y. BP and subsequent shallowing conditions due to progressive aggradation until 4809 y BP. Units E and F mark the HST eustatic stage being characterised byprogradational shallow marine conditions and beach barrier progressive enclosing of the complex.Sedimentation rates were calculated at 7 intervals. An upward decrease is observed from 8,177 y BPto 2,001 y. BP, followed by a strong sudden increase, mostly in the last 500 years.