Negative Sea Level Oscillation in Bahia Blanca Estuary related to a Global Climatic Change around 2,650 yr. B.P.

GÓMEZ, E. A; MARTÍNEZ, D; BOREL, C. M; GUERSTEIN, G. R.; CUSMINSKY G. C.

JOURNAL OF COASTAL RESEARCH

JCR

Lugar: Lawrence; Año: 2006 p. 181 - 185

0749-0208

Bathymetric and side scan sonar surveys, sedimentological analyses and boreholes carried out  in the external zone of Bahía Blanca Estuary, determined the regional presence of cohesive fine-stratified layers cropping out at depths up to 17 m below the present sea level. Sedimentological and micropalaeontological studies carried out on the most representative core  give evindence of an alternating environmental energy during deposition as it currently  occurs in muddy tidal plains. The lower core section consists of  sediments which are  deposited in a restricted intertidal environment.  The middle section represents an intertidal environment which is  more  strongly influenced by the action of tidal currents as it currently occurs  in tidal flats  in close relation with a channel system.The upper section shows the gradual passage to present conditions (strong tidal currents).The core lower section (14 C 6350 yr B.P.) would have been deposited before the maximum Holocene transgression, while its middle section (14 C 2460 yr B.P.) indicates the occurrence of an important negative mean sea level oscillation that is correlated with emerged evidences from the coasts of southern Argentina and central-southern Brazil. The magnitude of this  negative oscillation below current sea level may be correlated with the worldwide climatic change  that occurred around 2650 yr B.P. This suggests that the consequences resulting from relatively short perturbations in the global climate are more importantt than  heretofore believed.