TAPHONOMIC SIGNATURE OF GLYCYMERIS LONGIOR SHELLS (BIVALVIA) AND ITS POTENCIAL AS PALEOENVIRONMENTAL PROXY FOR QUATERNARY NORTHERN PATAGONIA (ARGENTINA)

BAYER, M. SOL; NÓBILE, JULIETA; MUÑOZ, DIEGO F.; MORSAN, ENRIQUE; MORÁN, GISELA; FUCKS, ENRIQUE; GORDILLO, SANDRA

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2023

0002-7014

One of the most abundant species of bivalves found on modern beaches and Quaternary deposits in the San Matías Gulf (SMG, Patagonia Argentina, SW Atlantic Ocean) is Glycymeris longior. Its high abundance and broad geographical distribution turn G. longior into a target species for taphonomical studies. Here, we described the taphonomic signature registered on its shells from San Antonio Bay (SMG, Rio Negro). This study will contribute to future taphonomic comparisons in the SW Atlantic Ocean, as well as in other Quaternary deposits and provide insight about the spatial variation of the taphonomic processes influenced by the ambient environment. Glycymeris longior valves from the Holocene Punta Delgado deposits showed two taphonomic signatures whose shell assemblages were differentiated by fragmentation, rounding and cementation intensities. Shells from PD2018A and PD2018B (two sampling localities representing similar environment) were subject to continuous and low energy water flow. Those remained in a low intensity hydrodynamic sediment-water interface that would favour high shell cementation. On the other hand, shells from PD2016 were also subject to continuous, but more energetic water flow. Those would remain in thetaphonomic active zone for enough time to confer smooth edges and to be colonized by clionid sponges but not enough favourable for carbonate precipitation. Punta Delgado site was interpreted as a protected area during the Holocene (last 4200 yrs.) similar to the modern one, but with differences in carbonate precipitation as the product of differences in water flow intensities. Finally, the high mechanical resistance of G. longior shells, together with its abundance and broad geographical distribution turn this species into a suitable target taxon for further taphonomic and ecologic analyses and comparisons.