CONICET | Buscador de Institutos y Recursos Humanos

We presented preliminary results from two cores obtained in 1) OMP and 2)RMP, which were integrated with geomorphic evidences to infer landscape evolution during the mid-to-late Holocene. Sediment cores were recovered using a vibracore, and core depths were corrected according to the registered sediment compaction during collection. Site stratigraphy was described based on sediment color and textural changes throughout respective cores. Radiocarbon measurements were conducted on macrofossils and bulk organic matter from varying depths down the cores. The OMP core was extracted from the Old Marine Plain, in an area covered by woody associations of salt tolerant bushes.The base of the core is dominated by fine sands and silts, fining upwards to thinly laminated deposits, up to a depth of 288 cm (2.21 m above MTL). Specimens of Olivella tehuelcha and Nucula nucleus (marine subtidal to intertidal gastropods) were dated 5660+-30 yr BP and 5470 +-30 yr BP (cal 6171-5967 yrs BP and cal 5916-5744 yr BP, respectively) at elevations 0.12 and 0.26 m above MTL respectively. The RMP core was extracted from the Recent Marine Plain, in a flat bare salt flat close to an old tidal channel, presently unconnected to tides. Vegetation in this unit has a mound-intermound structure, and soils in the large barren areas between mounds develop bright salt crusts. Fine sands at the base intergrade with silty-clayed layers up to 1 cm thick. Bulk organic matter from a thick cohesive layer the base of the core (271 cm depth), was dated 6170+-30 yr BP (cal 7155-6935 yrs BP). Upwards, lamination becomes finer and extends up to a depth of 211 cm (0.31 m below MTL), where a sharp discontinuity separates laminated sediments from the overlying massive muds. Bulk organic matter from the top laminated layers (0.35 m below MTL) was dated 4170+-30 yr BP (cal 5570-5560 and cal 5470-5315 yrs BP).