Environmental significance of microfaunal associations in the pampean regions, Buenos Aires, Argentina

CALVO MARCILESE, L; BEILINSON, E; RAIGEMBORN; CUSMINSKY, G.,; PIAZZA, D

Mendoza

Congreso; 4th International Paleontological Congress; 2014

International Paleontological Asociation

ENVIRONMENTAL SIGNIFICANCE OF MICROFAUNAL ASSOCIATIONS IN THE PAMPEAN REGION, BUENOS AIRES, ARGENTINALydia Calvo-Marcilese1,3, Elisa Beilinson2, María S. Raigemborn,Gabriela C. Cusminsky1 and David Piazza1. Centro Regional Universitario Bariloche, Universidad Nacional del Comahue, INIBIOMACONICET,Quintral 1250, Bariloche, CP 8400, Río Negro, Argentina.lydiacalvom@gmail.com2. Centro de Investigaciones Geológicas (CONICET ? UNLP), 1 #644, La Plata, B1900TAC, Argentina.3. Laboratorio de Bioestratigrafía, Área de Geociencias, YPF Tecnología S.A., Baradero s/n, CP 1925, Ensenada, Buenos Aires, Argentina.4. Dirección de Paleontología, Secretaría de Desarrollo Humano, Municipalidad de Marcos Paz (Buenos Aires), Argentina.The Cantera Vignogna is a quarry located in the NE of Buenos Aires province and since the lastdecade vertebrate fossils have been recovered from this location, establishing an exceptional record of megafauna with a remarkable degree of preservation. Within this area, four particular sections werestudied for sedimentological and facies analysis, with the aim of establishing paleonvironmental conditions during the late Pleistocene. The succession starts with laminated mudstones and that accumulation of the lower units took place during highstand or transgressive base-level (orcsea-level) conditions of the Marine Isotope Stage 3 (MIS 3) and that the upper units correspond tohave been collected in order to be used as proxy for paleoenvironmental reconstructions. In three of the four analyzed sections, a conspicuous association of freshwater to brackish ostracods has been registered. Even though the diversity and abundance is low, and some specimens presented signs oftransport and reworking, various valves and carapaces were recovered. The ostracods assemblage is dominated by Candona sp., Cyprideis multidentata Hartmann, Cyprideis salebrosa hartmanni Ramírez and Limnocythere sp. This assemblage is common in continental to brackish environments, fromtruly freshwater to saline, with the presence of pools and ponds where salinity could be higher than in the surrounding areas. These preliminary data along with additional information in process, will be significant to characterize the climate variability occurred during the MIS3 in South America