Pleistocene and Holocene interglacial molluscan assemblages from Patagonian and Bonaerensian littoral (Argentina, SWAtlantic): palaeobiodiversity and palaeobiogeography

AGUIRRE, MARINA; DONATO, MARIANO; RICHIANO, SEBASTIÁN; FARINATI , ESTER A.

PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY

ELSEVIER SCIENCE BV

Año: 2011 vol. 308 p. 277 - 292

0031-0182

Analysis of palaeobiodiversity and palaeobiogeography of marine Quaternary molluscan assemblages from Argentina help in our understanding of the last coastal scenarios in the SWAtlantic. Cyclic Pleistocene-Holocene climatic fluctuations were large enough to alter benthic molluscan associations. A southwards decreasing diversity trend is apparent since the Mid-Late Pleistocene (ca. 400 ka ). Salinity barriers, temperature gradients, hydrodynamic forces, can explain diversity and between areas relationships. During the last interglacials along Patagonia, the highest peaks coincide with MIS5e and MIS11, warmer than today. Multivariate and cladistic methods showed congruent patterns between localities and AE, discriminating marginal from open marine environments. Combining PCO with PAE was most advantageous for our area and dataset (721 taxa, 48 localities). The AE varied through time: Holocene and Pleistocene shifts suggest minor salinity, SST, circulation changes linked to sea-level fluctuations to present; the more homogeneous Holocene scenario linked to more uniform salinity conditions regionally. Thermally anomalous taxa (bivalves and gastropods) together with PAE confirm higher Mid-Holocene SST. Even during warmer Pleistocene interglacials, south of SAO colder nearshore conditions can be assumed. Tegula atra is a Pleistocene biostratigraphical and palaeoclimatic tool, probably representing a signal of post-LGM palaeoceanographical changes in the SW Atlantic.