International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

ECOLOGY OF KARPATIAN (EARLY MIOCENE) FORAMINIFERS AND CALCAREOUS NANNOPLANKTON FROM LAA AN DER THAYA, LOWER AUSTRIA: A STATISTICAL APPROACH

Pages: 361 - 374

Authors: SILVIA SPEZZAFERRI, STJEPAN CORIC

Abstract: In this study we present a paleoecological interpretation based on quantitative analysis of middle Karpatian (latest Burdigalian) benthic and planktonic foraminifers and calcareous nannofossils from Hole BL 503 (Wienerberger) drilled at Laa an der Thaya, Lower Austria. Multivariate statistics based on the Bray-Curtis Similarity, non-metric MultiDimensional Scaling (nMDS) and Similarity and Dissimilarity Term Analyses are applied to raw data to identify the ecological gradients subtending the assemblages. Species abundance curves (%) were also plotted. A paleoclimatic curve was obtained using the algebraic sum of planktonic foraminifers warm- and temperate-water indicators (positive) and cool-water indicators (negative) to highlight the paleoclimatic trend during the middle Karpatian. Our data indicate that the sediments drilled at Laa Th. were deposited in water depth not exceeding 200 m, relatively "near shore" in an environment characterized by a generally high concentration of organic matter, suboxic to dysoxic conditions, high nutrient availability, variable salinity and generally cool paleoclimate. On the basis of nannoplankton distribution we also suggest that nutrient availability and upwelling conditions, rather than other ecological factors, control the distribution of calcareous nannoplankton in the Molasse Basin.

Keywords: Miocene, Karpatian, Lower Austria, Laa an der Thaya, foraminifers, nannofossils, ecology, statistic

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