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Age, origin and stratigraphic potential of the volcanic ash layers interbedded within the Quaternary terrestrial deposits of the Lower Danube region, Romania

Daniel Veres1, Ulrich Hambach2, Alida Timar-Gabor3, Christine S. Lane4, Kathryn E. Fitzsimmons5, Alexandru Szakács6, Slobodan B. Marković7
1 Institute of Speleology/Dept of Geology, Romanian Academy/Babes Bolyai University
2 Chair of Geomorphology, University of Bayreuth, Germany
3 Faculty of Environmental Science and Engineering, Babes-Bolyai University, Cluj, Romania
4 Research Laboratory for Archaeology and the History of Art, University of Oxford, UK
5 Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
6 Sapientia University, Department of Environmental Sciences, Cluj, Romania
7 Department of Geography, Tourism and Hotel Management, University of Novi Sad, Novi Sad, Serbia

V 2.3 in Löss und terrestrische Archive

17.09.2012, 16:50-17:10, H8

Terrestrial sedimentary sequences, in particular loess and alluvial deposits, are instrumental in defining past environments in the Carpathian-Lower Danube area, as they are the most widespread Quaternary archives in this region. Decades of sedimentological investigations, augmented by more recent applications of luminescence dating, environmental magnetism and geochemical provenance studies, have opened new perspectives for elucidating palaeoclimates preserved within the loess of this region. Improved site-specific chronologies and palaeoclimatic reconstructions add to our understanding, yet, a secure regional-scale correlation of records remains to be established due to significant variability in loess characteristics and composition between sites. Hence, advancements in chronological techniques are of utmost importance for correctly identifying the sequence of climatic events and improving inter-site correlations.

One way to circumvent some of these limitations is provided by the identification of non-climatic marker horizons such as tephra layers, particularly since recent work has demonstrated that some events can be traced over areas far more distal than previously realized. The Lower Danube region is favorably located within the dispersal area of several major volcanic fields, including the nearby Carpathian volcanic fields and the more distal, but exceptionally productive, central and eastern Mediterranean volcanic provinces. A number of tephra occurrences spanning the Quaternary timescale of the southeastern European sedimentary deposits have already been reported at regional scale. Here we present new chemical and chronological data resulting from the investigation of several volcanic ash layers embedded in Pleistocene loess and alluvial deposits from southern Romania.

The chemical compositions of volcanic glass, combined with recent improvements in the chronological data, demonstrate that the investigated volcanic ashes relate to the Campanian Ignimbrite/Y5 tephra layer deposited at ca. 39-40 ka BP. Given its widespread geographical distribution, the Y5 tephra may act as a marker horizon for deposits of middle Marine Isotope Stage 3 age. Identification of this tephra has already played a crucial role in the assessment of regional environmental response within the terrestrial environments of central-eastern Europe. In addition, we review a number of Quaternary volcanic ash reports from the Carpathian region, proposing that, in order to explore distribution patterns and to determine their potential as time-parallel markers for correlating palaeoarchives, further work must be undertaken by identifying and dating sedimentary tephra occurrences.

One way to circumvent some of these limitations is provided by the identification of non-climatic marker horizons such as tephra layers, particularly since recent work has demonstrated that some events can be traced over areas far more distal than previously realized. The Lower Danube region is favorably located within the dispersal area of several major volcanic fields, including the nearby Carpathian volcanic fields and the more distal, but exceptionally productive, central and eastern Mediterranean volcanic provinces. A number of tephra occurrences spanning the Quaternary timescale of the southeastern European sedimentary deposits have already been reported at regional scale. Here we present new chemical and chronological data resulting from the investigation of volcanic ash layers embedded in Pleistocene loess and alluvial deposits from southern Romania.

The chemical compositions of volcanic glass, combined with recent improvements in the chronological data, demonstrate that many of these volcanic ashes relate to the Campanian Ignimbrite/Y5 tephra layer deposited at ca. 39-40 ka BP. Given its geographical distribution, the Y5 tephra may act as a marker horizon for deposits of middle Marine Isotope Stage 3 (MIS 3) age. Identification of this tephra has already played a crucial role in the assessment of regional environmental response within the terrestrial environments of central-eastern Europe. In addition, we review a number of Quaternary volcanic ash reports from the Carpathian region, proposing that in order to explore distribution patterns and to determine their potential as time-parallel markers for correlating palaeoarchives, further work must be undertaken by identifying and dating sedimentary tephra occurrences.

 

Acknowledgments: D.V. acknowledges support from SOPHRD e project no. POSDRU 89/1.5/S/60189.



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Letzte Änderung 07.08.2012