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Evaluation of bulk carbonate stable isotope composition from the Süttő loess sequence (Hungary) - What can we interpret with an existing chronology?

The 18 m thick loess/paleosol sequence from Süttő, Hungary (47°44.26’ N, 18°26.87’ E, 256 m a.m.s.l.), was investigated for bulk carbonate stable isotope composition (13C, 18O). Bulk loess and soil samples were collected during field samplings conducted in steps of 25 cm and 2 cm resolution on eight separate sub-profiles. Detailed chronological investigations (optically stimulated luminescence, infrared stimulated luminescence, infrared radiofluorescence, radiocarbon dating, and amino-acid racemisation) are available from earlier work at this site. Age estimates range from 15 to 140 ka for the entire sequence indicating a sediment sequence covering the time span ranging from MIS 6 to MIS 1. The aim of this study is to evaluate possibilities to interpret stable isotope signals in the context of soil development (transformation, bioturbation, vegetation), carbonate solution/dissolution processes and potential paleo-climate signals, which might be compared with implications from high-resolution grain-size and magnetic susceptibility data. Isotope composition measured for about 1.000 samples show mean values of -2.0‰ and -4.9‰ with standard deviations of 2‰ and 1‰ (vs. VPDB) for 13C and 18O, respectively. Isotope values were measured and normalized against the international standards scale (NBS-19 and L-SVEC) with an analytical precision of 0.1‰ and 0.2‰ for 13C and 18O, respectively, for multiple sequences (reproduced by an independent quality check sample, IAEA-CO-1). Soil development as well as carbonate redistribution will alter bulk carbonate isotope composition on one hand, but might also indicate phases of intense precipitation or climate impacts on the other hand, especially when absolute ages are interpreted. Those signals might also allow an inter-correlation of separate sub-profiles that were taken from the sequence ; problems and results that we will report here.

loess; paeosol; stable isotope; bulk carbonate; Süttő; Hungary

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