Isotope Geochemical Studies on Carbonates of Quaternary Glacio-Lacustrine Lake Sediments as indicators of Paleoenvironment |
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Authors: | F W Junge T Böttger |
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Institution: | Leipzig University, Institute of Geophysics and Geology , Paleoclimatological Laboratory, Leipzig |
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Abstract: | Selected silty “summer” and argillaceous “winter” layers of profiles of the rhythmically bedded glacio-lacustrine ice-marginal lake sediment of the Dehlitz-Leipzig varved clay (Leipziger Tieflandsbucht, Central Germany) have been examined for isotope composition (18O/16O, 13C/12C) of carbonate and organic fraction. In addition, mineralogical and grain size compositions were determined. The results show 1) a change in source of carbonate sediment (provenance) through time; 2) the oxygen isotope ratios differed between the “summer” and “winter” layers of varves couplets due to different rates of sedimentation; 3) anoxic events occurred in the lake; 4) carbon isotope ratios suggest organics in lake sediments which were derived from land and the primary productivity was low in the lake itself. In the study of cold-climatic lake sediments, isotope investigations can efficiently be used as additional paleosedimentological and facies indicators. |
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Keywords: | Carbonates carbon 13 carbon 12 glacio-lacustrine sediment natural abundances oxygen 18 oxygen 16 paleoenvironment stable isotopes varved clay |
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