Amino Acid Geochronology Applied to Loess Deposits: Where Do We Stand Today?
Abstract
Paleoclimatic investigations of loess deposits rely on numerical dating techniques, including radiocarbon, luminescence, and paleomagnetic methods, in order to develop reliable time series for the proxies being studied. Commonly, the utility of luminescence and radiocarbon dating is limited by their applicable dating range, while ages of lower to middle Pleistocene strata can be only coarsely estimated using pedostratigraphy, biostratigraphy, and paleomagnetic reversal stratigraphy. During the last two decades, amino acid racemisation (AAR) geochronology, although primarily a relative dating technique, has provided an independent assessment of numerical age estimates, when results are at or near their methodological limits, and has assisted in the chronostratigraphic evaluation of loess units. In this paper we highlight the potential of amino acid geochronology applied to loess research using examples from SE Europe and Central Asia. A comprehensive regional application of AAR to different loess series in Serbia demonstrates the potential of the method to establish an independent chronostratigraphic framework for SE European loess sequences. The method also assists in the identification and age evaluation of stratigraphic unconformities, such as fluvial erosion layers, in support of reliable regional chronostratigraphic and paleoclimatic interpretations. Applied to the Central Asian loess sequence Remisowka, amino acid geochronology provides an independent age model for the loess series, and the combination with numerical dating techniques allows us to confidently determine the position of the last and penultimate interglacial periods in the Remisowka sequence, casting new light on the chronostratigraphy of the last three glacial cycles in Central Asian loess. Ultimately, we show that AAR has contributed significantly to the leverage of high-resolution paleoclimate proxies, such as grain-size data, toward an improved understanding of the paleoenvironmental dynamics of SE Europe and Central Asia in an intra-hemispheric context.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMPP23B1840O
- Keywords:
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- 1105 GEOCHRONOLOGY / Quaternary geochronology;
- 1125 GEOCHRONOLOGY / Chemical and biological geochronology;
- 3344 ATMOSPHERIC PROCESSES / Paleoclimatology