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UP: Umweltphysik

UP 22: Atmosph
äre und Klima

UP 22.7: Fachvortrag

Mittwoch, 15. März 2006, 15:45–16:00, D

Chronology and paleoenvironment of Marine Isotope Stage 3 from two high-elevation speleothems, Austrian Alps — •Augusto Mangini¹, Christoph Spötl², and David Richards³ — ¹Forschungsstelle Radiometrie, Heidelberger Akademie der Wissenschaften, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany — ²Institut für Geologie und Paläontologie, Leopold-Franzens-Universität Innsbruck, Innrain 52, 6020 Innsbruck, Austria — ³School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK

A new high-resolution stable isotope record from the alpine Kleegruben Cave (2165 m, Central Alps) largely duplicates a previously reported speleothem record form this site (QSR, in press). High-precision U-series TIMS dates constrain the growth history of this new sample (56-48 kyr) to the Marine Isotope Stage (MIS) 3. Both stalagmites reveal highly similar variations in O isotopes that can be directly compared to O isotope variability associated with Dansgaard-Oeschger interstadials recorded in the Greenland ice cores (Greenland Interstadials, GIS). Based on the new record we refine our previous age assignments of the GIS during this time interval, i.e. GIS 15b at 55.7 kyr, GIS 15a at 55.3 kyr, onset (mid point) of the prominent GIS 14 at 54.5 yr and onset of GIS 12 at  48 kyr. The timing of these Dansgaard-Oeschger interstadials is within 0.2 kyr of the newly proposed GRIP SFCP04 timescale. Given the present-day low temperature (+2.4 ^∘C) we propose that these unusual speleothems formed in a karst system overlain by a warm-based glacier.