Multiple Speleothem Record of Orbital to Millennial-scale Climate Variability During MIS 21 to MIS 26
Abstract
Despite increasing interest in the study of orbital to millenial-scale climate variability during the Middle Pleistocene Transition our understanding of climate forcings as well as teleconnections is restricted in part by the lack of radiometrically-dated records. Furthermore, almost all high-resolution records have been recovered from marine setttings while continental archives remain highly under-represented. Here we present a multiple U-Pb radiometrically dated speleothem δ18O and δ13C record from Corchia Cave (Italy) which spans the Marine Isotope Stage (MIS) 21 to MIS 26 time interval. The record is based on four stalagmites and one subaqueous core. More than 100 U-Pb analyses secured a robust chronology and all climate events of interest were dated with a precision of 5ka or better. The speleothem chronology was transposed on to the marine benthic records through matching the speleothem δ18O and the SST records from the North Atlantic. Our results reveal that Terminations XII and X are separated by two obliquity cycles, and that Marine Isotope Stages 25 to 22 are not part of a 100-kyr cycle as previously thought. Furthermore, our time series reveal that precession also played an important role with each Termination occurring when summer insolation in either the Northern or Southern Hemisphere was high. This rules out the importance of an exclusively Northern Hemisphere summer insolation maximum in triggering the timing of these terminations and implicates obliquity as the major forcing parameter. Superimposed on the glacial-interglacial climate variability in our record we also recognise four interstadial periods during MIS 21. These millenial-scale events are in agreement with deep sea records distributed across the North Atlantic. The interstadials are recorded in both speleothem δ18O and δ13C proxies and are interpreted as reflective of a decrease in rainfall amount and temperature at the Corchia cave site probably as a response to precession-modulation of insolation.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMPP34B..06H
- Keywords:
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- 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCESDE: 4901 Abrupt/rapid climate change;
- PALEOCEANOGRAPHYDE: 4910 Astronomical forcing;
- PALEOCEANOGRAPHYDE: 4962 Thermohaline;
- PALEOCEANOGRAPHY