Abstract
Abstract. Investigating the precise timing of regional-scale climate changes during glacial terminations and the interglacial periods that follow is key to unraveling the mechanisms behind these global climate shifts. Here, we present a high-precision time series of climate changes in the Austrian Alps that coincide with the later portion of Termination III (TIII), the entire penultimate interglacial (Marine Isotope Stage (MIS) 7), Termination IIIa (TIIIa), and the penultimate glacial inception (MIS 7–6 transition). Using state-of-the-art mass spectrometry techniques, we have constructed a uranium-series chronology with relative age uncertainties averaging 1.7 ‰ (2σ) for our study period (247 to 191 thousand years before present, ka). Results reveal the onset of warming in the Austrian Alps associated with TIII at 242.5 ± 0.2 ka and the duration of MIS 7e warming between 241.8 and 236.7 (±0.6) ka. An abrupt shift towards higher δ18O values at 216.8 ka marks the onset of regional warming associated with TIIIa. Two periods of high δ18O values (greater than −10 ‰ Vienna Pee Dee Belemnite (VPDB)) between 215.9–213.3 and 204.3–197.5 (±0.4) ka coincide with interglacial substages MIS 7c and 7a, respectively. Multiple fluorescent inclusions suggest a partial retreat of the local Alpine glacier during peak obliquity forcings at 214.3 ± 0.4 ka. Two newly collected stalagmites from Spannagel Cave (SPA146 and 183) provide high-resolution replications of the latter portion of the MIS 7a-to-6e transition. The resulting multi-stalagmite record reveals important chronological constraints on climate shifts in the Austrian Alps associated with MIS 7 while offering new insight into the timing of millennial-scale changes in the North Atlantic realm leading up to TIII and TIIIa.
Highlights
Marine Isotope Stage (MIS) 7 (ca. 246–186 thousand years before present, where present is 1950 CE) stands distinctively apart from the last several interglacial cycles
We present a high-precision time series of climate changes in the Austrian Alps that coincide with the later portion of Termination III (TIII), the entire penultimate interglacial (Marine Isotope Stage (MIS) 7), Termination IIIa (TIIIa), and the penultimate glacial inception (MIS 7–6 transition)
Due to our unprecedented age control, we can determine the precise timing of regional changes associated with each MIS 7 substage, as well as the onset of warming in the Austrian Alps associated with TIII and TIIIa (Fig. 4)
Summary
Marine Isotope Stage (MIS) 7 (ca. 246–186 thousand years before present (ka), where present is 1950 CE) stands distinctively apart from the last several interglacial cycles. In the North Atlantic realm, marine records show that major meltwater pulse events punctuated a period of rapid sea surface warming associated with TIII and TIIIa (e.g., Channell et al, 2012; Hodell et al, 2008; Martrat et al, 2004, 2007). The chronologies of these marine records, are frequently dependent on orbital tuning or alignment to global benthic δ18O stacks, which feature large uncertainties of ±10 ka during MIS 7
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