Precise timing of MIS 7 substages from the Austrian Alps

oleh: K. A. Wendt, K. A. Wendt, X. Li, R. L. Edwards, H. Cheng, H. Cheng, C. Spötl

Format: Article
Diterbitkan: Copernicus Publications 2021-07-01

Deskripsi

<p>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 ‰ (2<span class="inline-formula"><i>σ</i></span>) for our study period (247 to 191 thousand years before present, <span class="inline-formula">ka</span>). Results reveal the onset of warming in the Austrian Alps associated with TIII at 242.5 <span class="inline-formula">±</span> 0.2 <span class="inline-formula">ka</span> and the duration of MIS 7e warming between 241.8 and 236.7 (<span class="inline-formula">±0.6</span>) <span class="inline-formula">ka</span>. An abrupt shift towards higher <span class="inline-formula"><i>δ</i><sup>18</sup>O</span> values at 216.8 <span class="inline-formula">ka</span> marks the onset of regional warming associated with TIIIa. Two periods of high <span class="inline-formula"><i>δ</i><sup>18</sup>O</span> values (greater than <span class="inline-formula">−</span>10 ‰ Vienna Pee Dee Belemnite (VPDB)) between 215.9–213.3 and 204.3–197.5 (<span class="inline-formula">±0.4</span>) <span class="inline-formula">ka</span> 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 <span class="inline-formula">±</span> 0.4 <span class="inline-formula">ka</span>. 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.</p>