Precise timing of MIS 7 sub-stages from the Austrian Alps

Abstract. Determining the precise timing of glacial terminations and the interglacials that follow is key to addressing questions surrounding future warming. Here, we present a high-precision record of Termination III (TIII), Termination IIIa (TIIIa), the penultimate interglacial (MIS 7), and the penultimate glacial inception (MIS 7/6 transition) from Spannagel Cave in the Austrian Alps. Using state-of-the-art mass spectrometry techniques, we have constructed a uranium-series dated chronology with relative age uncertainties averaging 1.7 ‰ (2σ) during our study period (247 to 191 thousand years before present). Results reveal the onset of TIII at 242.5 ± 0.2 ka and the duration of MIS 7e between 241.8 to 236.7 (±0.6) ka. Depleted δ¹⁸O values indicating MIS 7b center at 229.5 ± 2.3 ka. An abrupt shift towards higher δ¹⁸O values at 217.1 ± 0.5 ka marks the beginning of TIIIa. Two periods of high δ¹⁸O values (greater than −10 ‰) between 215.9–213.3 and 204.3–197.5 (±0.4) ka coincide with interglacial substages MIS 7c and 7a, respectively. Two newly collected stalagmites from Spannagel Cave (SPA146 & 183) provide high-resolution replications of the latter portion of the MIS 7a/6e transition, which occurred between approximately 197.1 and 191.4 (±0.3) ka. The resulting multi-stalagmite timeseries provides important chronological constraints on climate shifts in Europe and the North Atlantic during MIS 7. This study also provides a clear answer to the exact timing of TIIIa, which has been previously debated.