Abstract A set of four outwash terraces in the northern Alpine Foreland motivated Penck and Bruckner's classical scheme of four great Alpine ice ages: Gunz, Mindel, Riss, and Wurm. While it is now established that the Wurm corresponds to marine isotope stages (MIS) 5d–2 (∼117–14 ka) and the Riss type locality to MIS 6 (∼191–130 ka), there is no consensus regarding the age of the older glaciations. The two oldest terraces, known as Hohere Deckenschotter (HDS) and Tiefere Deckenschotter (TDS) in Switzerland and neighbouring Germany, contain interbedded tills that directly indicate the first arrival of glaciers into the northern Alpine Foreland. Here, we set out to constrain the timing of the HDS, which signal the first major glaciations in the Alps. To achieve this goal, we devised a new burial-dating model tailored to glaciogenic sediments: P-PINI (Particle Pathway Inversion of Nuclide Inventories). The method applies a source-to-sink framework to a cosmogenic 10Be-26Al inversion model accounting for variable cosmic-ray exposure and non-steady erosion. Taking published 10Be-26Al data from five HDS sites (Feusi, Tromsberg, Siglistorf, Irchel Steig, and Irchel Hutz) and one TDS site (Iberig), we obtain age distributions (±1σ) that are especially well constrained for Feusi (0.93 ± 0.13 Ma), Iberig (0.93 ± 0.17 Ma), and Tromsberg (0.88 ± 0.14 Ma), less well-constrained for Irchel Steig (0.69 ± 0.25 Ma) and Siglistorf (0.94 ± 0.27 Ma), and very poorly constrained for Irchel Hutz (1.39 ± 0.56 Ma). Consistent with the morphostratigraphy, which dictates that the TDS postdates the HDS, we implemented a Bayesian modelling framework, yielding an age of 0.69 ± 0.12 Ma for Iberig (TDS) and a combined age of 0.95 ± 0.07 Ma for the HDS sites. Based on the P-PINI burial ages as well as the combined, Bayesian burial age, we propose an age around 1.0–0.9 Ma for the onset of the large Alpine glaciations that triggered the accumulation of the HDS outwash sediments. This roughly accords with the first long glaciation of the Pleistocene (MIS 24–22), identified as a step-change to colder climate and larger glaciations towards the end of the Middle Pleistocene Transition. While our results challenge previously reported ages of ∼2 Ma or more for the HDS in Switzerland, they corroborate evidence from the southern Alpine retroforeland and provide quantitative support for the early hypothesis by G.J. Kukla, who ascribed the oldest glacial deposits in the northern Alpine Foreland to around MIS 22. Finally, we suggest that the source-to-sink approach of P-PINI offers a viable alternative to the established isochron burial-dating method in cases involving non-steady exposure and erosion.

中文翻译：

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新的宇宙成因核素埋藏测年模型表明中更新世过渡期间阿尔卑斯山主要冰川的开始

摘要 阿尔卑斯前陆北部的一组四个外冲阶地激发了彭克和布鲁克纳关于四大阿尔卑斯冰河时代的经典方案：Gunz、Mindel、Riss 和 Wurm。虽然现在已经确定亚龙对应于海洋同位素阶段 (MIS) 5d–2 (∼117–14 ka) 和 Riss 型位置到 MIS 6 (∼191–130 ka)，但关于年龄尚无共识较旧的冰川。瑞士和邻国德国被称为 Hohere Deckenschotter (HDS) 和 Tiefere Deckenschotter (TDS) 的两个最古老的梯田包含互层耕作，直接表明冰川首次到达阿尔卑斯前陆北部。在这里，我们开始限制 HDS 的时间，它标志着阿尔卑斯山的第一次主要冰川。为了实现这一目标，我们设计了一个新的埋藏年代模型，专门针对冰川沉积物：P-PINI（核素清单的粒子通路反演）。该方法将源到汇框架应用于宇宙成因 10Be-26Al 反演模型，以解释可变的宇宙射线暴露和非稳态侵蚀。使用来自五个 HDS 站点（Feusi、Tromsberg、Siglistorf、Irchel Steig 和 Irchel Hutz）和一个 TDS 站点（Iberig）的已发布 10Be-26Al 数据，我们获得了对 Feusi (0.93 ± 0.13 Ma)、Iberig (0.93 ± 0.17 Ma) 和 Tromsberg (0.88 ± 0.14 Ma)，对 Irchel Steig (0.69 ± 0.25 Ma) 和 Siglistorf (0.94 ± 0.27 Ma) 的约束不太好，对 Irchel Hutz 的约束很差(1.39 ± 0.56 毫安)。与表明 TDS 晚于 HDS 的形态地层一致，我们实施了贝叶斯建模框架，得出的年龄为 0.69 ± 0。Iberig (TDS) 为 12 Ma，HDS 站点的综合年龄为 0.95 ± 0.07 Ma。基于 P-PINI 埋藏年龄以及组合的贝叶斯埋藏年龄，我们提出了引发 HDS 外冲沉积物积累的大型高山冰川开始的年龄约为 1.0-0.9 Ma。这大致符合更新世的第一次长冰期（MIS 24-22），被确定为在中更新世过渡期结束时向更冷的气候和更大的冰期的阶跃变化。虽然我们的结果挑战先前报告的瑞士 HDS 的年龄约为 2 Ma 或更多，但它们证实了来自阿尔卑斯山后前陆南部的证据，并为 GJ Kukla 的早期假设提供了定量支持，他将最古老的冰川沉积物归因于阿尔卑斯山前陆北部到 MIS 22 左右。最后，