Abstract. In the European Alps, the Younger Dryas (YD) was characterized by the last major glacier advance with equilibrium line altitudes being ~ 220 to 290 m lower than during the Little Ice Age and also by the development of rock glaciers. Dating of these geomorphic features, however, is associated with substantial uncertainties leading to considerable ambiguities on the internal structure of this stadial, the most intensively studied one of the last glacial period. Here we provide robust physical evidence based on precise ²³⁰Th-dated cryogenic cave carbonates (CCC) coupled with thermal modelling indicating that early YD winters were only moderately cold in the Southern Alps, challenging the commonly held view of extreme YD seasonality. Our data argue for a negative temperature anomaly of ≤ 3 °C in mean annual air temperature at the Allerød-YD transition in a mountain cave (Cioccherloch, 2274 m a.s.l.) in the Dolomites of northern Italy. Our data suggest that autumns and early winters in the early part of the YD were relatively snow-rich, resulting in a stable winter snow cover. The latter insulated the shallow subsurface in winter and allowed the cave interior to remain close to the freezing point (0 °C) year-round, promoting CCC formation. The main phase of CCCs precipitation at ~ 12.2 ka BP coincides with the mid-YD transition recorded in other archives across Europe. Based on thermal modelling we propose that CCC formation at ~ 12.2 ka BP was most likely associated with a slight warming of approximately +1 °C in conjunction with drier autumns and early winters in the second half of the YD. These changes triggered CCC formation in this alpine cave as well as ice glacier retreat and rock glacier expansion in the Alps.

中文翻译：

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白云岩中的深冷洞穴碳酸盐（意大利北部）：深入了解年轻树蛙的降温和季节性降水

摘要。在欧洲的阿尔卑斯山，年轻的得里亚斯（YD）的特征是最后一次主要的冰川发展，其平衡线高度比小冰河时期低约220至290 m，并且还具有岩石冰川的发展。然而，这些地貌特征的年代确定与不确定性有关，导致该恒星内部结构的模棱两可，这个恒星是最近冰川期研究最深入的一个。在此，我们根据精确的²³⁰提供可靠的物理证据年代久远的低温洞穴碳酸盐岩（CCC）加上热模型表明，南阿尔卑斯山的早期YD冬季仅属中度寒冷，这挑战了人们普遍认为的极端YD季节性观点。我们的数据表明，意大利北部多洛米蒂山洞（Cioccherloch，2274 m asl）的Allerød-YD过渡处的年平均气温负温度异常≤3°C。我们的数据表明，YD早期的秋季和初冬相对富含雪，导致冬季积雪稳定。后者在冬季使浅层地下表面隔热，并使洞穴内部全年保持接近冰点（0°C），从而促进了CCC的形成。CCCs沉淀的主要阶段为〜12。2 ka BP与欧洲其他档案中记录的YD中期过渡相吻合。根据热模型，我们建议在〜12.2 ka BP处形成CCC最有可能与YD下半年的秋季干燥和初冬结合略微升温约+1°C。这些变化触发了该高山洞穴中CCC的形成，以及阿尔卑斯山的冰冰川撤退和岩石冰川扩张。