Subannual climate reconstructions of the Holocene are rare despite the ability of such records to provide a better understanding of the underlying factors that drive subannual climate variability. We used specialized confocal laser fluorescent microscope imaging and automated secondary ion mass spectrometry microanalysis to resolve a seasonal oxygen isotope (δ18O) record of a late Holocene–aged (2.7–2.1 ka) speleothem from mid-continental North America. We did this by measuring intra-band δ18O variability (Δ18O) within 117 annual bands over a 600 yr span of the late Holocene. We interpret a change in Δ18O values after 2.4 ± 0.1 ka to reflect an increase in the amount of winter precipitation. Our study produced direct measurements of past seasonality, offers new insights into shifting seasonal precipitation patterns that occurred during the late Holocene in central North America, and adds a new tool for understanding the complex precipitation and temperature histories of this region.

中文翻译：

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从季节性解析的 speleothem 记录来看，北美大陆中部冬季降水的晚全新世增加

尽管此类记录能够更好地理解驱动次年气候变率的潜在因素，但全新世的次年气候重建很少见。我们使用专门的共聚焦激光荧光显微镜成像和自动二次离子质谱微量分析来解析来自北美大陆中部的全新世晚期（2.7-2.1 ka）speleothem 的季节性氧同位素（δ18O）记录。我们通过测量晚全新世 600 年跨度的 117 个年度波段内的波段内 δ18O 变异性 (Δ18O) 来做到这一点。我们解释 2.4 ± 0.1 ka 后 Δ18O 值的变化，以反映冬季降水量的增加。我们的研究直接测量了过去的季节性，