Subfossil trees with their annual rings constitute the most accurate and precise archive to calibrate the radiocarbon (14C) method. The Holocene part of the IntCal curve is based on tree-ring chronologies, absolutely dated by dendrochronological matching. For the Northern Hemisphere, the absolute curve starts at 12,325 cal BP. For the early part of the Younger Dryas (YD) climatic event (≈ 12,850–11,650 cal BP), there are only a few floating dendrochronological sequences, mainly from Switzerland and France. We present new 14C results from subfossil trees (Pinus sylvestris L.) collected from the Barbiers site (southeast French Alps). The dendrochronological series covers 416 years, corresponding to the onset of the YD period. In order to date our sequence, we matched it with the 14C record based on kauri trees from New Zealand. The Barbiers data were first averaged at the same decadal resolution as the kauri record. Statistical comparison of the different averaging options and matching techniques enables dating the Barbiers sequence to 13,008–12,594 ±10 cal BP, which thus includes the boundary between the Allerød and YD events. The new Barbiers record allows to calculate the 14C inter-hemispheric gradient (14C-IHG) during the period overlapping the kauri sequence. For the optimal dating option, the mean 14C-IHG is 37 yr with a standard deviation (SD) of 21 yr based on 43 decadal estimations (−6‰ with SD of 2‰). The 14C-IHG record exhibits minimal values, down to zero, between 12,960–12,840 cal BP. Excluding these minima leads to an average 14C-IHG of 45 yr with a SD of 14 yr based on 33 decadal values, in agreement with observations for the last two millennia. The Barbiers record suggests a 14C-IHG increase between the end of the Allerød period (IHG of 37 yr with SD of 14 yr) and the early part of the YD (IHG of 48 yr with SD of 14 yr), which is compatible with previously reported drop of deep-water convection in the North-Atlantic and the associated increase in wind-driven upwelling in the Southern Ocean.

中文翻译：

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在法国亚化石树中以 14C 的年分辨率记录的年轻仙女木的发病

带有年轮的亚化石树构成了校准放射性碳的最准确和最精确的档案（14C) 方法。IntCal 曲线的全新世部分基于树木年轮年表，完全由树木年代学匹配确定。对于北半球，绝对曲线始于 12,325 cal BP。对于新仙女木 (YD) 气候事件的早期部分（≈ 12,850–11,650 cal BP），只有少数漂浮的树木年代序列，主要来自瑞士和法国。我们提出新的14C 结果来自亚化石树 (樟子松L.) 从 Barbiers 遗址（法国阿尔卑斯山东南部）收集。树木年代序列涵盖 416 年，对应于 YD 时期的开始。为了确定我们的序列的日期，我们将其与14C 记录基于来自新西兰的贝壳杉树。Barbiers 数据首先以与贝壳杉记录相同的十年分辨率进行平均。不同平均选项和匹配技术的统计比较使 Barbiers 序列的年代测定为 13,008–12,594 ±10 cal BP，因此包括 Allerød 和 YD 事件之间的边界。新的 Barbiers 记录允许计算14C 半球间梯度 (14C-IHG）在与贝壳杉序列重叠的时期。对于最佳约会选项，均值14C-IHG 为 37 年，基于 43 个年代际估计的标准偏差 (SD) 为 21 年（-6‰，SD 为 2‰）。这14C-IHG 记录在 12,960–12,840 cal BP 之间显示出最小值，降至零。排除这些最小值会导致平均值14C-IHG 为 45 年，SD 为 14 年，基于 33 个年代际值，与过去两千年的观测结果一致。Barbiers 的记录表明，14在 Allerød 期结束（IHG 为 37 年，SD 为 14 年）和 YD 早期（IHG 为 48 年，SD 为 14 年）之间的 C-IHG 增加，这与先前报道的深度下降相一致- 北大西洋的水对流和南大洋风驱动的上升流的相关增加。