Isotopic characterization of rapid climatic events during OIS3 and OIS4 in Villars Cave stalagmites (SW-France) and correlation with Atlantic and Mediterranean pollen records
Isotopic characterization of rapid climatic events during OIS3 and OIS4 in Villars Cave stalagmites (SW-France) and correlation with Atlantic and Mediterranean pollen records
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DOI：
10.1016/j.quascirev.2010.06.035
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发表时间：
2010-09-01
影响因子：
4
通讯作者：
Brauer, A.
中科院分区：
文献类型：
--
作者：
Genty, Dominique;Combourieu-Nebout, Nathalie;Brauer, A.
我们提出了来自 Villars Cave 的 OIS3 期间千禧年尺度气候变率的新中纬度洞穴记录，与之前发表的同一洞穴的同期样本相结合，给出了法国西南部大约 55 ka 和大约 30 ka 之间气候变化的连贯图像。 0.82 m 长的石笋 Vil-stm27 通过 26 次 TIMS U-Th 分析进行了年代测定，其生长曲线显示出与稳定同位素相关的变化，而稳定同位素均受气候条件控制。它包含先前发表的 Vil-stm9 和 Vil-stm14 石笋的高分辨率复制品，其中观察到了 Dansgaard-Oeschger (DO) 事件。这三个石笋之间良好的一致性以及与其他古气候重建的比较，特别是高分辨率花粉记录（来自阿尔沃兰海的 ODP 976，来自意大利南部的蒙蒂基奥湖记录）和附近的 MD04-2845 大西洋记录，允许绘制 063 年法国西南部的特定气候模式，并看到这些地点之间的区域差异。这一时期的主要特征是：1）与格陵兰间质气候（GIS）相对应的温暖事件，其特征是低洞穴沉积物三角洲C-13、高温带花粉百分比、温暖的气温和高湿度；在这些事件中，GIS#12 是 Villars 最明显的事件，其特征是在大约 46.6 ka 突然爆发，持续时间约为 2.5 ka。另一个个性化的温暖事件与 GIS#8 重合，但不太明显，并且发生在较冷的时期，如较低的增长率和较高的 Delta C-13 所示； 2) 与格陵兰Stadials (GS)相对应的寒冷事件，其明显特征是高洞穴藻δ C-13、低温花粉丰度、低温和增强的干燥度，在与海因里希事件H5和H4同时发生的GS期间表现得尤其好。 Villars记录的主要特征是DO#12事件与大约45.5 ka之间的总体变冷趋势和三块石笋在大约30 ka +/- 1处同步停止之间的总体冷却趋势，第一个明显的气候阈值大约为41 ka，之后所有石笋的生长速度和直径都显着减慢。这种气候演变与地中海南部地区显示的气候演变不同，那里没有观察到这种趋势。大约 30 ka 年龄标志着第二个气候阈值，在此之后，低温和低降雨量阻止了 Villars 地区洞穴植物的生长，直到大约 16.5 +/- 0.5 ka 发生的晚冰期变暖。这 15 ka 长的中断，即发生在 67.4 ka 至 61 ka 之间的维拉尔生长中断，与海平面低、海洋环流减少以及极锋向南移动有关，这可能引发了当地永久冻土的形成。这些寒冷时期与夏季 65 度的低日照、大气二氧化碳浓度低和大冰盖发育（尤其是芬诺斯坎迪亚冰盖）同时发生。 (C) 2010 Elsevier Ltd. 保留所有权利。
We present a new mid-latitude speleothem record of millennial-scale climatic variability during OIS3 from the Villars Cave that, combined with former published contemporaneous samples from the same cave, gives a coherent image of the climate variability in SW-France between similar to 55 ka and similar to 30 ka. The 0.82 m long stalagmite Vil-stm27 was dated with 26 TIMS U-Th analyses and its growth curve displays variations that are linked with the stable isotopes, both controlled by the climatic conditions. It consists in a higher resolved replicate of the previously published Vil-stm9 and Vil-stm14 stalagmites where Dansgaard-Oeschger (DO) events have been observed. The good consistency between these three stalagmites and the comparison with other palaoeclimatic reconstructions, especially high resolution pollen records (ODP 976 from the Alboran Sea, Monticchio Lake record from southern Italy) and the nearby MD04-2845 Atlantic Ocean record, permits to draw a specific climatic pattern in SW-France during the 063 and to see regional differences between these sites. Main features of this period are: 1) warm events corresponding to Greenland Interstadials (GIS) that are characterized by low speleothem delta C-13, high temperate pollen percentages, warm temperatures and high humidity; among these events, GIS#12 is the most pronounced one at Villars characterized by an abrupt onset at similar to 46.6 ka and a duration of about 2.5 ka. The other well individualized warm event coincides with GIS#8 which is however much less pronounced and occurred during a cooler period as shown by a lower growth rate and a higher delta C-13; 2) cold events corresponding to Greenland Stadials (GS) that are clearly characterized by high speleothem delta C-13, low temperate pollen abundance, low temperature and enhanced dryness, particularly well expressed during GS coinciding with Heinrich events H5 and H4. The main feature of the Villars record is a general cooling trend between the DO#12 event similar to 45.5 ka and the synchronous stop of the three stalagmites at similar to 30 ka +/- 1, with a first well marked climatic threshold at similar to 41 ka after which the growth rate and the diameter of all stalagmites slows down significantly. This climatic evolution differs from that shown at southern Mediterranean sites where this trend is not observed. The similar to 30 ka age marks the second climatic threshold after which low temperatures and low rainfalls prevent speleothem growth in the Villars area until the Lateglacial warming that occurred at similar to 16.5 +/- 0.5 ka. This 15 ka long hiatus, as the older Villars growth hiatus that occurred between 67.4 and 61 ka, are linked to low sea levels, reduced ocean circulation and a southward shift of the Polar Front that likely provoked local permafrost formation. These cold periods coincide with both low summer 65 degrees N insolation, low atmospheric CO2 concentration and large ice sheets development (especially the Fennoscandian). (C) 2010 Elsevier Ltd. All rights reserved.