Radiocarbon Calibration Beyond the Dendrochronology Range
Radiocarbon Calibration Beyond the Dendrochronology Range
复制标题
超出树木年代学范围的放射性碳校准
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
Alexandra Schramm
中科院分区：
文献类型：
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作者：
M. Stein;S. Goldstein;Alexandra Schramm
放射性碳时间尺度已校准树木年代学回到11.8万年CAL BP，并延长到14.8万年CAL BP使用层压海洋沉积物从Cariaco盆地。根据珊瑚的~（14）C和U-Th年龄的比较，推断出近23.5 ka cal BP。最近，有人试图将校准曲线进一步扩展到4万年以上，他们的依据是日本水月湖的层状沉积物、北大西洋沉积物中的有孔虫、南非洞穴沉积物、西班牙的凝灰岩和巴哈马的石笋。在这里，我们比较这些记录与一个新的比较曲线所获得的234 U-230 Th年龄沉积在里三湖（最后的冰川死海）文石。这一比较揭示了20 - 32 ka cal BP时间间隔的广泛一致性，但其他时间间隔的数据存在分歧。所有记录都表明，在20 - 32 ka cal BP时，Δ 14 C值在250 - 450 ‰之间。对于大于32 ka cal BP的年龄，水月湖数据表明Δ 14 C值较低，小于200 ‰，且变化较小。其他记录大致同意，在32 - 39 ka cal BP时，Δ 14 C值在250 - 600 ‰之间。北大西洋校准的Δ 14 C值在1.42 ka cal BP时较低，而珊瑚、Lisan文石和西班牙石灰华的Δ 14 C值则有700 - 900 ‰的较大偏差。这个年龄比最近估计的Laschamp地磁事件的时间稍年轻，并且与该事件期间增加的14C生产一致。
The radiocarbon timescale has been calibrated by dendrochronology back to 11.8 ka cal BP, and extended to 14.8 ka cal BP using laminated marine sediments from the Cariaco Basin. Extension to nearly 23.5 ka cal BP is based on comparison between 14C and U-Th ages of corals. Recently, attempts to further extend the calibration curve to >40 kyr are based on laminated sediments from Lake Suigetsu, Japan, foraminifera in North Atlantic sediments, South African cave deposits, tufa from Spain, and stalagmites from the Bahamas. Here we compare these records with a new comparison curve obtained by 234U-230Th ages of aragonite deposited at Lake Lisan (the last Glacial Dead Sea). This comparison reveals broad agreement for the time interval of 20–32 ka cal BP, but the data diverge over other intervals. All records agree that Δ14C values range between ∼250–450‰ at 20–32 ka cal BP. For ages >32 ka cal BP, the Lake Suigetsu data indicate low Δ14C values of less than 200‰ and small shifts. The other records broadly agree that Δ14C values range between ∼250 and 600‰ at 32–39 ka cal BP. At ∼42 ka cal BP, the North Atlantic calibration shows low Δ14C values, while the corals, Lisan aragonites, and the Spanish tufa indicate a large deviations of 700–900‰. This age is slightly younger than recent estimates of the timing of the Laschamp Geomagnetic Event, and are consistent with increased 14C production during this event.