Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada.
Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Hannover, Germany.
PLoS One. 2024 Sep 25;19(9):e0310041. doi: 10.1371/journal.pone.0310041. eCollection 2024.
Here we present a new 850-year long coccolithophore record from core SO130-289KL in the northeastern Arabian Sea that spans the Greenland Interstadial 20-Greenland Stadial 20 transition including the timing of the ∼74 ka Youngest Toba Tuff (YTT) supereruption. During the warm interstadial, the coccolithophore assemblage is characterized by Gephyrocapsa oceanica (41%) and Florisphaera profunda (30%) while the succeeding cold stadial is distinguished by the abundance of small placolith species (Emiliania huxleyi + G. ericsonii) (52%). However, the oldest samples of the study interval seem to show a stadial-like coccolithophore assemblage. Spectral analysis revealed an interdecadal cycle imprinted in the coccolithophore record during the interstadial that was also independently reported in other terrestrial and marine proxies. Immediately after the YTT eruption, small placoliths increased by 42% from 5% right below the YTT layer to 47% ∼1 mm above the YTT layer, while G. oceanica and Helicosphaera carteri increased and F. profunda decreased within the ∼1.15 cm layer representing about 8-19 years. Subsequently, the coccolithophore assemblage returned to a composition similar to the warm interstadial period before abruptly changing to a stadial composition characterized by the abundance of small placoliths about 100-130 years after the YTT eruption. Therefore, the YTT eruption had a significant impact on the overall coccolithophore assemblage but appears to have not caused the climate transition from interstadial to stadial conditions, supporting proxy and modeling data. However, the overall mechanism driving the observed changes and cyclicities remains unknown but might be related to rapid atmospheric teleconnections of North Atlantic climate variability to the low latitudes.
我们在此展示了来自东北阿拉伯海 SO130-289KL 岩芯的一段长达 850 年的新颗石藻记录，这段记录跨越了格陵兰间冰期 20 到格陵兰冰期 20 的转变，包括了约 74ka 的年轻多巴火山超级喷发（YTT）的时间。在温暖的间冰期，颗石藻组合以 Gephyrocapsa oceanica（41%）和 Florisphaera profunda（30%）为特征，而随后的寒冷冰期则以小型盘形石藻物种（Emiliania huxleyi+G. ericsonii）（52%）的丰度为特征。然而，研究区间的最老样本似乎显示出一种类似于冰期的颗石藻组合。谱分析显示，在间冰期期间，颗石藻记录中存在一个十年际周期，这在其他陆地和海洋代用指标中也有独立报道。在 YTT 喷发后，小型盘形石藻的丰度立即增加了 42%，从 YTT 层以下的 5%增加到 YTT 层以上的 47%，约 1mm 厚，而 G. oceanica 和 Helicosphaera carteri 的丰度增加，F. profunda 的丰度减少，这一变化发生在约 1.15cm 厚的层中，代表了大约 8-19 年的时间。随后，颗石藻组合恢复到类似于温暖间冰期的组成，然后在 YTT 喷发后约 100-130 年，突然转变为以小型盘形石藻丰度为特征的冰期组成。因此，YTT 喷发对整体颗石藻组合有重大影响，但似乎并没有导致气候从间冰期到冰期条件的转变，这与代理和建模数据一致。然而，驱动所观察到的变化和周期性的整体机制尚不清楚，但可能与北大西洋气候变率的快速大气远距离联系有关。
