School of Geography, The University of Melbourne, Parkville, 3010, VIC, Australia.
Laboratoire EDYTEM, UMR CNRS 5204, Université Savoie Mont Blanc, 73376, Le Bourget-du-Lac cedex, France.
Nat Commun. 2020 Oct 6;11(1):5027. doi: 10.1038/s41467-020-18083-7.
Few palaeoclimate archives beyond the polar regions preserve continuous and datable palaeotemperature proxy time series over multiple glacial-interglacial cycles. This hampers efforts to develop a more coherent picture of global patterns of past temperatures. Here we show that Mg concentrations in a subaqueous speleothem from an Italian cave track regional sea-surface temperatures over the last 350,000 years. The Mg shows higher values during warm climate intervals and converse patterns during cold climate stages. In contrast to previous studies, this implicates temperature, not rainfall, as the principal driver of Mg variability. The depositional setting of the speleothem gives rise to Mg partition coefficients that are more temperature dependent than other calcites, enabling the effect of temperature change on Mg partitioning to greatly exceed the effects of changes in source-water Mg/Ca. Subaqueous speleothems from similar deep-cave environments should be capable of providing palaeotemperature information over multiple glacial-interglacial cycles.
在极地以外的少数古气候记录中，很少有能够在多个冰期-间冰期循环中保存连续和可定年的古温度代理时间序列。这阻碍了我们对过去温度全球模式的更连贯的认识。在这里，我们表明，意大利洞穴中一个水下洞穴钟乳石的镁浓度记录了过去 35 万年的区域海表温度。在温暖的气候间隔期间，镁显示出更高的值，而在寒冷的气候阶段则呈现相反的模式。与以前的研究不同，这表明温度而不是降雨量是镁变化的主要驱动因素。钟乳石的沉积环境导致镁分配系数比其他方解石更依赖于温度，从而使温度变化对镁分配的影响大大超过了源水镁/钙变化的影响。来自类似深洞穴环境的水下钟乳石应该能够提供多个冰期-间冰期循环的古温度信息。
