Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
Science. 2011 Feb 18;331(6019):903-6. doi: 10.1126/science.1200803. Epub 2011 Jan 27.
Understanding ancient climate changes is hampered by the inability to disentangle trends in ocean temperature from trends in continental ice volume. We used carbonate "clumped" isotope paleothermometry to constrain ocean temperatures, and thereby estimate ice volumes, through the Late Ordovician-Early Silurian glaciation. We find tropical ocean temperatures of 32° to 37°C except for short-lived cooling by ~5°C during the final Ordovician stage. Evidence for ice sheets spans much of the study interval, but the cooling pulse coincided with a glacial maximum during which ice volumes likely equaled or exceeded those of the last (Pleistocene) glacial maximum. This cooling also coincided with a large perturbation of the carbon cycle and the Late Ordovician mass extinction.
了解古代气候变化受到阻碍，因为无法将海洋温度趋势与大陆冰量趋势区分开来。我们使用碳酸盐“凝聚”同位素古温度计来限制海洋温度，从而通过晚奥陶世-早志留世冰川作用来估计冰量。我们发现热带海洋温度为 32°C 至 37°C，除了在最后奥陶世阶段短暂冷却约 5°C 之外。冰盖的证据跨越了研究间隔的大部分时间，但冷却脉冲与冰川最大值同时发生，在此期间，冰量可能与最后一次（更新世）冰川最大值相等或超过。这种冷却还与碳循环的大扰动和晚奥陶世大灭绝同时发生。
