南极冰芯为研究地球大气层及现存最大冰盖提供了独特档案。目前最古老的连续冰芯记录可追溯至80万年前，而来自阿兰山蓝冰区的不连续冰芯样本更保存了至少270万年前的冰体与大气信息。
研究组通过阿兰山蓝冰区浅层冰芯钻探，获得了中新世与上新世时期的冰体与大气样本。通过测定古代空气中Ar40相对现代大气的亏损程度进行定年，发现该冰层具有复杂的地层结构。尽管如此，根据水同位素推算的古地表温度仍与样本年龄呈现相关性，显示南极地区在600万年前至晚更新世期间经历了12±2°C的降温过程。基底冰层几乎不含气体，现有定年方法尚无法确定其年代。这类未定年冰体的同位素温度特征显示，其比最古老的已定年样本（600万年）高出5±1°C。研究组推测这些冰体可能反映了中晚中新世时期东南极冰盖扩张过程中保存的表层积雪或永久冻土。
附：英文原文
Title: Miocene and Pliocene ice and air from the Allan Hills blue ice area, East Antarctica
Author: Shackleton, S., Hishamunda, V., Davidge, L., Brook, E., Peterson, J. Marks, Carter, A., Aarons, S., Kurbatov, A., Introne, D., Yan, Y., Nesbitt, I. M., Buizert, C., Steig, E. J., Schauer, A. J., Morgan, J., Neff, P. D., Epifanio, J. A., Severinghaus, J., Bender, M., Higgins, J. A.
Issue&Volume: 2025-10-28
Abstract: Antarctic ice cores provide a unique archive of Earth’s atmosphere and its largest extant ice sheet. The oldest continuous ice core extends back 800 ky, though discontinuous ice cores from the Allan Hills blue ice area (BIA) have been shown to preserve snapshots of ice and air back to at least 2.7 million years ago (Ma). Here, we provide snapshots of putatively Miocene and Pliocene ice and air from shallow ice cores drilled in the Allan Hills BIA. The ice, dated using the deficit in 40Ar in ancient air compared to the modern atmosphere, is stratigraphically complex. Nevertheless, surface temperatures inferred from water isotopes correlate with sample age and indicate 12 ± 2 °C of cooling in Antarctica between 6 Ma and the late Pleistocene. Basal ice is nearly devoid of gases and remains to be dated with existing methods. This undated ice is characterized by an isotopic temperature 5 ± 1 °C warmer than the oldest dated (6 million year old) sample. We speculate that this ice reflects surface snowpack or permafrost that was preserved by the growth of the East Antarctic ice sheet in the Middle to Late Miocene.
DOI: 10.1073/pnas.2502681122
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2502681122