Abstract In Antarctica, the near-source exposures of volcanic eruption deposits are often limited as they are not well preserved in the dynamic glacial environment, thus making volcanological reconstructions of explosive eruptions extremely challenging. Fortunately, pyroclastic deposits from explosive eruptions are preserved in Southern Ocean sediments surrounding Antarctica, and the tephrostratigraphy of these sequences offers crucial volcanological information including the timing and tempo of past eruptions, their magnitude, and eruption dynamics. Here we report the results of a tephrostratigraphy and tephrochronology study focused on four sediment cores recovered from the Wood Bay area in the western Ross Sea, Antarctica. In all these sedimentary sequences, we found a well-stratified primary tephra of considerable thickness, up to 80 cm, hereafter named the Aviator Tephra (AVT). According to the characteristics of the tephra deposit and its distribution, the AVT was associated with an eruption of considerable intensity, potentially representing one of the largest Holocene eruptions recorded in Antarctica. Based on the major and trace element geochemistry and the mineral assemblage of the tephra, Mount Rittmann was identified as the source of the AVT. A Holocene age of ∼11 ka was determined by radiocarbon dating organic material within the sediments and 40Ar-39Ar dating of alkali-feldspar crystals included in the tephra. Eruption dynamics were initially dominated by hydromagmatic magma fragmentation conditions producing a sustained, relatively wet and ash-rich eruptive cloud. The eruption then evolved into a highly energetic, relatively dry magmatic Plinian eruption. The last phase was characterized by renewed efficient magma-water interaction and/or collapse of the eruptive column producing pyroclastic density currents and associated co-ignimbritic plumes. The distal tephra deposits might be linked to the widespread lag breccia layer previously identified on the rim of the Mount Rittmann caldera which share the same geochemical composition. Diatoms found in the sediments surrounding the AVT and the primary characteristics of the tephra indicate that the Wood Bay area was open sea at the time of the eruption, which is much earlier than previously thought. AVT is also an excellent tephrostratigraphic marker for the Wood Bay area, in the Ross Sea, and a useful marker for future synchronization of continental ice and marine archives in the region.

中文翻译：

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里特曼山（南极洲）全新世大规模喷发的证据：利用海洋火山灰记录的火山学重建

摘要 在南极洲，火山喷发沉积物的近源暴露往往有限，因为它们在动态冰川环境中保存得不好，这使得爆发性喷发的火山学重建极具挑战性。幸运的是，爆炸性喷发的火山碎屑沉积物保存在南极洲周围的南大洋沉积物中，这些序列的火山岩地层提供了重要的火山学信息，包括过去喷发的时间和节奏、它们的规模和喷发动态。在这里，我们报告了一项针对从南极洲罗斯海西部伍德湾地区回收的四个沉积岩芯进行的火山地层学和火山年代学研究的结果。在所有这些沉积层序中，我们发现了一个分层良好的原始火山灰，厚度可达 80 厘米，此后命名为 Aviator Tephra (AVT)。根据火山灰矿床的特征及其分布，AVT 与相当强度的喷发有关，可能代表南极洲记录的最大的全新世喷发之一。根据主要和微量元素地球化学以及火山灰的矿物组合，Rittmann 山被确定为 AVT 的来源。通过沉积物中有机物质的放射性碳测年和火山灰中碱长石晶体的 40Ar-39Ar 测年确定了约 11 ka 的全新世年龄。喷发动力学最初由水岩浆破碎条件主导，产生持续的、相对潮湿和富含灰烬的喷发云。喷发然后演变成高能量的、相对干燥的岩浆普林尼亚喷发。最后一个阶段的特点是重新有效的岩浆-水相互作用和/或喷发柱的坍塌，产生火山碎屑密度流和相关的共燃烟羽。远端的火山灰沉积物可能与先前在 Rittmann 火山口边缘发现的广泛的滞后角砾岩层有关，它们具有相同的地球化学成分。在 AVT 周围沉积物中发现的硅藻和火山灰的主要特征表明，火山爆发时伍德湾地区是公海，这比以前认为的要早得多。AVT 还是罗斯海伍德湾地区极好的火山岩地层标记，也是该地区大陆冰和海洋档案未来同步的有用标记。