Evidence for a large-magnitude Holocene eruption of Mount Rittmann (Antarctica): A volcanological reconstruction using the marine tephra record
Evidence for a large-magnitude Holocene eruption of Mount Rittmann (Antarctica): A volcanological reconstruction using the marine tephra record
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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进行火山学重建
DOI：
10.1016/j.quascirev.2020.106629
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发表时间：
2020
影响因子：
4
通讯作者：
Di Roberto A
中科院分区：
文献类型：
--
作者：
Di Roberto A
在南极洲，火山喷发沉积物的近源暴露往往是有限的，因为它们在动态的冰川环境中没有得到很好的保存，因此使火山喷发的重建极具挑战性。幸运的是，南极洲周围的南大洋沉积物中保存着爆炸喷发的火山碎屑沉积，这些序列的火山地层学提供了关键的火山学信息，包括过去喷发的时间和节奏、规模和喷发动力学。本文报道了南极洲罗斯海西部伍德湾地区四个沉积物岩芯的沉积地层和年代学研究结果。在所有这些沉积层序中，我们发现了一层状良好的原生盖板，厚度相当大，可达80厘米，此后被称为航空盖板(AVT)。根据特弗拉矿床的特征及其分布，AVT与一次相当强度的喷发有关，可能是南极洲有记录以来最大的全新世喷发之一。根据主量元素和痕量元素的地球化学特征以及火山喷发的矿物组合，确定里特曼山为火山喷发的源区。通过对沉积物中有机质的放射性碳测年和含碱长石晶体的40Ar-39Ar测年，确定了∼为11ka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、相对潮湿和富含火山灰的喷发云。然后，喷发演变成了一次能量很高、相对干燥的普林尼安岩浆喷发。最后一个阶段的特征是重新出现有效的岩浆-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生木质柱。远端的特弗拉矿床可能与先前在里特曼火山破火山口边缘发现的广泛存在的滞后角砾岩层有关，它们具有相同的地球化学成分。在AVT周围的沉积物中发现的硅藻和Tephra的主要特征表明，伍德湾地区在喷发时是外海，这比之前认为的要早得多。AVT也是罗斯海伍德湾地区的一个很好的海底地层学标志，也是该地区未来大陆冰和海洋档案同步的有用标志。
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 and40Ar-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.
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DOI：
--
发表时间：
2013
期刊：
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DOI：
--
发表时间：
1994
期刊：
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