The upper Cenozoic tephra record in the south polar region: A review
The upper Cenozoic tephra record in the south polar region: A review
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南极地区上新生代火山灰记录：综述
DOI：
10.1016/s0921-8181(99)00007-7
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发表时间：
1999
期刊：
影响因子：
12.4
通讯作者：
J. Smellie
中科院分区：
文献类型：
--
作者：
J. Smellie
对南极地区的温度年代学研究进行了回顾和评价。对冰芯中的低温层进行了大量的研究，反映了冰芯作为古环境信息的主要来源的持续重要性。相比之下，海洋沉积物岩心中的温体在很大程度上被忽视了。玻璃碎片的化学分析在整个地区并不统一。特别是，它们目前无法用于南极半岛北部。很少有tephras被直接定年，尽管钾质玻璃和矿物质普遍存在，应该很容易适用于同位素定年。化学“指纹图谱”似乎在层间关联和识别来源区域方面具有很高的潜力，但只有少数研究考虑了微量元素和主要氧化物。灰内成分变化和分析不精确的影响限制了“指纹识别”的一般效用。当地的火山记录比源火山本身保存的要完整得多。然而，频繁的火山喷发对当地沉积中心的影响可能会淹没其他重要的环境指标，并使环境记录比在没有火山泥的演替中更难解释。对南极地区冰中的火山灰和火山产生的气溶胶进行关联研究，对于定量计算火山对大气通量的贡献和评估火山作用对全球气候可能产生的影响的尝试具有至关重要的意义。
Tephrochronology studies in the south polar region are reviewed and evaluated. There have been numerous investigations of tephra layers in ice cores, reflecting the continuing importance of ice cores as a principal source of palaeoenvironmental information. By contrast, tephra in marine sediment cores have been largely neglected. Chemical analyses of glass shards are not uniformly available across the region. In particular, they are currently unavailable for the northern Antarctic Peninsula. Few tephras have been dated directly, although potassic glass and minerals are commonly present and should be readily amenable to isotopic dating. Chemical ‘fingerprinting’ seems to have a high potential for successfully correlating layers and identifying source areas, but only a few studies have considered trace elements as well as major oxides. The effects of within-ash compositional variations and analytical imprecision limit the general utility of ‘fingerprinting’. The tephra record is locally much more complete than is preserved in the source volcanoes themselves. However, the effects of frequent eruptions on local depocentres may swamp other environmentally significant indicators and make the environmental record harder to interpret than in tephra-free successions. Linked studies of tephra and volcanically-derived aerosols in ice in the south polar region could be of critical importance for quantitative calculations of the volcanic contribution to atmospheric fluxes and attempts to assess the possible effects of volcanism on global climate.