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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Contemporaneous phreatomagmatic and effusive activity along the Hverfjall eruptive fissure, north Iceland: Eruption chronology and resulting deposits
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Contemporaneous phreatomagmatic and effusive activity along the Hverfjall eruptive fissure, north Iceland: Eruption chronology and resulting deposits

机译：冰岛北部Hverfjall喷发裂缝的同时岩浆和喷发活动：喷发年代和由此产生的沉积物

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摘要

The 2500 BP Hverfjall eruption in northern Iceland produced pyrodastic and effusive deposits of widely different characteristics along the length of the eruptive fissure. The southern half of the fissure was located in a shallow lake, whereas the northern part of the fissure extended onto dry land. This specific setting, with overlapping periods of activity at the different vents, resulted in various mingling features between finegrained phreatomagmatic deposits and lava flows. Here we reconstruct the course of events during this eruption based on field observations and granulometric analyses of the resulting deposits. The eruption can be divided into three main phases depending on the main depositional characteristics and vent locations. The initial phase is dominated by phreatomagmatic fall deposits which are attributed to an overall high eruption rate in a shallow lacustrine setting. The second phases involved opening of two new vents on dry ground, and deposition of scoria and lava flows. The third and final phase of the eruption is associated with a lowering of the eruption rate in the southernmost vent, with a shift in the activity from continuous uprush and fall deposits to discrete explosions and emplacement of base surges. These surges display features consistent with drying up with increasing distance from the vent, suggesting that their dynamics changed during emplacement. Most wet surges were channelized within a preexisting graben structure close to the vent, but some more dilute (i.e., dry) surges were able to flow over this obstacle and continued to flow for more than 5 km away from the vent and 100 m uphill before stopping.
机译：冰岛北部的2500 BP Hverfjall火山喷发沿裂隙的长度方向产生了特征迥异的火山岩和喷出沉积物。裂缝的南部一半位于一个浅湖中，而裂缝的北部则延伸到了干燥的土地上。这种特定的环境在不同的喷口处有重叠的活动时间，导致细粒岩浆沉积物与熔岩流之间存在各种混杂特征。在这里，我们根据实地观察和对最终矿床的粒度分析，重建了喷发过程中的事件过程。根据主要的沉积特征和喷口位置，喷发可分为三个主要阶段。初始阶段以岩浆岩秋季沉积物为主，这归因于浅湖相环境中总体喷发率高。第二阶段包括在干燥的地面上打开两个新的通风口，以及沉积矿渣和熔岩流。喷发的第三和最后阶段与最南端喷口喷发速率的降低有关，活动性从连续的上冲和下降沉积物转移到离散的爆炸和基波涌入位置。这些电涌的显示特征与随着距通风孔距离的增加而变干的特征一致，表明在安装过程中其动力发生了变化。大多数湿气涌流是在靠近通风口的既有抓斗结构内引导的，但是更多的稀（即干）涌流能够越过该障碍物，并持续流离通风口超过5公里，并在上坡前100 m停下来

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  • 来源
    《Journal of Volcanology and Geothermal Research》 |2011年第4期|p.241-252|共12页
  • 作者

    Hannes B. Mattsson; Armann Hoeskuldsson;

  • 作者单位

    Institute for Geochemistry and Petrology, Swiss Federal Institute of Technology (ETH Zurich), Clausiusstrasse 25, CH-8092 Zurich, Switzerland,Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Askja, Sturlugata 7, IS-101 Reykjavik, Iceland;

    Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Askja, Sturlugata 7, IS-101 Reykjavik, Iceland,Institute of Earth Sciences, University of Iceland, Askja, Sturlugata 7, IS-WI Reykjavik, Iceland;

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  • 正文语种 eng
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  • 关键词

    hverfjall; iceland; fissure eruption; tuff ring; scoria cone; phreatomagmatic; base surge;

    机译：韦弗雅尔;冰岛;裂隙喷发;凝灰岩环;sco骨锥;发岩浆;底涌;

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