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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Internal architecture of La Reunion (Indian Ocean) inferred from geophysical data
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Internal architecture of La Reunion (Indian Ocean) inferred from geophysical data

机译：根据地球物理数据推断的留尼汪岛（印度洋）内部结构

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摘要

The internal structure of La Reunion (Indian Ocean) is investigated using gravity, magnetic and electromagnetic data. A general model of the island is derived, providing new information on the individual volcanoes as well as on the growth of the island as a whole. The reconstructed topography of the island at 780 ka (Brunhes-Matuyama magnetic reversal) shows a paleoisland organized around a huge Piton des Neiges volcano and a smaller Les Alizfa volcano, both having large offshore extensions and dense hypovolcanic complexes. During the Brunhes period, the Piton des Neiges has growth predominantly in its central and west-southwest areas, and to a less extent to the north. The construction of Piton de la Fournaise, at the east, has caused the other major change in the topography of the island. This latter volcano, the youngest and the smallest of the three identified volcanoes of La Reunion, only achieves a large thickness beneath its central and southern zones. The resistivity and magnetic patterns of its central area support the presence of a hydrothermal system. In its western, older part, shallow, highly resistive and dense layers are interpreted as piles of thick lava flows filling paleo-depressions. In the same area, a deep dense body may represent the hypovolcanic intrusive complex from the early stages of Piton de la Fournaise. Piton des Neiges is by far the largest volcano of La Reunion. The resistivity data show that its products are more altered than those of Piton de la Fournaise. A hydrothermal alteration is particularly developed around the dense central hypovolcanic intrusive complex. This latter, characterized by resistive and dense terrains has a lateral extent that coincides with that of the overlying topographic depressions, the three central Cirques, the Bebour-Belouve depression and, at its eastern tip, the Plaine des Palmistes. A genetic link between the morphology of the volcano and a possible subsidence of the dense complex is investigated, but no definitive conclusion is reached. The offshore part and the hypovolcanic complex of Les Alizes volcano have been described by previous works. Here, we identified the reversely magnetized terrains beneath Piton de la Fournaise with at least part of the construction of Les Alizes volcano, but no geophysical contrast marking at depth the boundary between Piton de la Fournaise and Les Alizes is recognized suggesting that the products of both volcanoes are lithologically similar, at the scale of our work.
机译：使用重力，磁和电磁数据研究了留尼汪岛（印度洋）的内部结构。导出了该岛的一般模型，提供了有关各个火山以及整个岛的增长的新信息。该岛的重建地形为780 ka（布鲁斯-玛图山磁逆），显示了一个围绕着巨大的Piton des Neiges火山和较小的Les Alizfa火山组成的古岛，这两个火山均具有较大的近海扩展和密集的低层火山复合体。在Brunhes时期，Piton des Neiges主要在其中部和西南偏南地区增长，而在北部则相对较少。东部的Piton de la Fournaise的建筑引起了该岛地形的另一项重大变化。后一个火山是留尼汪岛三个已识别火山中最年轻和最小的火山，仅在其中部和南部区域下方形成较大的厚度。其中心区域的电阻率和磁模式支持热液系统的存在。在西部较旧的部分，浅层，高电阻层和致密层被解释为一堆堆厚厚的熔岩流，填充了古凹陷。在同一地区，一个深密的物体可能代表了Piton de la Fournaise早期的火山爆发侵入复合体。内格斯峰（Piton des Neiges）是到目前为止，留尼汪岛最大的火山。电阻率数据表明，其产品比Piton de la Fournaise的产品变化更大。特别是在致密的中央火山爆发侵入复合体周围发生了热液蚀变。后者的特点是具有电阻性和密集的地形，其横向范围与上覆的地形凹陷，三个中部Cirques，Bebour-Belouve凹陷以及在其东端的Plaine des Palmistes一致。研究了火山的形态与致密复合体的可能沉陷之间的遗传联系，但没有得出明确的结论。 Les Alizes火山的近海部分和低火山复合体在先前的工作中已有描述。在这里，我们用至少一部分Les Alizes火山的构造确定了Piton de la Fournaise下方的反向磁化地形，但是在深处没有发现任何地球物理学对比标志，这表明这两个产品都是就我们的工作规模而言，火山在岩性上相似。

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  • 来源
    《Journal of Volcanology and Geothermal Research》 |2012年第1期|p.83-98|共16页
  • 作者

    Lydie-Sarah Gailler; Jean-Francois Linat;

  • 作者单位

    Clermont Universite, University Blaise Pascal, Laboratoire Magmas et Volcans, UP 10448, F-63000 Clermont-Ferrand, France,CNRS, UMR 6524, LMV, F-S3038 Clermont-Ferrand, France,IRD, R 163, LMV, F-63038 Clermont-Ferrand, France,BRGM, 45060 Orleans Cedex 02, France,Clermont Universite, Universite Blaise Pascal, Laboratoire Magmas et Volcans, BP 10448, F-63000 Clermont-Ferrand, France;

    Clermont Universite, University Blaise Pascal, Laboratoire Magmas et Volcans, UP 10448, F-63000 Clermont-Ferrand, France,CNRS, UMR 6524, LMV, F-S3038 Clermont-Ferrand, France,IRD, R 163, LMV, F-63038 Clermont-Ferrand, France;

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  • 原文格式 PDF
  • 正文语种 eng
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  • 关键词

    la reunion; gravity; magnetic; electromagnetic data and; modeling; internal structure; hypovolcanic complex; geomagnetic reversal;

    机译：留尼汪岛重力;磁性;电磁数据;造型;内部结构;低火山复合体;地磁反转;

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