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首页> 外文期刊>Journal of Volcanology and Geothermal Research2012V243-244NOCT,15 >Facing geological mapping at low-latitude volcanoes: The Dona Juana Volcanic Complex study-case, SW-Colombia
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Facing geological mapping at low-latitude volcanoes: The Dona Juana Volcanic Complex study-case, SW-Colombia

机译：面向低纬度火山的地质图绘制：Dona Juana火山群研究案例，西南哥伦比亚

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We present the Dona Juana Volcanic Complex (DJVC) geological map, stratigraphy, Ar/Ar-and-C-14 geochronology resulting from a pilot-mapping project in Colombia, as a study-case for the application of modern, international volcano geology techniques in low-latitude environments. Lithostratigraphy and lithofacies analysis (for description of rock bodies and mapping), lithosomes (for the definition of eruptive centres) and unconformity-bounded units (for stratigraphic correlation), as well as new geochronological data and the interpretation of eruption units were successfully integrated. The geological mapping and stratigraphic analysis provided an effective representation of the volcanic edifices/vents that make up the DJVC, so that we could reconstruct the geological evolution from the time and spatial distribution of the corresponding volcanic products and the range of lithofacies associations. The geological database and the forthcoming interpretation in terms of eruption behaviour establish the basis for realistic long-term hazard assessment.The DJVC is a calc-alkaline dacitic volcanic complex within the Central Cordillera of Colombia, which started its activity about 1125.4 +/- 4.4 ka ago. It comprises three spatially overlapping edifices and three adventive cones, which unconformably overlay Lower Cretaceous metasedimentary and metavolcanic rocks of oceanic origin. Each of the three overlapping edifices is truncated at the summit by a volcano-tectonic depression, without identifiable caldera-forming products. Two of these volcano-tectonic features display important proximal unconformities and, together with their correlative disconformities and paleosols, indicate significant quiescences of volcanic activity. The Holocene record has been mostly characterized by the emission of three lava-dome fields infilling the youngest volcano-tectonic depression and interrupting the corresponding unconformity. These lava domes have recurrently collapsed to originate block-and-ash flows followed by vulcanian explosions producing pyroclastic density currents and lahars. The corresponding eruptive products have drained along the present river basins to the NE and SW of DJVC, forming depositional terraces currently populated by nearly 49,000 rural and urban inhabitants. (C) 2018 Elsevier B.V.
机译：我们介绍了多纳胡安娜火山群（DJVC）的地质图，地层，Ar / Ar-和C-14地质年代学，这是哥伦比亚的一个试点项目产生的结果，作为应用现代国际火山地质技术的研究案例在低纬度环境中。岩石地层学和岩相分析（用于岩体描述和制图），岩体（用于火山喷发中心的定义）和不整合面界线单元（用于地层相关性），以及新的年代学数据和喷发单元的解释已成功整合。地质填图和地层分析提供了组成DJVC的火山构造/喷口的有效表示，因此我们可以根据相应火山产物的时间和空间分布以及岩相组合的范围来重建地质演化。地质数据库和即将爆发的火山喷发行为的解释为现实的长期危害评估奠定了基础.DJVC是哥伦比亚中部山脉的一种钙碱性碱性火山岩复合体，其活动始于1125.4 +/- 4.4嘉前。它包括三个在空间上重叠的建筑物和三个外生圆锥体，它们不整合地覆盖了海洋起源的下白垩统变质沉积和变火山岩。三个重叠的建筑物中的每一个在山顶处都被火山构造的凹陷截断，没有可识别的火山口形成产物。这些火山构造特征中的两个显示出重要的近端不整合面，以及它们的相关不整合面和古土壤，表明火山活动明显静止。全新世记录的主要特征是发射了三个熔岩圆顶区域，这些区域充满了最年轻的火山构造凹陷，并中断了相应的不整合面。这些熔岩穹顶经常倒塌，形成块状和灰烬状的流动，然后是火山爆发，产生火山碎屑密度流和拉哈斯。相应的火山喷发物沿目前的流域流向DJVC的东北部和西南部，形成了沉积梯田，目前有近49,000名城乡居民居住。 （C）2018爱思唯尔B.V.

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