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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Evolution and hazards of a long-quiescent compound shield-like volcano: Cofre de Perote, Eastern Trans-Mexican Volcanic Belt
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Evolution and hazards of a long-quiescent compound shield-like volcano: Cofre de Perote, Eastern Trans-Mexican Volcanic Belt

机译：长时间静止的复合盾状火山的演化和危害：墨西哥东部东部科弗雷德佩罗特火山

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摘要

Cofre de Perote (Nauhcampatepetl) volcano lies at the northern end of the Citlaltepetl-Cofre de Perote volcanic range (CCVR) that is the easternmost of several volcanic chains orthogonal to the E-W trend of the Trans-Mexican Volcanic Belt (TMVB). The CCVR is an important physiographic feature separating the Gulf coastal plains from the Altiplano, with pronounced differential relief of more than 1000 m and sloping substrate promoting major edifice failures toward the Gulf of Mexico coastal plain of most of the volcanoes that form that chain. Its structure, composition, and volcanic history diverge significantly from that of the large dominantly andesitic stratovolcanoes that have been the major focus of research efforts in the TMVB. Cofre de Perote volcano is dominated by the successive emplacement of basaltic andesite, andesitic-trachyandesitic to dacitic lava flows and associated breccias erupted through different vents that built a massive low-angle compound shield-like volcano, in contrast to a typical steep stratocone. Despite that apparently stable morphology, repeated edifice collapse has left massive horseshoe-shaped scarps that truncate the eastern side of the edifice. Five major evolutionary stages characterize the growth of this volcano including: 1) emplacement of a multiple-vent dome complex forming the basal structure of Cofre de Perote around 1.3-0.51 Ma; 2) construction of the basal part of the compound shield volcano from at least two main upper-edifice vents and minor flank vents at about 0.42-0.31 Ma; 3) effusion of the summit lavas through multiple vents at 0.25-0.2 Ma; 4) late-stage, large-volume edifice collapse on at least two occasions (ca. 40 ka and ca. 11-13 ka), producing long-runout debris avalanches and debris flows that traveled to the east; and 5) nearly simultaneous eruption of both alkaline and calc-alkaline Pleistocene-to-Holocene monogenetic cones (likely related to regional volcanism) through the flanks of the Cofre de Perote edifice. Long-term factors influencing edifice failure include hydrothermal alteration, increased pore pressure from glacially derived water, extension produced by repetitive volcanism along the chain parallel to the maximum horizontal compression, and perhaps most significantly, construction of the edifice over a sharply eastward-sloping substrate. Evolution of a compound shield volcano like Cofre de Perote reveals that even relatively stable, long-quiescent edifices with a gentle morphology that are considered apparently extinct structures pose a significant hazard to the nearby populated areas, as post-eruptive sector collapses have occurred in recent times (40-11 ka) not associated with contemporaneous volcanic activity.
机译：科弗雷德佩罗特（Nauhcampatepetl）火山位于Citlaltepetl-科弗雷德佩罗特火山范围（CCVR）的北端，它是与墨西哥跨火山带（TMVB）的E-W趋势正交的几条火山链中的最东端。 CCVR是一个重要的地貌特征，将墨西哥湾沿岸平原与高原分开，明显的差异起伏超过1000 m，倾斜的基底促使形成该链的大多数火山向墨西哥湾沿岸平原的主要建筑物破坏。它的结构，组成和火山历史与大型的安第斯平流层火山有很大的不同，后者一直是TMVB研究工作的重点。 Cofre de Perote火山以玄武岩安山岩，安第斯-长曲安山岩到Datictic熔岩流以及依次形成的角砾岩的相继沉积为主，而火山口则通过不同的喷口喷出，与典型的陡峭平顶锥形成了巨大的低角度复合盾状火山。尽管形态看似稳定，但建筑物的反复倒塌仍留下大量马蹄形的陡峭物，将其截断了建筑物的东侧。该火山的生长有五个主要的演化阶段，包括：1）围绕多通风孔的穹顶复合体的形成，该复合体在1.3-0.51 Ma左右形成了Cofre de Perote的基础结构； 2）在至少约0.42-0.31 Ma处，从至少两个主上层通风口和次要侧面通风口构造复合屏蔽火山的基础部分； 3）在0.25-0.2 Ma处通过多个喷口喷出山顶熔岩； 4）至少有两次（大约40 ka和大约11-13 ka）后期大体积建筑物倒塌，产生了长碎片的雪崩和流向东部的泥石流； 5）通过Cofre de Perote大厦的侧翼几乎同时喷出了碱性和钙碱性的更新世至全新世的单基因锥（可能与区域火山作用有关）。影响建筑物破坏的长期因素包括热液蚀变，冰川水产生的孔隙压力增加，重复火山作用沿链条平行于最大水平压缩所产生的延伸，以及可能最显着的是，在急剧向东倾斜的基底上建造了建筑物。像科弗雷·德·佩罗特这样的复合式盾构火山的演变表明，即使是相对稳定的，长时间静止的，具有缓和形态的建筑物，也被认为是绝种的结构，对附近人口稠密地区构成了重大危害，因为最近喷发后的扇形塌陷已经发生。时间（40-11 ka）与同期火山活动无关。

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