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An unusual syn-eruptive bimodal eruption: The Holocene Cuicuiltic Member at Los Humeros caldera, Mexico

dc.contributor.authorDávila Harris, Pablo
dc.contributor.authorCarrasco Núñez, Gerardo
dc.identifier.citationPablo Dávila-Harris, Gerardo Carrasco-Núñez, An unusual syn-eruptive bimodal eruption: The Holocene Cuicuiltic Member at Los Humeros caldera, Mexico, Journal of Volcanology and Geothermal Research, Volume 271, 2014, Pages 24-42.
dc.description.abstract"The Cuicuiltic Member (CM) at Los Humeros Caldera, eastern Mexican Volcanic Belt is a Holocene (6.4 ka B.P.) succession of alternated fallout deposits of contrasting composition (trachydacite pumice and basaltic andesite scoria). The CM covers approximately 250 km(2) on its proximal fades and its thickness ranges from 1.5 m to 8.0 m. It postdates two caldera-forming ignimbrites (Xaltipan and Zaragoza) and numerous Plinian successions. It is subdivided in 9 units (C1 to C9) according to its textural and chemical characteristics. Sub-horizontal, topography-draping layers of trachydacite pumice lapilli, andesitic pumice lapilli and basaltic-andesite scoria lapilli with sporadic one-meter blocks are common lithofacies. The base is formed by coarse trachydacite pumice lapilli (C1 and C2), overlain by a layer with banded pumice (C3). Thin layers of ash and ash-tuff are intermittent on lower units, whilst continuous at the base of C4. The middle units, C4 and C6 are basaltic-andesite pumice, and scoria lapilli to blocks; C5 is in-between the two mafic units and it is represented by a layer of pale grey pumice lapilli. Units C7 and C8 are a mixture of white trachydacite pumice, scoria lapilli and banded pumice. The uppermost layer, C9, is a brown to grey andesitic pumice lapilli. Extensive fieldwork allowed a close and reliable correlation of layers that helps to understand the complexity of stratigraphic relations and sources for those layers. The distribution of these units is varied across the caldera, with the trachydacite layers dispersal from the centre towards the NW, whilst the andesitic units have maximum thicknesses over the SE and NE sectors of the caldera. Isopach and isopleth maps, combined with detailed mapping of near-vent spatter facies, orientation of local bomb sags and variation of mean clasts size for some layers were very useful to determine the vent location, particularly for the andesitic-basaltic layers."
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 Internacional
dc.subjectHeterogeneous pumice-fall deposit
dc.subjectPlinian eruptions
dc.subjectStrombolian eruptions
dc.subjectLos Humeros caldera
dc.subjectMagma mingling and mixing
dc.subjectBimodal volcanism
dc.titleAn unusual syn-eruptive bimodal eruption: The Holocene Cuicuiltic Member at Los Humeros caldera, Mexico
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Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 Internacional