The Evolution of Santa María Volcano, Guatemala

Rose, William I.; Grant, Norman K.; Hahn, Gregory A.; Lange, I. A.; Powell, J. W.; Easter, J.; DeGraff, James M.

doi:10.1086/628269

Cited by 77 publications

(31 citation statements)

References 17 publications

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“…It also rules out any isotopic zonation due to incorporation of sialic crustal material in the upper parts of the magma chamber as described by Noble and Hedge (1969). Indeed, the Sr-isotope compositions of these volcanic rocks are very close to the 0.704 value quoted for non-ash-flow Central American volcanic rocks (Pushkar, 1968), particularly the values determined for nearby basaltic andesite lavas of Volcán Santa Maria and the dacites of Santiaguito (0.70397, Rose and others, 1977). The source rock for the ash flows may have been the same as that of the more mafic lavas nearby.…”

Section: Sr-isotope Datasupporting

confidence: 75%

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Geochemistry of the Los Chocoyos Ash, Quezaltenango Valley, Guatemala

Rose

Grant²,

Easter³

1979

Geological Society of America Special Papers

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Analysis of 30 individual pumice blocks, together with bulk samples from the ash-flow member of the Los Chocoyos Ash within the Quezaltenango Valley, Guatemala, demonstrates that prior to its eruption, its associated magma-chamber was zoned. Eruption of a high-K (K 2 0/Na 2 0 > 1), crystal-poor, biotitebearing rhyolite with crystal equilibration temperatures of less than 800 °C produced the widespread H-tephra member and the initial phases of the ash-flow member. As the ash-flow eruption continued, a more-heterogeneous, low-K, crystal-rich, cummingtonite-and hornblende-bearing rhyolite became predominant; its phenocrysts had equilibrated at temperatures of about 950 °C. The water content of the high-K rhyolite was several percent, whereas the low-K rhyolite was much drier. Bulk samples of the ash-flow member are homogenized mixtures of matrix shards that represent either the high-K or low-K rhyolite magmas; the overall ratio for the ash-flow member is 60% high-K and 40% low-K type. The 87 Sr/ 86 Sr ratios for both high-K and low-K magma types are identical and average 0.70405 ± 0.00003. This value is nearly the same as all basaltic, all andesitic, and most rhyolitic Quaternary volcanic rocks tested in Guatemala so far. The 87 Sr/ 86 Sr ratios for bulk samples of the ash are significantly higher and more variable (0.70426 ± 0.00009), probably because of xenocrystic contamination. Detailed mixing and Rayleigh calculations using observed mineral phases in the ash show that the concentrations of 8 major and 17 minor elements in the ash are consistent with the derivation of high-K rhyolite from low-K magma by crystal fractionation at shallow depths. The time required for such

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Section: Sr-isotope Datasupporting

confidence: 75%

“…Where relationships can be observed, the ash appears to predate the active generation of composite cones of the Guatemalan Highlands. One of these cones, Santa Maria, has been tentatively assigned an age of 30,000 yr (Rose and others, 1977). Lava from these young cones is generally basaltic to andesitic; more-silicic lavas are minor.…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of the Los Chocoyos Ash, Quezaltenango Valley, Guatemala

Rose

Grant²,

Easter³

1979

Geological Society of America Special Papers

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“…Eruptive activity at Santa Maria began around 103 ka, and the edifice was constructed in four stages before a 25 thousand-year period of quiescence prior to 1902 (Rose et al, 1977;Rose, 1987a;Conway et al, 2013). Numerous lineations cut through the Santa Maria and Santiaguito edifices with a rough east to west orientation (Figure 2; Escobar-Wolf et al, 2010).…”

Section: Geological and Volcanological Contextmentioning

confidence: 99%

Textural Insights Into the Evolving Lava Dome Cycles at Santiaguito Lava Dome, Guatemala

et al. 2018

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The structures and textures preserved in lava domes reflect underlying magmatic and eruptive processes, and may provide evidence of how eruptions initiate and evolve. This study explores the remarkable cycles in lava extrusion style produced between 1922 and 2012 at the Santiaguito lava dome complex, Guatemala. By combining an examination of eruptive lava morphologies and textures with a review of historical records, we aim to constrain the processes responsible for the range of erupted lava type and morphologies. The Santiaguito lava dome complex is divided into four domes (El Caliente, La Mitad, El Monje, El Brujo), containing a range of proximal structures (e.g., spines) from which a series of structurally contrasting lava flows originate. Vesicular lava flows (with a'a like, yet non-brecciated flow top) have the highest porosity with interconnected spheroidal pores and may transition into blocky lava flows. Blocky lava flows are high volume and texturally variable with dense zones of small tubular aligned pore networks and more porous zones of spheroidal shaped pores. Spines are dense and low volume and contain small skeletal shaped pores, and subvertical zones of sigmoidal pores. We attribute the observed differences in pore shapes to reflect shallow inflation, deflation, flattening, or shearing of the pore fraction. Effusion rate and duration of the eruption define the amount of time available for heating or cooling, degassing and outgassing prior to and during extrusion, driving changes in pore textures and lava type. Our new textural data when reviewed with all the other published data allow a cyclic model to be developed. The cyclic eruption models are influenced by viscosity changes resulting from (1) initial magmatic composition and temperature, and (2) effusion rate which in turn affects degassing, outgassing and cooling time in the conduit. Each lava type presents a unique set of hazards and understanding the morphologies and dome progression is useful in hazard forecasting.

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“…Ash-cloud surges are known to detach and overrun dense basal avalanches after traversing a break in slope, as at Mount Ngauruhoe, New Zealand (Nairn & Self 1978), Santiaguito Volcano, Guatemala (Rose et al 1977), and Merapi (Bourdier & Abdurachman 2001;Lube et al 2011;Jenkins et al 2013). Surges may separate from valley-confined flows when steep topography or barriers are encountered, as was (Charbonnier & Gertisser 2011;Lube et al 2011;Charbonnier et al 2013;Jenkins et al 2013;Komorowski et al 2013).…”

Section: Previous Workmentioning

confidence: 99%

Chapter 10 The effect of topography on ash-cloud surge generation and propagation

Ogburn

Calder

Cole

et al. 2014

Memoirs

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Abstract:The relationship between valley morphology and ash-cloud surge development for 12 pyroclastic density currents (PDCs) at Soufrière Hills Volcano (SHV), Montserrat is investigated. Channel slope, sinuosity and cross-sectional area were measured from highresolution digital elevation models (DEMs) using geographical information system (GIS) software; and were compared to geometric parameters of the deposits. The data illustrate three surge-generation regimes: a proximal area of rapid expansion; a medial deflation zone; and a steadier distal surge 'fringe'. The extent to which these regimes develop varies with flow volume. For larger flows, within the proximal and medial regimes, a strong inverse correlation exists between surge detachment and valley cross-sectional area. Surge detachment is also correlated with observed and modelled flow velocities. Areas of topography-induced increases in velocity are interpreted to result in more pervasive fragmentation and fluidization, and thus enhanced surge generation. Distally, surge deposits appear as fringes with decaying extents, indicative of more passive expansion and decreasing velocity. The results indicate that surge mobility and detachment are a complex product of flow mass flux and topography, and that future efforts to model dense-dilute coupled flows will need to account for and integrate several mechanisms acting on different parts of the flow.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.The development and subsequent decoupling of dilute, turbulent ash-cloud surges from dense basal pyroclastic flows is poorly understood, unpredictable and often results in deadly consequences. Ash-cloud surges can have a significant lateral component of motion, and have been known to detach and move independently from their parent flows (Fisher 1995). For example, decoupled pyroclastic surges were responsible for fatalities

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The Evolution of Santa María Volcano, Guatemala

Cited by 77 publications

References 17 publications

Geochemistry of the Los Chocoyos Ash, Quezaltenango Valley, Guatemala

Geochemistry of the Los Chocoyos Ash, Quezaltenango Valley, Guatemala

Textural Insights Into the Evolving Lava Dome Cycles at Santiaguito Lava Dome, Guatemala

Chapter 10 The effect of topography on ash-cloud surge generation and propagation

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