气候变化领域集成服务门户(CCPortal): Top–down control on eruptive style at Masaya volcano inferred from melt composition

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DOI	10.1016/j.epsl.2021.117138
	Top–down control on eruptive style at Masaya volcano inferred from melt composition
	Hlinka L.; Longpré M.-A.; Pérez W.; Kutterolf S.; Monteleone B.
发表日期	2021
ISSN	0012821X
卷号	572
英文摘要	Highly explosive Plinian eruptions of basaltic magma are enigmatic because low melt viscosities should inhibit such eruptive style. Masaya volcano, Nicaragua, is a persistently active basaltic system capable of a wide range of eruptive styles, from open-conduit lava lake activity to voluminous Plinian eruptions; it is thus an ideal natural laboratory to constrain potential controls on basaltic eruption style. Here we report the major, trace, and volatile (CO2, H2O, S, Cl, F) element composition of olivine-, plagioclase- and clinopyroxene-hosted melt inclusions as well as matrix glasses from lava lake ejecta and two Plinian tephra deposits—the 2.1 ka Masaya Triple Layer and the 1.8 ka Ticuantepe Lapilli—to test whether pre-eruptive volatile contents and degassing history may be linked to eruptive style. All samples display a relatively narrow and largely overlapping basaltic–basaltic andesitic compositional range (51.7±1.0 wt.% SiO2, 4.8±0.4 wt.% MgO) with similar trace element signatures (e.g., Ce/Y=0.82±0.10, Ba/La=74±11). However, lava lake and Plinian samples show systematic differences in pre-eruptive volatile contents, forming distinct groups with mean H2O contents of 0.6±0.2 wt.% (lava lake), 1.1±0.2 wt.% (Masaya Triple Layer), and 1.9±0.3 wt.% (Ticuantepe Lapilli). Together, these groups generate broad positive correlations between S, Cl and H2O concentrations, with maximum values reaching 920 ppm, 1300 ppm and 2.3 wt.%, respectively, which are low compared to typical Central American arc magmas. Magma temperature estimates overlap and average at 1115±30 °C, while volatile saturation pressures are low, mainly <100 MPa, although only lava lake samples record pressures <31 MPa. These observations reiterate the compositionally buffered state of the volcano's magmatic system highlighted by previous work and demonstrate that — regardless of eruption style — all Masaya magmas undergo variable, but extensive, pre-eruptive degassing at low pressure. Geohygrometry, gas emissions, and H2O/Ce–Ba/La systematics suggest initial, undegassed H2O contents on the order of 3.9–5.5 wt.%. Our results imply that pre-eruptive volatile contents are not the culprit for Plinian events at Masaya. Instead, we propose that the volcano's vigorous magma supply is modulated in a top–down manner to produce a wide range of eruptive styles, whereby temporary sealing of the conduit may instigate a transition to explosive behavior. In this model, rapid magma ascent is triggered when the seal eventually breaks from degassing-induced pressurization, yielding high degrees of undercooling, rapid microlite growth, and a dramatic increase in magma viscosity and explosive eruption potential. There may thus be a thin line between open-conduit conditions and Plinian eruptions at Masaya. © 2021 Elsevier B.V.
关键词	basaltic Plinian eruptions eruptive style lava lake Masaya volcano melt inclusions volatile degassing
英文关键词	Basalt; Degassing; Feldspar; Lakes; Magnesia; Silica; Trace elements; Basaltic plinian eruption; Eruptive style; Lava lake; Masaya volcano; Melt inclusions; Plinian; Plinian eruption; Top-down control; Volatile degassing; Volatiles content; Volcanoes
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203132
作者单位	School of Earth and Environmental Sciences, Queens College, City University of New York, Queens, NY 11367, United States; Earth and Environmental Sciences, The Graduate Center, City University of New York, New York, NY 10016, United States; GEOMAR, Helmholtz Centre for Ocean Research, Kiel, Germany; Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, United States
推荐引用方式 GB/T 7714	Hlinka L.,Longpré M.-A.,Pérez W.,等. Top–down control on eruptive style at Masaya volcano inferred from melt composition[J],2021,572.
APA	Hlinka L.,Longpré M.-A.,Pérez W.,Kutterolf S.,&Monteleone B..(2021).Top–down control on eruptive style at Masaya volcano inferred from melt composition.Earth and Planetary Science Letters,572.
MLA	Hlinka L.,et al."Top–down control on eruptive style at Masaya volcano inferred from melt composition".Earth and Planetary Science Letters 572(2021).