Relations entre dynamismes éruptifs et réalimentations magmatiques d'origine profonde au Popocatépetl

1988 ◽  
Vol 25 (7) ◽  
pp. 955-971 ◽  
Author(s):  
Christian Boudal ◽  
Claude Robin
Keyword(s):  
Volcanic Activity ◽  
Magma Mixing ◽  
Basaltic Magma ◽  
Lava Flows ◽  
Pyroclastic Flows ◽  
Explosive Activity ◽  
Mixing Processes ◽  
Effusive Activity ◽  
Fall Deposits

The modern volcano Popocatépetl is 30 000 – 50 000 years old. Until 5000 years BP, its volcanic activity led to the construction of a 2000 m high cone, the El Fraile volcano. This edifice was later topped by the Popocatépetl summit. The volcanic activity was characterized by long-term construction by lava flows, alternating with periods of 1000–2000 years of mixed explosive and effusive activity. The El Fraile volcano experienced three periods of this type, marked by back-falling pyroclastic flows with heterogeneous magma products and thick air-fall deposits (ash and scoria). The first one occurred more than 10 000 years BP; the second, between 10 000 and 8000 years BP; the third, from 5000 to 3800 years BP. Each of these periods showed violent explosive episodes alternating with lava flows in cycles of 100 to several hundreds of years in duration. Whenever the explosive activity occurred, it destroyed the upper part of the volcano, opening large craters. After a ~ 2500 year period of lava-flow construction (from ~ 3800 to 1200 years BP), the Popocatépetl summit began a similar activity. The last event, producing pyroclastic flows, occurred just before me Hispanic Conquest, and since that time the activity has been effusive and Plinian.Heterogeneous to subhomogeneous pyroclastic flow products exhibit a complex mineralogy: Fe clinopyroxene, Mg clinopyroxene, Fe orthopyroxene, Mg orthopyroxene, plagioclase in equilibrium or disequilibrium, and scarce olivine. All lava flows show a similar paragenesis, suggesting magma-mixing processes. A model in which a basaltic magma is periodically injected in a differentiated chamber at the beginning of each explosive period (or each cycle?) is proposed to explain the heterogeneous products. However, calculations of mixing models do not agree with the high Mg and Ni values observed in some hybrid lavas. This excess is probably due to the remobilization of cumulative olivine by basic magma supplies in the lower part of the reservoir. On the other hand, lava flows emitted during the long phases of effusive activity correspond to evolution in a closed and zoned chamber, partly affected by convective movements. The convection explains the complex mineralogy of these lavas, which result from differentiation of a previously homogenized magma rather than directly from magma mixing.

A quantitative study of five thousand years of volcanism on Sao Miguel, Azores

1978 ◽  
Vol 288 (1352) ◽  
pp. 271-319 ◽  
Keyword(s):  
Quantitative Study ◽  
Basaltic Magma ◽  
Volcanic Eruptions ◽  
Lava Flows ◽  
Explosive Eruptions ◽  
Lateral Movement ◽  
The Past ◽  
Pumice Fall ◽  
Eruptive Fissures ◽  
Fall Deposits

The activity of the three stratovolcanoes on the island of Sao Miguel is documented by tephrochronology, and during the past 5000 years a total of some 57 volcanic eruptions have taken place, mostly of magnitudes 4-6 on Tsuya’s scale. Approximately half were trachytic, and half basaltic. Each stratovolcano has a caldera within which each has had one historic eruption. The trachytic eruptions were predominantly explosive, and most took place from vents situated within the calderas. Isopach and isograde maps of most of the resulting pumice fall deposits are given. The basaltic eruptions produced both lava flows and pyroclastics, and isopach and isograde maps are given for some of the main fall deposits. The Agua de Pau volcano has had particularly large explosive eruptions, several of them (including Fogo A, the largest in the past 5000 years) being of plinian type. The output of the three volcanoes over the 5000 years is equivalent to 4.6 km 3 of dense rock, at which rate the exposed parts of the volcanoes could have accumulated in 150000 years. At least half of the erupted material is trachytic, a proportion typical of the entire accessible parts of the volcanoes. The 50 known eruptive vents of the past 5000 years are distributed in a zone 55 km long by 8 km wide which may lie above a major fracture zone. Some eruptive fissures trend obliquely across this zone, suggesting right-lateral movement along the fracture. Basaltic eruptions were confined to a much smaller area than in the preceding millennia perhaps due to the formation, at the time of the great Fogo A eruption 5000 years ago, of a broad trachytic magma chamber underlying the Agua de Pau and Furnas volcanoes which basaltic magma has since been unable to penetrate.

scholarly journals The July/August 2019 Lava Flows at the Sciara del Fuoco, Stromboli–Analysis from Multi-Sensor Infrared Satellite Imagery

2019 ◽  
Vol 11 (23) ◽  
pp. 2879 ◽  
Author(s):  
Plank ◽  
Marchese ◽  
Filizzola ◽  
Pergola ◽  
Neri ◽  
...  
Keyword(s):  
Satellite Imagery ◽  
Volcanic Activity ◽  
Infrared Imaging ◽  
Lava Flows ◽  
Joint Analysis ◽  
Landsat 8 ◽  
Output Rate ◽  
Effusive Activity ◽  
Infrared Imager ◽  
Rapid Sequence

On 3 July 2019 a rapid sequence of paroxysmal explosions at the summit craters of Stromboli (Aeolian-Islands, Italy) occurred, followed by a period of intense Strombolian and effusive activity in July, and continuing until the end of August 2019. We present a joint analysis of multi-sensor infrared satellite imagery to investigate this eruption episode. Data from the Spinning-Enhanced-Visible-and-InfraRed-Imager (SEVIRI) was used in combination with those from the Multispectral-Instrument (MSI), the Operational-Land-Imager (OLI), the Advanced-Very High-Resolution-Radiometer (AVHRR), and the Visible-Infrared-Imaging-Radiometer-Suite (VIIRS). The analysis of infrared SEVIRI-data allowed us to detect eruption onset and to investigate short-term variations of thermal volcanic activity, providing information in agreement with that inferred by nighttime-AVHRR-observations. By using Sentinel-2-MSI and Landsat-8-OLI imagery, we better localized the active lava-flows. The latter were quantitatively characterized using infrared VIIRS-data, estimating an erupted lava volume of 6.33×106±3.17×106 m3 and a mean output rate of 1.26 ± 0.63 m3/s for the July/August 2019 eruption period. The estimated mean-output-rate was higher than the ones in the 2002–2003 and 2014 Stromboli effusive eruptions, but was lower than in the 2007-eruption. These results confirmed that a multi-sensor-approach might provide a relevant contribution to investigate, monitor and characterize thermal volcanic activity in high-risk areas.

scholarly journals The summer 2019 basaltic Vulcanian eruptions (paroxysms) of Stromboli

2020 ◽  
Vol 83 (1) ◽  
Author(s):  
G. Giordano ◽  
G. De Astis
Keyword(s):  
Time Scales ◽  
Pyroclastic Flows ◽  
Level System ◽  
Subsequent Evolution ◽  
Strombolian Activity ◽  
Effusive Activity ◽  
Convective Region ◽  
Operational Time ◽  
Fall Deposits ◽  
Visual Observations

AbstractStromboli is an active, open conduit mafic volcano, whose persistent mild Strombolian activity is occasionally punctuated by much stronger explosions, known as paroxysms. During summer 2019, the volcano unexpectedly produced one such paroxysm on July 3, followed by intense explosive and intermittent effusive activity culminating in a second paroxysm on August 28. Visual observations and the analysis of the fall deposits associated with the two paroxysms allowed us to reconstruct ballistic exit velocities of up to 160 m s−1. Plume heights of ~ 8.4 km and 6.4 km estimated for the two events correspond to mass eruption rates of 1.1 × 106 kg s−1 and 3.6 × 105 kg s−1, respectively. This is certainly an underestimate as directional pyroclastic flows into which mass was partitioned immediately formed, triggering small tsunamis at the sea entrance. The mass of ballistic spatters and blocks erupted during the July 3 event formed a continuous cover at the summit of the volcano, with a mass calculated at ~ 1.4 × 108 kg. The distribution of fall deposits of both the July 3 and August 28 events suggests that pyroclasts characterized by terminal fall velocities < 10–20 m s−1 remained fully suspended within the convective region of the plume and did not fall at distances closer than ca 1700 m to the vent. Based on the impulsive, blast-like phenomenology of paroxysms as well as the deposit distribution and type, paroxysms are classified as basaltic Vulcanian in style. The evolution of the summer 2019 eruptive events was not properly captured within the framework of the alert level system which is focused on tsunamigenic processes, and this is discussed so as to provide elements for the implementation of the reference scenarios and an upgrade of the system to take into account such events. In particular we find that, although still largely unpredictable, at least at operational time scales, and not necessarily tsunamigenic, Vulcanian eruptions and the subsequent evolution of the eruptive phenomena should be considered for the alert level system. This serves as a warning to the implementation of alert systems where the unexpected needs to be taken into account, even at systems that are believed to be relatively “predictable” as is the case at many persistently active, open vent mafic systems.

Stratigraphy of the Bandas del Sur Formation: an extracaldera record of Quaternary phonolitic explosive eruptions from the Las Cañadas edifice, Tenerife (Canary Islands)

1998 ◽  
Vol 135 (5) ◽  
pp. 605-636 ◽  
Author(s):  
S. E. BRYAN ◽  
J. MARTÍ ◽  
R. A. F. CAS
Keyword(s):  
Magma Mixing ◽  
Explosive Volcanism ◽  
Explosive Eruptions ◽  
Caldera Collapse ◽  
Explosive Activity ◽  
Pyroclastic Deposits ◽  
Progressive Development ◽  
The Third ◽  
Effusive Activity ◽  
Summit Caldera

Explosive volcanism has dominated the large phonolitic shield volcano of Tenerife, the Las Cañadas edifice, for the last 1.5 m.y. Pyroclastic deposits of the Bandas del Sur Formation are exposed along the southern flanks, and record the last two of at least three long-term cycles of caldera-forming explosive eruptions. Each cycle began with flank fissure eruptions of alkali basalt lava, followed by minor eruptions of basanite to phonotephrite lavas. Minor phonotephritic to phonolitic lava effusions also occurred on the flanks of the edifice during the latter stages of the second explosive cycle. Non-welded plinian fall deposits and ignimbrites are the dominant explosive products preserved on the southern flanks. Of these, a significant volume has been dispersed offshore. Many pyroclastic units of the second explosive cycle exhibit compositional zonation. Banded pumice occurs in most units of the third (youngest) explosive cycle, and ignimbrites typically contain mixed phenocryst assemblages, indicating the role of magma mixing/mingling prior to eruption. At least four major eruptions of the third cycle began with phreatomagmatic activity, producing lithic-poor, accretionary lapilli-bearing fallout and/or surge deposits. The repeated, brief phase of phreatomagmatism at the onset of these eruptions is interpreted as reflecting an exhaustive water supply, probably a small caldera lake that was periodically established during the third cycle. Accidental syenite becomes an increasingly important lithic clast type in ignimbrites up-sequence, and is interpreted as recording the progressive development of a plutonic complex beneath the summit caldera.Successive eruptions during each explosive cycle increased in volume, with the largest eruption occurring at the end of the cycle. More than ten major explosive eruptions vented moderately large volumes (1−[ges ]10 km3) of phonolitic magma during the last two cycles. Culminating each explosive cycle was the emplacement of relatively large volume (>5−10 km3) ignimbrites with coarse, vent-derived lithic breccias, interpreted to record a major phase of caldera collapse. In the extracaldera record, explosive cycles are separated by ∼0.2 m.y. periods of non-explosive activity. Repose periods were characterized by erosion, remobilization of pyroclastic deposits by discharge events, and pedogenesis. The current period of non-explosive activity is characterized by the construction of the Teide-Pico Viejo stratovolcanic complex within the summit caldera. This suggests that eruptive hiatuses in the extracaldera record may reflect effusive activity and stratovolcano or shield-building phases within the summit caldera. Alternating effusive and explosive cycles have thus been important in the volcanic evolution of the Las Cañadas edifice.

scholarly journals Effusive Monogenetic Volcanism

2020 ◽  
Author(s):  
Hugo Murcia ◽  
Károly Németh
Keyword(s):  
Classification Scheme ◽  
Wide Spectrum ◽  
Lava Flows ◽  
Magma Ascent ◽  
Explosive Activity ◽  
Monogenetic Volcanism ◽  
Future Studies ◽  
Lava Domes ◽  
Tectonic Settings ◽  
Monogenetic Volcanoes

The study of monogenetic volcanism around Earth is rapidly growing due to the increasing recognition of monogenetic volcanic edifices in different tectonic settings. Far from the idea that this type of volcanism is both typically mafic and characteristic from intraplate environments, it occurs in a wide spectrum of composition and geological settings. This volcanism is widely known by the distinctive pyroclastic cones that represent both magmatic and phreatomagmatic explosive activity; they are known as scoria or spatter cones, tuff cones, tuff rings, maars and maar-diatremes. These cones are commonly associated with lava domes and usually accompanied by lava flows as part of their effusive eruptive phases. In spite of this, isolated effusive monogenetic emissions also appear around Earth’s surface. However, these isolated emissions are not habitually considered within the classification scheme of monogenetic volcanoes. Along with this, many of these effusive volcanoes also contrast with the belief that this volcanism is indicative of rapidly magma ascent from the asthenosphere, as many of the products are strongly evolved reflecting differentiation linked to stagnation during ascent. This has led to the understanding that the asthenosphere is not always the place that directly gives rise to the magma batches and rather, they detach from a crustal melt storage. This chapter introduces four singular effusive monogenetic volcanoes as part of the volcanic geoforms, highlights the fact that monogenetic volcanic fields can also be associated with crustal reservoirs, and outlines the processes that should occur to differentiate the magma before it is released as intermediate and acidic in composition. This chapter also provides an overview of this particular volcanism worldwide and contributes to the monogenetic comprehension for future studies.

Supercooling and the crystallization of plagioclase from a basaltic magma

1974 ◽  
Vol 39 (306) ◽  
pp. 641-653 ◽  
Author(s):  
Fergus G. F. Gibb
Keyword(s):  
Liquidus Temperature ◽  
Basaltic Magma ◽  
Equilibrium Phase ◽  
Phase Relations ◽  
Lava Flows ◽  
Cooling Rates ◽  
Time Space ◽  
Columbia River Basalt ◽  
Temperature Time ◽  
Basaltic Liquid

SummaryThe liquidus temperature (1198 °C) and equilibrium phase relations of a sample of Columbia River basalt from the Picture Gorge section have been determined at I atmosphere by heating in a controlled atmosphere. When this basalt is cooled from above its liquidus temperature the liquidus phase (plagioclase) may fail to crystallize depending on the degree of undercooling and the duration of the experiment. A field in temperature-time space in which plagioclase fails to crystallize on cooling is separated from another in which plagioclase always crystallizes by a third in which the nucleation of plagioclase is unpredictable in terms of temperature and time. The extent to which this basaltic liquid can be supercooled without the crystallization of plagioclase is independent of the time it is held above the liquidus or the temperature in excess of the liquidus to which it is heated.The exceptionally long times required to ensure the nucleation of plagioclase at or near the liquidus temperature suggest that many so-called ‘equilibrium’ phase relations determined from experiments of a few hours' duration could be in serious error if the ‘equilibration’ involves a nucleation process.It is demonstrated that, over a range of cooling rates, the temperature at which plagioclase begins to crystallize on cooling varies markedly and the temperature and times required for both possible and certain nucleation of plagioclase are calculated for a range of constant cooling rates. The range of cooling rates over which the nucleation temperature of plagioclase varies is likely to occur in nature only in certain lava flows and small minor intrusions. In such cases this could lead to changes in the order in which the minerals appear on cooling and other petrologically significant effects.

scholarly journals Petrologic Insights into Rift Zone Magmatic Interactions from the 2011 Eruption of Kīlauea Volcano, Hawaiʻi

2019 ◽  
Vol 60 (11) ◽  
pp. 2051-2075
Author(s):  
Brett H Walker ◽  
Michael O Garcia ◽  
Tim R Orr
Keyword(s):  
Trace Element ◽  
Rift Zone ◽  
Magma Mixing ◽  
Major And Trace Elements ◽  
Kilauea Volcano ◽  
The Other ◽  
Least Squares Regression ◽  
Mixing Processes ◽  
Residual Magma ◽  
Kīlauea Volcano

Abstract The high frequency of historical eruptions at Kīlauea Volcano presents an exceptional opportunity to address fundamental questions related to the transport, storage, and interaction of magmas within rift zones. The Nāpau Crater area on Kīlauea’s East Rift Zone (ERZ) experienced nine fissure eruptions within 50 years (1961–2011). Most of the magma intruded during these frequent eruptions remained stored within the rift zone, creating a potential magma mixing depot within the ERZ. The superbly monitored and sampled 2011 eruption (Puʻu ʻŌʻō episode 59) presents an extraordinary opportunity to evaluate magma mixing processes within the ERZ. Whole-rock, glass, and olivine compositions were determined, not only for lava from the 2011 eruption, but also for a new suite of Nāpau Crater area samples from the 1963, 1965, 1968, 1983, and 1997 eruptions, as well as the previously undocumented 1922 eruption. Whole-rock XRF data revealed two geochemically distinct magma batches for episode 59: one less evolved (∼6·6 wt % MgO, 0·46 wt % K2O) than the other (∼6·2 wt % MgO, 0·58 wt % K2O). Episode 59 lava is remarkably aphyric (∼0·1 vol. % phenocrysts), making use of mineralogy to identify parent magma affinities problematic. Linear compositional trends of whole-rock major and trace elements, and reversely zoned olivine crystals indicate episode 59 lavas underwent magma mixing. Least squares regression calculations and plots of major and trace element data, were used to evaluate whether the episode 59 samples are products of mixing summit-derived magma with residual magma from previous Nāpau Crater area eruptions. The regression results and trace element ratios are inconsistent with previously proposed mixing scenarios, but they do support mixing between summit-derived magma and residual magma from the 1983 and 1997 Nāpau Crater area eruptions. These magmas were stored in physically and chemically distinct pods at depths of 1·6–3·0 km prior to mixing with new magma intruded from the summit to produce the episode 59 lava. One pod contained a fractionated equivalent of 1983 lava, and the other a hybrid of compositions similar to 1983 and 1997 lavas. The petrology of episode 59 lava demonstrates that magmas from two previous eruptions (1983 and 1997) were available to mix with magma intruded from the summit region. This study clarifies the pre-eruptive history of the mixed episode 59 lava, and elucidates the evolution of the volcano's magmatic system in a region of frequent eruptions.

Crystallization of basaltic magma as recorded by variation of crystal-size in dikes

1949 ◽  
Vol 28 (205) ◽  
pp. 557-574 ◽  
Author(s):  
Helmut G. F. Winkler
Keyword(s):  
Grain Size ◽  
Quantitative Data ◽  
Crystal Size ◽  
Basaltic Magma ◽  
Size Variation ◽  
Progressive Increase ◽  
Lava Flows ◽  
The Individual

It is a familiar fact that in dikes, lava-flows, and sills the grain-size of the individual minerals normally varies according to the distance from the contacts. At or near the margins of the igneous body the grainsize is usually very much less than in the centre, and this phenomenon has been attributed to differences in the cooling-velocities at these spots. On the basis of measurements carried out by Queneau (8) the opinion seems to have been formed that the crystal-size always shows a progressive increase from the contacts towards the centre. This is not so, however, for as Lane (6) has shown, the crystal-size may increase to a maximum at a certain distance from the margin, and thereafter decrease again towards the centre of the intrusion. Apart from these investigations, carried out by Queneau and Lane, the only additioual quantitative data oil crystal-size variation known to the writer concerns a series of measurements made on an olivine-diabase by B. H. Dollen, under the direction of H. L. Alling.

Element and Sr isotope zoning in plagioclase in the dacites from the southwestern Okinawa Trough: Insights into magma mixing processes and time scales

Lithos ◽  
2020 ◽  
Vol 376-377 ◽  
pp. 105776
Author(s):  
Zuxing Chen ◽  
Zhigang Zeng ◽  
Xiaoyuan Wang ◽  
Xing Peng ◽  
Yuxiang Zhang ◽  
...  
Keyword(s):  
Time Scales ◽  
Magma Mixing ◽  
Okinawa Trough ◽  
Sr Isotope ◽  
Mixing Processes
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