MAGMA CHAMBER DYNAMICS AND ERUPTIVE MECHANISMS IN THE CASCADE ARC: INSIGHTS FROM MELT INCLUSIONS AND TITANIUM-IN-QUARTZ THERMOBAROMETRY

2017 ◽  
Author(s):  
Jeremy S. Rosen ◽  
◽  
Brian G. Rusk ◽  
Michael A. Clynne ◽  
Susan M. DeBari
Keyword(s):  
Magma Chamber ◽  
Melt Inclusions ◽  
Cascade Arc

Glass-bearing felsic nodules from the crystallizing sidewalls of the 1944 Vesuvius magma chamber

2000 ◽  
Vol 64 (3) ◽  
pp. 481-496 ◽  
Author(s):  
P. Fulignati ◽  
P. Marianelli ◽  
A. Sbrana
Keyword(s):  
Magma Chamber ◽  
Melt Inclusions ◽  
Mineral Chemistry ◽  
Glassy Matrix ◽  
Crystal Mush ◽  
Stratigraphic Sequence ◽  
Shallow Magma Chamber ◽  
Mineral Assemblages ◽  
Pressure Crystallization

AbstractIn the 1944 Vesuvius eruption, the shallow magma chamber was disrupted during the highly energetic explosive phases. Abundant cognate xenoliths such as subvolcanic fergusites and cumulates, hornfels, skarns and rare marbles occur in tephra deposits.Mineral chemistry, melt inclusions in minerals and glassy matrix compositions show that fergusites (highly crystalline rocks made of leucite, clinopyroxene, plagioclase, olivine, apatite, oxides and glass) do not correspond to melt compositions but result from combined sidewall accumulation of crystals, formed from K-tephriphonolitic magma resident in the chamber, and in situ crystallization of the intercumulus melt. Very low H2O contents in the intercumulus glass are revealed by FTIR and apatite composition. Whole rock compositions are essentially determined by the bulk mineral assemblages.Glass–bearing fergusites constitute the outer shell of the magma chamber consisting of a highly viscous crystal mush with a melt content in the range 20–50 wt.%. The leucite/(clinopyroxene+olivine) modal ratio, varies with the extraction order of magmas from the chamber, decreasing upwards in the stratigraphic sequence. This reflects a vertical mineralogical zonation of the crystal mush. These data contribute to the interpretation of the subvolcanic low–pressure crystallization processes at the magma chamber sidewalls affecting alkaline potassic magmas.

scholarly journals Evaluation of Caldera Hosted Geothermal Potential during Volcanism and Magmatism in Subduction System, NE Japan

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Fajar F. Amanda ◽  
Ryoichi Yamada ◽  
Masaoki Uno ◽  
Satoshi Okumura ◽  
Noriyoshi Tsuchiya
Keyword(s):  
Water Content ◽  
Magma Chamber ◽  
Melt Inclusions ◽  
Electric Energy ◽  
Geothermal Reservoir ◽  
Arc Length ◽  
Geothermal Potential ◽  
Subduction System ◽  
Chamber Size ◽  
Ne Japan

Deep-seated geothermal reservoirs beneath calderas have high potential as sources of renewable energy. In this study, we used an analysis of melt inclusions to estimate the amount of water input to the upper crust and quantify the properties of a deep-seated geothermal reservoir within a fossil caldera, the late Miocene Fukano Caldera (formation age 8–6 Ma), Sendai, NE Japan. Our research shows that Fukano Caldera consists of the southern part and northern part deposits which differ in the age and composition. The northern deposits are older and have higher potassium and silica contents than the southern deposits. Both the northern and southern deposits record plagioclase and plagioclase–quartz differentiation and are classified as dacite–rhyolite. The fossil magma chamber underlying the caldera is estimated to have a depth of ~2–10 km and a water content of 3.3–7.0 wt.%, and when the chamber was active it had an estimated temperature of 750°C–795°C. The water input into the fossil magma chamber is estimated at 2.3–7.6 t/yr/m arc length based on the magma chamber size the water content in the magma chamber and the length of volcanism periods of Fukano Caldera, NE Japan arc. The total amount of water that is stored in the chamber is ~1014 kg. The chamber is saturated in water and has potential as a deep-seated geothermal reservoir. Based on the shape of the chamber, the reservoir measures ~10 km × 5 km in the horizontal dimension and is 7–9 km in vertical extent. The 0th estimate shows that the reservoir can hold the electric energy equivalent of 33–45 GW over 30 years of power generation. Although the Fukano reservoir has great potential, commercial exploitation remains challenging owing to the corrosive nature of the magmatic fluids and the uncertain permeability network of the reservoir.

Silicate-carbonate-salt liquid immiscibility and origin of the sodalite-haüyne rocks: study of melt inclusions in olivine foidite from Vulture volcano, S. Italy

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
Liya Panina ◽  
Francesco Stoppa
Keyword(s):  
Magma Chamber ◽  
Melt Inclusions ◽  
Liquid Immiscibility ◽  
Pyroclastic Flows ◽  
Silicate Inclusions ◽  
Low Degree ◽  
Primary Inclusion ◽  
Probable Presence ◽  
Silicate Carbonate ◽  
Carbonate Salt

AbstractMelt inclusions in clinopyroxenes of olivine foidite bombs from Serra di Constantinopoli pyroclastic flows of the Vulture volcano (Southern Italy) were studied in detail. The rocks contain abundant zoned phenocrysts and xenocrysts of clinopyroxene, scarce grains of olivine, leucite, haüyne, glass with microlites of plagioclase and K-feldspar. The composition of clinopyroxene in xenocrysts (Cpx I), cores (Cpx II), and in rims (Cpx III) of phenocrysts differs in the content of Mg, Fe, Ti, and Al. All clinopyroxenes contain two types of primary inclusion-pure silicate and of silicate-carbonate-salt composition. This fact suggests that the phenomena of silicate-carbonate immiscibility took place prior to crystallization of clinopyroxene. Homogenization of pure silicate inclusions proceeded at 1 225 – 1 190°C. The composition of conserved melts corresponded to that of olivine foidite in Cpx I, to tephrite-phonolite in Cpx II, and phonolite-nepheline trachyte in Cpx III. The amount of water in them was no more than 0.9 wt.%. Silicate-carbonate inclusions decrepitated on heating. Salt globules contained salts of alkali-sulphate, alkali-carbonate, and Ca-carbonate composition somewhat enriched in Ba and Sr. This composition is typical of carbonatite melts when decomposed into immiscible fractions. The formation of sodalite-haüyne rocks from Vulture is related to the presence of carbonate-salt melts in magma chamber. The melts conserved in clinopyroxenes were enriched in incompatible elements, especially in Cpx III. High ratios of La, Nb, and Ta in melts on crystallization of Cpx I and Cpx II suggest the influence of a carbonatite melt as carbonatites have extremely high La/Nb and Nb/Ta and this is confirmed by the appearance of carbonatite melts in magma chamber. Some anomalies in the concentrations and relatives values of Eu and especially Ga seems typical of Italian carbonatite related melts. The mantle source for initial melts was, most likely, rather uniform, undepleted and was characterized by a low degree of melting and probable presence of garnet in restite.

Origin and Evolution of Magmas in the Porphyry Au-mineralized Javorie Volcano (Central Slovakia): Evidence from Thermobarometry, Melt Inclusions and Sulfide Inclusions

2019 ◽  
Vol 60 (12) ◽  
pp. 2449-2482 ◽  
Author(s):  
Bertrand Rottier ◽  
Andreas Audétat ◽  
Peter Koděra ◽  
Jaroslav Lexa
Keyword(s):  
Magma Chamber ◽  
Melt Inclusions ◽  
Mass Spectrometry Analysis ◽  
Magmatic System ◽  
Monosulfide Solid Solution ◽  
Porphyry Deposits ◽  
Magmatic Sulfides ◽  
Magmatic Sulfide ◽  
Sulfide Precipitation ◽  
Crustal Magma

Abstract The effect of magmatic sulfide precipitation on the potential of magmatic systems to produce porphyry-type ore deposits is still a matter of debate. In particular, we need to know whether magmatic sulfide precipitation has an impact on the Cu and Au content of the exsolving magmatic volatile phases and, by this way, on the Cu/Au ratio of porphyry deposits. The Javorie volcano is a perfect place to explore these questions. First, it hosts several Au-only porphyry-type mineralized occurrences which have among the lowest Cu/Au ratios reported in the literature. Secondly, the geology of the Javorie volcano and the timing of porphyry Au mineralization are well established. The evolution of the Javorie magmatic system was reconstructed by detailed petrographic studies and laser ablation inductively coupled plasma mass spectrometry analysis of minerals, melt inclusions and sulfide inclusions. The Javorie volcano was formed during the post-subduction magmatic activity affecting the Western Carpathians. It is a typical stratovolcano, composed dominantly of basaltic andesites and andesites which were intruded by several small stocks of dacitic to dioritic composition. According to our thermobarometric data, the volcano was fed by a transcrustal magmatic system in which two levels of magma chambers could be identified. Part of the magma evolved in the lower crust as suggested by the occurrence of magmatic garnet antecrysts in some of the studied rocks. The occurrence of magmatic sulfide inclusions in garnet indicates that sulfide saturation was reached in this lower crustal magma chamber. Most of the rocks crystallized in an upper crustal magma chamber (∼2 ± 1 kbar) that was fed by a basaltic to basaltic andesite magmas. A large variation in temperatures, ranging between 820°C and 1025°C, recorded by the extrusive and intrusive rocks suggest either that the upper crustal magma chamber was thermally zoned, or that the temperature of the whole magma chamber varied dramatically during its lifetime. Magmatic sulfide inclusions are present in all minerals and rocks of the upper crustal magma chamber, independent of their timing relative to porphyry Au mineralization (pre-, syn-, post-ore). These observations suggest that the magmatic system was sulfide saturated during its entire evolution. With very few exceptions, the precipitating sulfides were composed of monosulfide solid solution containing 0·2–9·2 wt % Cu and 0·05–11 ppm Au. The presence of these magmatic sulfides, together with results of a numerical model, suggest that the primitive magma feeding the upper crustal magma chamber contained less than 2·75 wt % H2O and that only a minor part of the magmatic sulfides was fractionated out of the system. Finally, the Cu/Au ratios measured in the magmatic sulfide inclusions and the ones predicted for the exsolved aqueous fluids are 10 to 100 times higher than the Cu/Au ratios of the porphyry deposits. Therefore, the extremely low Cu/Au ratios of the porphyry deposits must have been acquired during the hydrothermal stage.

Depleted melt inclusions in MORB plagioclase: messages from the mantle or mirages from the magma chamber?

2002 ◽  
Vol 183 (1-4) ◽  
pp. 43-61 ◽  
Author(s):  
Peter J Michael ◽  
William F McDonough ◽  
Roger L Nielsen ◽  
Winton C Cornell
Keyword(s):  
Magma Chamber ◽  
Melt Inclusions
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