The water content and parental magma of the second chassignite NWA 2737: Clues from trapped melt inclusions in olivine

AbstractThe discrepancy between Na-rich compositions of modern carbonatitic lavas (Oldoinyo Lengai volcano) and alkali-poor ancient carbonatites remains a topical problem in petrology. Although both are supposedly considered to originate via fractional crystallization of a “common parent” alkali-bearing Ca-carbonatitic magma, there is a significant compositional gap between the Oldoinyo Lengai carbonatites and all other natural compositions reported (including melt inclusions in carbonatitic minerals). In an attempt to resolve this, we investigate the petrogenesis of Ca-carbonatites from two occurrences (Guli, Northern Siberia and Tagna, Southern Siberia), focusing on mineral textures and alkali-rich multiphase primary inclusions hosted within apatite and magnetite. Apatite-hosted inclusions are interpreted as trapped melts at an early magmatic stage, whereas inclusions in magnetite represent proxies for the intercumulus environment. Melts obtained by heating and quenching the inclusions, show a progressive increase in alkali concentrations transitioning from moderately alkaline Ca-carbonatites through to the “calcite CaCO3 + melt = nyerereite (Na,K)2Ca2(CO3)3” peritectic, and finally towards Oldoinyo Lengai lava compositions. These results give novel empirical evidence supporting the view that Na-carbonatitic melts, similar to those of the Oldoinyo Lengai, may form via fractionation of a moderately alkaline Ca-carbonatitic melt, and therefore provide the “missing piece” in the puzzle of the Na-carbonatite’s origin. In addition, we conclude that the compositions of the Guli and Tagna carbonatites had alkali-rich primary magmatic compositions, but were subsequently altered by replacement of alkaline assemblages by calcite and dolomite.

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Constraining Mantle Heterogeneity beneath the South China Sea: A New Perspective on Magma Water Content

Minerals ◽

10.3390/min9070410 ◽

2019 ◽

Vol 9 (7) ◽

pp. 410 ◽

Cited By ~ 1

Author(s):

Wei Wang ◽

Fengyou Chu ◽

Xichang Wu ◽

Zhenggang Li ◽

Ling Chen ◽

...

Keyword(s):

South China Sea ◽

Water Content ◽

South China ◽

Mantle Source ◽

Melt Inclusions ◽

The South China Sea ◽

Spreading Ridge ◽

Mantle Heterogeneity ◽

The South ◽

China Sea

The nature of upper mantle is important to understand the evolution of the South China Sea (SCS); thus, we need better constrains on its mantle heterogeneity. Magma water concentration is a good indicator, but few data have been reported. However, the rarity of glass and melt inclusions and the special genesis for phenocrysts in SCS basalts present challenges to analyzing magmatic water content. Therefore, it is possible to estimate the water variations through the characteristics of partial melting and magma crystallization. We evaluated variations in Fe depletion, degree of melt fractions, and mantle source composition along the fossil spreading ridge (FSR) using SCS basalt data from published papers. We found that lava from the FSR 116.2° E, FSR 117.7° E, and non-FSR regions can be considered normal lava with normal water content; in contrast, lava from the FSR 117° E-carbonatite and 114.9–115.0° E basalts have higher water content and show evidence of strong Fe depletion during the fractional crystallization after elimination of the effects of plagioclase oversaturation. The enriched water in the 117° E-carbonatite basalts is contained in carbonated silicate melts, and that in the 114.9–115.0° E basalts results from mantle contamination with the lower continental crust. The lava from the 117° E-normal basalt has much lower water content because of the lesser influence of the Hainan plume. Therefore, there must be a mantle source compositional transition area between the southwestern and eastern sub-basins of the SCS, which have different mantle evolution histories. The mantle in the west is more affected by contamination with continental materials, while that in the east is more affected by the Hainan mantle plume.

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New FTIR data of calc-alkaline volcanic rocks from the Oas-Gutai Mts. and post eruption effects on the water content of phenocrysts

10.5194/egusphere-egu2020-18034 ◽

2020 ◽

Author(s):

Ákos Kővágó ◽

Marinel Kovacs ◽

Dóra Kesjár ◽

Csaba Szabó ◽

István Kovács

Keyword(s):

Water Content ◽

Volcanic Rocks ◽

Parental Magma ◽

Volcanic Eruptions ◽

Ftir Spectra ◽

Future Research ◽

Calc Alkaline ◽

Structural Hydroxyl ◽

Volcanic Facies ◽

Water Contents

We studied volcanic rocks from the Oas-Gutai Mts. (Transylvania, Romania) to measure the &#8216;structural hydroxyl&#8217; content of the nominally anhydrous minerals (NAMs such as clinopyroxene, plagioclase, quartz), from which water content of the parental magma can be estimated.&#160; The Neogene volcanic chain of the Carpathian-Pannonian region (CPR), due to petrologic variability, is an excellent area for such investigation.Recent FTIR studies on the calc-alkaline rocks from CPR, showed that the &#8216;structural hydroxyl&#8217; content of NAMs could be modified during and after volcanic eruptions [1], [2], [3]. However, transmission FTIR-microscopy is an adequate technique for recognizing this these changes because FTIR spectra of the NAMs indicate signs in the case of hydroxyl loss [4].For studying the pre-eruptive water contents clinopyroxenes are the most promising mineral because it has one of the lowest diffusion rates for hydroxyl in NAMs [5]. With the detailed study of the clinopyroxenes FTIR spectra, conclusions can be drawn concerning the potential post-eruptive loss of hydroxyl [4].We have examined 8 volcanic rock samples, four dacite samples from Oas and one basalt two andesite and one rhyolite sample from the Gutai Mts. The samples show diverse volcanic facies such as lava, ignimbrite and debris avalanche. The diversity of samples is important for future research because it will help to choose the most adequate volcanic facies to estimate the magmatic equilibrium water contents.The studied clinopyroxenes contain 83-371 ppm &#8216;structural hydroxyl&#8217; content,which can be considered as normal values compared to the work of [6] where &#8216;structural hydroxyl&#8217; content in clinopyroxenes show a range from 75 to 390 ppm in the mafic calc-alkaline lavas from Salina, Italy.[1] Lloyd, A.S., Ferriss, E., Ruprecht, P., Hauri, E.H., Jicha, B.R., & Plank, T. (2016): Journal of Petrology, 57, pp. 1865-1886[2] Bir&#243;, T., I. Kov&#225;cs, D. Kar&#225;tson, R. Stalder, E. Kir&#225;ly, G. Falus, T. Fancsik, J. & S&#225;ndorn&#233; Kov&#225;cs (2017): American Mineralogist, 102, pp.[3] P&#225;los, Z., Kov&#225;cs, I. J., Kar&#225;tson, D., Bir&#243;, T., S&#225;ndorn&#233; Kov&#225;cs, J., Bertalan, &#201;., & Wesztergom, V. (2019): Central European Geology, 62(1)[4] Patk&#243;, L., Liptai, N., Kov&#225;cs, I., Aradi, L., Xia, Q.K., Ingrin, J., Mih&#225;ly, J., O'Reilly, S.Y., Griffin, W.L., Wesztergom, V., & Szab&#243;, C. (2019): Chemical Geology, 507, pp. 23-41.[5] Farver, J.R. (2010): Reviews in Mineralogy and Geochemistry, 72 (1), pp. 447&#8211;507.[6] Nazzareni, S., Skogby H., & Zanazzi, P.F. (2011): Contributions to Mineralogy and Petrology, 162, pp. 275&#8211;288.

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Water content, δD and δ11B tracking in the Vanuatu arc magmas (Aoba Island): Insights from olivine-hosted melt inclusions

Lithos ◽

10.1016/j.lithos.2014.08.011 ◽

2014 ◽

Vol 206-207 ◽

pp. 400-408 ◽

Cited By ~ 17

Author(s):

Nicole Métrich ◽

Etienne Deloule

Keyword(s):

Water Content ◽

Melt Inclusions ◽

Arc Magmas

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

Geofluids ◽

10.1155/2019/3031586 ◽

2019 ◽

Vol 2019 ◽

pp. 1-14 ◽

Cited By ~ 2

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.

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Melt Inclusions in Plagioclase Macrocrysts at Mount Jourdanne, Southwest Indian Ridge (~64° E): Implications for an Enriched Mantle Source and Shallow Magmatic Processes

Minerals ◽

10.3390/min9080493 ◽

2019 ◽

Vol 9 (8) ◽

pp. 493 ◽

Cited By ~ 2

Author(s):

Wei Li ◽

Chunhui Tao ◽

Wen Zhang ◽

Jia Liu ◽

Jin Liang ◽

...

Keyword(s):

Mantle Source ◽

Melt Inclusions ◽

Parental Magma ◽

Southwest Indian Ridge ◽

Host Magma ◽

Enriched Mantle ◽

Magma Supply ◽

General Chemical ◽

Indian Ridge ◽

Ocean Ridge

Plagioclase ultraphyric basalts (PUBs) with up to 40% millimeter-sized plagioclase crystals, were sampled from the Mount Jourdanne volcanic massif (~64° E) in the Southwest Indian Ridge. The geochemistry of the host glass, the glassy melt inclusions and their host plagioclase macrocrysts (An60-69) are used to reveal the mantle heterogeneity and to discuss the origin of Mount Jourdanne PUBs. The melt inclusions trapped in plagioclase display low MgO and high SiO2 contents and show rare earth element (REE) patterns resembling enriched mid-ocean ridge basalts (E-MORB). Together with their positive Sr and Eu anomalies, these features indicate that they were derived from an enriched mantle source, likely a refertilized peridotite or a pyroxenite. In contrast to some 61–67° E basalts, there is a lack of negative Eu anomalies in the PUB host glasses, precluding large amounts of plagioclase crystallization from their parental magma. Petrographic observations and the general chemical similarity between melt inclusions and melts equilibrated with the clinopyroxene cores in regional gabbros and/or troctolites suggest that these plagioclase macrocrysts originate from gabbroic mush within the lower crust. The density contrasts allow the effective segregation of plagioclase prior to their incorporation into the host magma. We propose that these plagioclase macrocrysts were entrained when a new batch of magma passed through the crustal mush zone, and resulted in the formation of the PUB. Eruption of Mount Jourdanne PUBs requires a minimum ascending velocity of 5 m d−1 for the host magma, which is not as high as the eruption rate for typical MORB samples. It is likely that the PUB host magma erupts during a period with reduced magma supply, whereas eruption of aphyric lavas correspond to the fast volcanic formation of the Mount Jourdanne massif.

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The Lower Silurian Osmundsberg K-bentonite. Part II: mineralogy, geochemistry, chemostratigraphy and tectonomagmatic significance

Geological Magazine ◽

10.1017/s001675689700811x ◽

1998 ◽

Vol 135 (1) ◽

pp. 15-26 ◽

Cited By ~ 47

Author(s):

WARREN D. HUFF ◽

STIG M. BERGSTRÖM ◽

DENNIS R. KOLATA ◽

HEPING SUN

Keyword(s):

Melt Inclusions ◽

Tectonic Setting ◽

Analytical Data ◽

Clay Fraction ◽

Parental Magma ◽

Margin Setting ◽

Lower Silurian ◽

Regional Correlation ◽

Tectonically Active ◽

Chemical Fingerprinting

The Lower Silurian Osmundsberg K-bentonite is a widespread ash bed that occurs throughout Baltoscandia and parts of northern Europe. This paper describes its characteristics at its type locality in the Province of Dalarna, Sweden. It contains mineralogical and chemical characteristics that permit its regional correlation in sections elsewhere in Sweden as well as Norway, Estonia, Denmark and Great Britain. The <2 μm clay fraction of the Osmundsberg bed contains abundant kaolinite in addition to randomly ordered (RO) illite/smectite (I/S). Modelling of the X-ray diffraction tracings showed the I/S consists of 18% illite and 82% smectite. The high smectite and kaolinite content is indicative of a history with minimal burial temperatures. Analytical data from both pristine melt inclusions in primary quartz grains as well as whole rock samples can be used to constrain both the parental magma composition and the probable tectonic setting of the source volcanoes. The parental ash was dacitic to rhyolitic in composition and originated in a tectonically active collision margin setting.Whole rock chemical fingerprinting of coeval beds elsewhere in Baltoscandia produced a pronounced clustering of these samples in the Osmundsberg field of the discriminant analysis diagram. This, together with well-constrained biostratigraphic and lithostratigraphic data, provides the basis for regional correlation and supports the conclusion that the Osmundsberg K-bentonite is one of the most extensive fallout ash beds in the early Phanerozoic. The source volcano probably lay to the west of Baltica as part of the subduction complex associated with the closure of Iapetus.

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Refractory megacrysts and magnesium-rich melt inclusions within spinel in oceanic tholeiites: Indicators of magma mixing and parental magma composition

Earth and Planetary Science Letters ◽

10.1016/0012-821x(77)90148-0 ◽

1977 ◽

Vol 37 (1) ◽

pp. 81-89 ◽

Cited By ~ 81

Author(s):

Colin H. Donaldson ◽

Roy W. Brown

Keyword(s):

Melt Inclusions ◽

Magma Mixing ◽

Parental Magma ◽

Magma Composition

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Magma water content of Pico Volcano (Azores Islands, Portugal): a clinopyroxene perspective

Contributions to Mineralogy and Petrology ◽

10.1007/s00410-020-01728-7 ◽

2020 ◽

Vol 175 (9) ◽

Author(s):

S. Nazzareni ◽

V. Barbarossa ◽

H. Skogby ◽

V. Zanon ◽

M. Petrelli

Keyword(s):

Water Content ◽

Parental Magma ◽

Mineral Chemistry ◽

Mantle Lithosphere ◽

X Ray Diffraction ◽

X Ray ◽

History Of ◽

Historical Times ◽

Dehydration Processes ◽

Annealing Experiments

Abstract Clinopyroxenes from the Pico Volcano (Pico Island, Azores Archipelago) have been used as a proxy to define the water content of primitive magmas and the volcanological history of the erupted rocks. This very young volcano (53 ± 5 ka) is at a primordial stage of its evolution in comparison with the other volcanoes of the Azores. Clinopyroxenes from Pico Volcano underwent important dehydration processes and after annealing experiments under H2 gas flux, a pre-eruptive H2O content between 93 and 182 ppm was recovered. A moderately high cooling rate for the cpx-host lavas expressed by the clinopyroxene closure temperature (Tc = 755–928 °C ± 20 °C) correlates with the dehydration, suggesting that this process may have occurred during magma ponding at the Moho Transition Zone (17.3–17.7 km) and/or after the eruption. By applying an IVAl-dependent partition coefficient to the measured H amount in clinopyroxene, the pre-eruptive water content of the parental magma was calculated to vary between 0.71 and 1.20 (average of 1.0) wt%. Clinopyroxene geobarometry performed by combining X-ray diffraction with mineral chemistry points to a general crystallisation from the mantle lithosphere (~ 8–9 kbar) to the oceanic mantle/crust boundary (~ 4–5 kbar). The similar major and trace chemistry, water content and Fe3+/Fetot ratio of clinopyroxene, suggest similar conditions of oxygen fugacity, water content and fractional crystallisation of the magma from which clinopyroxene cores crystallised during the Pico Volcano central eruptions from 40 ka to historical times.

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