Melting and Crystallization of Moderately Alkaline Volcanic Rocks: Physicochemical Modeling and Experimental Study

2020 ◽  
Vol 65 (9) ◽  
pp. 1378-1383
Author(s):  
V. A. Krenev ◽  
N. N. Efimov ◽  
P. N. Vasil’ev ◽  
D. F. Kondakov ◽  
E. N. Pechenkina ◽  
...  
Keyword(s):  
Experimental Study ◽  
Volcanic Rocks ◽  
Physicochemical Modeling ◽  
Melting And Crystallization

Physicochemical modeling and experimental study of the interaction in the Si-Al-Ca-Mg-Fe-Na-K-V-Cl-H-O system

2009 ◽  
Vol 54 (7) ◽  
pp. 1144-1150
Author(s):  
N. V. Kochetkova ◽  
N. P. Dergacheva ◽  
S. V. Fomichev ◽  
V. A. Krenev
Keyword(s):  
Experimental Study ◽  
Physicochemical Modeling

scholarly journals Experimental study of amphibole crystallization from the highly magnesian melt of Shiveluch volcano

2019 ◽  
Vol 27 (5) ◽  
pp. 476-495 ◽  
Author(s):  
A. G. Simakin ◽  
V. N. Devyatova ◽  
T. P. Salova ◽  
O. Yu. Shaposhnikova
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Oxygen Fugacity ◽  
Volcanic Rocks ◽  
Maximum Size ◽  
Rapid Quenching ◽  
Shiveluch Volcano ◽  
Modified Technique ◽  
Before And After ◽  
Partial Transfer

The paper reports results of an experimental study of amphibole crystallization from the highly magnesian andesite melt of Shiveluch volcano, Kamchatka. The experiments were carried out in IHPV at 300 MPa and 940–980°С in iron-saturated platinum capsules, using rapid quenching and temperature oscillations (in some experiments). The redox state of iron in the system was measured before and after the experiments using Mössbauer spectroscopy. The maximum size of the experimental amphibole crystals (up to 200 μm) was close to those of natural amphibole phenocrysts in the volcanic rocks of Shiveluch volcano. The experimental data show that the content of octahedrally coordinated Al (Al6) in the amphibole considerably varies with small variations in the intensive parameters (P, T, and fO2) and composition of the melt, and the maximum Al6 concentration can be evaluated only by using a reasonably large dataset of amphibole analyses. A modified 13eCNK method is suggested to calculate the values of Al6 and Fe3+/Fe2+ with regard for the Ti concentration and the probable partial transfer of Mg into site B in high-Mg amphibole. Calculations with this modified technique yield lower Fe3+/Fe2+ and higher Al6 values. Our experimental data show that the temperature of amphibole liquidus crystallization decreases from about 990 to 960°C when the oxygen fugacity drops from NNO + 1.5 to NNO + 0.4. In view of this, the transition from amphibole-bearing to anhydrous mineral assemblage in the magmas of Shiveluch volcano might have been caused by variations of the oxygen fugacity but not water. The application of our geobarometer to amphiboles from Shiveluch volcano (extrusions Krasnaya and Karan) yields the highest pressure estimate of above 1 GPa, corresponding to the P-T conditions of the melting of garnet-bearing amphibolite in the lower crust.

scholarly journals Experimental evidence on the origin of Ca-rich carbonated melts formed by interaction between sedimentary limestones and mantle-derived ultrabasic magmas

Geology ◽  
2022 ◽  
Author(s):  
Michele Lustrino ◽  
Natascia Luciani ◽  
Vincenzo Stagno ◽  
Silvia Narzisi ◽  
Matteo Masotta ◽  
...  
Keyword(s):  
Experimental Study ◽  
Central Europe ◽  
Bohemian Massif ◽  
Potential Temperature ◽  
Volcanic Rocks ◽  
Maximum Amount ◽  
Primitive Character ◽  
Complete Dissolution ◽  
Massif Central ◽  
Limestone Assimilation

In this experimental study, we documented the formation of strongly ultrabasic and ultracalcic melts through the interaction of melilititic and basanitic melts with calcite. Three strongly to moderately SiO2-undersaturated volcanic rocks from the Bohemian Massif (central Europe) were mixed with 10, 30, and 50 wt% CaCO3 and melted at 1100, 1200, and 1300 °C at 2 kbar to evaluate the maximum amount of carbonate that can be assimilated by natural ultrabasic melts at shallow depths. Experiments revealed a surprisingly complete dissolution of the CaCO3, only rarely reaching carbonate saturation, with typical liquidus phases represented by olivine, spinel, melilite, and clinopyroxene. Only in the runs with the most SiO2-undersaturated compositions did abundant monticellite form instead of clinopyroxene. For all starting mixtures, strongly ultrabasic (SiO2 down to 15.6 wt%), lime-rich (CaO up to 43.6 wt%), ultracalcic (CaO/Al2O3 up to ~27) melt compositions were produced at 1200 and 1300 °C, with up to ~25 wt% dissolved CO2. When present, quenched olivine showed much higher forsterite content (Fo95–97) than olivine in the natural samples (Fo79–85). The two major results of this study are (1) silicate-carbonatite melt compositions do not necessarily imply the existence of carbonatitic components in the mantle, because they are also produced during limestone assimilation, and (2) Fo-rich olivines cannot be used to infer any primitive character of the melt nor high potential temperature (Tp).

scholarly journals Experimental study on propagation of hydraulic fracture in volcanic rocks using industrial CT technology

2013 ◽  
Vol 40 (3) ◽  
pp. 405-408 ◽  
Author(s):  
Lichun JIA ◽  
Mian CHEN ◽  
Liangtian SUN ◽  
Zhiyu SUN ◽  
Wei ZHANG ◽  
...  
Keyword(s):  
Experimental Study ◽  
Hydraulic Fracture ◽  
Volcanic Rocks ◽  
Industrial Ct ◽  
Ct Technology

Experimental study on a basanite from the McMurdo Volcanic Group, Antarctica: inference on its mantle source

2000 ◽  
Vol 12 (1) ◽  
pp. 105-116 ◽  
Author(s):  
Andrea Orlando ◽  
Sandro Conticelli ◽  
Pietro Armienti ◽  
Daniele Borrini
Keyword(s):  
Experimental Study ◽  
Partial Melting ◽  
Mantle Source ◽  
Volcanic Rocks ◽  
Liquidus Curve ◽  
Mantle Xenoliths ◽  
Primary Magma ◽  
Geochemical Evidence ◽  
Volcanic Group ◽  
Phase Relationships

Experiments to reconstruct the liquidus curve and establish the phase relationships of a basanite (Mg# = 72) from the McMurdo Volcanic Group, (thought to represent a nearly primary magma) used 1.0– 3.0 GPa and 1175–1550°C. The results suggest that this basanite could be generated by partial melting either of a spinel Iherzolite (at P = 1.5–2.0 GPa and T = 1390–1490°C) or of a garnet pyroxenite (at P > 3.0 GPa and T > 1550°C) source. Several lines of petrological and geochemical evidence support the latter hypothesis. Moreover, experimental results indicate the presence of mica in the source if it is assumed that the magma lost some water during its ascent to the surface. This is supported by the presence of mica and amphibole-bearing mantle xenoliths hosted in the most primitive volcanic rocks of the McMurdo Volcanic Group. These results and observations suggest that the source of magmas underwent metasomatism prior to partial melting.

scholarly journals Polybaric fractional crystallisation of arc magmas: an experimental study simulating trans-crustal magmatic systems

2021 ◽  
Vol 177 (1) ◽  
Author(s):  
Felix Marxer ◽  
Peter Ulmer ◽  
Othmar Müntener
Keyword(s):  
Experimental Study ◽  
Volcanic Rocks ◽  
Pressure Vessels ◽  
Fractional Crystallisation ◽  
Magma Ascent ◽  
Stability Field ◽  
Calc Alkaline ◽  
Compositional Evolution ◽  
Arc Magmas ◽  
Lines Of Descent

AbstractCrystallisation-driven differentiation is one fundamental mechanism proposed to control the compositional evolution of magmas. In this experimental study, we simulated polybaric fractional crystallisation of mantle-derived arc magmas. Various pressure–temperature trajectories were explored to cover a range of potential magma ascent paths and to investigate the role of decompression on phase equilibria and liquid lines of descent (LLD). Fractional crystallisation was approached in a step-wise manner by repetitively synthesising new starting materials chemically corresponding to liquids formed in previous runs. Experiments were performed at temperatures ranging from 1140 to 870 °C with 30 °C steps, and pressure was varied between 0.8 and 0.2 GPa with 0.2 GPa steps. For most fractionation paths, oxygen fugacity (fO2) was buffered close to the Ni-NiO equilibrium (NNO). An additional fractionation series was conducted at fO2 corresponding to the Re-ReO2 buffer (RRO ≈ NNO+2). High-pressure experiments (0.4–0.8 GPa) were run in piston cylinder apparatus while 0.2 GPa runs were conducted in externally heated pressure vessels. Resulting liquid lines of descent follow calc-alkaline differentiation trends where the onset of pronounced silica enrichment coincides with the saturation of amphibole and/or Fe–Ti–oxide. Both pressure and fO2 exert crucial control on the stability fields of olivine, pyroxene, amphibole, plagioclase, and Fe–Ti–oxide phases and on the differentiation behaviour of arc magmas. Key observations are a shift of the olivine–clinopyroxene cotectic towards more clinopyroxene-rich liquid composition, an expansion of the plagioclase stability field and a decrease of amphibole stability with decreasing pressure. Decompression-dominated ascent trajectories result in liquid lines of descent approaching the metaluminous compositional range observed for typical arc volcanic rocks, while differentiation trends obtained for cooling-dominated trajectories evolve to peraluminous compositions, similar to isobaric liquid lines of descent at elevated pressures. Experiments buffered at RRO provide a closer match with natural calc-alkaline differentiation trends compared to fO2 conditions close to NNO. We conclude that decompression-dominated fractionation at oxidising conditions represents one possible scenario for arc magma differentiation.

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