EQUILIBRIUM CRYSTALLIZATION OF MASSIF-TYPE ANORTHOSITE RESIDUAL MELTS

2020 ◽  
Author(s):  
Riikka Maria Fred ◽  
◽  
Aku Heinonen ◽  
Jussi S. Heinonen
Keyword(s):  
Equilibrium Crystallization

scholarly journals Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland

2020 ◽  
Vol 175 (9) ◽  
Author(s):  
Riikka Fred ◽  
Aku Heinonen ◽  
Jussi S. Heinonen
Keyword(s):  
Magma Chambers ◽  
Equilibrium Crystallization ◽  
Liquid Line ◽  
Rock Types ◽  
Residual Magma ◽  
Icp Ms ◽  
Mineral Assemblages ◽  
Residual Melt ◽  
Liquid Line Of Descent

Abstract Fe–Ti–P-rich mafic to intermediate rocks (monzodiorites and oxide–apatite–gabbronorites, OAGNs) are found as small intrusions in most AMCG (anorthosite–magnerite–charnokite–granite) suites. The origin of the monzodioritic rocks is still debated, but in many studies, they are presumed to represent residual liquid compositions after fractionation of anorthositic cumulates. In the 1.64 Ga Ahvenisto complex, SE Finland, monzodioritic rocks occur as minor dike-like lenses closely associated with anorthositic rocks. We report new field, petrographic, and geochemical (XRF, ICP-MS, EMPA) data complemented with crystallization modeling (rhyolite-MELTS, MAGFRAC) for the monzodioritic rocks, apatite–oxide–gabbronorite, and olivine-bearing anorthositic rocks of the Ahvenisto complex. The presented evidence suggest that the monzodioritic rocks closely represent melt compositions while the apatite–oxide–gabbronorite and olivine-bearing anorthositic rocks are cumulates. The monzodioritic rocks seem to form a liquid line of descent (LLD) from primitive olivine monzodiorites to more evolved monzodiorites. Petrological modeling suggests that the interpreted LLD closely corresponds to a residual melt trend left after fractional crystallization (FC) and formation of the cumulate anorthositic rocks and minor apatite–oxide–gabbronorite in shallow magma chambers. Consequent equilibrium crystallization (EC) of separate monzodioritic residual magma batches can produce the observed mineral assemblages and the low Mg numbers measured from olivine (Fo25–45) and pyroxenes (En48–63, Mg#cpx 60–69). The monzodioritic rocks and apatite–oxide–gabbronorites show similar petrological and geochemical characteristics to corresponding rock types in other AMCG suites, and the model described in this study could be applicable to them as well.

Role of the interfaces and the charge of a molecule in the non-equilibrium crystallization of dipeptide nanomaterials onto solid substrates

CrystEngComm ◽  
2018 ◽  
Vol 20 (47) ◽  
pp. 7688-7699 ◽  
Author(s):  
Alexander I. Loskutov ◽  
Boris V. Lokshin ◽  
Tatiana A. Gudasheva ◽  
Vadim B. Oshurko ◽  
Nestor Solis Pinargote ◽  
...  
Keyword(s):  
Critical Role ◽  
Structure And Properties ◽  
Net Charge ◽  
Equilibrium Crystallization ◽  
Solid Substrates ◽  
Non Equilibrium

A critical role of the net charge of molecule and nature of interfaces on the structure and properties of crystallized dipeptide layers was established.

Non-Equilibrium Crystallization of a Eutectic Alloy - Mathematical Model

2019 ◽  
Vol 946 ◽  
pp. 417-422
Author(s):  
Alexander D. Drozin ◽  
Maxim V. Dudorov ◽  
Natalia M. Yaparova
Keyword(s):  
Mathematical Model ◽  
Eutectic Alloy ◽  
Liquid State ◽  
Transformation Temperature ◽  
Amorphous State ◽  
Eutectic Alloys ◽  
Equilibrium Crystallization ◽  
Eutectic Transformation ◽  
Solid Phases ◽  
The Mathematical Model

The process of a eutectic alloy crystallization is considered when the eutectic alloy is instantly cooled from the liquid state to below the eutectic transformation temperature. The features of such crystallization are considered. The mathematical model of the process is constructed that takes into account the nucleation of new phases particles, their growth and the associated change the concentrations of the melt components. The nuclei of new phases are supposed be spherical. As they grow, they come into contact and become lamellar. The developed approach was applied to the amorphization process of the eutectic alloys. An amorphous state has been reached if the clusters of solid phases can’t grow above nanosize. The model allows researching the necessary amorphization conditions.

Origin of Iron Meteorite Groups IAB and IIICD

1980 ◽  
Vol 35 (8) ◽  
pp. 781-795 ◽  
Author(s):  
John T. Wasson ◽  
John Willis ◽  
Chien M. Wai ◽  
Alfred Kracher
Keyword(s):  
Parent Body ◽  
Iron Meteorite ◽  
Iron Meteorites ◽  
Impact Melt ◽  
Equilibrium Crystallization ◽  
Ni Content ◽  
Oxide Phases ◽  
Host Metal ◽  
Impact Melts ◽  
The Impact

AbstractSeveral low-Ni iron meteorites previously assigned to group IAB are reclassified IIICD on the basis of lower Ge, Ga, W and Ir concentrations and higher As concentrations; the low-Ni extreme of IIICD is now 62 mg/g, that of IAB is 64 mg/g. The resulting fractionation patterns in the two groups are quite similar. It has long been established that, in contrast to the magmatic iron meteorite groups, IAB and IIICD did not form by fractional crystallization of a metallic magma. Other models have been proposed, but all have serious flaws. A new model is proposed involving the formation of each iron in small pools of impact melt on a parent body consisting of material similar to the chondritic inclusions found in some IAB and IIICD irons, but initially unequilibrated. These impact melts ranged in temperatures from ~ 1190 K to ~ 1350 K. The degree of equilibration between melt and unmelted solids ranged from minimal at the lowest temperature to moderate at the highest temperature. The lowest temperature melts were near the cotectic in the Fe-Ni-S system with Ni contents of ~ 12 atom %. Upon cooling, these precipitated metal having ~ 600 mg/g Ni by equilibrium crystallization. The Ni-rich melt resulted from the melting of Ni-rich sulfides and metal in the unequilibrated chondritic parent. Low-Ni irons formed in high temperature melts near the composition of the FeS-Fe eutectic or somewhat more metal rich. We suggest that the decreasing Ge, Ga and refractory abundances with increasing Ni concentration reflect the trapping of these elements in oxide phases in the unequilibrated chondritic material, and that very little entered the Ni-rich melt parental to the Oktibbeha County iron. The remaining elements tended to have element/Ni ratios in the melts that were more or less independent of temperature. The remarkable correlation between I-Xe age of the chondritic inclusions and Ni content of the host metal is explained by a detailed evolution of (mega)regolith in which these groups originated. The most Ni-rich melts could only be generated from an unequilibrated chondrite parent; as the continuing deposition of impact energy produced increasingly higher grades of metamorphism, the maximum Ni content of the impact melts (and their subsequently precipitated metal) gradually decreased.

scholarly journals Non-Equilibrium Crystallization of Monotectic Zn-25%Bi Alloy under 600 g

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4341
Author(s):  
Grzegorz Boczkal ◽  
Pawel Palka ◽  
Piotr Kokosz ◽  
Sonia Boczkal ◽  
Grazyna Mrowka-Nowotnik
Keyword(s):  
Normal Gravity ◽  
Separation Zone ◽  
Separation Boundary ◽  
Equilibrium Crystallization ◽  
Flat Interface ◽  
Monotectic System ◽  
High Degree ◽  
Narrow Area ◽  
Manufacturing Stage ◽  
Gravitational Segregation

This study investigated the influence of supergravity on the segregation of components in the Zn–Bi monotectic system and consequently, the creation of an interface of the separation zone of both phases. The observation showed that near the separation boundary, in a very narrow area of the order of several hundred microns, all types of structures characteristic for the concentration range from 0 to 100% bismuth occurred. An additional effect of crystallization in high gravity is a high degree of structural order and an almost perfectly flat separation boundary. This is the case for both the zinc-rich zone and the bismuth-rich zone. Texture analysis revealed the existence of two privileged orientations in the zinc zone. Gravitational segregation also resulted in a strong rearrangement of the heavier bismuth to the outer end of the sample, leaving only very fine precipitates in the zinc region. For comparison, the results obtained for the crystallization under normal gravity are given. The effect of high orderliness of the structure was then absent. Despite segregation, a significant part of bismuth remained in the form of precipitates in the zinc matrix, and the separation border was shaped like a lens. The described method can be used for the production of massive bimaterials with a directed orientation of both components and a flat interface between them, such as thermo-generator elements or bimetallic electric cell parts, where the parameters (thickness) of the junction can be precisely defined at the manufacturing stage.

Influence of Modifiers on the Structure and Properties of Composite Coatings System Ti-B-Fe

2014 ◽  
Vol 880 ◽  
pp. 80-87
Author(s):  
Nina K. Galchenko ◽  
Ksenia A. Kolesnikova ◽  
S.I. Belyuk ◽  
B.V. Dampilon
Keyword(s):  
Electron Beam ◽  
Composite Coatings ◽  
Reactive Diffusion ◽  
Amorphous Boron ◽  
Structure And Properties ◽  
Coating Structure ◽  
Equilibrium Crystallization ◽  
Structure Degradation ◽  
Boride Coatings ◽  
Two Factors

The paper studies how microalloying with amorphous boron (Bam) and zirconia (ZrO2) influences the structure and properties of boride coatings. Two factors are found to strongly affect the structure and phase formation in composite coatings produced by electron beam surfacing, especially when using thermoreactive powders: (i) high reactive diffusion between the composite and substrate components, which causes the coating structure degradation, and (ii) slight deviations from phase concentrations and equilibrium crystallization, which give rise to such nonequilibrium phases in the coating structure under the electron beam as ferroboron, ferrotitanium and binary eutectics.

Aluminium in quartz as an indicator of the temperature of formation of agate

2001 ◽  
Vol 65 (3) ◽  
pp. 407-413 ◽  
Author(s):  
J. Götze ◽  
M. Plötze ◽  
M. Tichomirowa ◽  
H. Fuchs ◽  
J. Pilot
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Oxygen Isotope ◽  
Paramagnetic Resonance ◽  
Equilibrium Crystallization ◽  
Isotope Data ◽  
Direct Estimation ◽  
Oxygen Isotope Data ◽  
Good Accord ◽  
Parent Rocks ◽  
Electron Paramagnetic

AbstractAn ‘Al-thermometer’ was applied to agate samples of volcanic parent rocks to provide information about the temperature of agate formation. The temperatures were calculated from concentrations of [AlO4]0 centres determined by electron paramagnetic resonance (EPR) measurements. The calculations for agate bands in some cases yield temperatures of up to 655°C, which are assumed to be invalid; they are thought to be artifacts resulting from non-equilibrium crystallization processes. In contrast, the formation temperatures (60–198°C) estimated for associated quartz incrustations within the agate geodes are in good accord with those calculated from oxygen isotope data. Direct estimation of the formation temperatures of agates is problematic. The best results will be obtained by analyses of associated phanerocrystalline quartz incrustations.

Chemistry of ilmenites crystallized within the anhydrous melting range of a tholeiitic andesite at pressures between 5 and 26 kb

1976 ◽  
Vol 40 (316) ◽  
pp. 857-862 ◽  
Author(s):  
R. N. Thompson
Keyword(s):  
Liquid Glass ◽  
Significant Trend ◽  
Snake River Plain ◽  
The Other ◽  
Snake River ◽  
Melting Range ◽  
Equilibrium Crystallization ◽  
Titaniferous Magnetite ◽  
Positive Correlations ◽  
River Plain

SummaryMicroprobe analyses of eight ilmenites, a titaniferous magnetite, and a rutile are presented. They were synthesized at pressures from 5 to 26 kb and temperatures between 1075 and 1225°C in the anhydrous melting interval of a tholeiitic andesite from the Snake River Plain, Idaho, U.S.A. Both the Fe/Ti distribution between coexisting ilmenite and titanomagnetite at 11 kb/1075°C and the low calculated Fe3+ contents of the other ilmenites confirm previous suggestions that the fo2 in these experiments was buffered by graphite capsules to values near those generated by the wüstitemagnetite assemblage. Mn in the ilmenites (0·30-0·51% MnO) shows moderate negative correlations with both the pressures and temperatures of their formation, whilst Al (0·41-1·06 % Al2O3) shows poor positive correlations with these parameters. In contrast, the only significant trend shown by Mg in the ilmenites (2·09-5·26 % MgO) is with the position of each experimental run in the melting interval of the lava. Mg/(Mg + Fe2+) of the ilmenite decreases during equilibrium crystallization at a given pressure and appears to be controlled solely by Mg/Fe2+ distribution amongst the coexisting ferromagnesian minerals and interstitial liquid (glass).

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