SPINMELT-2.0: ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ РАВНОВЕСИЯ Шпинелид-Расплав В БАЗАЛЬТОВЫХ СИСТЕМАХ ПРИ ДАВЛЕНИЯХ ДО 15 КБАР: I. ФОРМУЛИРОВКА, КАЛИБРОВКА И ТЕСТИРОВАНИЕ МОДЕЛИ, "Геохимия"

Николае, Г. С.; Арискин, А.А.; Бармина, Г. С.

doi:10.7868/s0016752518010041

Cited by 3 publications

(1 citation statement)

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“…Программа SPINMELT-2.0, которая использовалась нами при расчётах, -новая высокобарная версия [11] численной модели для расчёта ликвидусных температуры и состава хромшпинелида в широком диапазоне составов базальтовых магм нормальной щёлочности. Верификация модели на соответствие принципу кислотно-основного взаимодействия [12] показала, что модельные тенденции соответствуют этой фундаментальной закономерности, которая не использовалась при формулировке модели [13].…”

Section: геохимияunclassified

Numerical modeling of the effects of major components in the melt on the chrome-spinel stability and a possible solution of the origin chromitites problem

Nikolaev

Ariskin

Barmina

2019

Доклады Академии наук

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Using a new model of the spinel-melt equilibrium SPINMELT-2.0, the effect of variations of fo-, fa-, en-, fs-, di-, an- and ab-components in high-Mg basaltic melts on the topology of the spinel liquidus was quantified. It has been established that enrichment of the melt in pyroxene components leads to an increase, and with plagioclase components, to a decrease in the solubility of chromite. This effect can be important during gravitational compaction of cumulates, accompanied by the extraction of intercumulus melt and its infiltration upward. In this case, one can expect a sequential re-equilibration of the infiltrating melt with cumulative piles of different composition. This suggests the possibility of transfer and new concentration of chrome-spinel at the postcumulus stage of solidification of layered intrusions. The nature of the concentration consists in the extraction of chrome-spinel into the melt enriched in pyroxene components, followed by its discharge during the reaction of this melt with a feldspar-rich matrix of proto-anorthosite layers. The realism of the proposed mechanism is evidenced by the well-known spatial association of chromite layers with anorthosites (intrusion of Ram island, Bushveld complex).

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Section: геохимияunclassified

Numerical modeling of the effects of major components in the melt on the chrome-spinel stability and a possible solution of the origin chromitites problem

Nikolaev

Ariskin

Barmina

2019

Доклады Академии наук

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Effect of Sulfide Sulfur on the Crystallization of Low-Alkali Magmas: Prolegomena

Nikolaev

2023

Geohimiâ

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The effect of sulfide sulfur on the crystallization of ultramafic–mafic–intermediate magmatic systems is considered in order to assess its scale and direction during the crystallization of rock-forming phases. The study carried out a theoretical analysis of the effect of sulfur on the activity of the components of the silicate melt according to the Korzhinskii’s principle of acid–base interaction. To test the theoretical constructions, published experimental data analyzed to select data allowing a direct comparison of sulfur-saturated and sulfur-free runs. Despite the very limited number of such experiments, they all fit well with theoretically predicted trends. It has been established that the addition of sulfur to the system moderately reduces the liquidus temperature of rock-forming minerals within 20–30°C, and significantly affects their composition. In particular, chrome spinel is enriched in chromium by 10–12 mol % and complementary depleted in aluminum. The composition of plagioclase is enriched in the anorthite component by 3 mol % in dacites and 8 mol % in andesites; this effect was not established in basalts, but its strengthening can be expected. Olivine and orthopyroxene demonstrate an insignificant increase in magnesian content, but the field of their coexistence is significantly reduced in favor of orthopyroxene, which should inevitably lead to a change in their cotectic and peritectic proportions. Natural observations that can be interpreted as the result of the sulfur effect are taken from publications. The results obtained lead to the conclusion that sulfur significantly affects the crystallization of silicate magmas. It follows that the petrological dependences calibrated for sulfur-free experiments should be applied with caution to the interpretation of sulfur-bearing systems.

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Updated COMAGMAT-5: Modeling the Effects of Sulfide Precipitation in Parallel to Crystallization Of Alumino-Chromian Spinel

Ariskin,

Bychkov,

Nikolaev

et al. 2023

Petrologiâ

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An updated version of the COMAGMAT-5.3 program is presented, which enables simulations of the silicate-sulfide immiscibility in parallel to crystallization of Al-Cr spinel and other rock-forming minerals. Main changes include a completed recalibration of the previous Fe-Ni sulfide solubility model (Ariskin et al., 2013) and incorporation of equations describing spinel-melt equilibria in a wide range of magmatic systems (Nikolaev et al., 2018а, 2018b). This allowed us to specify more accurately the link between compositions of immiscible sulfides and magma crystallization temperatures, as well as to correct partitioning of alumina between the model spinel and crystallizing melt. The updated COMAGMAT-5.3 can be used for calculations of the crystallization of basaltic to komatiitic magmas, as well as the history of solidification of mafic to ultramafic cumulates, including relative proportions of Al-Cr spinel and immiscible sulfides. Application example includes solidification of sulfide-bearing primitive olivine cumulate from the endocontact of the Yoko-Dovyren intrusion in Northern Transbaikalia (Russia). It is established that maximum crystallization proportions of Al-Cr spinel as much as 3.5 wt % are observed at Ol-Spl cotectic, following an abrupt decrease to slightly negative values during crystallization of plagioclase-bearing assemblages. This results in the inflection point on the trend of evolution of the spinel compositions, which changes from descending the Cr/Al ratio in the field of olivine to its increase when plagioclase starts to crystallize. As compared to previous version COMAGMAT-5.2, the updated model predicts somewhat higher proportions of precipitated sulfides.

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Cited by 3 publications

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Numerical modeling of the effects of major components in the melt on the chrome-spinel stability and a possible solution of the origin chromitites problem

Numerical modeling of the effects of major components in the melt on the chrome-spinel stability and a possible solution of the origin chromitites problem

Effect of Sulfide Sulfur on the Crystallization of Low-Alkali Magmas: Prolegomena

Updated COMAGMAT-5: Modeling the Effects of Sulfide Precipitation in Parallel to Crystallization Of Alumino-Chromian Spinel

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