Article
Article name Forces generating crystallization differentiation, and the evolution of the melt composition on the example of plagioclase
Authors Kirdyashkin A.A. doctor of geology and mineralogy sciences, aak@igm.nsc.ru;
Kirillin A.. research scientist, mouks@ya.ru
Bibliographic description
Category Earth science
DOI 551.2+551.14+552.1
DOI 10.21209/2227-9245-2020-26-7-44-52
Article type
Annotation Crystallization differentiation processes in the melt volume are investigated for albite-anorthite continuous solid solution series. It has shown that crystallization differentiation occurs in the isothermal melt volume due to hydrodynamic instability of the melt/solid particles system. The time of particle settling in a 10 cm thick melt layer is estimated for different particle sizes. In terrestrial conditions, the existence of large melt volumes with long lifetime is possible in the case of a long-lived heat source of high thermal power. This source is a mantle thermochemical plume with a mushroom-shaped head. The particle settling time is estimated for the melt layer thickness, i. e. plume head thickness equal to 10 km. A calculation technique is presented for composition of the melt remaining after settling of plagioclase particles. The results of calculations of changes in the melt composition due to crystallization differentiation at a temperature T = 1410 °C and a pressure P = 6,3 kbar are presented. For a melt whose composition corresponds to N 47,5 (weight percentage of anorthite is 47,5 %), the oxide content in the settled plagioclase, the composition of the melt in its intercrystalline spaces, and the residual melt composition are calculated. At constant temperature, the crystallization differentiation of the melt whose composition corresponds to plagioclase leads to the compositional changes in the initial melt. Calculations of the melt composition have shown that the melt is depleted in anorthite component owing to settling of plagioclase particles. The composition of plagioclase therewith shifts to the liquidus line, reaching its limit on this line
Key words plagioclase; phase diagram; hydrodynamic instability; melt; plume head; settling of solid particles; composition calculations
Article information Kirdyashkin А., Kirdyashkin А. Forces generating crystallization differentiation, and the evolution of the melt composition on the example of plagioclase // Transbaikal State University Journal, 2020, vol. 26, no. 7, pp. 44–52. DOI: 10.21209/2227-9245-2020-26-7-44-52.
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Full articleForces generating crystallization differentiation, and the evolution of the melt composition on the example of plagioclase