Abstract
Minerals formed during magma crystallization trap droplets of melt that are preserved as primary or secondary inclusions. Depending on the rate of cooling, the droplets may solidify as glass, or crystallize. Inclusions may contain one or more bubbles, or none. When inclusions are heated the glass or crystalline material are melted and the inclusion expands, the size of bubbles diminishes, and homogenization of the inclusion occurs. It is possible to observe these transformations by means of high-temperature cameras which permit visual observations to 1600°C and above. The possibility of using the homogenization of inclusions to determine the temperature of formation of the host mineral has been demonstrated experimentally, using inclusions in artificial diopside formed at 1300 ± 10°.
Melt inclusions in phenocrysts from nepheline basalt, fergusite porphyry, and tephrite were investigated. In the leucite-bearing rocks leucite crystallized at 1600° or above, and clinopyroxene in the range 1380–1250°. The central part of olivines in nepheline basalt formed at 1290–1270° and the peripheral zones at 1160–1120°; nepheline formed at 1290–1250°; the central part of pyroxenes at 1280–1250° and the peripheral zones at 1160–1120°. These temperatures suggest almost dry magma.
Gas from the bubbles of individual inclusions has been analyzed. The predominant gaseous component of the early crystallization stage of the nepheline basalt and fergusite porphry was CO2, H2S, SO2, NH., HCl, HF, and H. comprise less than 5 volume percent except in olivine of olivine basalt in which the total content of these gases was on average 6.22 volume percent, and in leucite of fergusite porphyry in which H2 was on average 12.7 volume percent. The main gas component in the crystallization of the leucite tephrite were nitrogen and rare gases. Liquid hydrocarbons in the secondary inclusions in pyroxene from nepheline basalt can be accounted for by their assimilation by the magma from enclosing rocks during its rise.
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References
Bazarov, L. S., 1968,A microcamera for the investigation of inclusions in minerals. Geologia i geophizika, No. 8 (in Russian).
Bazarova, T. Yt. 1965,Mineralthermometric investigations of inclusions in minerals of some nepheline bearing rocks. Dokl. Akad. Nauk. No. 4 (in Russian).
----- andDmitriev, E. A., 1967,Crystallization temperature of the fergusite-porphyry of eastern Pamir. Dokl. Akad. Nauk, Vol. 177, No. 1 (in Russian).
----- andShugurova, N. A., 1968,Role of the volatile components in the crystallization of some alkali effusive and hypabyssal rocks. Dokl. Akad. Nauk SSSR, Vol. 178, No. 6 (in Russian).
Bakumenko, I. T., 1968,Study of the glass and crystallized inclusions in the magmatic minerals. In:Problemy petrologii i genetichesoi mineralogii, Vol. 2 (in Russian).
-----et al., 1967,The problem of interprctation of thermometric investigations on the glass inclusions in minerals as indicated by the initial results of tests with artificial inclusions. Dokl. Akad. Nak SSSR, Vol. 175, No. 5 (in Russian).
-----et al., 1968,Crystallized inclusions in quartz of palaeotypical rocks. Dokl. Akad. Nauk SSSR, Vol. 178 (in Russian).
Barrabe, L. andDeicha, G., 1956,Experiences de fusion et de crystallisation magmatique sur des reliquants vitreux des quarts dihexadriques de la Guadeloupe. Bull. Soc franç. Minèr. Cryst., LXXIX, p. 146–55.
—————, 1957,Réanimation de magmas et interpretation de quelques particulatités de leurs éléments de première consolidation. Bull. Soc. franç. geolog., 6e série, T. VII, p. 159–169.
Clocchiatti, M., 1967,Divers aspects des reliquats magmatiques des phénocristaux de quartz des porphires de la region de Bolzano (Italie). C. R. Acad. Sc. Partis, T. 265, p. 1861–1863, série D.
Dolgov, Yu. A. andL. S. Bazarov, 1965,The microcamera for the study of the inclusions of the mineral forming solutions and melts at high temperatures. In:Mineralogicheskaya termometriya barometriya, Izd. Nauka. (in Russian).
----- an dN. A. Shugurova, 1966,Sbornik po geneticheskoi i eksperimentalnoi mineralogii. Vol. 4.
Kalyujni, V. A., 1965,Optical and thermometrical investigations on the glass in the phenocrysts of hyalodacites of the Transcarpathian region. Dokl. Akad. Nauk SSSR, Vol. 160, No. 2.
Lèzier, M., 1966,Inclusions dans quelques nodules de peridotites d’Auvergne. C. R. Acad. Sci. Paris, Série D, T. 263, p. 209–211.
Sobolev, V. S. et al., 1967,Inclusions of melts in phenocrysts of nepheline basalts. Dokl. Akad. Nauk SSR, Vol. 173, No. 2 (in Russian).
Roedder, E., 1965,Liquid CO 2 inclusions in olivine bearing nodules and phenocrysts from basalts. Am. Miner., Vol. 50, p. 1746–1782.
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Sobolev, V.S., Bazarova, T.Y. & Bakumenko, I.T. Crystallization temperature and gas phase composition of alkaline effusives as indicated by primary melt inclusions in the phenocrysts. Bull Volcanol 35, 479–496 (1971). https://doi.org/10.1007/BF02596969
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DOI: https://doi.org/10.1007/BF02596969