Abstract
In some abyssal tholeiite magmas having a relatively high content of olivine component, olivine is the first mineral to crystallize. In others having a relatively high content of plagioclase component, plagioclase is the first mineral to crystallize. The rooks of these two groups are called OL- and PL-tholeiites respectively. Continued crystallization drives the residual liquids to the cotectic curve between the olivine and plagioclase fields. Subsequent cotectic crystallization results in an increase of pyroxene component in residual magmas, eventually leading to the crystallization of clinopyroxene. Marked enrichment of iron and TiO2 takes place in later stages. The total iron/MgO ratio may be used as an indicator for the degree of fractional crystallization. Average compositions of OL- and PL-tholeiites are calculated for a series of total iron/MgO ranges (Table 7). PL-tholeiites are usually but not always higher in Al2O3 than OL-tholeiites.
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Cann, J. R.: Spilites from the Carlsberg Ridge, Indian Ocean. J. Petrol. 10, 1–19 (1969).
—, Vine, F. J.: An area on the crest of the Carlsberg Ridge: petrology and magnetic survey. Phil. Trans. Roy. Soc. London, Ser. A 259, 198–217 (1966).
Engel, A. E. J., Engel, C. G.: Composition of basalts from the Mid-Atlantic Ridge. Science 144, 1330–1333 (1964a).
—: Igneous rocks of the East Pacific Rise. Science 146, 477–485 (1964b).
—, Havens, R. G.: Chemical characteristics of oceanic basalts and the upper mantle. Geol. Soc. Amer. Bull. 76, 719–734 (1965).
Engel, C. G., Fischer, R. L., Engel, A. E. J.: Igneous rocks of the Indian Ocean floor. Science 150, 605–610 (1965).
Green, D. H., Ringwood, A. E.: The genesis of basaltic magmas. Contr. Mineral. and Petrol. 15, 103–190 (1967).
Hekinian, R.: Rocks from the mid-oceanic ridge in the Indian Ocean. Deep-Sea Res. 15, 195–213 (1968).
Kay, R., Hubbard, N. J., Gast, P. W.: Chemical characteristics and origin of oceanic ridge volcanic rocks. J. Geophys. Res. 75, 1585–1613 (1970).
McBirney, A. R., Aoki, K.: Petrology of the Galapagos Islands. In: R. I. Bowman (ed.), The Galapagos, p. 71–77. Berkeley: Univ. California Press 1966.
Miyashiro, A., Shido, F., Ewing, M.: Diversity and origin of abyssal tholeiite from the MidAtlantic Ridge near 24° and 30° north latitude. Contr. Mineral. and Petrol. 23, 38–52 (1969).
—: Crystallization and differentiation in abyssal tholeiites and gabbros from midoceanic ridges. Earth and Planetary Sci. Letters 7, 361–365 (1970).
Mueller, R. F.: Oxidative capacity of magmatic components. Am. J. Sci. 270, 236–243 (1971).
Muir, I. D., Tilley, C. E.: Basalts from the northern part of the Mid-Atlantic Ridge. II. The Atlantis collections near 30° N. J. Petrol. 7, 193–201 (1966).
Nicholls, G. D.: Basalts from the deep ocean floor. Mineral. Mag. 34 (Tilley Vol.), 373–388 (1965).
Osborn, E. F.: Reaction series for subalkaline igneous rocks based on different oxygen pressure conditions. Amer. Mineralogist 47, 211–226 (1962).
Shido, F., Miyashiro, A., Ewing, M.: Compositional variation in pillow lavas from the Mid-Atlantic Ridge. (In press.)
Shih, Chi-yu, Gast, P. W.: Rare earths in abyssal tholeiites, gabbros and their mineral separates from Mid-Atlantic Ridge near 24° N (abstract). Trans. Am. Geophys. Union 52, 376 (1971).
Vinogradov, A. P., Udintsev, G. B., Dmitriev, L. V., Kanaev, V. F., Neproehnov, Y. P., Petrova, G. N., Rikunov, L. N.: The structure of the mid-oceanic rift zone of the Indian Ocean and its place in the world rift system. Tectonophysics 8, 377–401 (1969).
Wager, L. R., Brown, G. M.: Layered Igneous Rooks. San Francisco: Freeman 1967.
Yoder, H. S., Jr., Tilley, C. E.: Origin of basalt magmas: an experimental study of natural and synthetic rock systems. J. Petrol. 3, 342–532 (1962).
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Lamont-Doherty Geological Observatory Contribution No. 1653.
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Shido, F., Miyashiro, A. & Ewing, M. Crystallization of abyssal tholeiites. Contr. Mineral. and Petrol. 31, 251–266 (1971). https://doi.org/10.1007/BF00371148
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DOI: https://doi.org/10.1007/BF00371148