Abstract
Liquidus phase relationships determined on the join CaAl2Si2O8 (anorthite)-Mg2SiO4 (forsterite)-SiO2 (quartz) at 10 kbar show that increasing pressure causes the forsterite and anorthite primary phase fields to shrink and the spinel, enstatite and silica fields to expand. The boundary line between the enstatite and forsterite fields and that between the enstatite and quartz fields both move away from the SiO2 apex as pressure increases. Therefore, simplified source peridotite would yield simplified basaltic partial melts with decreasing silica as pressure increases, as has been found in other studies. Also, increasing pressure decreases the amount of silica enrichment in residual liquids produced by fractional crystallization. Although anorthite is unstable in simplified peridotite above 9 kbar in the system CaO-MgO-Al2O3-SiO2, it is an important phase in the fractional crystallization of simplified basalts at 10 kbar and probably also in natural basalts.
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References
Andersen O (1915) The system anorthite-forsterite-silica. Am J Sci 4th Ser 39:407–454
Anonymous (1969) The international practical temperature scale of 1968. Metrologia 5:35–44
Boyd FR, England JL (1963) Effect of pressure on the melting of diopside, CaMgSi2O6, and albite, NaAlSi3O8, in the range up to 50 kilobars. J Geophys Res 68:311–323
Chen C-H, Presnall DC (1975) The system Mg2SiO4-SiO2 at pressures up to 25 kilobars. Am Mineral 60:398–406
Clark SP, Schairer JF, de Neufville J (1962) Phase relations in the system CaMgSi2O6-CaAl2Si2O6-SiO2 at low and high pressures. Yearb Carnegie Inst Washington 61:59–68
Green DH, Ringwood AE (1967) The genesis of basaltic magmas. Contrib Mineral Petrol 15:103–190
Irvine TN (1975) Olivine-pyroxene-plagioclase relations in the system Mg2SiO4-CaAl2Si2O8-KAlSi3O8-SiO2 and their bearing on the differentiation of stratiform intrusions. Yearb Carnegie Inst Washington 74:492–500
Kuno H (1950) Petrology of Hakone volcano and the adjacent areas, Japan. Geol Soc Am Bull 61:957–1020
Kushiro I (1968) Compositions of magmas formed by partial zone melting of the earth's upper mantle. J Geophys Res 73:619–634
Longhi J (1978) Pyroxene stability and the composition of the lunar magma ocean. Proc Lunar Sci Conf, 9th, 285–306
Muir ID, Tilley CE, Scoon JH (1957) Contributions to the petrology of Hawaiian basalts. I. The picrite basalts of Kilauea. Am J Sci 255:241–253
O'Hara MJ (1965) Primary magmas and the origin of basalts. Scot J Geol 1:19–40
O'Hara MJ (1968) The bearing of phase equilibria studies in synthetic and natural systems on the origin and evolution of basic and ultrabasic rocks. Earth Sci Revs 4:69–133
O'Hara MJ, Yoder HS, Jr (1967) Formation and fractionation of basic magmas at high pressures. Scot J Geol 3:67–117
O'Hara MJ, Biggar GM, Richardson SW, Ford CE, Jamieson BG (1970) The nature of seas, mascons and the lunar interior in the light of experimental studies. Proc Appolo 11 Lunar Sci Conf, 695–710
Presnall DC (1966) The join forsterite-diopside-iron oxide and its bearing on the crystallization of basaltic and ultramafic magmas. Am J Sci 264:753–809
Presnall DC (1975) Alumina content of enstatite as a geobarometer for plagioclase and spinel lherzolites. Am Mineral 61:398–406
Presnall DC, Brenner NL, O'Donnell TH (1973) Drift of Pt/Pt10Rh and W3Re/W25Re thermocouples in single stage piston-cylinder apparatus. Am Mineral 58:771–777
Presnall DC, Dixon JR, O'Donnell TH, Dixon SA (1979) Generation of mid-ocean ridge tholeiites. J Petrol 20:3–35
Presnall DC, Dixon SA, Dixon JR, O'Donnell TH, Brenner NL, Schrock RL, Dycus DW (1978) Liquidus phase relations on the join diopside-forsterite-anorthite from 1 atm to 20 kbar: their bearing on the generation and crystallization of basaltic magma. Contrib Mineral Petrol 66:203–220
Presnall DC, Simmons CL, Porath H (1972) Changes in electrical conductivity of a synthetic basalt during melting. J Geophys Res 77:5665–5672
Snyder GL (1959) Geology of Little Sitkin Island, Alaska. US Geol Survey Bull 1028-H:169–210
Stolper E (1980) A phase diagram for mid-ocean ridge basalts: preliminary results and implications for petrogenesis. Contrib Mineral Petrol 74:13–27
Yoder HS, Jr, Tilley CE (1962) Origin of basalt magmas: an experimental study of natural and synthetic rock systems. J Petrol 3:342–532
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Contribution no. 419, Department of Geosciences, University of Texas at Dallas
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Sen, G., Presnall, D.C. Liquidus phase relationships on the join anorthite-forsterite-quartz at 10 kbar with applications to basalt petrogenesis. Contr. Mineral. and Petrol. 85, 404–408 (1984). https://doi.org/10.1007/BF01150296
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DOI: https://doi.org/10.1007/BF01150296