Abstract
An experimental investigation of plagioclase crystallization in broadly basaltic/andesitic melts of variable Ca# (Ca/(Ca+Na)*100) and Al# (Al/(Al+Si)*100) values and H2O contents has been carried out at high pressures (5 and 10 kbar) in a solid media piston-cylinder apparatus. The H2O contents of glasses coexisting with liquidus or near-liquidus plagioclases in each experiment were determined via an FTIR spectroscopic technique. This study has shown that melt Ca# and Al#, H2O content and crystallization pressure all control the composition of liquidus plagioclase. Increasing melt Ca# and Al# increase An content of plagioclase, whereas the effect of increasing pressure is the opposite. However, the importance of the role played by each of these factors during crystallization of natural magmas varies. Melt Ca# has the strongest control on plagioclase An content, but melt Al# also exerts a significant control. H2O content can notably increase the An content of plagioclase, up to 10 mol% for H2O-undersaturated melts, and 20 mol% for H2O-saturated melts. Exceptionally calcic plagioclases (up to An100) in some primitive subduction-related boninitic and related rocks cannot be attributed to the presence of the demonstrated amounts of H2O (up to 3 wt%). Rather, they must be due to the involvement of extremely refractory (CaO/Na2O>18) magmas in the petrogenesis of these rocks. Despite the refractory nature of some primitive MORB glasses, none are in MORB. These plagioclases were likely produced from more refractory melts with CaO/Na2O=12–15, or from melts with exceptionally high Al2O3(>18%). Magmas of appropriate compositions to crystallize these most calcic plagioclases are sometimes found as melt inclusions in near liquidus phenocrysts from these rocks, but are not known among wholerock or glass compositions. The fact that such melts are not erupted as discrete magma batches indicates that they are effectively mixed and homogenized with volumetrically dominant, less refractory magmas. The high H2O contents (∼6 wt%) in some high-Al basaltic arc magmas may be responsible for the existence of plagioclases up to An95 in arc lavas. However, an alternative possibility is that petrogenesis involving melts with abnormally high CaO/Na2O values (>8) may account for the presence of highly anorthitic plagioclases in these rocks.
Similar content being viewed by others
References
Arculus RJ (1978) Mineralogy and petrology of Grenada, Lesser Antilles Island Arc. Contrib Mineral Petrol 65:413–424
Arulus RJ, Wills KJA (1980) The petrology of plutonic blocks and inclusions from the Lesser Antilles island arc. J Petrol 21: 43–799
Autio LK, Rhodes JM (1984) Costa Rica rift zone basalts: geochemical and experimental data from a possible example of multistage melting. Initial Rep Deep Sea Drill Proj 60:729–745
Bailey JC, Frolova TI, Burikova IA (1989) Mineralogy, geochemistry and petrogenesis of Kurile island-arc basalts. Contrib Mineral Petrol 102:265–280
Baker DR (1987) Depths and H2O content of magma chambers in the Aleutian and Mariana island arcs. Geology 15:496–499
Baker DR, Eggler DH (1987) Compositions of anhydrous and hydrous melts coexisting with plagioclase, augite, and olivine or low-Ca pyroxene from 1 atm to 8 kbar: application to the Aleutian volcanic center of Atka. Am Mineral 72:12–28
Barsdell M (1988) Petrology and petrogenesis of clinopyroxene-rich tholeiitic. Iavas, Merelava Volcano, Vanuatu. J Petrol 29:927–964
Barsdell M, Berry RF (1990) Origin and evolution of primitive ankaramitic lavas from western Epi, Vanuatu. J Petrol 31:747–777
Beard JS, Borgia A (1989) Temporal variation of mineralogy and petrology in cognate gabbroic enclaves at Arenal volcano, Costa Rica. Contrib Mineral Petrol 103:110–122
Bender JF, Hodges FN, Bence AE (1978) Petrogenesis of basalts from the project FAMOUS area: experimental study from 0 to 15 kbars. Earth Planet Sci Lett 41:277–302
Boyd FR, England JL (1960) Apparatus for phase-equilibrium measurements at pressures up to 50 kbar and temperatures up to 1750°C. J Geophys Res 65:741–748
Brophy JG (1986) The Cold Bay volcanic centre, Aleutian volcanic arc. Contrib Mineral Petrol 93:368–380
Cole JW (1978) Andesites of the Tongariro volcanic centre, North Island, New Zealand. J Volcanol Geotherm Res 3:121–153
Crawford AJ, Beccaluva L, Serri G, Dostal J (1986) Petrology, geochemistry and tectonic implications of volcanics dredged from the intersection of the Yap Mariana trenches. Earth Planet Sci Lett 80:265–280
Crawford AJ, Falloon TJ, Eggins S (1987) The origin of island arc high-alumina basalts. Contrib Mineral Petrol 97:417–430
Danyushevsky LV, Sobolev AV, Dmitriev LV (1988) Orthopyroxene-bearing low-Ti tholeiites-the new type of ceanic ridge tholeiite. Doklady Akad Navk SSSR 292:102–105
Danyushevsky LV, Falloon TJ, Sobolev AV, Crawford AJ, Carroll M, Price RC (1993) The H2O content of basalt glasses from Southwest Pacific back-arc basins. Earth Planet Sci Lett 117:347–362
Dmitriev LV, Sobolev AV, Suschevskaya NM, Zapunny SA (1985) Abyssal glasses, petrologic mapping of the oceanic floor and “geochemical leg” 82. Initial Rep Deep Sea Drill Proj 82:509–518
Donaldson CH, Brown RW (1977) Refractory megacrysts and magnesium-rich melt inclusions within spinel in oceanic tholeiites: indicators of magma mixing and parental magma composition. Earth Planet Sci Lett 37:81–89
Duncan RA, Green DH (1980) Role of multistage melting in the formation of oceanic crust. Geology 8:22–26
Duncan RA, Green DH (1987) The genesis of refractory melts in the formation of oceanic crust. Contrib Mineral Petrol 96:326–342
Ewart A (1976) A petrological study of the younger Tongan andesites and dacites, and the olivine tholeiites of Niua Fo'ou Island, S.W. Pacific. Contrib Mineral Petrol 58:1–21
Falloon TJ, Crawford AJ (1991) The petrogenesis of high-calcium boninite lavas dredged from the north Tonga ridge. Earth Planet Sci Lett 102:375–394
Falloon TJ, Green DH (1986) Glass inclusions in magnesian olivine phenocrysts from Tonga: evidence for highly refractory parental magmas in the Tongan arc. Earth Planet Sci Lett 81:95–103
Fisk MR (1984) Depth and temperatures of mid-ocean-ridge magma chambers and the composition of their source magmas. In: Gass IG, Lippard SJ, Shelton AW (eds) Ophiolites and oceanic lithosphere. Blackwell Scientific, Oxford, pp 17–23
Fram MS, Longhi J (1992) Phase equilibria of dikes associated with Proterozoic anorthosite complexes. Am Mineral 7:605–616
Fujimaki H (1986) Fractional crystallization of the basaltic suite of Usu volcano, southwest Hokkaido, Japan, and its relationships with the associated felsic suite. Lithos 19:129–140
Gaetani GA, Grove TL, Bryan WB (1994) Experimental phase relations of basaltic andesite from hole 839B under hydrous and anhydrous conditions. Proc Ocean Drilling Proj Res Leg 135, in press.
Gerlach DC, Grove TL (1982) Petrology of Medicine Lake Highland volcanics-characterization of end members of magma mixing. Contrib Mineral Petrol 80:147–159
Gladney ES, Jones EA, Nickell EJ, Roelandts I (1990) 1988 compilation of elemental concentration data for USGS basalt BCR-1. Geostandards Newsletter 14:209–359
Green DH, Ringwood AE (1967) The genesis of basaltic magmas. Contrib Mineral Petrol 15:103–190
Green DH, Hibberson WO, Jaques AL (1979) Petrogenesis of midoccan ridge basalts. In: McElhinny MW (ed) The Earth: its origin, structure and evolution. Academic Press, London, pp 265–290
Grove TL, Bryan WB (1983) Fractionation of pyroxene-phyric MOR at low pressure: an experimental study. Contrib Mineral Petrol 84:293–309
Grove TL, Gerlach DC, Sando TW (1982) Origin of calc-alkaline series lavas at Medicine Lake volcano by fractionation, assimilation and mixing. Contrib Mineral Petrol 80:160–182
Grove TL, Juster TC (1989) Experimental investigation of low-Ca pyroxene stability and olivine-pyroxene-liquid equilibria at 1-atm in natural basaltic liquids. Contrib Mineral Petrol 103:287–305
Grove TL, Kinzler RJ, Bryan WB (1992) Fractionation of midocean ridge basalt (MORB). Geophys Monogr Am Geophys Union 71:281–310
Haskell K, Forsythe L, Nielsen RL, Fisk MR (1993) Experimental constraints on the parental magma for the high An feldspar bearing Lamont Seamount lavas. EOS Trans Am Geophys Union 74 Supplement No 43:357
Heming RF (1977) Mineralogy and proposed P-T paths of basaltic lavas from Rabaul Caldera, Papua New Guinea. Contrib Mineral Petrol 61:15–33
Housh TB, Luhr JF (1991) Plagioclase-melt equilibria in hydrous systems. Am Mineral 76:477–492
Johannes W (1978) Melting of plagioclase in the system Ab−An−H2O and Qz−Ab−An−H2O at PH2O=5kbars, an equilibrium problem. Contrib Mineral Petrol 66:295–303
Juster TC, Grove TL, Perfit MR (1989) Experimental constraints on the generation of FeTi basalts, andesites and rhyodacites at the Galapagos Spreading Center, 85°W and 95°W. J Geophys Res 94B:9251–9274
Kinzler RJ, Grove TL (1992) Primary magmas of mid-ocean ridge basalts 1. Experiments and methods. J Geophys Res 97:6885–6906
Koyaguchi T (1986) Evidence for two-stage mixing in magmatic inclusions and rhyolitic lava domes on Niijima Island, Japan. J Volcanol Geotherm Res 29:71–98
Kudo AM, Weill DF (1970) An igneous plagioclase thermometer. Contrib Mineral Petrol 25:52–65
Lopez-Escobar L, Vergara M, Frey FA (1981) Petrology and geochemistry of lavas from Antuco Volcano, a basaltic volcano of the southern Andes (37°25′ S). J Volcanol Geotherm Res 11:329–352
Malpas J, Brace T, Dunsworth SM (1989) Structural and petrologic relationships of the CY-4 drill hole of the Cyprus Crustal Study Project. Geol Surv Canada Pap 88–9, pp 39–68
Marsh BD, Fournelle J, Myers JD, Chou I-M (1990) On plagioclase thermometry in island arc rocks: experiments and theory. In: Spencer RJ, Chou I-M (eds) Fluid-mineral interaction (Geochem Soc Spec Pub 2). Geochemical Society, Penn State University, pp 65–83
Meijer A, Reagan M (1981) Petrology and geochemistry of the island of Sarigan in the Mariana Arc; calc-alkaline volcanism in an oceanic setting. Contrib Mineral Petrol 77:337–354
Natland JH (1989) Partial melting of a lithologically heterogeneous mantle-inferences from crystallization histories of magnesian abyssal tholeiites from the Siqueiros Fracture Zone. In: Saunders AD, Norry MJ (eds) Magmatism in the ocean basins. Blackwell Scientific, Oxford, pp 41–70
Price RC, Kennedy AK, Riggs-Sneeringer M, Frey FA (1986) Geochemistry of basalts from the Indian Ocean triple junction: implications for the generation and evolution of Indian Ocean ridge basalts. Earth Planet Sci Lett 78:379–396
Rose WI Jr, Anderson AT Jr, Woodruff LG, Bonis SB (1978) The October 1974 basaltic tephra from Fuego Volcano-description and history of the magma body. J Volcanol Geotherm Res 4:3–53
Sack RO, Walker D, Carmichael ISE (1987) Experimental petrology of alkalic lavas: constraints on cotectics of multiple saturation in natural basaltic liquids. Contrib Mineral Petrol 96:1–23
Sekine T, Katsura T, Aramaki S (1979) H2O saturated phase relations of some andesites with application to the estimation of the initial temperature and H2O pressure at the time of eruption. Geochim Cosmochim Acta 43:1367–1376
Sinton CW, Christie DM, Coombs VL, Nielsen RL, Fisk MR (1993) Near primary melt inclusions in anorthite phenocrysts from the Galapagos Plattform. Earth Planet Sci Lett 119:527–537
Sisson TW, Grove TL (1993) Experimental investigations of the role of H2O in calc-alkaline differentiation and subduction zone magmatism. Contrib Mineral Petrol 113:143–166
Sisson TW, Layne GD (1993) H2O in basalt and basaltic andesite glass inclusions from four subduction-related volcanoes. Earth Planet Sci Lett 117:619–635
Smith TE, Huang CH, Walawender MJ, Cheung P, Wheeler C (1983) The gabbroic rocks of the peninsular ranges batholith, southern California—cumulate rocks associated with calcalkalic basalts and andesites. J Volcanol Geotherm Res 18:249–278
Sobolev AV, Danyushevsky LV (1994) Petrology and geochemistry of the high-Ca boninites from the north termination of the Tonga Trench: constraint on high-Ca boninite primary magma generation conditions. J Petrology (in press)
Sobolev AV, Shimizu N (1993) Ultra-depleted primary melt included in an olivine from the Mid-Atlantic Ridge. Nature 363:151–154
Sobolev AV, Danyushevsky LV, Dmitriev LV, Suschevskaya NM (1989) High-alumina magnesian tholeiite as the primary basalt magma at Midocean ridge. Geochem Int 26:128–133
Sobolev AV, Portnyagin MV, Dmitriev LV, Tsamerian OP, Danyushevsky LV, Kononkova NN, Shimizu N, Robinson PT (1993) Petrology of ultramafic lavas and associated rocks of the Troodos Massif, Cyprus. Petrology 1:331–361
Stakes DS, Shervais JW, Hopson CA (1984) The volcanic-tectonic cycle of the FAMOUS and AMAR Valleys, mid-Atlantic Ridge (36°47′ N): evidence from basalt glass and phenocryst compositional variations for a steady state magma chamber beneath the valley midsections, AMAR 3. J Geophys Res 89:6995–7028
Stolper E (1980) A phase diagram for mid-ocean ridge basalts: preliminary results and implications for petrogenesis. Contrib Mineral Petrol 74:13–27
Stolz AJ, Varne R, Wheller GE, Foden JD, Abbott MJ (1988) The geochemistry and petrogenesis of K-rich alkaline volcanics from the Batu Tara volcano, eastern Sunda arc. Contrib Mineral Petrol 98:374–389
Thy P (1991) High and low pressure phase equilibria of a mildly alkalic lava from the 1965 Surtsey eruption: Experimental results. Lithos 26:223–243
Thy P, Schiffman P, Moores EM (1989) Igneous mineral stratigraphy and chemistry of the Cyprus Crustal Study Project drill core in the plutonic sequences of the Troodos ophiolite. Geol Surv Canada Pap 88–9, pp 147–186
Thy P, Lofgren GE, Imsland P (1991) Melting relations and the evolution of the Jan Mayen magma systems. J Petrol 32:303–332
Tormey DR, Grove TL, Bryan WB (1987) Experimental petrology of normal MORB near the Kane Fracture Zone−22°−25°N, mid-Atlantic ridge. Contrib Mineral Petrol 96:121–139
Walker DA, Shibata T, DeLong SE (1979) Abyssal tholeiites from the Oceanographer Fracture Zone. II Phase equilibria and mixing. Contrib Mineral Petrol 70:111–125
Walker JA, Carr MJ (1986) Compositional variations caused by phenocryst sorting at Cerro Negro volcano, Nicaragua. Geol Soc Am Bull 97:1156–1162
Wilkinson JFG (1982) The genesis of mid-ocean ridge basalts. Earth Sci Rev 18:1–57
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Panjasawatwong, Y., Danyushevsky, L.V., Crawford, A.J. et al. An experimental study of the effects of melt composition on plagioclase-melt equilibria at 5 and 10 kbar: implications for the origin of magmatic high-An plagioclase. Contr. Mineral. and Petrol. 118, 420–432 (1995). https://doi.org/10.1007/s004100050024
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s004100050024