Abstract
About 12.3 km3 of basaltic magma were erupted from the Lakagigar fissure in Iceland in 1783, which may have been derived from the high-level reservoir of Grimsvotn central volcano, by lateral flow within the rifted crust. We have studied the petrology of quenched, glassy tephra from sections through pyroclastic cones along the fissure. The chemical composition of matrix glass of the 1783 tephra is heterogeneous and ranges from olivine tholeiite to Fe−Ti rich basalt, but the most common magma erupted is quartz tholeiite (Mg#43.6 to 37.2). The tephra are characterized by low crystal content (5 to 9 vol%). Glass inclusions trapped in plagioclase and Fo86 to Fo75 olivine phenocrysts show a large range of compositions, from primitive olivine tholeiite (Mg#64.3), quartz tholeiite (Mg#43–37), to Fe−Ti basalts (Mg#33.5) which represent the most differentiated liquids and are trapped as rare melt inclusions in clinopyroxene. Both matrix glass and melt inclusion data indicate a chemically heterogeneous magma reservoir, with quartz tholeiite dominant. LREE-depleted olivine-tholeiite melt-inclusions in Mg-rich olivine and anorthitic-plagioclase phenocrysts may represent primitive magma batches ascending into the reservoir at the time of the eruption. Vesicularity of matrix glasses correlates with differentiation, ranging from 10 to 60 vol.% in evolved quartz-tholeiite glasses, whereas olivine-tholeiite glasses contain less than 10 vol.% vesicles. FTIR analyses of olivine-tholeiite melt-inclusions indicate concentrations of 0.47 wt% H2O and 430 to 510 ppm for CO2. Chlorine in glass inclusions and matrix glasses increases from 50 ppm in primitive tholeiite to 230 ppm in Fe−Ti basalts, without clear evidence of degassing. Melt inclusion analyses show that sulfur varies from 915 ppm to 1970 ppm, as total FeO* increases from 9 to 13.5 wt%. Sulfur degassing correlates both with vesicularity and magma composition. Thus sulfur in matrix glasses decreases from 1490 ppm to 500 ppm, as Mg # decreases from 47 to 37 and vesicularity of the magma strongly increases. These results indicate loss of at least 75% of sulfur during the eruption. The correlation of low sulfur content in matrix glasses with high vesicularity is regarded as evidence of the control of a major exsolving volatile phase on the degassing efficiency of the magma. Our model is consistent a quasi-permanent CO2 flux through the shallow-level magmatic reservoir of Grimsvotn. Following magma withdrawal from the reservoir and during eruption from the Lakagigar fissure, sulfur degassing was controlled by inherent CO2-induced vesicularity of the magma.
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References
Anderson AT (1974) Chlorine, sulfur and water in magmas and oceans. Geol Soc Amer Bull 85:1485–1492
Beblo M, Bjornsson A (1978) Magnetotelluric investigation of the lower crust and upper mantle beneath Iceland. J Geophys 45:1–16
Bell JD, Humphries DJ (1972) Lakagigar fissure eruption. Progress in experimental petrology. Nat Environ Res Counc UK Publ, Series D, 2:110–112
Bjornsson H (1982) The calorimeter in Grimsvotn, volcanism, and causes and geothermal activity (in Icelandic). Eldur Nordri, 139–144
Bjornsson H (1988) Hydrology of ice caps in volcanic regions. Oddi, Reykjavik
Bjornsson H, Kristmannsdottir H (1984) The Grimsvotn geothermal area, Vatnajokull, Iceland. Jokull 34:25–35
Bjornsson H, Bjornsson S, Sigurgeirsson T (1982) Penetration of water into hot rock boundaries of magma at Grimsvotn. Nature 295:580–581
Bottinga Y, Javoy M (1989) MORB degassing: evolution of CO2. Earth Planet Sci Lett 95:215–225
Brandsdottir B, Einarsson P (1979) Seismic activity associated with the September 1977 deflation of the Krafla central volcano in NE-Iceland. J Volcanol Geotherm Res 6:197–212
Burnham CW (1979) The importance of volatile constituents. In: Yoder Hs Jr (ed) The evolution of the igneous rocks. Princeton University Press, Princeton, USA. Chap 16
Byers CD, Garcia MO, Muenow DW (1986) Volatiles in basaltic glasses from the East Pacific Rise at 21° N: implications for MORB sources and submarine lava flow morphology. Earth Planet Sci Lett 79:9–20
Clausen HB, Hammer CU (1988) The Laki and Tambora eruptions as revealed in Greenland ice cores from 11 locations. Ann Glaciol 10:16–22
Condomines M, Morand P, Allègre CJ (1981) 230Th-238U disequilibria in historical lavas from Iceland. Earth Planet Sci Lett 55:393–406
Condomines M, Gronvold K, Hooker PJ, Muehlenbachs K, O'Nions RK, Oskarsson N, Oxburgh ER (1983) Helium, oxygen, strontium and neodynium isotopic relationships in Iceland volcanics. Earth Planet Sci Lett 66:125–136
Danckwerth PA, Hess P, Rutherford MJ (1979) The solubility of sulfur in high-TiO2 mare basalts. Proc Lunar Sci Conf 10:517–530
Delany JR, Muenow DW, Graham DG (1978) Abundance and distribution of water, carbon and sulfur in the glassy rims of submarine pillow basalts. Geochim Cosmochim Acta 42:581–594
Devine JD, Sigurdsson H, Davis AN, Self S (1984) Estimates of sulfur and chlorine yield to the atmosphere from volcanic eruptions and potential climatic effects. J Geophys Res 89:6309–6325
Dixon JE, Stolper E, Delaney JR (1988) Infrared spectroscopic measurements of CO2 and H2O in Juan de Fuca ridge basaltic glasses. Earth Planet Sci Lett 90:87–104
Dzurisin D, Koyanagi RY, English TT (1984) Magma supply and storage at Kilauca volcano, Hawaii, 1956–1983. J Volcanol Geotherm Res 21:177–206
Einarsson P, Brandsdottir B (1980) Seismological evidence for lateral magma intrusion during the July 1978 deflation of the Krafla central volcano in NE-Iceland. J Geophys 47:160–165
Einarsson P, Brandsdottir B (1984) Seismic activity preceding and during the 1983 volcanic eruption in Grimsvotn, Iceland. Jokull 34:13–23
Eysteinsson H (1987) The inversion of two dimensional magnetotelluric and magnetic variation data. PhD Thesis, Brown University, Providence, RI, USA
Eysteinsson H, Hermance JF (1985) Magnetotelluric measurements across the eastern neovolcanic zone insouth Iceland. J Geophys Res 90:10,093–10,103
Fine G, Stolper E (1986) Dissolved carbon dioxide in basaltic glasses: concentrations and speciation. Earth Planet Sci Lett 76:263–278
Gerlach TM, Graeber EJ (1985) Volatile budget of Kilauea volcano. Nature 313:273–277
Gronvold K (1972) Structural and petrochemical studies in the Kerlingarfjoll region, central Iceland. PhD Thesis, University of Oxford, UK
Gronvold K (1984) Petrology of Skaftareldar lava. In: Skaftareldar 1783–1784. Mal og Menning, Reykjavik, 49–57
Gronvold K, Johannesson H (1984) Eruption in Grimsvotn 1983; course of events and chemical studies of the tephra. Jokull 34:1–11
Hammer CU (1977) Past volcanism revealed by Greenland ice sheet impurities. Nature 270:482–486
Harris DM (1981) The concentration of CO2 in submarine tholeiitic basalts. J Geol 89:689–701
Harris DM, anderson AT (1983) Concentrations, sources and losses of H2O, CO2 and S in Kilauean basalt. Geochim Cosmochim Acta 47:1139–1150
Haughton D, Roeder PL, Skinner BJ (1974) Solubility of sulfur in mafic magmas. Econ Geol 69:451–467
Katsura T, Nagashima S (1974) Solubility of sulfur in some magmas at 1 atmosphere. Geochim Cosmochim Acta 38:517–531
Killingley JS, Muenow DH (1975) Volatiles from Hawaiian submarine basalts determined by dynamic high temperature mass spectrometry. Geochim Cosmochim Acta 39:1467–1473
Kitharov NI, Kadik AA (1973) Water and carbon dioxide in magmatic melts and peculiarities of the melting process. Contrib Mineral Petrol 41:205–215
Kutz MD, Meyer PS, Sigurdsson H (1985) Helium isotope systematics within the neovolcanic zones of Iceland. Earth Planet Sci Lett 74:291–306
Larsen G, Thordarson T (1984) Tephza of Skaftareldar (in Icelandic) In: Skaftareldar 1783–84 (in Icelandic). Mal og Menning, Reykjavik, 59–66
Mathez EA (1976) Sulfur solubility and magmatic sulfides in submarine basalt glasses. J Geophys Res 81:4269–4276
Metrich N, Clocchiatti C (1989) Melt inclusion investigation of the volatile behaviour in historic alkali basaltic magmas of Etna. Bull Volcanol 51:185–198
Meyer PS, Sigurdsson H, Schilling JG (1985) Petrological and geochemical variations along Iceland's neovolcanic zones. J Geophys Res 90:10043–10072
Moore JG, Batchelder JN, Cunningham CJ (1977) CO2-filled vesicles in mid-ocean ridge basalts. J Volcanol Geotherm Res 2:309–327
Moore JG, Schilling JG (1973) Vesicles, water and sulfur in Reykjanes ridge basalts. Contrib Mineral Petrol 41:105–118
Muchlenbachs K, Anderson AT, Sigvaldason GE (1974) Low-O18 basalts from Iceland. Geochim Cosmochim Acta 38:577–588
Nielsen CH, Sigurdsson H (1981) Quantitative methods of electron microprobe analysis of sodium in natural and synthetic glasses. Am Mineral 66:547–552
Oskarsson N, Sigvaldason GE, Steinthorsson S (1982) A dynamic model of rift zone petrogenesis and regional petrology of Iceland. J Petrol 23:28–74
Oskarsson N, Gronvold K, Larsen G (1984) Aerosols of Skaftareldar (in Icelandic). In: Skaftareldar 1783–84 (in Icelandic). Mal og Mennig, Reykjavik
Palais JM, Sigurdsson H (1989) Petrologic evidence of volatile emissions from major historic and pre-historic volcanic eruptions. In: Berger AR, Dickinson, Kidson J. (eds) Understanding climate change. AGU Geophysical Monograph 52, 31–53
Pineau F, Javoy M (1983) Carbon isotopes and concentrations in mid-oceanic ridge basalts. Earth Planet Sci Lett 62:239–257
Ray GL (1980) An ion microprobe study of trace element partitioning between clinopyroxene and liquid in the diopside (CaMgSi2O6)-albite (NaAlSi3O8)-anorthite (CaAl2Si2O8) system. PhD thesis, Massachusetts Inst. Technol, Cambridge, Mass, USA
Rose WI, Stoiber RE, Malinconico LL (1982) Eruptive gas compositions and fluxes of explosive volcanoes: budget of S and Cl emitted from Fuego volcano, Guatemala. In: Thorpe RS, (ed) Andesites. Wiley, New York, pp 669–676
Schilling JG, Bergeron MB, Evans R (1980) Halogens in the mantle beneath the North Atlantic. Philos Trans R Soc London A297:147–178
Shimizu N, Hart SR (1982) Applications of the ion microprobe to geochemistry and cosmochemistry. Ann Rev Earth Planet Sci 10:483–526
Shimizu N, Le Roex AP (1986) The chemical zoning of augite phenocrysts in alkaline basalts from Gough Island, South Atlantic. J Volcanol Geotherm Res 29:159–188
Sigurdsson H (1982) Volcanic pollution and climate: The 1783 Laki eruption. EOS 63:601–602
Sigurdsson H (1983) The 1783 Lakagigar fissure eruption. EOS 64:887
Sigurdsson H (1987) Dyke injection in Iceland: a review. In: Halls HC, and Fahrig WF (eds) mafic dyke swarms. Geol Assoc Can Spec Pap 34:55–64
Sigurdsson H, Sparks RSJ (1978) Lateral magma flow within rifted Icelandic crust. Nature 274:126–130
Sigurdsson H, Sparks RSJ (1981) Petrology of rhyolitic and mixed magma ejecta from the 1875 eruption of Askja, Iceland. J Petrol 22:41–84
Sigvaldason GE, Oskarsson N (1976) Chlorine in basalts from Iceland. Geochim Cosmochim Acta 40:777–789
Sigvaldason GE, Oskarsson N (1986) Fluorine in basalts from Iceland. Contrib Mineral Petrol 94:263–271
Sparks RSJ, Meyer P, Sigurdsson H (1980) Density variation amongst mid-ocean ridge basalts: Implications for magma mixing and the scarcity of primitive lavas. Earth Planet Sci Lett 46:419–430
Stolper E, Holloway JR (1988) Experimental determination of the solubility of carbon dioxide in molten basalt at low pressure. Earth Planet Sci Lett 87:397–408
Thorarinsson S (1969) The Lakagigar eruption of 1783. Bull Volcanol 33:910–927
Thordarson T, Self S (1989) The Skaftarfires fissure basalt eruption in 1783–85. Abstract, Continental Magmatism IAVCEI General Assembly, Santa Fe, USA, June 1989
Tryggvason E (1982) Some thoughts on Grimsvotn, the world's largest geothermal field (in Icelandic). Eldur Nordri 29–36
Wendlandt RF (1982) Sulfide saturation of basalt and andesite melts at high pressures and temperatures. Am Mineral 67:877–885
Wendlandt RF, Harrison WJ (1979) Rare earth partitioning between immiscible carbonate and silicate liquids and CO2 vapor: results and implications for the formation of light rare earth-enriched rocks. Contrib Mineral Petrol 69:409–419
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Metrich, N., Sigurdsson, H., Meyer, P.S. et al. The 1783 Lakagigar eruption in Iceland: geochemistry, CO2 and sulfur degassing. Contr. Mineral. and Petrol. 107, 435–447 (1991). https://doi.org/10.1007/BF00310678
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DOI: https://doi.org/10.1007/BF00310678