Abstract
In the eastern, external part of the Grenvillian Belt in SW Sweden, five formations of granitic rocks were found in the basement of the Dalslandian Supracrustal Group. The granitic rocks have been strongly recrystallized but have preserved most of their granitic texture in the process. Most magmatic crystals have been pseudomorphed by metamorphic minerals: quartz, albite, chlorite, biotite, white mica, epidote, titanite, hematite, pyrite and carbonate. Two of the formations have subsequently been affected by a cataclastic deformation and at present consist of mylogneisses.
δ 18O whole-rock values for the granitic rocks vary from +3.0‰ to +11.1‰. Quartz-apatite, quartz-zircon and quartz-titanite pairs show 18O/16O fractionations corresponding to equilibrium temperatures of 550–700° C, which are believed to reflect in the main continued closed-system isotopic exchange at high temperatures following solidification. In contrast highly positive 18O/16O fractionations for quartz-K-feldspar, quartz-biotite, quartz-chlorite and quartz-sericite pairs in some granitic samples indicate that these rocks have exchanged oxygen with heated, meteoric, H2O dominated fluids. Other granitic samples, however, show virtually undisturbed magmatic 18O/16O fractionation values for the same mineral pairs, even though these rocks are equally altered.
It is concluded that all granitic rock units recrystallized under greenschist facies conditions during the infiltration of fluids under the influence of hydrothermal convection systems set up by the intrusion of the granitic plutons. The fluids probably had a range of δ 18O values from ca. -14‰ to ca. +10‰, indicating the mixing of distinct fluid reservoirs, one of meteoric origin and the others of magmatic and/or metamorphic origin. The temperature of alteration is estimated at 450–500° C.
Estimation of pre-alteration δ 18O whole rock values for the five granitic units suggests that three units should be assigned a dominantly S-type origin, where as the other two units may partly or wholly have an I-type origin.
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References
Bottinga Y, Javoy M (1973) Comments on oxygen isotope geothermometry. Earth Planet Sci Lett 20:250–265
Bottinga Y, Javoy M (1975) Oxygen isotope partitioning among the minerals in igneous and metamorphic rocks. Rev Geophys Space Phys 13:401–418
Chappell BW, White AJR (1974) Two contrasting granite types. Pacific Geol 8:173–174
Clayton RN, Mayeda TK (1963) The use of bromine pentafluoride in extraction of oxygen from oxides and silicates for isotopic analysis. Geochim Cosmochim Acta 27:43–52
Craig H (1961) Isotopic variations in meteoric waters. Science 133:1702–1703
Dansgaard W (1964) Stable isotopes in precipitation. Tellus 16:436–468
Field D, Råheim A (1981) Age relationships in the Proterozoic high-grade gneiss regions of southern Norway. Precambr Res 14:261–275
Gorbatschev R (1971) Aspects and problems of Precambrian geology in Western Sweden. Sveriges Geol Unders (C) 650:1–63
Gorbatschev R (1975) Fundamental subdivisions of Precambrian granitoids in Åmål mega-unit and the evolution of the southwestern Baltic Shield, Sweden. Geol Fören Stockholm Förhand 97:107–114
Hanson GN (1978) The application of trace elements to the petrogenesis of igneous rocks of granitic composition. Earth Planet Sci Lett 38:26–43
Jakobsen H, Munksgaard NC, Zeck HP (in prep) Pre-Dalslandian deformation and recrystallization in the basement of the Dalslandian supracrustals, Grenvillian Belt, SW Sweden: the Larsson — van Overeem controversy. Geol Fören Stockholm Förhand
Javoy M (1977) Stable isotopes and geothermometry. J Geol Soc London 133:609–636
Knauth LP, Epstein S (1976) Hydrogen and oxygen isotope ratios in nodular and bedded cherts. Geochim Cosmochim Acta 40:1095–1108
Kolodny Y, Epstein S (1976) Stable isotope geochemistry of deep sea cherts. Geochim Cosmochim Acta 40:1195–1209
Magnusson NH (1960) Age Determinations of Swedish Precambrian rocks. Geol Fören Stockholm Förhand 82:407–32
Magnusson NH, Asklund B, Kulling O, Kautsky G, Esklund J, Larsson W, Lundegårdh PH, Hjelmquist S, Gavelin G, Ödman O (1958) Karta över Sveriges berggrund (tre blad), skala 1∶1,000,000, södra bladet. Sveriges Geol Unders Ba 16
Norton D, Knight J (1977) Transport phenomena in hydrothermal systems: cooling plutons. Am J Sci 277:932–981
Norton D, Taylor HP (1979) Quantitative simulation of the hydrothermal systems of crystallizing magmas on the basis of transport theory and oxygen isotope data: an analysis of the Skaergaard Intrusion. J Petrol 20:421–486
O'Neil JR (1979) Stable isotope geochemistry of rocks and minerals. I: Lectures in isotope geology (E Jäger and JC Hunziker, eds) Berlin Heidelberg New York: Springer-Verlag, pp 235–263
O'Neil JR, Shaw SE, Flood RH (1977) Oxygen and hydrogen isotope compositions as indicators of granite genesis in the New England Batholith, Australia. Contrib Mineral Petrol 62:313–328
Sauter BCC, Hermans GAEM, Jansen JBH, Maijer C, Spits P, Wegelin A (in press) Polyphase Caledonian metamorphism in the Precambrian basement of Rogaland/Vest-Agder, Southwest Norway. Nor Geologisk Unders Bull
Taylor HP (1967) Oxygen isotope studies of hydrothermal mineral deposits. In: Barnes HL (ed) Geochemistry of hydrothermal ore deposits. Holt, Rinehart and Winston, INC. New York
Taylor HP (1968) The oxygen isotope geochemistry of igneous rocks. Contrib Mineral Petrol 19:1–71
Taylor HP (1974) The application of oxygen and hydrogen isotope studies to problems of hydrothermal alteration and ore deposition. Econ Geol 69:843–883
Taylor HP (1978) Oxygen and hydrogen isotope studies of plutonic granitic rocks. Earth Planet Sci Lett 38:177–210
Taylor HP, Forester RW (1971) Low-18O igneous rocks from the intrusive complexes of Skye, Mull, and Ardnamurchan, western Scotland. J Petrol 12:465–497
Taylor HP, Forester RW (1979) An oxygen and hydrogen isotope study of the Skaergaard Intrusion and its country rocks: a description of a 55-M.Y. old fossil hydrothermal system. J Petrol 20:355–419
Turner FJ (1981) Metamorphic petrology. McGraw Hill, New York, pp 403
Winkler HGF (1979) Petrogenesis of metamorphic rocks, 5th ed. Springer Verlag: New York Heidelberg Berlin
Zeck HP (1971) Prehnite-pumpellyite facies metamorphism in Precambrian basement rocks of S Sweden. Contrib Mineral Petrol 32:307–314
Zeck HP (1974) Cataclastites, hemiclastites, holoclastites, blastoditto and myloblastites — cataclastic rocks. Am J Sci 274:1064–1073
Zeck HP, Malling S (1974) The Gillberga synform (Precambrian basement, SW Värmland, Sweden); Literature synopsis and preliminary notes on its re-interpretation. Bull Geol Soc Denmark 23:159–174
Zeck HP, Wallin B (1980) A 1,220±60 M.Y. Rb-Sr isochron age representing a Taylor-convection caused recrystallization event in a granitic rock suite. Contrib Mineral Petrol 74:45–53
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Munksgaard, N.C., Zeck, H.P. Oxygen-isotope systematics of a strongly recrystallized granitic rock complex, Grenvillian Belt, SW Sweden. Contr. Mineral. and Petrol. 85, 67–73 (1984). https://doi.org/10.1007/BF00380222
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DOI: https://doi.org/10.1007/BF00380222