Skip to main content
SpringerLink
Log in

Rhyolite volcanism in the Krafla central volcano, north-east Iceland

  • Original Paper
  • Published:
Bulletin of Volcanology Aims and scope Submit manuscript

Abstract

At the Krafla central volcano in north-east Iceland, two main phases of rhyolite volcanism are identified. The earlier phase (last interglacial) is related to the formation of a caldera, whereas the second phase (last glacial) is related to the emplacement of a ring dike. Subsequently, only minor amounts of rhyolite have been erupted. The volcanic products of Krafla are volumetrically bimodal. Geochemically, there is a series of basaltic to basalto-andesitic rocks and a cluster of rhyolitic rocks. Rocks of intermediate to silicic composition (icelandites and dacites) show clear signs of mixing. The rhyolites are Fe-rich (tholeiitic), and aphyric to slightly porphyritic (plagioclase, augite, pigeonite, fayalitic olivine and magnetite). They are minimum melts on the quartz-plagioclase cotectic plane in the granite system (Qz-Or-Ab-An). The rhyolites at Krafla were produced by near-solidus, rather than nearliquidus fractionation. They are interpreted as silicic minimum melts of hydrothermally altered crust, mainly of basaltic composition. They were primarily generated on the peripheries of an active basaltic magma chamber or intrusive domain, where sufficient volumes of crust were subjected to temperatures favorable for rhyolite genesis (850–950° C). The silicic melts were extracted crystal-free from their source in response to crustal deformation.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Ármannsson H, Gudmundsson Á, Steingrímsson BS (1987) Exploration and development of the Krafla geothermal area. Jökull 37:13–30

    Google Scholar 

  • Arth JG (1976) Behavior of trace elements during magmatic processes — a summary of theoretical models and their applications. J Res US Geol Surv 4:41–47

    Google Scholar 

  • Arzi AA (1978) Critical phenomena in the rheology of partially melted rocks. Tectonophysics 44:173–184

    Google Scholar 

  • Björnsson A (1985) Dynamics of crustal rifting in NE Iceland. J Geophys Res 90:10151–10162

    Google Scholar 

  • Björnsson A, Saemundsson K, Einarsson P, Tryggvason E, Grönvold K (1977) Current rifting episode in north Iceland. Nature 266:318–323

    Google Scholar 

  • Björnsson A, Johnsen G, Sigurdsson S, Thorbergsson G (1979) Rifting of the plate boundary in North Iceland 1975–1978. J Geophys Res 84:3029–3038

    Google Scholar 

  • Calderone GM, Grönvold K, Óskarsson N (1990) The welded airfall tuff layer at Krafla, northern Iceland: a composite eruption triggered by injection of basaltic magma. J Volcanol Geotherm Res 44:303–314

    Google Scholar 

  • Carmichael ISE (1964) The petrology of Thingmúli, a Tertiary volcano in eastern Iceland. J Petrol 5:435–460

    Google Scholar 

  • Carmichael ISE (1967) The iron-titanium oxides of salic volcanic rocks and their associated ferromagnesian silicates. Contrib Mineral Petrol 14:36–64

    Google Scholar 

  • Condomines M, Grönvold K, Hooker PJ, Muehlenbachs K, O'Nions RK, Óskarsson N, Oxburgh ER (1983) Helium, oxygen, strontium and neodymium isotopic relationships in Icelandic volcanics. Earth Planet Sci Lett 66:125–136

    Google Scholar 

  • Davidson PM, Lindsley DH (1989) Thermodynamic analysis of pyroxene-olivine-quartz equilibria in the system CaO−MgO−FeO−SiO2. Am Mineral 74:18–30

    Google Scholar 

  • Flower MFJ, Pritchard RG, Brem G, Cann JR, Delaney J, Emmerman R, Gibson IL, Oakley PI, Robinson PT, Schmincke H-U (1982) Chemical stratigraphy, Iceland research drilling project Reydarfjördur, Eastern Iceland. J Geophys Res 87:6489–6510

    Google Scholar 

  • Furnes H, Fridleifsson IB, Atkins FB (1980) Subglacial volcanics — on the formation of acid hyaloclastites. J Volcanol Geotherm Res 8:95–110

    Google Scholar 

  • Gibson IL, Kirkpatrick RJ, Emmerman R, Schmincke H-U, Pritchard G, Oakley PJ, Thorpe RS, Marriner GF (1982) The trace element composition of the lavas and dikes from a 3-km vertical section through the lava pile of Eastern Iceland. J Geophys Res 87:6532–6546

    Google Scholar 

  • Grönvold K (1972) Structural and petrochemical studies in Kerlingarfjöll region, Central Iceland. PhD Thesis, Univ Oxford: 1–237

  • Harrison TM, Watson EB (1984) The behavior of apatite during crustal anatexis: equilibrium and kinetic considerations. Geochim Cosmochim Acta 48:1467–1477

    Google Scholar 

  • Hattori K, Muehlenbachs K (1982) Oxygen isotope ratios of the Icelandic crust. J Geophys Res 87:6559–6565

    Google Scholar 

  • Helz RT (1976) Phase relations of basalts in their melting range at PH2O=5 kb as a function of oxygen fugacity, part II. Melt compositions. J Petrol 17:139–193

    Google Scholar 

  • Hemond C, Condomines M, Fourcade S, Allègre CI, Óskarsson N, Javoy M (1988) Thorium, strontium and oxygen isotopic geochemistry in recent tholeiites from Iceland: crustal influence on mantle-derived magmas. Earth Planet Sci Lett 87:273–285

    Google Scholar 

  • Hemond C, Arndt NT, Lichtenstein U, Hofmann AW, Óskarsson N, Steinthorsson S (1993) The heterogeneous Iceland plume: Nd−Sr−O isotopes and trace element constraints. J Geophys Res 98:15833–15850

    Google Scholar 

  • Jakobsson SP (1972) Chemistry and distribution pattern of recent basaltic rocks in Iceland. Lithos 5:365–386

    Google Scholar 

  • Jónasson K, Holm PM, Pedersen AK (1992) Petrogenesis of silicic rocks from the Króksfjördur central volcano, NW Iceland. J Petrol 33:1345–1369

    Google Scholar 

  • Lindsley DH (1983) Pyroxene thermometry. Am Mineral 68:477–493

    Google Scholar 

  • Macdonald R, Sparks RSI, Sigurdsson H, Mattey DP, McGarvie DW, Smith RL (1987) The 1875 eruption of Askja volcano, Iceland: combined fractional crystallization and selective contamination in the generation of rhyolitic magma. Min Mag 51:183–202

    Google Scholar 

  • Macdonald R, McGarvie DW, Pinkerton H, Smith RL, Palacz CA (1990) Petrogenetic evolution of the Torfajökull volcanic complex Iceland. I. Relationship between the magma types. J Petrol 31:429–459

    Google Scholar 

  • Mahood G, Hildreth W (1983) Large partition coefficients for trace elements in high-silica rhyolites. Geochim Cosmochim Acta 47:11–30

    Google Scholar 

  • Marsh BD, Gunnarsson B, Congdon R, Carmody R (1991) Hawaiian basalt and Icelandic rhyolite: indicators of differentiation and partial melting. Geol Rundsch 80:481–510

    Google Scholar 

  • McGarvie DW, Macdonald R, Pinkerton H, Smith RL (1990) Petrogenetic evolution of the Torfajökull volcanic compolex, Iceland II. The role of magma mixing. J Petrol 31:461–481

    Google Scholar 

  • McKenzie D (1985) The extraction of magma from the crust and mantle. Earth Planet Sci Lett 74:81–91

    Google Scholar 

  • Michael PJ (1988) Partition coefficients for rare earth elements in mafic minerals of high silica rhyolites: the importance of accessory mineral inclusions. Geochim Cosmochim Acta 52:275–282

    Google Scholar 

  • Nash WP, Crecraft HR (1985) Partition coefficients for trace elements in silicic magmas. Geochim Cosmochim Acta 49:2309–2322

    Google Scholar 

  • Nekvasil H (1988) Calculated effect of anorthite component on the crystallization paths of H2O-undersaturated haplogranitic melts. Am Mineral 73:966–981

    Google Scholar 

  • Nicholson H (1990) The magmatic evolution of Krafla, NE Iceland. PhD Thesis, Univ Edinburgh: 1–237

  • Nicholson H, Condomines M, Fitton JG, Fallick AE, Grönvold K, Rogers G (1991) Geochemical and isotopic evidence for crustal assimilation beneath Krafla, Iceland. J Petrol 32:1005–1020

    Google Scholar 

  • O'Nions RK, Grönvold K (1973) Petrogenetic relationships of acid and basic rocks in Iceland: Sr isotopes and rare earth elements in late postglacial volcanics. Earth Planet Sci Lett 19:397–409

    Google Scholar 

  • Óskarsson N, Sigvaldason GE, Steinthórsson S (1982) A dynamic model of rift zone petrogenesis and the regional petrology of Iceland. J Petrol 23:28–74

    Google Scholar 

  • Paquet J, François P (1980) Experimental deformation of partially melted granitic rocks at 600–900°C and 250 Mpa confining pressure. Tectonophysics 68:131–146

    Google Scholar 

  • Pearce JA, Norry MJ (1979) Petrogenetic implications of Ti, Zr, Y, and Nb variations in volcanic rocks. Contrib Mineral Petrol 69:33–47

    Google Scholar 

  • Saemundsson K (1972) Notes on the geology of the Torfajökull area. Náttúrufraedingurinn 42:81–99 [in Icelandic]

    Google Scholar 

  • Saemundsson K (1974) Evolution of the axial rifting zone in Northern Iceland and the Tjörnes fracture zone. Geol Soc Am Bull 85:495–504

    Google Scholar 

  • Saemundsson K (1978) Fissure swarms and central volcanoes of the neovolcanic zones of Iceland. Geol J Spec Issue 10:415–432

    Google Scholar 

  • Saemundsson K (1991) Geology of the Krafla system. In: Gardarsson A, Einarsson Á (eds) Náttúra Mývatns. Hid Íslenska Náttúrufraedifélag, Reykjavík, pp 25–95 [in Icelandic]

    Google Scholar 

  • Shaw HR (1972) Viscosities of magmatic silicate liquids: an empirical method of prediction. Am J Sci 272:870–893

    Google Scholar 

  • Sigmarsson O, Hémond C, Condomines M, Fourcade S, Óskarsson N (1991) Origin of silicic magma in Iceland revealed by Th isotopes. Geology 19:621–624

    Google Scholar 

  • Sigurdsson H (1977) Generation of Icelandic rhyolites by melting of plagiogranites in the oceanic layer. Nature 269:25–28

    Google Scholar 

  • Sigurdsson H, Sparks RSJ (1981) Petrology of rhyolitic and mixed magma ejecta from the 1875 eruption of Askja, Iceland. J Petrol 22:41–84

    Google Scholar 

  • Sigvaldason GE (1974) The petrology of Hekla and origin of silicic rocks in Iceland. Soc Sci Islandica V:1–44

    Google Scholar 

  • Sisson TW (1991) Pyroxene-high silica rhyolite trace element partition coefficients measured by ion microprobe. Geochim Cosmochim Acta 55:1575–1585

    Google Scholar 

  • Spulber SD, Rutherford MJ (1983) The origin of rhyolite and plagiogranite in oceanic crust: an experimental study. J Petrol 24:1–25

    Google Scholar 

  • Sveinbjörnsdottir AE (1992) Composition of geothermal minerals from saline and dilute fluids-Krafla and Reykjanes, Iceland. Lithos 27:301–315

    Google Scholar 

  • Thoroddsen Th (ed) (1907–15) Reports on the Mývatn fires 1724–1729. Safn til sögu Íslands 4: 385–411 [in Icelandic]

  • Thy P, Beard JS, Lofgren GE (1990) Experimental constraints on the origin of Icelandic rhyolites. J Geol 98:417–421

    Google Scholar 

  • van der Molen I, Paterson MS (1979) Experimental deformation of partially-melted granite. Contrib Mineral Petrol 70:299–318

    Google Scholar 

  • Warshaw CM, Smith RL (1988) Pyroxenes and fayalites in the Bandelier Tuff, New Mexico: temperatures and comparison with other rhyolites. Am Mineral 73:1025–1037

    Google Scholar 

  • Watson EB, Harrison TM (1983) Zircon saturation revisited: temperature and composition effects in a variety of crustal magma types. Earth Planet Sci Lett 64:295–304

    Google Scholar 

  • Wood DA, Gibson IL, Thompson RN (1976) Elemental mobility during zeolite facies metamorphism of the Tertiary basalts of Eastern Iceland. Contrib Mineral Petrol 55:241–254

    Google Scholar 

  • Wright TL, Doherty PC (1970) A linear programming and least squares computer method for solving petrographic mixing problems. Geol Soc Am Bull 81:1995–2008

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Nordic Volcanological Institute, University of Iceland, IS-101, Reykjavik, Iceland

    K. Jónasson

Authors
  1. K. Jónasson
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Jónasson, K. Rhyolite volcanism in the Krafla central volcano, north-east Iceland. Bull Volcanol 56, 516–528 (1994). https://doi.org/10.1007/BF00302832

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00302832

Key words

Search

Navigation