Skip to main content
SpringerLink
Log in

Structure of regional dykes and local cone sheets in the Midhyrna-Lysuskard area, Snaefellsnes Peninsula (NW Iceland)

  • Research Article
  • Published:
Bulletin of Volcanology Aims and scope Submit manuscript

Abstract

This paper provides the first detailed structural description of 48 vertical dykes, 384 inclined sheets and two large intrusions and the geometry (strike, dip direction and dip) of 1116 fractures in the central area of the Snaefellsnes peninsula, NW Iceland. Our data show a more complex setting than that depicted by the WNW-ESE en-echelon trend of the volcanic structures at the surface. In the Miocene basement lavas, dykes dominantly strike N50–100°E whereas other directions are also present with a higher dispersion. Two main swarms of centrally dipping sheets have also been recognized, focussing towards two areas. Sheet dips range from 2 to 75° with the higher frequency between 10 and 45°. In section view, there is no systematic variation of sheet dip with distance from the focus area. Gabbro and granophyre laccoliths are present in the studied area but cross-cutting relations indicate that most of the inclined sheets are younger. Comparison with regional tectonics suggests that the N50–80°E-striking dykes are coherent with emplacement under the stress field of the pre-6 Ma Snaefellsnes Rift dominated by a NNW-SSE-directed least principal stress (σ3). The N80–100°E dykes and the late Quaternary WNW-trending sub-aerial volcanic features are instead consistent with the development of a more recent E-W, right-lateral shear zone affecting the Snaefellsnes peninsula. Coherent sets of fractures have also been found. Within the inclined sheet swarms, the stress tensor rotated in response to an excess magma pressure linked to two underlying magma chambers of lobate shape, located at an estimated depth of about 400 and 500 m below sea level. This local magmatic stress also produced the centrally inclined fracture swarms that have been found in this area.

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

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10

Similar content being viewed by others

References

  • Acocella V, Neri M (2009) Dike propagation in volcanic edifices: overview and possible developments. Tectonophysics 471:67–77

    Article  Google Scholar 

  • Ancochea E, Brandle JL, Huertas MJ, Cubas CR, Hernan F (2003) The felsic dikes of La Gomera (Canary Islands): identification of cone-sheet and radial dyke swarms. J Volcanol Geotherm Res 120:197–206

    Article  Google Scholar 

  • Bailey EB, Clough CT, Wright WB, Richey JE, Wilson GV (1924) The Tertiary and post-Tertiary geology of Mull, Loch Aline and Oban. Geological Survey of Scotland Memoir, 445 p

  • Bald N, Noe-Nygaard A, Pedersen K (1971) The Kroksfjordur central volcano in North-West Iceland. Acta Naturalia Islandica, II, 10, 29 pages.

    Google Scholar 

  • Bistacchi A, Tibaldi A, Pasquarè FA, Rust D (2012) The association of cone-sheets and radial dykes: data from the Isle of Skye (UK), numerical modelling, and implications for shallow magma chambers. Earth Planet Sci Lett 339–340:46–56

    Article  Google Scholar 

  • Bonali FL, Corazzato C, Tibaldi A (2011) Identifying rift zones on volcanoes: an example from La Réunion Island. Indian Ocean B Volcanol 73(3):347–366. doi:10.1007/s00445-010-0416-1

    Article  Google Scholar 

  • Brown GC, Everett SP, Rymer H, McGarvie DW, Foster I (1991) New light on caldera evolution—Askja, Iceland. Geology 19:352–355

    Article  Google Scholar 

  • Burchardt S, Tanner DC, Troll VR, Krumbholz M, Gustafsson LE (2011) Three-dimensional geometry of concentric intrusive sheet swarms in the Geitafell and the Dyrfjöll volcanoes, eastern Iceland. Geochemy Geophy Geosy 12:Q0AB09, doi: 10.1029/2011GC003527.

  • Chadwick WW Jr, Dieterich JH (1995) Mechanical modelling of circumferential and radial dike intrusion on Galapagos volcanoes. J Volcanol Geotherm Res 66:37–52

    Article  Google Scholar 

  • Corazzato C, Tibaldi A (2006) Fracture control on type, morphology and distribution of parasitic volcanic cones: An example from Mt. Etna, Italy. J Volcanol Geotherm 823 Res 158(1–2):177–194

    Google Scholar 

  • Cox KG, Bell JD, Pankhurst RJ (1979) The interpretation of igneous rocks. George Allen and Unwin, London

    Book  Google Scholar 

  • Einarsson P (2008) Plate boundaries, rifts and transforms in Iceland. Jökull 58:35–58

    Google Scholar 

  • Einarsson P, Brandsdottir B (1980) Seismological evidence for lateral magma intrusion during the July 1978 deflation of the Krafla volcano in NE Iceland. J Geophys 47:160–165

    Google Scholar 

  • Einarsson P, Brandsdottir B, Gudmundsson MT, Bjornsson H, Gronvold K, Sigmundsson F (1997) Center of the Iceland hotspot experiences volcanic unrest, Eos Trans. AGU 78:369374–369375

    Google Scholar 

  • Flude S, Burgess R, McGarvie DW (2008) Silicic volcanism at Ljósufjöll, Iceland: insights into evolution and eruptive history from Ar–Ar dating. J Volcanol Geotherm 169(3–4):154–175

    Google Scholar 

  • Fridleifsson IB (1977) Distribution of large basaltic intrusions in the Icelandic crust and the nature of the layer 2–layer 3 boundary. Geol Socam Bull 11:1689–1693

    Google Scholar 

  • Galland O, Planke S, Neumann E-R, Malthe-Sørenssen A (2009) Experimental modelling of shallow magma emplacement: application to saucer-shaped intrusions. Earth Planet Sci Lett 277:373–383

    Article  Google Scholar 

  • Gautneb H, Gudmundsson A (1992) Effect of local and regional stress fields on sheet emplacement in West Iceland. J Volcanol Geotherm Res 51:339–356

    Article  Google Scholar 

  • Gautneb H, Gudmundsson A, Oskarsson N (1989) Structure, petrochemistry, and evolution of a sheet swarm in an Icelandic central volcano. Geol Mag 126:659–673

    Article  Google Scholar 

  • Geikie A (1897) The ancient volcanoes of Great Britain. Macmillan, London

    Google Scholar 

  • Geshi N (2005) Structural development of dike swarms controlled by the change of magma supply rate: the cone sheets and parallel dike swarms of the Miocene Otoge igneous complex, Central Japan. J Volcanol Geotherm Res 141:267–281

    Article  Google Scholar 

  • Gianelli G (1972) Cumulus textures of the Midhyrna layered intrusion, Snaefellsnes Peninsula, western Iceland. Boll Soc Geol Ital 91:419–438

    Google Scholar 

  • Gudmundsson A (1990) Emplacement of dikes, sills and crustal magma chambers at divergent plate boundaries. Tectonophysics 176(3–4):257–275

    Google Scholar 

  • Gudmundsson A (1995) Infrastructure and mechanics of volcanic systems in Iceland. J Volcanol Geotherm Res 64:1–22

    Article  Google Scholar 

  • Gudmundsson MT (1997) Gravity and magnetic studies of the subglacial Grímsvötn volcano, Iceland: implications for crustal and thermal structure. J Geophys Res 102(B4):7691–7704

    Article  Google Scholar 

  • Gudmundsson A (1998) Magma chambers modeled as cavities explain the formation of rift zone central volcanoes and their eruption and intrusion statistics. J Geophys Res 103(B4):7401–7412

    Article  Google Scholar 

  • Gudnmundsson A (2000) Dynamics of volcanic systems in Iceland: example of tectonism and volcanism at juxtaposed hot spot and mid-ocean ridge systems. Annu Rev Earth Planet Sci 28:107–140

    Article  Google Scholar 

  • Gudmundsson A (2002) Emplacement and arrest of sheets and dikes in central volcanoes. J Volcanol Geotherm Res 116:279–298

    Article  Google Scholar 

  • Gudmundsson A (2006) How local stresses control magma-chamber ruptures, dyke injections, and eruptions in composite volcanoes. Earth-Sci Rev 79:1–31

    Article  Google Scholar 

  • Gudmundsson A, Brenner SL (2004) How mechanical layering affects local stresses, unrests, and eruptions of volcanoes. Geophys Res Lett 31(16):L16606

    Google Scholar 

  • Gudmundsson A., Brenner SL (2005) On the conditions of sheet injections and eruptions in stratovolcanoes. Bull Volcanol 67:768–782

    Google Scholar 

  • Gudmundsson A, Bergerat F, Angelier J (1996) Off-rift and rift-zone palaeostresses in Northwest Iceland. Tectonophysics 255:211–228

    Article  Google Scholar 

  • Jacoby W, Gudmundsson MT (2007) Hotspot Iceland: an introduction. J Geodyn 43(1):1–5

    Google Scholar 

  • Jakobsdóttir SS, Roberts MJ, Gudmundsson GB, Geirsson H, Slunga R (2008) Earthquake swarms at Upptyppingar, north-east Iceland: a sign of magma intrusion? Stud Geophys Geod 52(4):513–528

    Google Scholar 

  • Jóhannesson H (1980) Stratigraphy and the development of rift zones in West Iceland. Náttúrufrædingurinn 50:13–31 (in Icelandic)

    Google Scholar 

  • Johnson SE, Paterson SR, Tate MC (1999) Structure and emplacement history of a multiple-center. cone-sheet-bearing ring complex: the Zarza intrusive complex, Baja California, Mexico. Geol Soc Am Bull 111(4):607–619

    Article  Google Scholar 

  • Kjartansson G (1968) Geological Map of Iceland. Sheet 2. Icelandic Museum of Natural History and Iceland Geodetic Survey, Reykjavik, scale 1:250,000.

  • Klausen MB (2004) Geometry and mode of emplacement of the Thverartindur cone sheet swarm, SE Iceland. J Volcanol Geotherm Res 138:185–204

    Article  Google Scholar 

  • Klausen MB (2006) Geometry and mode of emplacement of dike swarms around the Birnudalstindur igneous centre, SE Iceland. J Volcanol Geotherm Res 151(4):340–356

    Article  Google Scholar 

  • Kristjánsson L, Jónsson G (1998) Aeromagnetic results and the presence of an extinct rift zone in western Iceland. J Geodyn 25(1–2):99–108

    Google Scholar 

  • Magee C, Stevenson C, O’Driscoll B, Schofield N, McDermott K (2012) An alternative emplacement model for the classic Ardnamurchan cone sheet swarm, NW Scotland, involving lateral magma supply via regional dykes. J Struct Geol 43:73–91

    Article  Google Scholar 

  • Martin E, Sigmarsson O (2010) Thirteen million years of silicic magma production in Iceland: links between petrogenesis and tectonic settings. Lithos 116:129–144

    Article  Google Scholar 

  • Mathieu L, van Wyk de Vries B, Holohan EP, Troll VR (2008) Dykes, cups, saucers and sills: analogue experiments on magma intrusion into brittle rocks. Earth Planet Sci Lett 271:1–13

    Article  Google Scholar 

  • Mjelde R, Raum T, Breivik AJ, Faleide JI (2008) Crustal transect across the North Atlantic. Mar Geophys Res 29:73–87

    Google Scholar 

  • Moorbath S, Sigurdsson H, Goodwin R (1968) K-R ages of the oldest exposed rocks in Iceland. Earth Planet Sci Lett 4(3):197–205

    Article  Google Scholar 

  • Paquet F, Dauteuil O, Hallot E, Moreau F (2007) Tectonics and magma dynamics coupling in a dyke swarm of Iceland. J Struct Geol 29:1477–1493

    Article  Google Scholar 

  • Pasquarè F, Tibaldi A (2007) Structure of a sheet-laccolith system revealing the interplay between tectonic and magma stresses at Stardalur Volcano, Iceland. J Volcanol Geotherm Res 161(1–2):131–150

    Article  Google Scholar 

  • Phillips WJ (1974) The dynamic emplacement of cone sheets. Tectonophysics 24:69–84

    Article  Google Scholar 

  • Saemundsson K (1979) Outline of the geology of Iceland. Jokull 29:7–28

    Google Scholar 

  • Schilling JG (1973) Iceland Mantle Plume: Geochemical Study of Reykjanes Ridge. Nature 242(5400):565–571

    Google Scholar 

  • Schirnick C, van den Bogaard P, Schmincke H-U (1999) Cone sheet formation and intrusive growth of an oceanic island—the Miocene Tejeda complex on Gran Canaria (Canary Islands). Geology 27(3):207–210

    Article  Google Scholar 

  • Sigmundsson F, Schmundsson K (2008) Iceland: a window on North-Atlantic divergent plate tectonics and geologic processes. Episodes 31(1):92–97

    Google Scholar 

  • Sigurdsson H (1970) Structural origin and plate tectonics of the Snaefellsnes volcanic zone, Western Iceland. Earth Planet Sci Lett 10:129–135

    Article  Google Scholar 

  • Siler DL, Karson JA (2009) Three-dimensional structure of inclined sheet swarms: implications for crustal thickening and subsidence in the volcanic rift zones of Iceland. J Volcanol Geotherm Res 18(8):333–346

    Article  Google Scholar 

  • Steinthorsson S (1967) Tvær nýjar C14 aldurákvardanir á öskulögum úr Snæfellsjökli (Two new C14 dates on tephra layers from Snæfellsjökull). Náttúrufræðingurinn

  • Sturkell E, Einarsson P, Sigmundsson F, Hreinsdóttir S, Geirsson H (2003) Deformation of Grímsvötn volcano, Iceland: 1998 eruption and subsequent inflation. Geophys Res Lett 30:B4

    Article  Google Scholar 

  • Sturkell E, Einarsson P, Roberts MJ, Geirsson H, Gudmundsson MT, Sigmundsson F, Pinel V, Gudmundsson GB, Ólafsson H, Stefánsson R (2008) Seismic and geodetic insights into magma accumulation at Katla subglacial volcano, Iceland: 1999 to 2005. J Geophys Res 113:B3

    Article  Google Scholar 

  • Tchalenko JS (1970) Similarities between shear zones of different magnitudes. Geol Soc Am Bull 81(6):1625–1640

    Article  Google Scholar 

  • Tentler T, Temperley S (2007) Magmatic fissures and their systems in Iceland: a tectonomagmatic model. Tectonics 26, TC5019. doi:10.1029/2006TC002037

    Google Scholar 

  • Thordarson T, Hoskuldsson A (2002) Classic Geology in Europe. Monograph, VIII, pp 200

  • Tibaldi A (1995) Morphology of pyroclastic cones and tectonics. J Geophys Res 100(12):24521–24535

    Google Scholar 

  • Tibaldi A, Romero JL (2000) Morphometry of Late Pleistocene–Holocene faulting in the southern Andes of Colombia and volcano-tectonic relationships. Tectonics 19(2):358–377

    Article  Google Scholar 

  • Tibaldi A, Pasquarè FA (2008) A new mode of inner volcano growth: the “flower intrusive structure”. Earth Planet Sci Lett 271:202–208

    Article  Google Scholar 

  • Tibaldi A, Pasquarè FA, Tormey D (2010) Volcanism in reverse and strike-slip fault settings. In: New frontiers in integrated solid earth sciences, Editors: Cloetingh S, Negendank J, Springer, New York, 315–348. doi: 10.1007/978-90-481-2737-5

  • Tibaldi A, Pasquarè AF, Rust D (2011) New insights into the cone sheet structure of the Cuillin Complex, Isle of Skye, Scotland. J Geol Soc Lond 168:689–704

    Article  Google Scholar 

  • Upton BGJ, Wright JB (1961) Intrusions of gabbro and granophire in the Snaefelsness, western Iceland. Geol Mag 98(6):488–492

    Article  Google Scholar 

  • Walker GPL (1958) Geology of the Reydarfjordur Area, Eastern Iceland. Q J Geol Soc 114(1/4):367–391

    Article  Google Scholar 

  • Walker GPL (1960) Zeolite zones and dike distribution in relation to the structure of the basalts of eastern Iceland. J Geol 68:515–528

    Article  Google Scholar 

  • Walker GPL (1974) The structure of Eastern Iceland. In: Kristjánsson L (ed) Geodynamics of Iceland and the North Atlantic Area. Reidel, Dordrecht, pp 177–188

  • Walker GPL (1975) Intrusive sheet swarms and the identity of Crustal Layer 3 in Iceland. J Geol Soc Lond 131:143–161

    Article  Google Scholar 

  • Walker GPL (1992) “Coherent intrusion complexes” in large basaltic volcanoes — a new structural model. J Volcanol Geotherm 50(1–2):41–54

    Google Scholar 

  • Walker GPL (1999) Volcanic rift zones and their intrusion swarms. J Volcanol Geotherm 94(1–4):21–34

    Google Scholar 

  • Welke H, Moorbath S, Cumming GL, Sigurdsson H (1968) Lead isotope studies on igneous rocks from Iceland. Earth Planet Sci Lett 4(3):221–231

    Article  Google Scholar 

  • Wilson M (1989) Igneous petrogenesis. Unwin Hyman, London

    Book  Google Scholar 

Download references

Acknowledgements

This is a contribution to the International Lithosphere Program Task Force II “Volcanoes and society: environment, health and hazards”. The Authors are grateful to Andrea Villan, Luca Corti and Luca Fumagalli for field cooperation. Claudia Corazzato is acknowledged for her insights and comments to the 3D structural model. Agust Gudmundsson and an anonymous reviewer are acknowledged for their insightful comments and suggestions to the previous version of the manuscript.

Author information

Authors and Affiliations

  1. Department of Earth and Environmental Sciences, University of Milan-Bicocca, Milan, Italy

    Alessandro Tibaldi, Fabio Luca Bonali, Alessandro Cavallo & Alessandro D’Urso

  2. Department of Theoretical and Applied Sciences, Insubria University, Varese, Italy

    Federico Aligi Pasquaré

  3. Centre for Applied Geoscience, School of Earth and Environmental Sciences, University of Portsmouth, Portsmouth, UK

    Derek Rust

Authors
  1. Alessandro Tibaldi
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Fabio Luca Bonali
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Federico Aligi Pasquaré
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Derek Rust
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Alessandro Cavallo
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Alessandro D’Urso
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Alessandro Tibaldi.

Additional information

Editorial responsibility: A. Gudmundsson

Rights and permissions

Reprints and permissions

About this article

Cite this article

Tibaldi, A., Bonali, F.L., Pasquaré, F.A. et al. Structure of regional dykes and local cone sheets in the Midhyrna-Lysuskard area, Snaefellsnes Peninsula (NW Iceland). Bull Volcanol 75, 764 (2013). https://doi.org/10.1007/s00445-013-0764-8

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1007/s00445-013-0764-8

Keywords

Search

Navigation