Advertisement

Bulletin of Volcanology

, Volume 74, Issue 7, pp 1645–1666 | Cite as

Origin of internal flow structures in columnar-jointed basalt from Hrepphólar, Iceland: I. Textural and geochemical characterization

  • Sonja A. BosshardEmail author
  • Hannes B. MattssonEmail author
  • György Hetényi
Research Article

Abstract

Basalt columns from Hrepphólar (Iceland) show distinct internal structures produced by alternating brighter and darker bands through the column, locally exhibiting viscous fingering features. Here, we present geochemical and petrographic data retrieved from analyses of major and trace elements and mineral chemistry from a cross section of a single basaltic column. This is combined with petrographic descriptions and data on crystal size distributions of plagioclase. We use our data from Hrepphólar to test four existing models that have been proposed to explain banded structures inside columns: (1) deuteric alteration, (2) double-diffusive convection, (3) constitutional supercooling, and (4) crystallization-induced melt migration. We find that the internal structures at Hrepphólar represent primary magmatic features, because approximately 20 % of the observed structures crosscut the column-bounding fracture for each meter along the main axis of the column. These features must thus have been formed before the column-delimiting crack advanced. Major and trace element analyses show small but significant variations across the column and strong correlation between oxides like FeO and TiO2, as well as K2O and P2O5. The geochemical variations correlate with the presence of darker/brighter bands visible on a polished surface and can be explained by a variation in the modal proportions of the main phenocryst phases (specifically variable plagioclase and titanomagnetite content). This banding enhances the internal structures apparent in the polished cross section from columnar joints at Hrepphólar. The measured variations in major and trace element geochemistry, as well as mineral chemistry, are too small to distinguish between the proposed band-forming models. Plagioclase crystal size distributions, however, display a systematic change across the column that is consistent with late-stage migration of melt inside the column (i.e., the crystallization induced melt migration hypothesis). The central part of the columns have plagioclases indicative of slow cooling and these are also more steeply oriented (i.e., subparallel to the column axis) compared with plagioclases present in the more rapidly cooled edges. This redistribution of melt within individual columns may significantly affect the cooling rate of columnar-jointed lava flows and intrusions.

Keywords

Columnar jointing Hrepphólar Iceland Melt migration Crystal size distribution Magmatic banding 

Notes

Acknowledgments

The authors thank Bjarne Almqvist and Ann Hirt for introducing the AMS technique and many interesting discussions on the magnetic fabrics of the Hrepphólar columns. The authors are also grateful to Ármann Höskuldsson for first introducing the peculiar structures inside the columns from Hrepphólar and S. Helgason Ehf. (Reykjavik) who provided the polished slab that was used for this project. Finally, Lydia Zehnder and Markus Wälle are also acknowledged for assisting with XRF and LA-ICP-MS measurements.

References

  1. Almqvist BS, Bosshard SA, Hirt AM, Mattsson HB (2012) Internal flow structures in columnar jointed basalts from Hrepphólar, Iceland: II. Rock magnetic properties and magnetic anisotropy (this issue)Google Scholar
  2. Alt JC, Laverne C, Vanko D (1996) Hydrothermal alteration of a section of the upper oceanic crust in the eastern equatorial Pacific. A synthesis of results from site 504 (DSDP Legs, 69, 70 and 83 and ODP Legs 111, 137, 140 and 148). In: Alt JC, Kinoshita H, Stokking L, Michael PJ (eds). Proceedings of the ODP Scientific Results, vol. 148, pp. 417–434Google Scholar
  3. Andrews AJ (1980) Saponite and celadonite in layer 2 basalts, DSDP Leg 37. Contrib Mineral Petrol 73:323–340CrossRefGoogle Scholar
  4. Boudreau AE, Philpotts AR (2002) Quantitative modeling of compaction in the Holyoke flood basalt flow, Hartford Basin, Connecticut. Contrib Mineral Petrol 144:176–184CrossRefGoogle Scholar
  5. Brugger CR, Hammer JE (2010) Crystal size distribution analysis of plagioclase in experimentally decompressed hydrous rhyodacite magma. Earth Planet Sci Lett 300(3–4):246–254CrossRefGoogle Scholar
  6. Budkewitsch P, Robin PY (1994) Modelling the evolution of columnar joints. J Volcanol Geotherm Res 59(3):219–239CrossRefGoogle Scholar
  7. Bulkeley R (1693) Part of a letter concerning the Giants Causeway in the County of Atrim in Ireland. Philos Trans R Soc Lond 17:708CrossRefGoogle Scholar
  8. Burkhard D (2002) Kinetics of crystallization: example of micro-crystallization in basalt lava. Contrib Mineral Petrol 142(6):724–737CrossRefGoogle Scholar
  9. Ellwood BB (1979) Anisotropy of magnetic susceptibility in variations in Icelandic columnar basalts. Earth Planet Sci Lett 42:209–212CrossRefGoogle Scholar
  10. Ellwood BB, Fisk MR (1977) Anisotropy of magnetic susceptibility variations in a single icelandig columnar basalt. Earth Planet Sci Lett 35:116–122CrossRefGoogle Scholar
  11. Fritz WJ, Stillman CJ (1996) A subaqueous welded tuff from the Ordovician of County Waterford, Ireland. J Volcanol Geotherm Res 70(1–2):91–106CrossRefGoogle Scholar
  12. Gill R (2010) Igneous rocks and processes: a practical guide. Wiley-BlackwellGoogle Scholar
  13. Gilman JJ (2009) Basalt columns: large scale constitutional supercooling? J Volcanol Geotherm Res 184:347–350CrossRefGoogle Scholar
  14. Glicksman ME (2011) Constitutional supercooling. In: Principles of Solidification. Springer, New York, pp 213–235CrossRefGoogle Scholar
  15. Goehring L, Morris SW (2005) Order and disorder in columnar joints. Europhys Lett 69(5):739–745CrossRefGoogle Scholar
  16. Grossenbacher KA, McDuffie SM (1995) Conductive cooling of lava: columnar joint diameter and stria width as functions of cooling rate and thermal gradient. J Volcanol Geotherm Res 69(1–2):95–103CrossRefGoogle Scholar
  17. Guillong M, Meier DL, Allan MM, Heinrich CA, Yardley BWD (2008) Appendix A6: SILLS: a MatLab-based program for the reduction of Laser Ablation ICP-MS data of homogeneous materials and inclusions. Mineralogical Association of Canada Short Course 40, Vancouver, B.C.:328–333Google Scholar
  18. Guy B (2009) Basalt columns: large scale constitutional supercooling? Comments on the paper by John Gilman (JVGR, 2009) and presentation of some new data. J Volcanol Geotherm ResGoogle Scholar
  19. Guy B, Le Coze J (1990) Reflections on columnar jointing of basalts: the instability of the planar solidification front. C R Acad Sci Paris 311(II):943–949Google Scholar
  20. Hammer JE (2008) Experimental studies of the kinetics and energetics of magma crystallization. Rev Mineral Petrol 69:9–59Google Scholar
  21. Higgins MD (2000) Measurement of crystal size distributions. Am Mineral 85:1105–1116Google Scholar
  22. Higgins MD (2006) Quantitative textural measurements in igneous and metamorphic petrology. Cambridge University Press, Oxford, p 254CrossRefGoogle Scholar
  23. Juteau T, Noack Y, Whitechurch H (1979) Mineralogy and geochemistry of alteration products in holes 417A and 417A and 417D basement samples (Deep Sea Drilling project LEG 51). In: Donnelley T, Francheateau J, Bryan W, Robinson P, Flower M, Salisbury M (eds). Initial Reports of the Deep Sea Drilling Project, LI, LII:1273–1297Google Scholar
  24. Kantha L (1981) ‘Basalt fingers’—origin of columnar joints? Geol Mag 118:251–264CrossRefGoogle Scholar
  25. Kristinsdóttir BD (2010) Samanburður á punktálags- og einásabrotstyrk bergsýna úr Helguvík og Hólahnúkum. Bachelor thesis, Sigillum Universitatis IslandiaeGoogle Scholar
  26. Kristmannsdottir H (1979) Alteration of basaltic rocks by hydrothermal activity at 100–300 °C. In: Mortland MM, Farmer VC (eds) International Clay Conference. Elsevier, Amsterdam, pp 359–367Google Scholar
  27. Mattsson HB, Caricchi L, Almqvist BSG, Caddick MJ, Bosshard SA, Hetény G, Hirt AM (2011) Melt migration in basalt columns driven by crystallization-induced pressure gradients. Nat Commun 2:299CrossRefGoogle Scholar
  28. Michol KA, Russell JK, Andrews GDM (2008) Welded block and ash flow deposits from Mount Meager, British Columbia, Canada. J Volcanol Geotherm Res 169(3–4):121–144CrossRefGoogle Scholar
  29. Mock A, Jerram DA (2005) Crystal size distributions (CSD) in three dimensions: insights from the 3D reconstruction of a highly porphyritic rhyolite. J Petrol 46(8):1525–1541CrossRefGoogle Scholar
  30. Morgan DJ, Jerram DA (2006) On estimating crystal shape for crystal size distribution analysis. J Volcanol Geotherm Res 154:1–7CrossRefGoogle Scholar
  31. Philpotts AR, Dickson LD (2000) The formation of plagioclase chains during convective transfer in basaltic magma. Nature 406:59–61CrossRefGoogle Scholar
  32. Philpotts AR, Dickson LD (2002) Millimeter-scale modal layering and the nature of the upper solidification zone in thick flood-basalt flows and other sheets of magma. J Struct Geol 24:1171–1177CrossRefGoogle Scholar
  33. Philpotts AR, Shi J, Brustman CM (1998) Role of plagioclase crystal chains in the differentiation of partly crystallized basaltic magma. Nature 395:343–346CrossRefGoogle Scholar
  34. Philpotts AR, Brustman CM, Shi J, Carlson WD, Denison C (1999) Plagioclase-chain networks in slowly cooled basaltic magma. Am Mineral 84:1819–1829Google Scholar
  35. Pupier E, Duchene S, Toplis M (2008) Experimental quantification of plagioclase crystal size distribution during cooling of a basaltic liquid. Contrib Mineral Petrol 155(5):555–570CrossRefGoogle Scholar
  36. Rasband W (2008) ImageJ 1.41o Image Processing and Analysis in Java, Computer software. In: National Institutes of Health, USAGoogle Scholar
  37. Saemundsson K (1970) Interglacial lava flows in the lowlands of Southern Iceland and the problem of two-tiered columnar jointing. Jökull 20:62–77Google Scholar
  38. Sauerzapf U, Lattard D, Burchard M, Engelmann R (2008) The titanomagnetite–ilmenite equilibrium: new experimental data and thermo-oxybarometric application to the crystallization of basic to intermediate rocks. J Petrol 49(6):1161–1185CrossRefGoogle Scholar
  39. Schenato F, Formoso MLL, Dudoignon P, Meunier A, Proust D, Mas A (2003) Alteration processes of a thick basaltic lava flow of the Paraná Basin (Brazil): petrographic and mineralogical studies. J S Am Earth Sci 16(5):423–444CrossRefGoogle Scholar
  40. Shelley D (1993) Igneous and metamorphic rocks under the microscope. Chapman and Hall, London, p 445Google Scholar
  41. Smedes HW, Lang AJJ (1955) Basalt column rinds caused by deuteric alteration. Am J Sci 253:179–181CrossRefGoogle Scholar
  42. Smith JV (2002) Structural analysis of flow-related textures in lavas. Earth Sci Rev 57(3–4):279–297CrossRefGoogle Scholar
  43. Spry A (1962) The origin of columnar jointing, particulary in basalt flows. Aust J Earth Sci 8(2):191–216CrossRefGoogle Scholar
  44. Sun SS, McDonough WF (1989) Chemical and isotope systematics of oceanic basalts: implications for mantle composition and processes. In: Saunders AD, Norry MJ (eds) Magmatism in the Ocean Basins. Spec Publ Vol Geol Soc London 42:313–345Google Scholar
  45. Takagi D, Sato H, Nakagawa M (2005) Experimental study of a low-alkali tholeiite at 1–5 kbar: optimal condition for the crystallization of high-An plagioclase in hydrous arc tholeiite. Contrib Mineral Petrol 149(5):527–540CrossRefGoogle Scholar
  46. Tomkeieff SI (1940) The basalt lavas of the Giant’s Causeway district of Northern Ireland. Bull Volcanol 6:89–146CrossRefGoogle Scholar
  47. Turner JS (1973) Buoyancy effects in fluids. Cambridge University Press, OxfordCrossRefGoogle Scholar
  48. Wright TL, Okamura RT (1977) Cooling and crystallization of tholeiitic basalt, 1956 Makaopuhi lava lake, Hawaii. U S Geol Surv Prof Pap 1004:78Google Scholar

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Institute of Geochemistry and PetrologySwiss Federal Institute of Technology (ETH Zürich)ZurichSwitzerland
  2. 2.ZürichSwitzerland

Personalised recommendations