Advertisement

Contributions to Mineralogy and Petrology

, Volume 162, Issue 4, pp 709–723 | Cite as

Quantitative petrological evidence for the origin of K-feldspar megacrysts in dacites from Taapaca volcano, Chile

  • Michael D. Higgins
Original Paper

Abstract

K-feldspar megacrysts are common in granitoids, but relatively rare in chemically equivalent volcanic rocks. Dacites from Taapaca volcano have euhedral sanidine megacrysts up to 5 cm long. Small crystals, where present, are rounded. Growth of the megacrysts engulfed plagioclase and amphibole crystals. Crystal size distributions (CSD) of sanidine megacrysts are hump shaped. All these data show that megacrysts developed from the host magma by coarsening: this was enabled by the cycling of magma temperature around the sanidine liquidus temperature in response to injections of more mafic magma and subsequent magmatic overturns. Plagioclase crystals enclosed in the megacrysts are small and have short, steep, straight CSDs, which contrasts with the CSDs of plagioclase in the groundmass which are shallower and extend to larger sizes. This shows that plagioclase was also coarsened approximately synchronously with sanidine, in response to the same temperature conditions.

Keywords

K-feldspar Megacryst Crystal size distribution Plagioclase Lava Petrography 

Notes

Acknowledgments

I would like to thank Jorge Clavero and Georg Zellmer for helping me to plan the project. Judit Ozoray accompanied me in the field and made editorial comments. Georg Zellmer and an anonymous reviewer helped to improve the manuscript. UQAC awarded me a sabbatical which enabled this project. The ‘Departamento de geología, Universidad de Chile’ hosted me during my sabbatical. Funding was provided by a Discovery grant from NSERC (Canada).

References

  1. Bachmann O, Miller CF, de Silva SL (2007) The volcanic-plutonic connection as a stage for understanding crustal magmatism. J Volcanol Geotherm Res 167(1–4):1–23CrossRefGoogle Scholar
  2. Banaszak M, Wegner W, Simos K, Worner G (2009) Zoned sanidine in Taapaca dacites (I): textural and chemical characteristics of zoning patterns. In: Mineralogical society annual meeting, Edinburgh, UKGoogle Scholar
  3. Cabane H, Laporte D, Provost A (2005) An experimental study of Ostwald ripening of olivine and plagioclase in silicate melts: implications for the growth and size of crystals in magmas. Contrib Mineral Petrol 150(1):37–53CrossRefGoogle Scholar
  4. Clavero JE (2002) Evolution of Parinacota volcano and Taapaca Volcanic Complex, Central Andes of Northern Chile. PhD. University of Bristol, Bristol, UKGoogle Scholar
  5. Clavero JE, Sparks RSJ (2005) Geologia del complejo volcanico Taapaca, Region de Tarapaca, Serie geologia basica, No 93, Subdireccion nacional de geologia, Gobierno de ChileGoogle Scholar
  6. Clavero JE, Sparks RSJ, Pringle MS, Polanco E, Gardeweg MC (2004) Evolution and volcanic hazards of Taapaca Volcanic complex, central Andes of Northern Chile. J Geol Soc 161:603–618CrossRefGoogle Scholar
  7. Dehoff RT (1991) A geometrically general theory of diffusion controlled coarsening. Acta Metall Mater 39(10):2349–2360CrossRefGoogle Scholar
  8. Farina F, Dini A, Innocenti F, Rocchi S, Westerman DS (2010) Rapid incremental assembly of the Monte Capanne pluton (Elba Island, Tuscany) by downward stacking of magma sheets. Geol Soc Am Bull 122(9–10):1463–1479. doi: 10.1130/b30112.1 Google Scholar
  9. Higgins MD (1994) Determination of crystal morphology and size from bulk measurements on thin sections: numerical modelling. Am Mineral 79:113–119Google Scholar
  10. Higgins MD (1996) Magma dynamics beneath Kameni volcano, Greece, as revealed by crystal size and shape measurements. J Volcanol Geotherm Res 70:37–48CrossRefGoogle Scholar
  11. Higgins MD (1998) Origin of anorthosite by textural coarsening: quantitative measurements of a natural sequence of textural development. J Petrol 39:1307–1325CrossRefGoogle Scholar
  12. Higgins MD (1999) Origin of megacrysts in granitoids by textural coarsening: a crystal size distribution (CSD) study of microcline in the cathedral peak granodiorite, Sierra Nevada, California. In: Fernandez C, Castro A (eds) Understanding granites: integrating modern and classical techniques special publication 158. Geological Society of London, London, pp 207–219Google Scholar
  13. Higgins MD (2000) Measurement of crystal size distributions. Am Mineral 85:1105–1116Google Scholar
  14. Higgins MD (2006a) Quantitative textural measurements in igneous and metamorphic petrology. Cambridge University Press, CambridgeCrossRefGoogle Scholar
  15. Higgins MD (2006b) Use of appropriate diagrams to determine if crystal size distributions (CSD) are dominantly semi-logarithmic, lognormal or fractal (scale invariant). J Volcanol Geotherm Res 154:8–16CrossRefGoogle Scholar
  16. Higgins MD (2010) Imaging birefringent minerals without extinction using circularly polarized light. Can Min 48:231–235CrossRefGoogle Scholar
  17. Higgins MD (2011) Textural coarsening in igneous rocks. Int Geol Rev 53(3):354–376CrossRefGoogle Scholar
  18. Higgins MD, Chandrasekharam D (2007) Nature of sub-volcanic magma chambers, Deccan province, India: evidence from quantitative textural analysis of plagioclase megacrysts in the Giant Plagioclase Basalts. J Petrol 48:885–900. doi: 10.1093/petrology/egm005 CrossRefGoogle Scholar
  19. Higgins MD, Roberge J (2003) Crystal size distribution (CSD) of plagioclase and amphibole from Soufriere Hills volcano, Montserrat: evidence for dynamic crystallisation/textural coarsening cycles. J Petrol 44:1401–1411CrossRefGoogle Scholar
  20. Jerram DA, Martin VM (2008) Understanding crystal populations and their significance through the magma plumbing system. Geol Soc Lond Spec Publicat 304(1):133–148. doi: 10.1144/sp304.7 Google Scholar
  21. Johnson BR, Glazner AF (2010) Formation of K-feldspar megacrysts in granodioritic plutons by thermal cycling and late-stage textural coarsening. Contrib Mineral Petrol 159:599–619CrossRefGoogle Scholar
  22. Kaminsky W (2005) WinXMorph: a computer program to draw crystal morphology, growth sectors and cross sections with export files in VRML V2.0 utf8-virtual reality format. J Appl Crystallogr 38:566–567CrossRefGoogle Scholar
  23. Kent AJR, Darr C, Koleszar AM, Salisbury MJ, Cooper KM (2010) Preferential eruption of andesitic magmas through recharge filtering. Nature Geosci 3(9):631–636CrossRefGoogle Scholar
  24. Kouchi A, Tsuchiyama A, Sunagawa I (1986) Effects of stirring on crystallization of basalt: texture and element partitioning. Contrib Mineral Petrol 93:429–438CrossRefGoogle Scholar
  25. Le Maitre RW, Streckeisen A, Zanettin B, Bas MJL, Bonin B, Bateman P, Bellieni G, Dudek A, Efremova S, Keller J, Lameyre J, Sabine PA, Schmid R, Sorensen H, Woolley AR (2002) Igneous rocks: a classification and glossary of terms: recommendations of the international union of geological sciences, subcommission on the systematics of igneous rocks. Cambridge University Press, CambridgeGoogle Scholar
  26. Moore JG, Sisson TW (2008) Igneous phenocrystic origin of K-feldspar megacrysts in granitic rocks from the Sierra Nevada batholith. Geosphere 4(2):387–400. doi: 10.1130/ges00146.1 Google Scholar
  27. Morgan DJ, Jerram DA (2006) On estimating crystal shape for crystal size distribution analysis. J Volcanol Geotherm Res 154(1–2):1–7CrossRefGoogle Scholar
  28. Nelson ST, Montana A (1992) Sieve-textured plagioclase in volcanic-rocks produced by rapid decompression. Am Mineral 77(11–12):1242–1249Google Scholar
  29. Paterson SR (2009) Magmatic tubes, pipes, troughs, diapirs, and plumes: late-stage convective instabilities resulting in compositional diversity and permeable networks in crystal-rich magmas of the Tuolumne batholith, Sierra Nevada, California. Geosphere 5(6):496–527. doi: 10.1130/Ges00214.1
  30. Rasband WS (2010) ImageJ. U. S. National Institutes of Health, Bethesda, Maryland, USA http://www.rsb.info.nih.gov/ij/
  31. Schmidt MW (1992) Amphibole composition in Tonalite as a function of pressure—an experimental calibration of the Al-in-Hornblende barometer. Contrib Mineral Petrol 110(2–3):304–310CrossRefGoogle Scholar
  32. Simakin AG, Bindeman IN (2008) Evolution of crystal sizes in the series of dissolution and precipitation events in open magma systems. J Volcanol Geotherm Res 177(4):997–1010CrossRefGoogle Scholar
  33. Slaby E, Gotze J (2004) Feldspar crystallization under magma-mixing conditions shown by cathodoluminescence and geochemical modelling—a case study from the Karkonosze pluton (SW Poland). Mineral Mag 68:561–577. doi: 10.1180/0026461046840205 CrossRefGoogle Scholar
  34. Slaby E, Gotze J, Worner G, Simon K, Wrzalik R, Smigielski M (2008) K-feldspar phenocrysts in microgranular magmatic enclaves: a cathodoluminescence and geochemical study of crystal growth as a marker of magma mingling dynamics. Lithos 105(1–2):85–97. doi: 10.1016/j.lithos.2008.02.006 Google Scholar
  35. Sunagawa I (1987) Morphology of crystals. Reidel, DordrechtGoogle Scholar
  36. Vernon RH (1986) K-feldspar megacrysts in granites—phenocrysts not porphyroblasts. Earth-Sci Rev 23:1–63CrossRefGoogle Scholar
  37. Vernon RH, Paterson SR (2008) How late are K-feldspar megacrysts in granites? Lithos 104:327–336CrossRefGoogle Scholar
  38. Wagner C (1961) Theorie der Alterung von Niederschlagen durch Umlosen (Ostwald-Reifung). Zietschrift fur Elektrochem 65:581–591Google Scholar
  39. Wegner W (2004) Growth history of sanidine crystals in Taapaca Dacites (Northern Chile) diploma. Georg-August-Universität, GöttingenGoogle Scholar
  40. Wegner W, Wörner G, Kronz A (2005) Evolution of Taapaca Volcano, N. Chile: evidence from major and trace elements, Sr-, Nd-, Pb-isotopes, age dating and chemical zoning in sanidine megacrysts. In: 6th International symposium on andean geodynamics, Barcelona, pp 795–798Google Scholar
  41. Zellmer GF, Clavero JE (2006) Using trace element correlation patterns to decipher a sanidine crystal growth chronology: an example from Taapaca volcano, Central Andes. J Volcanol Geotherm Res 156(3–4):291–301. doi: 10.1016/j.jvolgeores.2006.03.004 Google Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  1. 1.Sciences de la TerreUniversité du Québec à ChicoutimiChicoutimiCanada

Personalised recommendations