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The pre-Alpine tectonic history of the Austroalpine continental basement in the Valpelline unit (Western Italian Alps)

Published online by Cambridge University Press:  20 August 2012

PAOLA MANZOTTI  and
MICHELE ZUCALI
PAOLA MANZOTTI*
Affiliation:
Institut für Geologie, Universität Bern, Baltzerstrasse 1+3, 3012 CH-Bern, Switzerland
MICHELE ZUCALI
Affiliation:
Dipartimento di Scienze della Terra ‘Ardito Desio’, Università degli Studi di Milano, Via Mangiagalli, 34 20133 Milano, Italy CNR-IDPA – Sezione di Milano, Via Mangiagalli 34 20133, Milano, Italy
*
†Author for correspondence: [email protected]
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Abstract

The Valpelline unit is a large slice of continental crust constituting the Austroalpine Dent Blanche nappe (NW Italy). The pre-Alpine evolution of this unit holds important clues about the Palaeozoic crustal structure at the northern margin of the Adria continent, about the history of rifting in the Alpine region, and thus about the thermomechanical conditions that preceded the Alpine convergent evolution. Several stages of the deformation history and of partial re-equilibration were identified, combining meso- and micro-structural analyses with thermobarometry. Reconstructed pre-Alpine P–T–t–d paths demonstrate that the Valpelline unit experienced an early stage at pressures between 4.5 and 6.5 kbar followed by migmatite formation. A subsequent stage reached amphibolite to granulite facies conditions. This stage was associated with the development of the most penetrative fabrics affecting all of the Valpelline lithotypes. The pre-Alpine evolution ended with a weak deformation associated with a local mineral-chemical re-equilibration under greenschist facies conditions at ≈ 4 kbar and T < 450°C. A Permo-Mesozoic lithospheric extension is thought to be responsible for asthenosphere upwelling, thereby causing high temperature metamorphism at medium pressure and widespread partial melting, which led to upper crustal magmatic activity.

Keywords

Valpelline unitpre-Alpine metamorphismAustroalpinePermiangeodynamic evolution
Type
Original Articles
Information
Geological Magazine , Volume 150 , Issue 1 , January 2013 , pp. 153 - 172
Copyright
Copyright © Cambridge University Press 2012

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References

Argand, E. 1906. Sur la carte tectonique du Massif de la Dent Blanche. Comptes Rendus de l'Académie des Sciences Paris 142, 527–29.Google Scholar
Ballèvre, M. & Kienast, J. R. 1987. Decouverte et signification de parageneses a grenat-amphibole bleu dans la couverture mesozoique de la nappe de la Dent-Blanche (Alpes Occidentales). Comptes Rendus de l'Académie des Sciences Paris 305, 43–6.Google Scholar
Bhandari, A., Pant, N. C., Bhowmik, S. K. & Goswami, S. 2011. ~1.6 Ga ultrahigh-temperature granulite metamorphism in the Central Indian Tectonic Zone: insights from metamorphic reaction history, geothermobarometry and monazite chemical ages. Geological Journal 46, 198–216.Google Scholar
Bhattacharya, A., Mohanty, L., Maji, A., Sen, S. K. & Raith, M. 1992. Non-ideal mixing in the phlogopite-annite binary: constraints from experimental data on Mg-Fe partitioning and a reformulation of the biotite-garnet geothermometer. Contributions to Mineralogy and Petrology 111, 87–93.Google Scholar
Bohlen, S. R. 1987. Pressure-temperature-time paths and a tectonic model for the evolution of granulites. Journal of Geology 95, 617–32.Google Scholar
Bonin, B., Braendlein, P., Bussy, F., Desmons, J. & Eggenberger, U. 1993. Late Variscan magmatic evolution of the Alpine basement. In Pre-Mesozoic Geology in the Alps (eds von Raumer, J. F. & Neubauer, F.), pp. 171–201. Berlin & Heidlberg: Springer-Verlag.CrossRefGoogle Scholar
Bussy, F., Venturini, G., Hunziker, J. C. & Martinotti, G. 1998. U-Pb ages of magmatic rocks of the Western Austroalpine Dent-Blanche-Sesia Unit. Schweizerische Mineralogische und Petrographische Mitteilungen 78, 163–68.Google Scholar
Caby, R., Kienast, J. R. & Saliot, P. 1978. Structure, metamorphism and model of tectonic evolution of the Western Alps. Revue de Geographie Physique et de Geologie Dynamique 20, 307–22.Google Scholar
Canepa, A., Castelletto, M., Cesare, B., Martin, S. & Zaggia, L. 1990. The Austroalpine Mont Mary nappe (Italian Western Alps). Memorie di Scienze Geologiche 42, 1–17.Google Scholar
Chatelineau, M. 1988. Cation site occupancy in chlorites and illites as a function of temperature. Clay Minerals 23, 471–85.Google Scholar
Dal Piaz, G. V. 1993. Evolution of Austrolapine and Upper Penninic basement in the northwestern Alps from Variscan convergence to post-Variscan extension. In Pre-Mesozoic Geology in the Alps (eds von Raumer, J. F. & Neubauer, F.), pp. 325–42. Berlin & Heidlberg: Spring-Verlag.Google Scholar
Dal Piaz, G. V., De Vecchi, G. & Hunziker, J. C. 1977. The Austroalpine layered gabbros of the Matterhorn and Mt. Collon-Dents de Bertol. Schweizerische Mineralogische und Petrographische Mitteilungen 57, 59–88.Google Scholar
Deer, W. A., Howie, R. A. & Zussman, J. 1996. An Introduction to the Rock-Forming Minerals. New York: Prentice Hall.Google Scholar
De Leo, S., Biino, G. & Compagnoni, R. 1987. Riequilibrazioni metamorfiche alpine nella serie di Valpelline e di Arolla a Nord di Bionaz (Valpelline-Aosta). Rendiconti della Società Italiana di Mineralogia e Petrologia 42, 181–82.Google Scholar
De Giusti, F., Dal Piaz, G. V., Massironi, M. & Schiavo, A. 2003. Carta geotettonica della Valle d'Aosta. Memorie di Scienze Geologiche 55 (2003/2004), 129–49.Google Scholar
Diehl, E. A., Masson, R. & Stutz, A. H. 1952. Contributo alla conoscenza del ricoprimento della Dent Blanche. Memorie degli Istituti di Geologia e Mineralogia dell'Università di Padova 17, 1–52.Google Scholar
Diella, V., Spalla, M. I. & Tunesi, A. 1992. Contrasting thermomechanical evolutions in the southalpine metamorphic basement of the Orobic Alps (Central Alps, Italy). Journal of Metamorphic Geology 10, 203–19.Google Scholar
Ellis, D. J. 1987. Origin and evolution of granulites in normal thickened crusts. Geology 15, 167–70.Google Scholar
Gaetani, M., Gnacollini, M., Jadoul, F. & Garzanti, E. 1998. Multiorder sequence stratigraphy in the Triassic system of the western Southern Alps. In Mesozoic and Cenozoic Sequence Stratigraphy of European Basins (eds De Graciansky, P. C., Hardenbol, J., Jacquin, T. & Vail, P. R.), pp. 701–17. Society for Sedimentary Geology (SEPM) Special Publication 60.Google Scholar
Galli, A., Le Bayon, B., Schmidt, M. W., Burg, J. P., Reusser, E., Sergeev, S. A. & Larionov, A. 2012. U-Pb zircon dating of the Gruf Complex: disclosing the late Variscan granulitic lower crust of Europe stranded in the Central Alps. Contributions to Mineralogy and Petrology 163, 353–78.Google Scholar
Gardien, V. 1994. Occurrence of kyanite in the gneisses from the Valpelline Series (Dent-Blanche Nappe, Western Alps). Comptes Rendus de l'Academie des Sciences Paris, Serie 2 319, 899–905.Google Scholar
Gardien, V., Reusser, E. & Marquer, D. 1994. Pre-Alpine metamorphic evolution of the gneisses from the Valpelline Series (Western Alps, Italy). Schweizerische Mineralogische und Petrographische Mitteilungen 74, 489–502.Google Scholar
Green, D. H. & Ringwood, A. E. 1967. An experimental investigation of the gabbro to eclogite transformation and its petrological applications. Geochimica et Cosmochimica Acta 31, 767–833.Google Scholar
Harley, S. L. 2008. Refining the P-T records of UHT crustal metamorphism. Journal of Metamorphic Geology 26, 125–54.Google Scholar
Henry, B., Guidotti, C. V. & Thomson, J. A. 2005. The Ti-saturation surface for low-to-medium pressure metapelitic biotite: implications for geothermometry and Ti-substitution mechanisms. American Mineralogist 90, 316–28.Google Scholar
Hodges, K. V. & Spear, F. S. 1982. Geothermometry, geobarometry and the Al2SiO5 triple point at Mt Moosilauke, New Hampshire. American Mineralogist 67, 1118–34.Google Scholar
Holdaway, M. J. 2001. Recalibration of the GASP geobarometer in light of recent garnet and plagioclase activity models and versions of the garnet-biotite geothermometer. American Mineralogist 86, 1117–29.Google Scholar
Holland, T. 2000. AX: a program to calculate activities of mineral end members from chemical analyses which uses the activity models outlined in Holland & Powell (1998). http://www.esc.cam.ac.uk/research/research-groups/holland/axGoogle Scholar
Holland, J. B. & Powell, R. 1998. An internally consistent thermodynamic data set for phases of petrologic interest. Journal of Metamorphic Geology 16, 309–43.Google Scholar
Hunziker, J. C. 1974. Rb-Sr and K-Ar determination and the Alpine tectonic history of the Western Alps. Memorie degli Istituti di Geologia e Mineralogia dell'Università di Padova 31, 1–54.Google Scholar
Johnson, T. E., White, R. W. & Powell, R. 2008. Partial melting of metagreywacke: a calculated mineral equilibria study. Journal of Metamorphic Geology 26, 837–53.Google Scholar
Kienast, J. R. & Nicot, E. 1971. Presence of a disthene paragenesis and chloritoid probably Alpine in sillimanite gneiss, garnet and cordierite of Valpelline (Val Daoste, Italy). Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences Serie D 272, 1836–40.Google Scholar
Kriegsman, L. M. & Alvarez-Valero, A. M. 2010. Melt-producing versus melt-consuming reactions in pelitic xenoliths and migmatites. Lithos 116, 310–20.CrossRefGoogle Scholar
Lardeaux, J. M. & Spalla, M. I. 1991. From granulites to eclogites in the Sesia Zone (Italian Western Alps) – a record of the opening and closure of the Piedmont Ocean. Journal of Metamorphic Geology 9, 35–59.CrossRefGoogle Scholar
Ledru, P., Courrioux, G., Dallain, C., Lardeaux, J. M., Montel, J. M., Vanderhaeghe, O. & Vitel, G. 2001. The Velay dome (French Massif Central): melt generation and granite emplacement during orogenic evolution. Tectonophysics 342, 207–37.Google Scholar
Lu, M. H., Hofmann, A. W., Mazzucchelli, M. & Rivalenti, G. 1997. The mafic-ultramafic complex near Finero (Ivrea-Verbano Zone). 2. Geochronology and isotope geochemistry. Chemical Geology 140, 223–35.CrossRefGoogle Scholar
Malavielle, J., Guihot, P., Costa, S., Lardeaux, J. M. & Gardien, V. 1990. Collapse of the thickened Variscan crust in the French Massif Central: Mont Pilat extensional shear zone and St. Etienne Late Carboniferous basin. Tectonophysics 177, 139–49.CrossRefGoogle Scholar
Malusà, M., Faccenna, C., Garzanti, E. & Polino, R. 2011. Divergence in subduction zones and exhumation of high pressure rocks (Eocene Western Alps). Earth and Planetary Science Letters 310, 21–32.CrossRefGoogle Scholar
Manzotti, P. 2011. Petro-structural map of the Dent Blanche tectonic system between Valpelline and Valtournenche valleys, Western Italian Alps. Journal of Maps v2011, 340–52.Google Scholar
Manzotti, P., Rubatto, D., Darling, J., Zucali, M., Cenki-Tok, B. & Engi, M. 2012. From Permo-Triassic lithospheric thinning to Jurassic rifting at the Adriatic margin: petrological and geochronological record in Valtournenche (Western Italian Alps). Lithos 146–147, 276–92.Google Scholar
Marschall, H. R., Kalt, A. & Hanel, M. 2003. P-T evolution of a Variscan lower-crustal segment: a study of granulites from the Schwarzwald, Germany. Journal of Petrology 44, 227–53.CrossRefGoogle Scholar
Marotta, A. M. & Spalla, M. I. 2007. Permian-Triassic high thermal regime in the Alps: result of late Variscan collapse or continental rifting? Validation by numerical modeling. Tectonics 26, TC4016, doi: 10.1029/2006TC002047, 27 pp.Google Scholar
Marotta, A. M., Spalla, M. I. & Gosso, G. 2009. Upper and lower crustal evolution during lithospheric extension: numerical modelling and natural footprints from the European Alps. Extending a Continent: Architecture, Rheology and Heat Budget (eds Ring, U. & Wernicke, B.), pp. 33–72. Geological Society of London, Special Publication no. 321.Google Scholar
Monjoie, P., Bussy, F., Lapierre, H. & Pfeifer, H. R. 2005. Modeling of in-situ crystallization processes in the Permian mafic layered intrusion of Mont Collon (Dent Blanche nappe, western Alps). Lithos 83, 317–46.Google Scholar
Müntener, O. & Hermann, J. 2001. The role of lower crust and continental upper mantle during formation of non-volcanic passive margins: evidence from the Alps. In Non-Volcanic Rifting of Continental Margins: A Comparison of Evidence from Land and Sea (eds. Wilson, R. C. L., Whitmarsh, R. B., Taylor, B. & Froitzheim, N.), pp. 267–88. Geological Society of London, Special Publication no. 187.Google Scholar
Muttoni, G., Kent, D. V., Garzanti, E., Brack, P., Abrahamsen, N. & Gaetani, M. 2003. Early Permian Pangea ‘B’ to Late Permian Pangea ‘A’. Earth and Planetary Science Letters 215, 379–94.Google Scholar
Passchier, C. W. & Trouw, R. A. J. 2005. Microtectonics. Berlin: Springer, 366 pp.Google Scholar
Pennacchioni, G. & Guermani, A. 1993. The mylonites of the Austroalpine Dent Blanche nappe along the northwestern side of the Valpelline Valley (Italian Western Alps). Memorie di Scienze Geologiche 45, 37–55.Google Scholar
Pin, C. & Vielzeuf, D. 1983. Granulites and related rocks in Variscan median Europe: a dualistic interpretation. Tectonophysics 93, 47–74.CrossRefGoogle Scholar
Pin, C. & Vielzeuf, D. 1988. Les granulites de haute-pression d'Europe moyenne témoins d'une subduction éo-hercynienne. Implications sur l'origine des goupes leptyno-amphibolitiques. Bulletin de la Societe Geologique de France 1, 3–20.Google Scholar
Quick, J. E., Sinigoi, S., Negrini, L., Demarchi, G. & Mayer, A. 1992. Synmagmatic deformation in the underplated igneous complex of the Ivrea-Verbano Zone. Geology 20, 613–16.Google Scholar
Roda, M. & Zucali, M. 2008. Meso and microstructural evolution of the Mont Morion metaintrusives complex (Dent Blanche nappe, Austroalpine domain, Valpelline, Western Italian Alps). Italian Journal of Geosciences 127, 105–23.Google Scholar
Roda, M. & Zucali, M. 2011. Tectono-metamorphic map of the Mont Morion Permian metaintrusives (Mont Morion – Mont Collon – Matterhorn Complex, Dent Blanche Unit), Valpelline – Western Italian Alps. Journal of Maps v2011, 519–35.Google Scholar
Sawyer, E. W. 2008. Working with Migmatites. Short Course Series: Mineralogical Association of Canada, vol. 38. Quebec: Mineralogical Association of Canada, 158 pp.Google Scholar
Scheurs, J. 1985. Prograde metamorphism of metapelites, garnet-biotite thermometry and prograde change of biotite chemistry in high grade rocks of West Uusimaa, southwest Finland. Lithos 18, 69–80.Google Scholar
Schuster, R. & Stüwe, K. 2008. Permian metamorphic event in the Alps. Geology 36, 603–6.CrossRefGoogle Scholar
Searle, M. P., Cottle, J. M., Streule, M. J. & Waters, D. J. 2010. Crustal melt granites and migmatites along the Himalaya: melt source, segregation, transport and granite emplacement mechanisms. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 100, 219–33.Google Scholar
Spalla, M. I., Gosso, G., Marotta, A. M., Zucali, M. & Salvi, F. 2010. Analysis of natural tectonic systems coupled with numerical modelling of the polycyclic continental lithosphere of the Alps. International Geology Review 52, 1268–302.Google Scholar
Spalla, M. I. & Marotta, A. M. 2007. P-T evolutions vs. numerical modelling: a key to unravel the Paleozoic to early-Mesozoic tectonic evolution of the Alpine area. Periodico di Mineralogia 76, 267–308.Google Scholar
Spalla, M. I., Siletto, G. B., Di Paola, S. & Gosso, G. 2000. The role of structural and metamorphic memory in the distinction of tectono-metamorphic units: the basement of the Como lake in the Southern Alps. Journal of Geodynamics 30, 191–204.Google Scholar
Spalla, M. I., Zucali, M., Di Paola, S. & Gosso, G. 2005. A critical assessment of the tectono-thermal memory of rocks and definition of tectono-metamorphic units: evidence from fabric and degree of metamorphic transformations. In Deformation Mechanisms, Rheology and Tectonics: From Minerals to the Lithosphere (eds Gapais, D., Brun, J. P. & Cobbold, P. R.), pp. 227–47. Geological Society of London, Special Publication no. 243.Google Scholar
Spear, F. S. & Cheney, J. T. 1989. A petrogenetic grid for pelitic schists in the system SiO2-Al2O3-FeO-MgO-K2O-H2O. Contributions to Mineralogy and Petrology 101, 149–64.Google Scholar
Thoni, M. & Miller, C. 2000. Permo-Triassic pegmatites in the eo-Alpine eclogite-facies Koralpe complex, Austria: age and magma source constraints from mineral chemical, Rb-Sr and Sm-Nd isotope data. Schweizerische Mineralogische und Petrographische Mitteilungen 80, 169–86.Google Scholar
Turner, F. J. & Weiss, L. E. (eds). 1963. Structural Analysis of Metamorphic Tectonites. New York: MacGraw-Hill.Google Scholar
Vavra, G., Schmid, R. & Gebauer, D. 1999. Internal morphology, habit and U-Th-Pb microanalysis of amphibolite-to-granulite facies zircons: geochronology of the Ivrea Zone (Southern Alps). Contributions to Mineralogy and Petrology 134, 380–404.Google Scholar
Vernon, H. V. (ed). 2004. A Practical Guide to Rock Microstructure. Cambridge: Cambridge University Press.Google Scholar
Vernon, R. & Clarke, G. 2008. Principles of Metamorphic Petrology. Cambridge: Cambridge University Press.Google Scholar
von Raumer, J. F., Stampfli, G. A. & Bussy, F. 2003. Gondwana-derived microcontinents – the constituents of the Variscan and Alpine collisional orogens. Tectonophysics 365, 7–22.Google Scholar
Weber, K. 1984. Variscan events: early Palaeozoic continental rift metamorphism and late Palaeozoic crustal shortening. In Variscan Tectonics of the North Atlantic Region (eds Hutton, d. H. W. & Sanderson, D. J.), pp. 3–23. Geological Society of London, Special Publication no. 14.Google Scholar
White, R. W. & Powell, R. 2002. Melt loss and the preservation of granulite facies mineral assemblages. Journal of Metamorphic Geology 20, 621–32.Google Scholar
White, R. W., Powell, R. & Holland, J. B. 2001. Calculation of partial melting equilibria in the system Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2 (NCKFMASH). Journal of Metamorphic Geology 19, 139–53.Google Scholar
Whitney, D. L. & Evans, B. W. 2010. Abbreviation for names of rock-forming minerals. American Mineralogist 95, 185–87.Google Scholar
Wu, C. & Cheng, B. 2006. Valid garnet-biotite (GB) geothermometry and garnet-aluminum silicate-plagioclase-quartz (GASP) geobarometry in metapelitic rocks. Lithos 89, 1–23.CrossRefGoogle Scholar
Zucali, M. 2005. JPT-Mineral formula calculation and geo-thermobarometry. http://users.unimi.it/mzucali/dev/java/JPT.htmGoogle Scholar
Zucali, M. 2011. Coronitic microstructures in patchy eclogitised continental crust: the Lago della Vecchia pre-Alpine metagranite (Sesia-Lanzo Zone, Western Italian Alps). In The Science of Microstructure – Part II (eds Forster, M. A. & Fitz Gerald, J. D.). Journal of the Virtual Explorer 38, paper 5.Google Scholar
Zucali, M., Manzotti, P., Diella, V., Pesenti, C., Risplendente, A., Darling, J. & Engi, M. 2011. Permian tectonometamorphic evolution of the Dent Blanche Unit (Austroalpine domain, Western Italian Alps). Rendiconti Online Società Geologica Italiana 15, 133–36.Google Scholar
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