Skip to main content
Log in

Early Cambrian oceanic plagiogranite in the Silvretta Nappe, eastern Alps: geochemical, zircon U-Pb and Rb-Sr data from garnet-hornblende-plagioclase gneisses

  • Original paper
  • Published:
Geologische Rundschau Aims and scope Submit manuscript

Abstract

Garnet-hornblende-plagioclase gneisses rich in incompatible elements occur in the crystalline basement of the Austro-Alpine Silvretta nappe and are associated with clinopyroxene norites and harzburgite cumulates. It is proposed here that the gneisses were formerly oceanic plagiogranites. An εNd(530) value of +5.6 for the gneisses as well as initial87Sr/86Sr values of 0.7036–0.7037 for the gabbroic rocks and 0.7026–0.7027 for the ultramafic rocks suggest a mantle source for this rock association. The geochemical characteristics of the garnet-hornblende-plagioclase gneisses indicate that their precursors were derived by fractional crystallization from a basaltic parent magma, by the same process which produced the adjacent clinopyroxene norites and ultramafic cumulates as well. The combined U-Pb upper intercept ages of zircons from two gneiss samples yield an igneous crystallization age of 532 ± 30 Ma, similar to previously dated (mostly calcalkaline) orthogneisses in the same area. High-quality transparent zircons showed the least degree of discordance, but contain extremely low U and Pb levels. The rock suite, including this plagiogranite, was emplaced within oceanic crust which formed in the latest Precambrian-early Palaeozoic off the northern continental margin of Gondwana.

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

Access this article

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

  • Abrecht J, Biino GG, Schaltegger U (1995) Building the European continent: late Proterozoic-early Palaeozoic accretion in the central alps of Switzerland. EUG 8, Terra Nova (abstracts) 7 (1): 460

    Google Scholar 

  • Arth JG (1979) Some trace elements in trondhjemites: their implications to magma genesis and paleotectonic setting. In: Barker F (ed) Trondhjemites, dacites, and related rocks. Elsevier, Amsterdam

    Google Scholar 

  • Berlepsch P (1992) Petrographie des Jakobshorns — Wuosthorns (Davos). Thesis, Univ Fribourg, Switzerland

    Google Scholar 

  • Coleman RG, Donato M (1979) Oceanic plagiogranite revisited. In: Barker F (ed) Trondhjemites, dacites, and related rocks. Elsevier, Amsterdam

    Google Scholar 

  • Coleman RG, Peterman ZE (1975) Oceanic plagiogranite. J Geophys Res 80:1099–1108

    Article  Google Scholar 

  • Finger F, Quadt A von (1995) U/Pb ages of zircons from a plagiogranite-gneiss in the south-eastern Bohemian massif, Austria: further evidence for an important early Paleozoic rifting episode in the eastern Variscides. Schweiz Mineral Petrogr Mitt 75:265–270

    Google Scholar 

  • Flisch M (1987) Teil 1: Geologische, petrographische und isotopengeologische Untersuchungen an Gesteinen des Silvrettakristallins. Teil 2: Die Hebungsgeschichte der oberostalpinen Silvretta-Decke seit der mittleren Kreide. PhD thesis, Univ Bern

  • Gebauer D (1989) Isotopic systems: geochronology of eclogites. In: Carswell DA (ed) Eclogite facies rocks. Blackie, Glasgow London, pp 141–159

    Google Scholar 

  • Gebauer D (1996) A P-T-t path for an (ultra?-) high-pressure ultramafic/mafic rock association and its felsic country rocks based on SHRIMP dating of magmatic and metamorphic zircon domains. Example: Alpe Arami (Central Swiss Alps). In: Basu A, Hart S (eds) Earth processes: reading the isotopic code. Geophys Monogr 95:307–329

  • Gebauer D, Söllner F (1993) U-Pb dating of zircons from eclogites of the austroalpine Oetztal crystalline complex (E-Alps, Austria): conventional and SHRIMP data. Terra Nova Abstr Suppl 4:10

    Google Scholar 

  • Krogh TE (1973) A low-contamination method for hydrothermal decomposition of zircon and extraction of U and Pb for isotopic age determinations. Geochim Cosmochim Acta 37:485–494

    Article  Google Scholar 

  • Ludwig KR (1980) Calculation of uncertainties of U-Pb isotope data. Earth Planet Sci Lett 46:212–220

    Article  Google Scholar 

  • Maggetti M, Flisch M (1993) Evolution of the Silvretta Nappe. In: Raumer JF von, Neubauer F] (eds) Pre-Mesozoic geology in the Alps. Springer, Berlin Heidelberg New York, pp 469–484

    Chapter  Google Scholar 

  • Maggetti M, Galetti G, Stosch HG (1990) Geochemische Argumente zur Genese der “Alteren Orthogneise” der Silvretta. Schweiz Mineral Petrogr Mitt 70:103–107

    Google Scholar 

  • Maniar PD, Piccoli PM (1989) Tectonic discrimination of granitoids. Geol Soc Am Bull 101:635–643

    Article  Google Scholar 

  • Ménot RP, Peucat JJ, Scarenzi D, Piboule M (1988) 496 My age of plagiogranites in the Chamrousse ophiolite complex (external crystalline massifs in the French Alps): evidence of a Lower Paleozoic oceanization. Earth Planet Sci Lett 88:82–92

    Article  Google Scholar 

  • Müller B, Klötzli US, Flisch M (1995) U-Pb and Pb-Pb zircon dating of the older orthogneiss suite in the Silvretta nappe, eastern Alps: Cadomian magmatism in the upper Austro-Alpine realm. Geol Rundsch 84:457–465

    Article  Google Scholar 

  • Oberli F, Meier M, Biino GG (1994) Time constraints on the preVariscan magmatic/metamorphic evolution of the Gotthard and Tavetsch units derived from single-zircon U-Pb results. Schweiz Mineral Petrogr Mitt 74:483–488

    Google Scholar 

  • Ochsner A (1993) U-Pb geochronology of the Upper Proterozoic-Lower Paleozoic geodynamic evolution in the Ossa-Morena zone (SW Iberia): constraints on the timing of the Cadomian Orogeny. PhD thesis ETH, Zurich

    Google Scholar 

  • Ohnenstetter M, Ohnenstetter D, Vidal P, Cornichet J, Hermitte D, Mace J (1981) Crystallization and age of zircon from Corsican ophiolitic albitites: consequences for oceanic expansion in Jurassic times. Earth Planet Sci Lett 54:397–408

    Article  Google Scholar 

  • Pearce JA (1983) Role of the sub-continental lithosphere in magma genesis at active continental margins. In: Hawkesworth CJ, Norry MJ (eds) Continental basalts and mantle xenoliths. Shiva, Nantwich, pp 230–249

    Google Scholar 

  • Pearce JA, Harris NBW, Tindle AG (1984) Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. J Petrol 25 (4): 956–983

    Article  Google Scholar 

  • Pin C, Marini F (1993) Early Ordovician continental breakup in Variscan Europe: Nd-Sr isotope and trace element evidence from bimodal igneous associations of the Southern Massif Central, France. Lithos 29:177–196

    Article  Google Scholar 

  • Pitcher WS (1993) The Nature and origin of granite. Blackie, London

    Book  Google Scholar 

  • Pupin JP (1988) Granites as indicators in paleogeodynamics. Rend Soc Ital Min Petr 43:237–262

    Google Scholar 

  • Pupin JP (1992) Les zircons des granites océaniques et continentaux: couplage typologie-géochimie des éléments en traces. Bull Soc Géol France 163:495–507

    Google Scholar 

  • Pupin JP, Turco G (1972) Une typologie originale du zircon accessoire. Bull Soc Franc Mineral Cristallogr 95:348–359

    Google Scholar 

  • Quadt A von (1992) U-Pb zircon and Sm-Nd geochronology of mafic and ultramafic rocks from the central part of the Tauern Window (eastern Alps). Contrib Mineral Petrol 110:57–67

    Article  Google Scholar 

  • Raumer JF von, Neubauer F (1993) Late Precambrian and Palaeozoic evolution of the Alpine Basement: an overview. In: Raumer JF von, Neubauer F (eds) Pre-Mesozoic geology in the Alps. Springer, Berlin Heidelberg New York, pp 625–639

    Chapter  Google Scholar 

  • Roddick JC (1987) Generalized numerical error analysis with applications to geochronology and thermodynamic. Geochim Cosmochim Acta 51:2129–2135

    Article  Google Scholar 

  • Size WB (1985) Origin of trondhjemite in relation to Appalachian-Caledonide palaeotectonic settings. In: Gee DG, Sturt BA (eds) The Caledonide orogen: Scandinavia and related areas. Wiley, New York

    Google Scholar 

  • Stacey JS, Kramers JD (1975) Approximation of terrestrial lead isotope evolution by a two-stage model. Earth Planet Sci Lett 26:207–221

    Article  Google Scholar 

  • Stoessel GFU, Ziegler URF (1989) Age determinations in the Rehoboth Basement Inlier, SWA/Namibia. PhD thesis, Univ Bern

  • Thierrin J (1983) Les éclogites et le complexe gabbroïque du Val Sarsura (Silvretta). Schweiz Mineral Petrogr Mitt 63:479–496

    Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Rights and permissions

Reprints and permissions

About this article

Cite this article

Müller, B., Schaltegger, U., Klötzli, U. et al. Early Cambrian oceanic plagiogranite in the Silvretta Nappe, eastern Alps: geochemical, zircon U-Pb and Rb-Sr data from garnet-hornblende-plagioclase gneisses. Geol Rundsch 85, 822–831 (1996). https://doi.org/10.1007/BF02440113

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF02440113

Key words

Navigation