Discovery of Ordovician–Silurian metamorphic monazite in garnet metapelites of the Alpine External Aiguilles Rouges Massif

Swiss Journal of Geosciences - Tập 104 - Trang 67-79 - 2011
Bernhard Schulz1, Jürgen F. von Raumer2
1TU Bergakademie Freiberg, Institute of Mineralogy, Freiberg, Germany
2Department of Geosciences, Université de Fribourg, Fribourg, Switzerland

Tóm tắt

The pre-Mesozoic, mainly Variscan metamorphic basement of the Col de Bérard area (Aiguilles Rouges Massif, External domain) consists of paragneisses and micaschists together with various orthogneisses and metabasites. Monazite in metapelites was analysed by the electron microprobe (EMPA-CHIME) age dating method. The monazites in garnet micaschists are dominantly of Variscan age (330–300 Ma). Garnet in these rocks displays well developed growth zonations in Fe–Mg–Ca–Mn and crystallized at maximal temperatures of 670°C/7 kbar to the west and 600°C/7–8 kbar to the east. In consequence the monazite is interpreted to date a slightly pressure-dominated Variscan amphibolite-facies evolution. In mylonitic garnet gneisses, large metamorphic monazite grains of Ordovician–Silurian (~440 Ma) age but also small monazite grains of Variscan (~300 Ma) age were discovered. Garnets in the mylonitic garnet gneisses display high-temperature homogenized Mg-rich profiles in their cores and crystallized near to ~800°C/6 kbar. The Ordovician–Silurian-age monazites can be assigned to a pre-Variscan high-temperature event recorded by the homogenised garnets. These monazite age data confirm Ordovician–Silurian and Devonian–Carboniferous metamorphic cycles which were already reported from other Alpine domains and further regions in the internal Variscides.

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Berger, A., Scherrer, N., & Bussy, F. (2005). Equilibration and disequilibration between monazite and garnet: Indication from phase composition and quantitative texture analysis. Journal of Metamorphic Geology, 23, 865–880. Berman, R., Aranovich, L., & Pattison, D. (1995). Reassessment of the garnet-clinopyroxene Fe–Mg exchange thermometer: II Thermodynamic analysis. Contributions to Mineralogy and Petrology, 115, 30–42. Bhattacharya, A., Mohanty, L., Maji, A., Sen, S., & Raith, M. (1992). Non-ideal mixing in the phlogopite-annite boundary: Constraint from experimental data on Fe–Mg partitioning and reformulation of the biotite-garnet geothermometer. Contributions to Mineralogy and Petrology, 111, 87–93. Biino, G. (1995). Pre-Variscan evolution of the eclogitised mafic rocks from the Helvetic basement of the Central Alps. European Journal of Mineralogy, 7, 57–70. Bussy, F., Hernandez, J., & von Raumer, J. (2000). Bimodal magmatism as a consequence of the post-collisonal readjustment of the thickened continental lithosphere (Aiguilles Rouges–Mont Blanc Massifs, Western Alps). Transactions of the Royal Society of Edinburgh: Earth Sciences, 91, 221–233. Bussy, F., & von Raumer, J. (1994). U–Pb geochronology of Palaeozoic magmatic events in the Mont-Blanc Crystalline Massif, Western Alps. Schweizerische Mineralogische und Petrographische Mitteilungen, 74, 514–515. Cocherie, A., Legendre, O., Peucat, J., & Koumelan, A. (1998). Geochronology of polygenetic monazites constrained by in situ microprobe Th–U-total lead determination: implications for lead behaviour in monazite. Geochimica et Cosmochimica Acta, 62, 2475–2497. Cocks, L., & Torsvik, T. (2002). Earth geography from 500 to 400 million years ago: a faunal and palaeomagnetic review. Journal of the Geological Society of London, 159, 631–644. Dobmeier, C. (1998). Variscan P–T-deformation paths from the southwestern Aiguilles Rouges massif (External massif, Western Alps) and their implication for its tectonic evolution. Geologische Rundschau, 87, 107–123. Donovan, J., Hanchar, J., Picolli, P., Schrier, M., Boatner, L., & Jarosewich, E. (2003). A re-examination of the rare-earth-element orthophosphate standards in use for electron-microprobe analysis. Canadian Mineralogist, 41, 221–232. Ellis, D., & Green, D. (1979). An experimental study of the effect of Ca upon garnet-clinopyroxene Fe–Mg exchange equilibria. Contributions to Mineralogy and Petrology, 71, 13–22. Faure, M., Bé Mézème, E., Cocherie, A., Rossi, P., Chemenda, A., & Boutelier, D. (2008). Devonian geodynamic evolution of the Variscan Belt, insights from the French Massif Central and Massif Armoricain. Tectonics, 27, TC2005. doi:10.1029/2007TC002115. Finger, F., Broska, I., Roberts, M., & Schermaier, A. (1998). Replacement of primary monazite by allanite–epidote coronas in an amphibolite-facies granite gneiss from the eastern Alps. American Mineralogist, 83, 248–258. Finger, F., & Helmy, H. (1998). Composition and total-Pb model ages of monazite from high-grade paragneisses in the Abu Swayel area, southern Eastern Desert, Egypt. Mineralogy and Petrology, 62, 269–289. Finger, F., & Krenn, E. (2007). Three metamorphic monazite generations in a high-pressure rock from the Bohemian Massif and the potentially important role of apatite in stimulating polyphase monazite growth along a P–T loop. Lithos, 95, 103–115. Finger, F., Krenn, E., Riegler, G., Romano, S., & Zulauf, G. (2002). Resolving Cambrian, Carboniferous, Permian and Alpine monazite generations in the polymetamorphic basement of eastern Crete (Greece) by means of the electron microprobe. Terra Nova, 14, 233–240. Fitzsimons, J., Kinny, P., Wetherley, S., & Hollingsworth, D. (2005). Bulk chemical control on metamorphic monazite growth in pelitic schists and implications for U–Pb age data. Journal of Metamorphic Geology, 23, 261–277. Franz, L., & Romer, R. (2007). Caledonian high-pressure metamorphism in the Strona–Ceneri Zone (Southern Alps of southern Switzerland and northern Italy). Swiss Journal of Geosciences, 100, 457–467. Frisch, W., & Neubauer, F. (1989). Pre-Alpine terranes and tectonic zoning in the Eastern Alps. In R. D. Dallmeyer (Ed.), Terranes in the circum-Atlantic Paleozoic orogens (Vol. 230, pp. 91–99). Geological Society of America Special Paper. Fritz, H., & Neubauer, F. (1988). Geodynamic aspects of the Silurian and Early Devonian sedimentation in the Paleozoic of Graz (Eastern Alps). Schweizerische Mineralogische und Petrographische Mitteilungen, 68, 359–367. Ganguly, J., Cheng, W., & Tirone, M. (1996). Thermodynamics of aluminosilicate garnet solid solution: New experimental data, an optimized model, and thermometric applications. Contributions to Mineralogy and Petrology, 123, 137–151. Genier, F., Bussy, F., Epard, J.-L., & Baumgartner, L. (2008). Water-assisted migmatization of metagraywackes in a Variscan shear zone, Aiguilles Rouges massif, western Alps. Lithos, 102, 575–597. Heinrich, W., Andrehs, G., & Franz, G. (1997). Monazite–xenotime miscibility gap thermometry I. An empirical calibration. Journal of Metamorphic Geology, 15, 3–16. Holdaway, M. (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, 1117–1129. Holland, T. (1980). The reaction albite = jadeite + quartz determined experimentally in the range 600–1200°C. American Mineralogist, 65, 129–134. Holland, T., & Powell, R. (1990). An enlarged and updated internally consistent thermodynamic dataset with uncertainties and correlations: The system K2O–Na2O–CaO–MgO–MnO–FeO–Fe2O3–Al2O3–TiO2–SiO2–C–H2–O2. Journal of Metamorphic Geology, 8, 89–124. Jarosewich, E., & Boatner, L. (1991). Rare-earth element reference samples for electron microprobe analysis. Geostandards Newsletter, 15, 397–399. Klötzli-Chowanetz, E., Klötzli, U., & Koller, F. (1997). Lower Ordovician migmatisation in the Ötztal crystalline basement (Eastern Alps, Austria): Linking U–Pb and Pb–Pb dating with zircon morphology. Schweizerische Mineralogische Petrographische Mitteilungen, 77, 315–324. Krenn, E., & Finger, F. (2007). Formation of monazite and rhabdophane at the expense of allanite during Alpine low temperature retrogression of metapelitic basement rocks from Crete, Greece: Microprobe data and geochronological implications. Lithos, 95, 130–147. Krogh, E. (1988). The garnet–clinopyroxene Fe–Mg geothermometer: A reinterpretation of existing experimental data. Contributions to Mineralogy and Petrology, 99, 44–48. Lombardo, B., Colombo, F., Compagnoni, R., Ghiglione, G., & Rubatto. D. (1997). Relics of pre-Variscan events in the Malinvern–Argentera Complex, Argentera Massif, Western Alps. In Abstract Volume of the 3D workshop on Alpine Geological Studies. Oropa-Biella 1997 (Vol. 4, 66 p.). Milan: Quaderni de Geodinamica alpina e quaternaria. Ludwig, K. (2001). Users manual for Isoplot/Ex (rev. 2.49): A geochronological toolkit for Microsoft Excel (Special Publication No. 1a, 55 p). Berkeley Geochronology Center. Montel, J.-M., Foret, S., Veschambre, M., Nicollet, C., & Provost, A. (1996). Electron microprobe dating of monazite. Chemical Geology, 131, 37–51. Newton, R. C., & Perkins, D. (1982). Thermodynamic cali-bration of geobarometers based on the assemblage garnet–plagioclase–orthopyroxene–clinopyroxene–quartz. American Mineralogist, 67, 203–222. Oberli, F., Meier, M., & Biino, G. (1994). Time constraints on the pre-Variscan magmatic/metamorphic evolution of the Gotthard and Tavetsch units derived from single-zircon U–Pb results. Schweizerische Mineralogische Petrographische Mitteilungen, 74, 483–488. Paquette, J., Ménot, R., & Peucat, J. (1989). REE, Sm–Nd and U–Pb zircon study of eclogites from the Alpine External massifs (Western Alps): Evidence for crustal contamination. Earth and Planetary Sciences Letters, 96, 181–198. Perchuk, L. (1991). Derivation of a thermodynamically consistent set of geothermometers and barometers for metamorphic and magmatic rocks. In L. Perchuk (Ed.), Progress in metamorphic and magmatic petrology (pp. 93–111). Cambridge: Cambridge University Press. Powell, R., & Holland, T. (1993). On the formulation of simple mixing models for complex phases. American Mineralogist, 78, 1174–1180. Pyle, J., Spear, F., Cheney, J., & Layne, G. (2005). Monazite ages in the Chesham Pond nappe, SW New Hampshire, USA: Implications for assembly of central New England thrust sheets. American Mineralogist, 90, 592–606. Pyle, J., Spear, F., Rudnick, R., & Mcdonough, W. (2001). Monazite–xenotime–garnet equilibrium in metapelites and a new monazite–garnet thermometer. Journal of Petrology, 42, 2083–2107. Romer, R., & Franz, L. (1998). Ordovician Barrow-type metamorphism in the Strona–Ceneri Zone (Northern Italy) dated by U–Pb on staurolite. Schweizerische Mineralogische Petrographische Mitteilungen, 78, 383–395. Rubatto, D., Schaltegger, U., Lombardo, B., Colombo, F., & Compagnoni, R. (2001). Complex Paleozoic magmatic and metamorphic evolution in the Argentera Massif (Western Alps) resolved with U–Pb dating. Schweizerische Mineralogische Petrographische Mitteilungen, 81, 213–228. Schaltegger, U. (1993). The evolution of the polymetamorphic basement in the central Alps unravelled by precise U–Pb zircon dating. Contributions to Mineralogy and Petrology, 113, 466–478. Schaltegger, U., Abrecht, J., & Corfu, F. (2003). The Ordovician orogeny in the Alpine basement: Constraints from geochronology and geochemistry in the Aar Massif (Central Alps). Schweizerische Mineralogische Petrographische Mitteilungen, 83, 183–195. Schulz, B. (1993). P–T-deformation paths of Variscan metamorphism in the Austroalpine basement: Controls on geothermobarometry from microstructures in progressively deformed metapelites. Schweizerische Mineralogische Petrographische Mitteilungen, 73, 257–274. Schulz, B. (2009). EMP-monazite age controls on P–T paths of garnet metapelites in the Variscan inverted metamorphic sequence of La Sioule, French Massif Central. Bulletin de la Société géologique de la France, 180, 271–282. Schulz, B., Bombach, K., Pawlig, S., & Brätz, H. (2004). Neoproterozoic to Early-Palaeozoic magmatic evolution in the Gondwana-derived Austroalpine basement to the south of the Tauern Window (Eastern Alps). International Journal of Earth Sciences, 93, 824–843. Schulz, B., Brätz, H., Bombach, K., & Krenn, E. (2007). In situ Th–Pb dating of monazite by 266 nm laser ablation and ICP-MS with a single collector, and its control by EMP analysis. Zeitschrift für Angewandte Geologie, 35, 377–392. Schulz, B., & Von Raumer, J. (1993). Syndeformational uplift of Varis-can high-pressure rocks (Col de Bérard, Aiguilles Rouges Massif, We-stern Alps). Zeitschrift der Deutschen Geologischen Gesellschaft, 144, 104–120. Sergeev, S., & Steiger, R. (1993). High-precision U–Pb single zircon dating of Variscan and Caledonian magmatic cycles in the Gotthard massif, Central Swiss Alps. Terra Nova Abstracts, 5, 394–395. Spear, F. (1993). Metamorphic phase equilibra and pressure–temperature–time paths (799 p). Mineralogical Society of America Monograph Series 1. Spear, F., & Pyle, J. (2002). Apatite, monazite and xenotime in metamorphic rocks. In Kohn, M. et al. (Eds.), Phosphates: Geochemical, Geobiological and Materials Importance. Reviews in Mineralogy and Geochemistry, 48, 293–335. Stampfli, G., & Borel, G. (2004). The TRANSMED transects in space and time: Constraints on the paleotectonic evolution of the Mediterranean domain. In W. Cavazza, F. Roure, W. Spakman, G. M. Stampfli, & P. A. Ziegler (Eds.), The TRANSMED Atlas: The Mediterranean Region from Crust to Mantle (pp. 53–80). Berlin: Springer. Stampfli, G., von Raumer, J., & Borel, G. (2002). The Paleozoic evolution of pre-Variscan terranes: from Gondwana to the Variscan collision. In: J. R. Martínez Catalán, R.D. Jr. Hatcher, R. Arenas & F. Díaz García (Eds.), Variscan–Appalachian Dynamics: The Building of the Late Paleozoic Basement (Vol. 364, pp. 263–280). Geological Society of America Special Paper. Stampfli, G., von Raumer, J., Wilhem, C., & Hochard, C. (2009). Variscan terrane accretion and Gondwana-Laurussia collision, a plate-tectonic approach. Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften, 63, 150. St-Onge, M. (1987). Zoned poikiloblastic garnets: P–T paths and synmetamorphic uplift through 30 km of structural depth, Wopmay orogen, Canada. Journal of Petrology, 28, 1–21. Suzuki, K., Adachi, M., & Kajizuka, I. (1994). Electron microprobe observations of Pb diffusion in metamorphosed detrital monazites. Earth and Planetary Science Letters, 128, 391–405. Thöny, W., Tropper, P., Schennach, F., Krenn, E., Finger, F., Kaindl, R., et al. (2008). The metamorphic evolution of migmatites from the Ötztal Complex (Tyrol, Austria) and constraints on the timing of the pre-Variscan high-T event in the Eastern Alps. Swiss Journal of Geosciences, 101(Suppl. 1), 111–126. Tracy, R. (1982). Compositional zoning and inclusions in metamorphic minerals. In: J. M. Ferry (Ed.), Characterization of metamorphism through mineral equilibria. Reviews in Mineralogy, 10, 355–397. Triboulet, C., & Audren, C. (1985). Continuous reactions between biotite, garnet, staurolite, kyanite-sillimanite-andalusite and P–T–time-deformation path in micaschists from the estuary of the river Vilaine, South Brittany, France. Journal of Metamorphic Geology, 3, 91–105. von Raumer, J. (1969). Stilpnomelan als alpinmetamorphes Produkt im Mont-Blanc-Granit. Contributions to Mineralogy and Petrology, 21, 257–271. von Raumer, J. (1998). The Palaeozoic evolution in the Alps - from Gondwana to Pangea. Geologische Rundschau, 87, 407–435. von Raumer, J., Abrecht, J., Bussy, F., Lombardo, B., Ménot, R., & Schaltegger, U. (1999). The Palaeozoic metamorphic evolution of the Alpine External Massifs. Schweizerische Mineralogische und Petrographische Mitteilungen, 79, 5–22. von Raumer, J., & Bussy, F. (2004). Mont-Blanc and Aiguilles-Rouges: Geology of their polymetamorphic basement (External massifs, France–Switzerland). Mémoires de Géologie (Lausanne), 42, 1–203. von Raumer, J., Bussy, F., & Sharp, Z. (1996). Lac Cornu revisited: The evolution from lower to upper crust (Aiguilles-Rouges Massif, western Alps). Schweizerische Mineralogische und Petrographische Mitteilungen, 76, 120–121. von Raumer, J., Bussy, F., & Stampfli, G. (2009). The Variscan evolution in the External massifs of the Alps and place in their Variscan framework. Comptes Rendus Geoscience, 341, 239–252. von Raumer, J., & Neubauer, F. (1993). Late Precambrian and Palaeozoic evolution of the Alpine basement an overview. In J. F. von Raumer & F. Neubauer (Eds.), The pre-Mesozoic geology in the Alps (pp. 625–639). Springer: Heidelberg. von Raumer, J., & Stampfli, G. (2008). The birth of the Rheic Ocean: Early Palaeozoic subsidence patterns and subsequent tectonic plate scenarios. Tectonophysics, 461, 9–20. von Raumer, J., Stampfli, G., Borel, G., & Bussy, F. (2002). Organization of pre-Variscan basement areas at the north-Gondwanan margin. International Journal of Earth Sciences, 91, 35–52. von Raumer, J., Stampfli, G., & Bussy, F. (2003). Gondwana-derived microcontinents: The constituents of the Variscan and Alpine collisional orogens. Tectonophysics, 365, 7–22. Willams, M., Jercinovic, M., Goncalves, P., & Mahan, K. (2006). Format and philosophy for collecting, compiling, and reporting microprobe monazite ages. Chemical Geology, 225, 1–15. Wing, B., Ferry, J., & Harrison, T. (2003). Prograde destruction and formation od monazite and allanite during contact and regional metamorphism of pelites: Petrology and geochronology. Contributions to Mineralogy and Petrology, 145, 228–250. Wu, C.-M., & Cheng, B. (2006). Valid garnet-biotite (GB) geothermometry and garnet–aluminium silicate–plagioclase–quartz (GASP) geobarometry in metapelitic rocks. Lithos, 89, 1–23. Zenk, M., & Schulz, B. (2004). Zoned Ca-amphiboles and related P–T evolution in metabasites from the classical Barrovian metamorphic zones in Scotland. Mineralogical Magazine, 68, 769–786. Zurbriggen, R., Franz, L., & Handy, M. (1997). Pre-Variscan deformation, metamorphism and magmatism in the Strona–Ceneri Zone (southern Alps of Northern Italy and Southern Switzerland). Schweizerische Mineralogische Petrographische Mitteilungen, 77, 361–381.