Abstract
Garnet in metapelites from the Wölz Complex of the Austroalpine crystalline basement east of the Tauern Window characteristically consists of two growth phases, which preserve a comprehensive record of the geothermal history during polymetamorphism. From numerical modelling of garnet formation, detailed information on the pressure–temperature–time (P–T–t) evolution during prograde metamorphism is obtained. In that respect, the combined influences of chemical fractionation associated with garnet growth, modification of the original growth zoning through intragranular diffusion and the nucleation history on the chemical zoning of garnet as P and T change during growth are considered. The concentric chemical zoning observed in garnet and the homogenous rock matrix, which is devoid of chemical segregation, render the simulation of garnet growth through successive equilibrium states reliable. Whereas the first growth phase of garnet was formed at isobaric conditions of ∼3.8 kbar at low heating/cooling rates, the second growth phase grew along a Barrovian P–T path marked with a thermal peak of ∼625°C at ∼10 kbar and a maximum in P of ∼10.4 kbar at ∼610°C. For the heating rate during the growth of the second phase of garnet, average rates faster than 50°C Ma−1 are obtained. From geochronological investigations the first growth phase of garnet from the Wölz Complex pertains to the Permian metamorphic event. The second growth phase grew in the course of Eo-Alpine metamorphism during the Cretaceous.
Similar content being viewed by others
References
Abart R, Martinelli W (1991) Variszische und alpidische Entwicklungsgeschichte des Wölzer Kristallins (Steiermark, Österreich). Mitteilungen der Gesellschaft der Geologie- und Bergbaustudenten in Österreich 37:1–14
Atherton MP (1968) The variation in garnet, biotite, and chlorite composition in medium grade pelitic rocks from the Dalradian, Scotland, with particular reference to the zonation in garnet. Contrib Mineral Petrol 18:347–361
Bernhard F, Hoinkes G (1999) Polyphase micaschists of the central Wölzer Tauern, Styria, Austria. Berichte der Deutschen Mineralogischen Gesellschaft, Beiheft zum European Journal of Mineralogy 11:32
de Capitani C (1994) Gleichgewichts-Phasendiagramme: Theorie und Software. Berichte der Deutschen Mineralogischen Gesellschaft, Beiheft zum European Journal of Mineralogy 6:48
Carlson WD (1991) Competitive diffusion-controlled growth of porphyroblasts. Mineral Mag 55:317–330
Chakraborty S, Ganguly J (1992) Cation diffusion in aluminosilicate garnets: experimental determination in spessartine–almandine diffusion couples, evaluation of effective binary, diffusion coefficients, and applications. Contrib Mineral Petrol 111:74–86
Connolly JAD, Cesare B (1993) C-O-H-S fluid composition and oxygen fugacity in graphitic metapelites. J Metamorph Geol 11:368–378
Evans TP (2004) A method for calculating effective bulk composition modification due to crystal fractionation in garnet-bearing schist: implications for isopleth thermobarometry. J Metamorph Geol 22:547–557
Faryad SW, Chakraborty S (2005) Duration of Eo-Alpine metamorphic events obtained from multicomponent diffusion modeling of garnet: a case study from the Eastern Alps. Contrib Mineral Petrol 150:306–318
Faryad SW, Hoinkes G (2003) P–T gradient of Eo-Alpine metamorphism within the Austroalpine basement units east of the Tauern Window (Austria). Mineral Petrol 77:129–159
Feenstra A (1996) An EMP and TEM—AEM study of margarite, muscovite and paragonite in polymetamorphic metabauxites of Naxos Cyclades (Greece) and the implications of fine-scale mica interlayering and multiple mica generations. J Petrol 37:201–233
Franz G, Hinrichsen T, Wannemacher E (1977) Determination of the miscibility gap on the solid solution series paragonite–margarite by means of infrared spectroscopy. Contrib Mineral Petrol 59:307–316
Gaidies F, Abart R, de Capitani C, Schuster R, Connolly JAD, Reusser E (2006) Characterization of polymetamorphism in the Austroalpine basement east of the Tauern Window using garnet isopleth thermobarometry. J Metamorph Geol 24:451–475
Gaidies F, de Capitani C, Abart R (2007) THERIA_G: a software program to numerically model prograde garnet growth. Contrib Mineral Petrol. doi:10.1007/s00410-007-0263-z
Habler G, Thöni M (2001) Preservation of Permo-Triassic low-pressure assemblages in the Cretaceous high-pressure metamorphic Saualpe crystalline basement (Eastern Alps, Austria). J Metamorph Geol 19:679–697
Hejl E (1984) Geochronologische und petrologische Beiträge zur Gesteinsmetamorphose der Schladminger Tauern. Mitteilungen der Gesellschaft der Geologie- und Bergbaustudenten in Österreich 30/31:289–318
Hejl E (1998) Über die känozoische Abkühlung und Denudation der Zentralalpen östlich der Hohen Tauern - eine Apatit-Spaltspurenanalyse. Mitteilungen der Österreichischen Geologischen Gesellschaft 89:179–199
Holland TJB, Powell R (1998) An internally consistent thermodynamic data set for phases of petrological interest. J Metamorph Geol 16:309–343
Hollister LS (1966) Garnet zoning: an interpretation based on the Rayleigh fractionation model. Science 154:1647–1651
Loomis T, Ganguly J, Elphick S (1985) Experimental determinations of cation diffusitivities in aluminosilicate garnets. II. Multicomponent simulation and tracer diffusion coefficients. Contrib Mineral Petrol 90:45–51
Mandl G (2000) The Alpine sector of the Tethyan shelf—examples of Triassic to Jurassic sedimentation and deformation from the Northern Calcereous Alps. Mitteilungen der Österreichen Geologischen Gesellschaft 92:61–77
Schmid SM, Fügenschuh B, Kissling E, Schuster R (2004) Tectonic map and overall architecture of the Alpine orogen. Eclogae Geologicae Helvetiae 97:93–117
Schuster R, Frank W (1999) Metamorphic evolution of the Austroalpine units east of the Tauern Window: indications for Jurassic strike slip tectonics. Mitteilungen der Gesellschaft der Geologie- und Bergbaustudenten in Österreich 42:37–58
Schuster R, Thöni M (1996) Permian garnets: indication for a regional Permian metamorphism in the southern part of the Austroalpine basement units. Mitteilungen der Gesellschaft der Geologie- und Bergbaustudenten in Österreich 141:219–221
Schuster R, Scharbert S, Abart R, Frank W (2001) Permo-Triassic extension and related HT/LP metamorphism in the Austroalpine—Southalpine realm. Mitteilungen der Gesellschaft der Geologie- und Bergbaustudenten in Österreich 45:111–141
Schuster R, Koller F, Hoeck V, Hoinkes G, Bousquet R (2004) Explanatory notes to the map: metamorphic structure of the Alps—metamorphic evolution of the Eastern Alps. Mitteilungen der Österreichen Mineralogischen Gesellschaft 149:175–199
Sölva H, Thöni M, Grasemann B, Linner M (2001) Emplacement of Eo-Alpine high-pressure rocks in the Austroalpine Ötztal complex (Texel group, Italy/Austria). Geodinamica Acta 14:345–360
Spear FS (1988) Metamorphic fractional crystallization and internal metasomatism by diffusional homogenization of zoned garnets. Contrib Mineral Petrol 99:507–517
Spear FS (1993) Metamorphic phase equilibria and pressure–temperature–time paths. Mineralogical Society of America Monograph. Mineralogical Society of America, Washington, DC
Stowell HH, Taylor DL, Tinkham DL, Goldberg SA, Ouderkirk KA (2001) Contact metamorphic P–T–t paths from Sm–Nd garnet ages, phase equilibria modelling and thermobarometry: garnet ledge, south-eastern Alaska, USA. J Metamorph Geol 19:645–660
Thöni M (2002) Sm–Nd isotope systematics in garnet from different lithologies (Eastern Alps): age results, and an evaluation of potential problems for garnet Sm–Nd chronometry. Chem Geol 185:255–281
Thöni M (2006) Dating eclogite-facies metamorphism in the Eastern Alps—approaches, results, interpretations: a review. Mineral Petrol 88:123–148
Tollmann A (1985) Geologie von Österreich. Band 2. Ausserzentralalpiner Anteil. Deuticke, Wien
Vance D, Mahar E (1998) Pressure–temperature paths from P–T pseudosections and zoned garnets: potential, limitations and examples from the Zanskar Himalaya, NW India. Contrib Mineral Petrol 132:225–245
Vielzeuf D, Baronnet A, Perchuk AL, Laporte D, Baker MB (2007) Calcium diffusivity in alumino-silicate garnets: an experimental and ATEM study. Contrib Mineral Petrol 154:153–170
Zeh A (2001) Inference of a detailed P–T path from P–T pseudosections using metapelitic rocks of variable composition from a single outcrop, Shackleton Rang, Antarctica. J Metamorph Geol 19:329–350
Zeh A, Holness MB (2003) The effect of reaction overstep on garnet microtextures in metapelitic rocks on the Ilesha Schist Belt, SW Nigeria. J Petrol 44:967–994
Acknowledgments
The assistance of E. Reusser, W. Tschudin and R. Milke is gratefully acknowledged. Comments from S. Chakraborty, F. Spear and Editor J. Hoefs were very helpful.
Author information
Authors and Affiliations
Corresponding author
Additional information
Communicated by J. Hoefs.
Electronic supplementary material
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Gaidies, F., de Capitani, C., Abart, R. et al. Prograde garnet growth along complex P–T–t paths: results from numerical experiments on polyphase garnet from the Wölz Complex (Austroalpine basement). Contrib Mineral Petrol 155, 673–688 (2008). https://doi.org/10.1007/s00410-007-0264-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00410-007-0264-y