Summary
The Mérida wollastonite deposits (SW Spain) occur in the inner part of a contact-metamorphic aureole developed on impure carbonate rocks of Lower Cambrian age, by the intrusion of a late Hercynian granite. Contact metamorphism associated with the granite emplacement did not only cause an important thermic anomaly but also triggered a complex fluid-rock interaction driven by infiltration of externally-derived fluids. Petrographic and stable isotope data suggest that the aureole was infiltrated by large amounts of aqueous fluids, emanating from the nearby granite, through lithological contacts. As a result of fluid infiltration, an extensive dilution of the CO2-rich fluid phase evolved by prograde devolatilization reactions took place, thus providing an environment suitable for wollastonite formation.
Nearly pure wollastonite bands resulted from chert interlayered in limestone by local exchange between CaO and SiO2 across bimetasomatic rims, in the presence of virtually pure water showing a magmatic-dominated isotope signature (Δ18O values as low as 11.8‰ are recorded for wollastonites adjacent to the granite contact). Distribution and modal abundance of wollastonite provide insights for determining the fluid flow paths and the extent of infiltration. Fluid circulation was dominantly parallel to bedding and clearly focused along marble-metachert boundaries, whi-ch acted as channelways for migration of fluids in the direction of decreasing temperature. Conditions of wollastonite formation have been estimated as follows: P=570-700 bars; T = 550-600°C; and XCO 2 ≈ 0.05.
Zusammenfassung
Die Woliastonitlagerstätten von Mérida (SW Spanien) treten im Innenteil einer kontaktmetamorphen Aureole, die sich durch die Intrusion späthercynischer Granite in unreine unterkambrische Karbonatgesteine bildete, auf. Die die Granitplatznahme begleitende Kontaktmetamorphose verursachte nicht nur eine bedeutende thermische Anomalie, sondern löste, kontrolliert durch die Infiltration externer Fluide, auch komplexe Fluid-Gesteinsinteraktion aus. Peterographische und stabile Isotopendaten weisen darauf hin, daß in die Aureole große Mengen an wäßrigen Lösungen, die aus dem nahegelegenen Granit abzuleiten sind, vor allem entlang lithologischer Grenzen infiltrierten. Als Folge der Fluidinfiltration kam es zu einer starken Verdünnung des durch prograde Devolatilisationsreaktionen entstandenen CO2-reichen Fluids und zur Bildung von Wollastonit.
Nahezu reine Wollastonitbänder entstanden aus den dem Kalk zwischengelagertem Chert durch lokalen CaO- und SiO2-Austausch über bimetasomatische Ränder und zwar in Gegenwart eines offenbar reinen wäßrigen Fluids mit rnagmatisch-dominierter Isotopensignatur (Δ18O Werte bis 11.8‰ sind für Wollastonite nahe des Granitkontaktes nachgewiesen). Die Verteilung und die Modalgehalte von Wollastonit erlauben Einblicke in die Bestimmung der Fluidpfade und das Ausmaß der Infiltration. Die Fluidzirkulation erfolgte hauptsächlich parallel zur Schichtung und ist auf die Marmor-Metachert-Grenzen fokussiert, die als Zufuhrkanäle für die Migration der Fluide in Richtung fallender Temperatur agierten. Die Bedingungen der Wollastonitbildung werden folgendermaßen abgeschätzt: P = 570-700 bar; T=550-600°C; XCO 2 2≈0.05.
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References
Abart R (1995) Phase equilibrium and stable isotope constraints on the formation of metasomatic garnet-vesuvianite veins (SW Adamello, N Italy). Contrib Mineral Petrol 122: 116–133
Abart R, Sperb R (1997) Grain-scale stable isotope disequilibrium during fluid-rock interaction. 1. Series approximations for advective-dispersive transport and first-order kinetic mineral-fluid exchange. Am J Sci 297: 679–706
Baumgartner LP, Ferry JM (1991) A model for coupled fluid-flow and mixed-volatile mineral reactions with applications to regional metamorphism. Contrib Mineral Petrol 106: 273–285
Bickle MJ, McKenzie D (1987) The transport of heat and matter by fluids during metamorphism. Contrib Mineral Petrol 95: 384–392
Cartwright I, Buick IS (1995) Formation of wollastonite-bearing marbles during late regional metamorphic channelled fluid flow in the Upper Calcsilicate Unit of the Reynolds Range Group, Central Australia. J Metamorph Geol 13: 397–417
Cartwright I, Weaver TR (1993) Fluid-rock interaction between syenites and marbles at Stephen Cross Quarry, Quebec, Canada: petrological and stable isotope data. Contrib Mineral Petrol 113: 533–544
Clayton RN, Mayeda TK (1963) The use of bromine pentafluoride in the extraction of oxygen from oxides and silicates for isotopic analysis. Geochim Cosmochim Acta 27: 43–52
Davis SR, Ferry JM (1993) Fluid infiltration during contact metamorphism of interbedded marble and talc-silicate hornfels. J Metamorph Geol 11: 71–88
Dipple GM, Ferry JM (1996) The effect of thermal history on the development of mineral assemblages during infiltration-driven contact metamorphism. Contrib Mineral Petrol 124: 334–345
Eppel H, Abart R (1997) Grain-scale stable isotope disequilibrium during fluid-rock interaction. 2. An example from the Penninic-Austroalpine tectonic contact in Eastern Switzerland. Am J Sci 297: 707–728
Fernández-Caliani JC, Galán E (1996) Fractal analysis of talc-silicate bands from Mérida (Spain) contact-metamorphic deposit: implications for fluid flow. Mineral Mag 60: 986–989
Fernández-Caliani JC, Casquet C, Galán E (1996a) Complex multiphase fluid inclusions in wollastonite from the Mérida (Spain) contact metamorphic deposit. Evidence for rock/HCl-rich fluid interaction. Eur J Mineral 8: 1015–1026
Fernández-Caliani JC, Galán E, Hernández-Arnedo MJ (1996b) Mineralogia y consideraciones sobre et origen de la wollastonite de Mérida (Badajoz). Bol Soc Esp Min 19: 147–160
Fernández-Caliani JC, Galán E, Liso MJ (1996c) Mineralogia, geoquímica y evolución diagenética de los materiales carbonatados del área de Mérida (Badajoz). Estudios Geol 52: 3–9
Ferry JM (1988) Contrasting mechanisms of fluid flow through adjacent stratigraphic units during regional metamorphism. Contrib Mineral Petrol 98: 1–12
Ferry JM, Dipple GM (1991) Fluid flow, mineral reactions and metasomatism. Geology 19: 211–214
Ferry JM, Dipple GM (1992) Models for coupled fluid flow, mineral reactions and isotopic alteration during contact metamorphism: the Notch Peak aureole, Utah. Am Mineral 77: 577–591
Gerdes ML, Valley JW (1994) Fluid flow and mass transport at the Valentine wollastonite deposit, Adirondack Mountains, New York State. J Metamorph Geol 12: 589–608
Gonzalo JC (1987a) Petrología y Estructura del Basamento en et Area de Mérida (Extremadura Central). Thesis, University of Salamanca (unpublished)
Gonzalo JC (1987b) El plutonismo hercínico en et área de Mérida (Extremadura Central, España). In: Geología de los Granitoides y Rocas Asociadas del Macizo Hespérico. Editorial Rueda, Madrid, pp 345–355
Greenwood HJ (1967) Wollastonite: stability in H2O-CO2 mixtures and occurrence in a contact-metamorphic aureole near Salmo, British Columbia, Canada. Am Mineral 52: 1669–1680
Hanson RB (1992) Effects of fluid production on fluid flow during regional and contact metamorphism. J Metamorph Geol 10: 87–97
Heinrich W (1993) Fluid infiltration through metachert layers at the contact aureole of the Bufa del Diente intrusion, northeast Mexico: implications for wollastonite formation and fluid inmiscibility, Am Mineral 78: 804–818.
Heinrich W, Gottschalk M (1994) Fluid flow patterns and infiltration isograds in melilite marbles from the Bufa del Diente contact metamorphic aureole, North-East Mexico. J Metamorph Geol 12: 345–359
Heinrich W, Hoffbauer R, Hubberten HW (1995) Contrasting fluid flow patterns at the Bufa del Diente contact metamorphic aureole, North-East Mexico: evidence from stable isotopes. Contrib Mineral Petrol 119: 362–376
Hoefs J (1997) Stable isotope geochemistry, 4th ed. Springer, Berlin Heidelberg New York Tokyo, 201 p
Holland TJB, 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. J Metamorph Geol 8: 89–124
Jamtveit B, Bucher-Nurminen K, Stijfhoorn DE (1992a) Contact metamorphism of layered shale-carbonate sequences in the Oslo rift. I. Buffering, infiltration and the mechanisms of mass transport. J Petrol 33: 377–422
Jamtveit B, Grorud HF, Bucher-Nurminen K (1992b) Contact metamorphism of layered shale-carbonate sequences in the Oslo rift. II. Migration of isotopic and reaction fronts around cooling plutons. Earth Planet Sci Lett 114: 131–148
Joesten R (1974) Local equilibrium and metasomatic growth of calc-silicate nodules from a contact aureole, Christmas Mountains, Texas. Am J Sci 274: 876–901
Joesten R, Fisher G (1988) Kinetics of diffusion-controlled mineral growth in the Christmas Mountains (Texas) contact aureole. Geol Soc Am Bull 100: 714–732
Julivert M, Fontboté JM, Ribeiro A, Conde L (1974) Memoria Explicativa del Mapa Tectónico de la Peninsula Ibérica y Baleares a escala 1:1.000.000. Instituto Geológico y Minero de España, Madrid, 113 pp
Kwak TAP (1986) Fluid inclusions in skarns (carbonate replacement deposits). J Metamorph Geol 4: 363–384
Labotka TC (1991) Chemical and physical properties of fluids. In:Kerrick DM (eded) Contact metamorphism. Min Soc Am, Rev Mineral 26: 43–104
Labotka TC, Nabelek PI, Papike JJ (1988) Fluid infiltration through the Big Horse Limestone in the Notch Peak contact-metamorphic aureole, Utah. Am Mineral 73: 1302–1324
Lattanzi P, Rye DM, Rice JM (1980) Behavior of13C and18O in carbonates during contact metamorphism at Marysville, Montana: implications for isotope systematics in impure dolomitic limestones. Am J Sci 280: 890–906
MacCrea JM (1950) On the isotope chemistry of carbonates and a paleotemperature scale. J Chem Phys 18: 849–857
Nabelek PI (1991) Stable isotope monitors. In:Kerrick DM (ed) Contact metamorphism. Min Soc Am, Rev in Mineral 26: 395–436
Nabelek PI, Labotka TC (1993) Implications of geochemical fronts in the Notch Peak contact-metamorphic aureole, Utah, USA. Earth Planet Sci Lett 119: 539–559
Nabelek PI, Labotka TC, O'Neil JR, Papike JJ (1984) Contrasting fluid/rock interaction between the Notch Peak granitic intrusion and argillites and limestones in Western Utah: evidence from stable isotopes and phase assemblages. Contrib Mineral Petrol 86: 25–34
Norton D, Taylor HP (1979) Quantitative simulation of the hydrothermal systems of crystallizing magmas on the basis of transport theory and oxygen isotope data: an analysis of the Skaergaard intrusion. J Petrol 20: 421–486
Rice JM (1977) Progressive metamorphism of the impure dolomitic limestone in the Marysville aureole, Montana. Am J Sci 277: 1–24
Rice JM, Ferry JM (1982) Buffering, infiltration and the control of intensive variables during metamorphism. In:Ferry JM (ed) Characterization of metamorphism through mineral equilibria. Min Soc Am, Rev Mineral 10: 263–326
Rutstein MS (1971) Re-examination of the wollastonite-hedenbergite (CaSiO3-CaFeSi2O6) equilibria. Am Mineral 56: 2040–2052
Rumble D (1982) Stable isotope fractionation during metamorphic devolatilization reactions. In:Ferry JM (ed) Characterization of metamorphism through mineral equilibria. Min Soc Am, Rev Mineral 10: 327–352
Soler A, Cardellach E, Ayora C (1991) Modelización de la interacción fluido-roca: Datos de isótopos estables de C y O en carbonatos de los skarns de la Cerdanya (Pirineo Central). Bol Soc Esp Min 14: 285–301
Todd CS (1990) Bleaching of limestones in the Notch Peak contact-metamorphic aureole, Utah. Geology 18: 83–86
Tracy RJ, Frost BR (1991) Phase equilibria and thermobarometry of calcareous, ultramafic and mafic rocks, and iron formations. In:Kerrick DM (ed) Contact metamorphism. Min Soc Am. Rev Mineral 26: 207–289
Valley JW (1985) Polymetamorphism in the Adirondacks: Wollastonite at contacts of shallowly intruded anorthosite. In:Tobi AC, Touret JLR (eds) The deep proterozoic crust in the North Atlantic provinces. Reidel, Dordrecht, pp 217–236
Valley JW (1986) Stable isotope geochemistry of metamorphic rocks. In:Valley JW,Taylor HP,O'Neil JR (eds) Stable isotopes in high temperature geological processes. Min Soc Am, Rev Mineral 16: 445–489
Valley JW, O'Neil JR (1981)13C/12C exchange between calcite and graphite: a possible thermometer in Greenville marbles. Geochim Cosmochim Acta 45: 411–419.
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Fernández-Caliani, J.C., Galán, E. Effects of fluid infiltration on wollastonite genesis at the Mérida contact-metamorphic deposits, SW Spain. Mineralogy and Petrology 62, 247–267 (1998). https://doi.org/10.1007/BF01178031
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DOI: https://doi.org/10.1007/BF01178031