Cordierite as a sensor of fluid conditions in high‐grade metamorphism and crustal anatexis

Harley, Simon L.; Thompson, Pauline; Hensen, B. J.; Buick, Ian S.

doi:10.1046/j.0263-4929.2001.00344.x

Cited by 66 publications

(83 citation statements)

References 40 publications

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“…5b) and is Bt (Kolesov and Geiger 2000). Although the data are only qualitative (Kaindl et al 2005 in preparation), the presence of CO 2 is in accordance with cordierite data from high-grade metamorphic rocks and shows that a(H 2 O) of the coexisting fluid phase will be < 1 (Vry et al 1990;Harley et al 2002).…”

Section: Analytical Techniquessupporting

confidence: 70%

“…This iteration process Cordierite thermobarometry An important part of the evaluation of the P-T-a(H 2 O) conditions of these high-grade metapelites is the application of additional thermobarometric techniques involving cordierite. In recent years, an extensive evaluation of cordierite as a petrogenetic indicator in highgrade metapelites was performed Knop and Mirwald 1998;Mirwald 2000;Harley and Carrington 2001;Thompson et al 2001Thompson et al , 2002Harley et al 2002). The studies of Knop and Mirwald (2000) and Thompson et al (2002) focused on the incorporation of sodium in cordierite as a function of temperature, pressure and a(H 2 O).…”

Section: Inverse Equilibrium Thermobarometry (Webinveq)mentioning

confidence: 98%

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P–T–t evolution of spinel–cordierite–garnet gneisses from the Sauwald Zone (Southern Bohemian Massif, Upper Austria): is there evidence for two independent late-Variscan low-P/high-T events in the Moldanubian Unit?

Tropper

Deibl

Finger

et al. 2006

Int J Earth Sci (Geol Rundsch)

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The Sauwald Zone, located at the southern rim of the Bohemian Massif in Upper Austria, belongs to the Moldanubian Unit. It exposes uniform biotite + plagioclase ± cordierite paragneisses that formed during the post-collisional high-T/low-P stage of the Variscan orogeny. Rare metapelitic inlayers contain the mineral assemblage garnet + cordierite + green spinel + sillimanite + K-feldspar + plagioclase + biotite + quartz. Mineral chemical and textural data indicate four stages of mineral growth: (1) peak assemblage as inclusions in garnet (stage 1): garnet core + cordierite + green spinel + sillimanite + plagioclase (An 35-65 ); (2) post-peak assemblages in the matrix (stages 2, 3): cordierite + spinel (brown-green and brown) ± sillimanite ± garnet rim + plagioclase (An 10-45 ); and (3) latestage growth of fibrolite, muscovite and albite (An 0-15 ) during stage 4. Calculation of the P-T conditions of the peak assemblage (stage 1) yields 750-840°C, 0.29-0.53 GPa and for the stage 2 matrix assemblage garnet + cordierite + green spinel + sillimanite + plagioclase 620-730°C, 0.27-0.36 GPa. The observed phase relations indicate a clockwise P-T path, which terminates below 0.38 GPa. The P-T evolution of the Sauwald Zone and the Monotonous Unit are very similar, however, monazite ages of the former are younger (321 ± 9 Ma vs. 334 ± 1 Ma). This indicates that high-T/low-P metamorphism in the Sauwald Zone was either of longer duration or there were two independent phases of late-Variscan low-P/high-T metamorphism in the Moldanubian Unit.

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Section: Analytical Techniquessupporting

confidence: 70%

Section: Inverse Equilibrium Thermobarometry (Webinveq)mentioning

confidence: 98%

P–T–t evolution of spinel–cordierite–garnet gneisses from the Sauwald Zone (Southern Bohemian Massif, Upper Austria): is there evidence for two independent late-Variscan low-P/high-T events in the Moldanubian Unit?

Tropper

Deibl

Finger

et al. 2006

Int J Earth Sci (Geol Rundsch)

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“…However, the position of [Spr, Spl] in the grid shown in Figure 9 will be shifted to higher temperatures than its position in the KFMASH through the stabilizing effect of Ti, octahedral Al and F (Dasgupta et al, 1995) as well as the stability relations of cordierite in presence of a fluid species (Hensen and Harley, 1990). The measurements of fluids (CO 2 and H 2 O) preserved in natural cordierites yield values less than those required for fluid saturation levels during peak metamorphism suggesting post peak fluid infiltration or leakage (Harley et al, 2002). The significance of CO 2 rich cordierites in CHT therefore needs to be evaluated further.…”

Section: Reaction Grid and Pressure Temperature Estimationsmentioning

confidence: 99%

Spinel+Quartz association from the Kerala khondalites, southern India: evidence for ultrahigh-temperature metamorphism

Morimoto

Santosh

Tsunogae

et al. 2004

Journal of Mineralogical and Petrological Sciences

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Granulite facies metapelites (khondalites) from Chittikara are characterized by the assemblage Grt + Sil + Bt + Crd + Spl + Kfs + Pl + Qtz ± graphite. The rocks show a series of mineral reactions such as: (1) Bt + Sil + Qtz = Grt + Crd ± Kfs, (2) Grt + Sil + Qtz = Crd, (3) Grt + Crd + Sil = Spl + Qtz , (4) Spl + Qtz = Crd, and (5) Grt + Sil = Spl + Crd. Spinel and quartz occur in direct grain contact and their stability considerations in appropriate reaction grids indicate > 950°C at 8 kbar. This, together with the ca. 1000°C temperatures derived from mesoperthites suggests ultrahigh temperature metamorphism in the khondalite belt. Electron microprobe data on the various minerals have been used to compute pressure temperature estimates from mineral phase equilibria thermobaromtery. Temperature estimates from spinel cordierite thermometry are around 900°C, while garnet cordierite thermometer yields an upper estimate of 818°C. Estimates based on garnet sillimanite plagioclase quartz barometer indicate pressures up to 8 kbar. Evaluation of the microstructures and reactions in the khondalites using available reaction grids for pelitic rocks provide evidence for peak metamorphism at high or ultrahigh temperatures followed by steep decompression from around 8 kbar down to 4 kbar. The P T path attests to a rapid exhumation history probably associated with the extensional collapse following collision of continental blocks during the assembly of Gondwana in the late Pan African.

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“…The a H 2 O conditions calculated for specific P T conditions in the KFMASH system following the methods of Harley et al (2002) (Carrington and Harley, 1995b). Osumilite bearing assemblages that have equilibrated at 7 9 kbar in the Napier Complex of East Antarctica Grew, 1982;Audibert et al, 1995) and other UHT terrains imply a H 2 O of <0.08.…”

Section: Fluids and Melts In Uht: Cordierite Volatile Contents And A mentioning

confidence: 99%

Extending our understanding of Ultrahigh temperature crustal metamorphism

Harley

2004

Journal of Mineralogical and Petrological Sciences

167

114

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Rapid developments in the scope and quality of internally consistent thermodynamic data sets arising from the incorporation of new experimental data and solid solution models for minerals and melts involved in ultrahigh temperature (UHT) metamorphism now place petrologists in an excellent position to evaluate the detailed mineral assemblage evolutions of many UHT rocks and place these in quantitative frameworks using P T diagrams and pseudosection approaches. These developments will soon be enhanced by extension of the methods to systems at high f o2 , enabling a wider range of critical mineral assemblages to be considered and their UHT P T evolutions, at present largely qualitatively constrained, to be determined quantitatively. Cordierite provides a useful monitor of the role and composition of any fluids and melts attending UHT metamorphism at <1000ºC. Such fluids or melts remaining in communication with the mineral assemblages following UHT have a significant effect on preservation of the metamorphic record and may also strongly influence the ages recorded by geochronological systems, even to the extent of producing widespread post UHT metamorphic zircon. Modelling of UHT metamorphism and P T paths, whether IBC, ITD or hybrid ITD IBC, in terms of specific and testable tectonic settings and processes is still problematic, with those models that can successfully duplicate the extraordinary temperatures attained in some UHT terrains generally being geologically unreasonable. Successful modelling of the thermal conditions and evolution of UHT terrains, constrained by quantitative P T t paths, is an important objective for future research that will inform our understanding of this intriguing aspect of the behaviour of the Earth system.

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Cordierite as a sensor of fluid conditions in high‐grade metamorphism and crustal anatexis

Abstract: Cordierite H 2 O and CO 2 volatile saturation surfaces derived from recent experimental studies are presented for P±T conditions relevant to high-grade metamorphism and used to evaluate¯uid conditions attending partial melting and granulite formation.

Cited by 66 publications

References 40 publications

P–T–t evolution of spinel–cordierite–garnet gneisses from the Sauwald Zone (Southern Bohemian Massif, Upper Austria): is there evidence for two independent late-Variscan low-P/high-T events in the Moldanubian Unit?

P–T–t evolution of spinel–cordierite–garnet gneisses from the Sauwald Zone (Southern Bohemian Massif, Upper Austria): is there evidence for two independent late-Variscan low-P/high-T events in the Moldanubian Unit?

Spinel+Quartz association from the Kerala khondalites, southern India: evidence for ultrahigh-temperature metamorphism

Extending our understanding of Ultrahigh temperature crustal metamorphism

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