Skip to main content
SpringerLink
Log in

The pyrope-coesite rocks and their country rocks at Parigi, Dora Maira Massif, Western Alps: detailed petrography, mineral chemistry and PT-path

  • Published:
Contributions to Mineralogy and Petrology Aims and scope Submit manuscript

Abstract

Both the coarse- and fine-grained varieties of the partly coesite-bearing pyrope-quartzites, their interlayered jadeite-kyanite rocks, and the biotite-phengite gneiss country rock common to all of them were subjected to detailed petrographic and textural studies in order to determine the sequence of crystallisation of their mineral constituents, which were also studied analytically by microprobe. Prior to pyrope and coesite growth, the Mg-rich metapelites were talc-kyanite-chlorite-rutile-ellenbergerite schists which — upon continued prograde metamorphism — developed first pyrope megacrysts in silica-deficient local environments at the expense of chlorite + talc + kyanite, and subsequently the smaller pyrope crystals with coesite inclusions from reacting talc + kyanite. Based on geobarometrically useful mineral inclusions as well as on experimentally determined phase relations, a prograde PT-path — simplified for water activity = 1 — is constructed which passes through the approximate PT-conditions 16 kbar and 560° C, 29 kbar and 720° C, and finally up to 37 kbar at about 800° C, where the Mg-rich metapelite was a pyrope-coesite rock with phengite, kyanite, and talc still present. During the retrograde path, pyrope was altered metasomatically either into phlogopite + kyanite + quartz or, at a later stage, to chlorite + muscovite + quartz. Both assemblages yield PT-constraints, the latter about 7–9 kbar, 500–600° C. The country rock gneisses have also endured high-pressures of at least 15 kbar, but they provide mostly constraints on the lowest portion of the uplift conditions within the greenschist facies (about 5 kbar, 450° C). Microprobe data are presented for the following minerals: pyrope, ellenbergerite, dumortierite (unusually MgTi-rich), jadeite, vermiculite (formed after Na-phlogopite?), paragonite, and for several generations of phengite, chlorite, talc, phlogopite, dravite, and glaucophane in the high-pressure rocks, as well as for biotite, chlorite, phengites, epidote, garnet, albite, and K-feldspar in the country rock gneisses. An outstanding open problem identified in this study is the preservation of minerals as inclusions within kyanite and pyrope beyond their PT-stability limits.

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

Access this article

Log in via an institution

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

  • Beller U (1987) Hochdruck-Synthese von phosphorhaltigem Ellenbergerit. Unpublished Dipl. Thesis Ruhr-Univ Bochum, 102 pp

  • Bishop FC, Smith JV, Dawson JB (1978) Na, K, P and Ti in garnet, pyroxene and olivine from peridotite and eclogite xenoliths from African kimberlites. Lithos 11:155–173

    Article  Google Scholar 

  • Carman JH (1974) Synthetic sodium phlogopite and its two hydrates: stabilities, properties, and mineralogic implications. Am Mineral 59:261–273

    Google Scholar 

  • Chatterjee ND (1991) Applied mineralogical thermodynamics: selected topics. Springer, Berlin Heidelberg New York Tokyo, pp 321

    Google Scholar 

  • Chopin C (1984) Coesite and pure pyrope in high-grade blueschists of the Western Alps: a first record and some consequences. Contrib Mineral Petrol 86:107–118

    Article  Google Scholar 

  • Chopin C (1986) Phase relationships of ellenbergerite, a new high-pressure Mg−Al−Ti-silicate in pyrope-coesite-quartzite from the Western Alps. Geol Soc Am Mem 164:31–42

    Google Scholar 

  • Chopin C (1987) Very high-pressure metamorphism in the Western Alps: implications for subduction of continental crust. Phil Trans R Soc Lond A 321:183–197

    Google Scholar 

  • Chopin C, Schreyer W (1983) Magnesiocarpholite and magnesiochloritoid: two index minerals of pelitic blueschists and their preliminary phase relations in the model system MgO−Al2O3−SiO2−H2O. Am J Sci 283-A:72–96

    Google Scholar 

  • Chopin C, Klaska R, Medenbach O, Dron D (1986) Ellenbergerite, a new high-pressure Mg−Al−(Ti, Zr)-silicate with a novel structure based on face-sharing octahedra. Contrib Mineral Petrol 92:316–321

    Article  Google Scholar 

  • Chopin C, Henry C, Michard A (1989) Geological setting of a coesite-bearing terrane, Dora Maira Massif, Western Alps. In: 28. Intern Geol Congr Abstracts Vol 1:286

  • Chopin C, Henry C, Michard A (1991) Geology and petrology of the coesite-bearing terrain, Dora Maira Massif, Western Alps. Europ J Mineral 3:263–291

    Google Scholar 

  • Ernst WG (1983) Phanerozoic continental accretion and the metamorphic evolution of northern and central California Tectonophys. 100:287–320

    Google Scholar 

  • Gillet P, Ingrin J, Chopin C (1984) Coesite in subducted continental crust: P−T history deduced from an elastic model. Earth Planet Sci Lett 70:426–436

    Article  Google Scholar 

  • Goffé B, Chopin C (1986) High-pressure metamorphism in the Western Alps: zoneography of metapelites, chronology and consequences. Schweiz Mineral Petrogr Mitt 66:41–52

    Google Scholar 

  • Holdaway MJ (1971) Stability of andalusite and the aluminium silicate phase diagram. Am J Sci 271:97–131

    Google Scholar 

  • Holland TJB (1979) Experimental determination of the reaction paragonite = jadeite + kyanite + water, internally consistent thermodynamic data for part of the system Na2O−Al2O3−SiO2−H2O, with applications to eclogites and blueschists. Contrib Mineral Petrol 68:293–301

    Google Scholar 

  • Holland TJB (1988) Preliminary phase relations involving glaucophane and applications to high pressure petrology: new heat capacity and thermodynamic data. Contrib Mineral Petrol 99:134–142

    Article  Google Scholar 

  • Huang WL, Wyllie PJ (1975) Melting reactions in the system NaAlSi3O8−KAlSi3O8−SiO2 to 35 kilobars, dry and with excess water. J Geol 83:737–748

    Google Scholar 

  • MacKenzie WS (1957) The crystalline modifications of NaAlSi3O8. Am J Sci 255:481–516

    Google Scholar 

  • Massonne H-J (1989) The upper thermal stability of chlorite + quartz: an experimental study in the system MgO−Al2O3−SiO2−H2O. J Metam Geol 7:567–581

    Google Scholar 

  • Massonne H-J (1990) Geothermobarometrie mit Al-Gehalten in Talk. Ber Dt Miner Ges, Beih z Europ J Mineral 2, 1:169

    Google Scholar 

  • Massonne H-J, Schreyer W (1987) Phengite geobarometrie based on the limiting assemblage with K-feldspar, phlogopite, and quartz. Contrib Mineral Petrol 96:212–224

    Article  Google Scholar 

  • Massonne H-J, Schreyer W (1989) Stability field of the high-pressure assemblage talc + phengite and two new phengite barometers. Europ J Mineral 1:391–410

    Google Scholar 

  • Mirwald PW, Massonne H-J (1980) The low-high quartz and quartz-coesite transition to 40 kbar between 600 and 1600° C and some reconnaisance data on the effect of NaAlO2 component on the low quartz-coesite transition. J Geophys Res 85:6983–6990

    Google Scholar 

  • Monié P, Chopin C (1991) 40Ar−39Ar dating in a coesite-bearing and associated units of the Dora Maira Massif, Western Alps. Europ J Mineral 3:239–262

    Google Scholar 

  • Moore PB, Araki T (1978) Dumortierite, 21-1: a detailed structure analysis. Neues Jahrb Mineral Abh 132:231–241

    Google Scholar 

  • Okay AI, Shutong X, Sengör AMC (1989) Coesite from the Dabie Shan eclogites, central China. Europ J Mineral 1:595–598

    Google Scholar 

  • Paquette J-L, Chopin C, Peucat I-J (1989) U−Pb zircon, Rb−Sr and Sm−Nd geochronology of high to very-high-pressure meta-acidic rocks from the Western Alps. Contrib Mineral Petrol 101:280–289

    Article  Google Scholar 

  • Raase P, Kern H (1969) Über die Synthese von Albiten bei Temperaturen von 250–700° C. Contrib Mineral Petrol 21:225–237

    Article  Google Scholar 

  • Schertl H-P (1987) Mineralogische und petrographische Untersuchungen an den Pyrop-Quarziten von Parigi, Dora Maira Massiv, Westalpen. Unpublished Dipl. Thesis Ruhr-Univ Bochum, 102 pp

  • Schreyer W (1977) Whiteschists: their compositions and pressure-temperature regimes based on experimental, field, and petrographic evidence. Tectonophys 43:127–144

    Article  Google Scholar 

  • Schreyer W (1985) Metamorphism of crustal rocks at mantle depths: high-pressure minerals and mineral assemblages in metapelites. Fortschr Mineral 63:227–261

    Google Scholar 

  • Schreyer W (1988a) Subduction of continental crust to mantle depths: petrological evidence. Episodes 11:97–104

    Google Scholar 

  • Schreyer W (1988b) Experimental studies on metamorphism of crustal rocks under mantle pressures. Min Mag 52:1–26

    Google Scholar 

  • Schreyer W, Abraham K, Kulke H (1980) Natural sodium phlogopite coexisting with potassium phlogopite and sodian aluminian talc in a metamorphic evaporite sequence from Derrag, Tell Atlas, Algeria. Contrib Mineral Petrol 74:223–233

    Article  Google Scholar 

  • Schreyer W, Massonne H-J, Chopin C (1987) Continental crust subducted to mantle depths near 100 km: implications for magma and fluid genesis in collision zones. Magmatic Processes: Physicochemical Principles Geochem Soc Spec Pub No 1:155–163

  • Smith DC, Lappin MA (1989) Coesite in the Straumen kyanite-eclogite pod, Norway. Terra Nova 1:47–56

    Google Scholar 

  • Sobolev NV, Shatsky VS (1990) Diamond inclusions in garnets from metamorphic rocks: a new environment for diamond formation. Nature 343:742–746

    Article  Google Scholar 

  • Tilton GR, Schreyer W, Schertl H-P (1989) Pb−Sr−Nd isotopic behavior of deeply subducted crustal rocks from the Dora Maira Massif, Western Alps, Italy Geochim Cosmochim Acta 53:1391–1400

    Google Scholar 

  • Tilton GR, Schreyer W, Schertl H-P (1991) Pb−Sr−Nd isotopic behavior of deeply subducted crustal rocks from the Dora Maira Massif, Western Alps, Italy. II: what is the age of the ultrahigh-pressure metamorphism? Contrib Mineral Petrol 108:22–23

    Google Scholar 

  • Vialon P (1966) Etude géologique du massiv cristallin Dora Maira, Alpes cottiennes internes, Italie. Thèse d'état Université de Grenoble, pp 293

  • Wang X, Liou JG, Mao HK (1989) Coesite bearing eclogite from the Dabie Mountains in central China. Geology 17:1085–1088

    Article  Google Scholar 

  • Werding G, Schreyer W (1984) Alkali-free tourmaline in the system MgO−Al2O3−B2O3−SiO2−H2O. Geochim Cosmochim Acta 48:1331–1344

    Article  Google Scholar 

  • Werding G, Schreyer W (1990) Synthetic dumortierite: its PTX-dependent compositional variations in the system Al2O3−B2O3−SiO2−H2O. Contrib Mineral Petrol 105:11–24

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Institut für Mineralogie, Ruhr-Universität, W-4630, Bochum 1, Germany

    H. -P. Schertl & W. Schreyer

  2. Laboratoire de Géologie, Ecole Normale Supérieure, URA du C.N.R.S., 24, rue Lhomond, F-75005, Paris, France

    H. -P. Schertl & C. Chopin

Authors
  1. H. -P. Schertl
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. W. Schreyer
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. C. Chopin
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Schertl, H.P., Schreyer, W. & Chopin, C. The pyrope-coesite rocks and their country rocks at Parigi, Dora Maira Massif, Western Alps: detailed petrography, mineral chemistry and PT-path. Contr. Mineral. and Petrol. 108, 1–21 (1991). https://doi.org/10.1007/BF00307322

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00307322

Keywords

Search

Navigation