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Partial eclogitisation of gabbroic rocks in a late Precambrian subduction zone (Zambia): prograde metamorphism triggered by fluid infiltration

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Abstract

Gabbros and eclogites occur closely associated in a 200-km-long and up to 40-km-wide area of the Zambezi Belt in central Zambia. This area is interpreted to represent part of a late Precambrian suture zone, with the mafic rocks being relics of subducted oceanic crust. Gradual stages of prograde transformation from gabbro to eclogite are preserved by disequilibrium textures of incomplete reactions. This resulted in kyanite–omphacite-bearing assemblages for eclogites that have Al-poor bulk compositions. Undeformed eclogites typically preserve features of a former gabbroic texture, reflected by replacements of plagioclase and magmatic pyroxene by eclogite facies minerals. Textures of deformed eclogites range from sheared porphyroclastic to porphyroblastic. Relics of magmatic pyroxene are common and complete eclogitisation occurred only in millimetre to centimetre-scale domains in most of the rocks. No evidence for prograde blueschist or amphibolite facies mineral assemblages was found in eclogites. In contrast, the fine grained intergrowth of omphacite, garnet, kyanite and quartz, which replace former plagioclase or was formed in the pressure shadow of magmatic pyroxene relics, indicates that eclogitisation might have affected the gabbroic protoliths directly without any significant intervening metamorphic reactions. Eclogitisation took place under P–T conditions of 630–690 °C and 26–28 kbar, suggesting a large overstepping (>10 kbar) of reaction boundaries. Eclogitisation was initialised and accompanied by a channelised fluid flow resulting in veins with large, subhedral grains of omphacite, kyanite and garnet. The gabbro-to-eclogite transformation was enhanced by a fluid which allowed the necessary material transport for the dissolution–precipitation mechanism that characterises the metamorphic mineral replacements. The process of eclogitisation was limited by reaction kinetics and dissolution–precipitation rates rather than by the metamorphic P–T conditions. Even though ductile deformation occurred and equilibrium phase boundaries were overstepped, the infiltration of fluids was necessary for triggering the gabbro-to-eclogite transformation.

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References

  • Aharonov E, Spiegelmann M, Kelemen P (1997) Three-dimensional flow and reaction in porous media: implications for the Earth's mantle and sedimentary basins. J Geophys Res 102:14821–14833

    CAS  Google Scholar 

  • Austrheim H (1986/87) Eclogitisation of lower crustal granulites by fluid migration through shear zones. Earth Planet Sci Lett 81:221–232

    Article  Google Scholar 

  • Austrheim H (1990) The granulite–eclogite facies transition: a comparison of experimental work and a natural occurrence in the Bergen Arcs, western Norway. Lithos 25:163–169

    CAS  Google Scholar 

  • Austrheim H (1998) Influence of fluid and deformation on metamorphism of the deep crust and consequences for the geodynamics of collision zones. In: Hacker BR, Liou JG (eds) When continents collide: geodynamics and geochemistry of ultrahigh-pressure rocks. Kluwer Academic, Dordrecht, pp 297–323

  • Barnicoat AC, Cartwright I (1997) The gabbro–eclogite transformation: an oxygen isotope and petrographic study of west Alpine ophiolites. J Metamorph Geol 15:93–104

    CAS  Google Scholar 

  • Berman RG (1988) Internally-consistent thermodynamic data for minerals in the system Na2O–K2O–CaO–MgO–FeO–Fe2O3–Al2O3–SiO2–TiO2–H2O–CO2. J Petrol 29:445–522

    CAS  Google Scholar 

  • Brunsmann A, Franz G, Erzinger J, Landwehr D (2000) Zoisite- and clinozoisite segregations in metabasites (Tauern window, Austria) as evidence for high-pressure fluid–rock interaction. J Metamorph Geol 18:1–21

    Article  CAS  Google Scholar 

  • Cahen L, Snelling NJ, Delhal J, Vail JR (1984) The geochronology and evolution of Africa. Clarendon, Oxford

  • Carmichael DM (1969) On the mechanism of prograde metamorphic reactions in quartz-bearing pelitic rocks. Contrib Mineral Petrol 20:244–267

    CAS  Google Scholar 

  • Carmichael DM (1987) Induced stress and secondary mass transfer: thermodynamic basis for tendency toward constant-volume constraint in diffusion metasomatism. In: Helgeson HC (ed) Chemical transport in metasomatic processes. Reidel, Dordrecht, pp 239–264

  • Carswell DA, O'Brien PJ, Wilson RN, Zhai M (1997) Thermobarometry of phengite-bearing eclogites in the Dabie Mountains of central China. J Metamorph Geol 15:239–252

    CAS  Google Scholar 

  • Carswell DA, Wilson, RN, Zhai M (2000) Metamorphic evolution, mineral chemistry and thermobarometry of schists and orthogneisses hosting ultra-high pressure eclogites in the Dabieshan of central China. Lithos 52:121–155

    CAS  Google Scholar 

  • Engvik AK, Austrheim H, Erambert M (2001) Interaction between fluid flow, fracturing and mineral growth during eclogitization, an example from the Sunnfjord area, Western Gneiss Region, Norway. Lithos 57:111–141

    Article  CAS  Google Scholar 

  • Ferry JM (2000) Patterns of mineral occurrence in metamorphic rocks. Am Mineral 85:1573–1588

    CAS  Google Scholar 

  • Gao J, Klemd R (2001) Primary fluids entrapped at blueschist to eclogite transition: evidence from the Tianshan meta-subduction complex in northwestern China. Contrib Mineral Petrol 142:1–14

    CAS  Google Scholar 

  • Goscombe B, Armstrong R, Barton JM (1998) Tectonometamorphic evolution of the Chewore inliers: partial re-equilibration of high-grade basement during the Pan-African Orogeny: J Petrol 39.1347–1384

    Google Scholar 

  • Goscombe B, Armstrong R, Barton JM (2000) Geology of the Chewore Inliers, Zimbabwe: constraining the Mesoproterozoic to Palaeozoic evolution of the Zambezi Belt. J Afr Earth Sci 30:589–627

    Article  CAS  Google Scholar 

  • Green D, Hellman PL (1982) Fe–Mg partitioning between coexisting garnet and phengite at high pressures, and comments on a garnet–phengite geothermometer. Lithos 15:253–266

    CAS  Google Scholar 

  • Hacker BR (1996) Eclogite formation and the rheology, buoyancy, seismicity, and H2O content of oceanic crust. In: Bebout GE, Scholl DW, Kirby SH, Platt JP (eds) Subduction top to bottom. Geophysical Monograph vol 96, pp 337–346

  • Hanson RE, Wilson TJ, Brueckner HK, Onstott TC, Wardlaw M, Johns CC, Hardcastle KC (1988) Reconnaissance geochronology, tectonothermal evolution, and regional significance of the middle Proterozoic Choma–Kalomo Block, southern Zambia. Precambrian Res 42:39–61

    CAS  Google Scholar 

  • Hanson RE, Wilson TJ, Munyanyiwa H (1994) Geologic evolution of the Neoproterozoic Zambezi Orogenic Belt in Zambia. J Afr Earth Sci 18:135–150

    Google Scholar 

  • Holland TJB (1979) Experimental determination of the reaction Paragonite = Jadeite + Kyanite + H2O, and the consistent thermodynamic data for part of the system Na2O–Al2O3–SiO2–H2O, with applications to eclogites and blueschists. Contrib Mineral Petrol 68:292–301

    Google Scholar 

  • John T, Schenk V, Haase K, Scherer EE, Tembo, F (2003a) Evidence for a Neoproterozoic ocean in south central Africa from MORB-type geochemical signatures and P–T estimates of Zambian eclogites. Geology 31:243–246

    Article  CAS  Google Scholar 

  • John T, Schenk V, Mezger K, Tembo F (2003b) Timing and P–T evolution of whiteschist metamorphism in the Lufilian Arc–Zambezi Belt orogen (Zambia): implications to the Gondwana assembly. J Geol (in press)

  • Johnson SP, Oliver GJH (2002) High ƒO2 metasomatism during whiteschist metamorphism, Zambezi Belt, Northern Zimbabwe. J Petrol 43:271–290

    Article  CAS  Google Scholar 

  • Kirby SH, Engdahl ER, Denlinger R (1996) Intermediate-depth intraslab earthquakes and arc volcanism as physical expressions of crustal and uppermost mantle metamorphism in subducting slabs. In: Bebout GE, Scholl DW, Kirby SH, Platt JP (eds) Subduction top to bottom. Geophysical Monograph vol 96, pp 195–214

  • Kleber W (1962) Über orientierte heterogene Keimbildung in kristallisierten Phasen. Forsch Fortschr 36:257–262

    Google Scholar 

  • Koons PO, Rubie DC, Frueh-Green G (1987) The effects of disequilibrium and deformation on the mineralogical evolution of quartz diorite during metamorphism in the eclogite facies. J Petrol 28:679–700

    CAS  Google Scholar 

  • Kretz R (1983) Symbols for rock-forming minerals. Am Mineral 68:277–279

    Google Scholar 

  • Kullerud K (1996) Chlorine-rich amphiboles: interplay between amphibole composition and an evolving fluid. Eur J Mineral 8:355–370

    Google Scholar 

  • Leake BE, Wooley AR, Arps CES, et al. (1997) Nomenclature of amphiboles; report of the Subcommittee on Amphiboles of the International Mineralogical Association Commission on New Minerals and Mineral Names. Eur J Mineral 9:623–651

    CAS  Google Scholar 

  • Markl G, Bucher K (1998) Compositions of fluids in the lower crust inferred from metamorphic salt in lower crustal rocks. Nature 391:781–783

    Article  CAS  Google Scholar 

  • Merino E, Dewers T (1998) Implications of replacement for reaction-transport modelling. J Hydrol 209:137–146

    Article  CAS  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 reconnaissance data on the effect of NaAlO2 component on the low quartz–coesite transition. J Geophys Res 85:6983–6990

    CAS  Google Scholar 

  • Morimoto N, Fabries J, Ferguson AK, Ginzburg IV, Ross M, Seifert FA, Zussman J, Aoki K, Gottardi G (1988) Nomenclature of pyroxenes. Am Mineral 73:1123–1133

    Google Scholar 

  • Mørk MBE (1985a) A gabbro to eclogite transition on Flemsøy, Sunnmøre, western Norway: Chem Geol 50:283–310

  • Mørk MBE (1985b) Incomplete high P–T metamorphic transitions within the Kvamsøy pyroxenite complex west Norway: a case study of disequilibrium. J Metamorph Geol 3:245–264

    Google Scholar 

  • Peacock SM (1990) Fluid processes in subduction zones. Science 248:329–337

    CAS  Google Scholar 

  • Pognante U (1985) Coronitic reactions and ductile shear zones in eclogitised ophiolite metagabbros, Western Alps, North Italy. Chem Geol 50:99–110

    CAS  Google Scholar 

  • Porada H, Berhorst V (2000) Towards a new understanding of the Neoproterozoic–Early Palaeozoic Lufilian and northern Zambezi Belts in Zambia and the Democratic Republic of Congo. J Afr Earth Sci 30:727–771

    Article  Google Scholar 

  • Powell R (1985) Regression diagnostics and robust regression in geothermometer/geobarometer calibration: the garnet–clinopyroxene geothermometer revisited. J Metamorph Geol 3:231–243

    CAS  Google Scholar 

  • Ridley J, Thompson AB (1985) The role of mineral kinetics in the development of metamorphic microtextures. In: Walther JV, Wood BJ (eds) Fluid–rock interaction during metamorphism. Springer, Berlin Heidelberg New York, pp 154–193

  • Rubie DC (1983) Reaction-enhanced ductility: the role of solid–solid univariant reactions in deformation of the crust and mantle. Tectonophysics 96:331–352

    Google Scholar 

  • Rubie DC (1998) Disequilibrium during metamorphism: the role of nucleation kinetics. In: Treloar PJ, O'Brien P (eds) What drives metamorphism and metamorphic reactions? Geological Society, London, Special Publications vol 138, pp 199–214

  • Rüpke LH, Phipps Morgan J, Hort M, Connolly JAD (2002) Are the regional variations in Central America arc lavas due to differing basaltic versus peridotitic slab sources of fluid? Geology 30:1035–1038

    Google Scholar 

  • Rumble D III, Ferry JM, Hoering TC, Boucot AJ (1982) Fluid flow during metamorphism at the Beaver Brook fossil locality. Am J Sci 282:866–919

    Google Scholar 

  • Scambelluri M, Piccardo GB, Philippot P, Robbiano A, Negretti L (1997) High salinity fluid inclusions formed from recycled seawater in deeply subducted alpine serpentinite. Earth Planet Sci Lett 148:485–499

    Article  Google Scholar 

  • Schenk V, Appel P (2001) Anti-clockwise P–T path during ultrahigh-temperature (UHT) metamorphism at ca. 1050 Ma in the Irumide Belt of Eastern Zambia. Berichte der Deutschen Mineralogischen Gesellschaft. Beih Eur J Mineral 13:161

    Google Scholar 

  • Schmidt MW, Poli S (1998) Experimentally based water budgets for dehydrating slabs and consequences for arc magma generation. Earth Planet Sci Lett 163:361–379

    CAS  Google Scholar 

  • Sikatali C, Legg CA, Bwalya JJ, Ng'ambi O (1994) Geological and mineral occurrence map (1:2,000,000). Geological Survey of Zambia

  • Spear FS (1993) Metamorphic phase equilibria and pressure–temperature–time paths. Monograph series, Mineralogical Society of America

  • Tembo F, Kampunzu AB, Porada H (1999) Tholeiitic magmatism associated with continental rifting in the Lufilian Fold Belt of Zambia. J Afr Earth Sci 28:403–425

    Article  CAS  Google Scholar 

  • Thieme JG (1984) Geological map of the Lusaka Area 1:250,000 sheet. Geological Survey of Zambia, Map No. SD-35–15

    Google Scholar 

  • Thompson JB Jr (1981) An Introduction to the mineralogy and petrology of the biopyriboles. In: Veblen DR (ed) Amphiboles and other hydrous pyriboles – mineralogy. Mineralogical Society of America, Reviews in Mineralogy vol 9a, pp 141–188

  • Turner FJ, Weiss LE (1965) Deformational kinks in brucite and gypsum. Proc Nat Acad Sci 54:359–364

    CAS  Google Scholar 

  • Vidale RJ (1974) Vein Assemblages and metamorphism in Dutchess County, New York. Geol Soc Am Bull 85 2:303–306

    Google Scholar 

  • Vinyu ML, Hanson RE, Martin MW, Bowring SA, Jelsma HA, Krol MA, Dirks PHGM (1999) U–Pb and 40Ar/39Ar geochronological constraints on the tectonic evolution of the easternmost part of the Zambezi orogenic belt, northeast Zimbabwe. Precambrian Res 98:67–82

    Article  CAS  Google Scholar 

  • Vrana S, Prasad R, Fediuková E (1975) Metamorphic kyanite eclogites in the Lufilian Arc of Zambia. Contrib Mineral Petrol 51:139–160

    CAS  Google Scholar 

  • Walther JV, Wood BJ (1984) Rate and mechanism in prograde metamorphism. Contrib Mineral Petrol 88:246–259

    CAS  Google Scholar 

  • Waters DJ, Martin HN (1993) Geobarometry of phengite-bearing eclogites. Terra Abstr 5:410–411

    Google Scholar 

  • Wayte GJ, Worden RH, Rubie DC, Droop GTR (1989) A TEM study of disequilibrium plagioclase breakdown at high pressure: the role of infiltrating fluid. Contrib Mineral Petrol 101:426–437

    CAS  Google Scholar 

  • Widmer T, Thompson AB (2001) Local origin of high pressure vein material in eclogite facies rocks of the Zermatt-Saas zone, Switzerland. Am J Sci 301:627–656

    CAS  Google Scholar 

  • Yuan X, Sobolev SV, Kind R, et al. (2000) Subduction and collision processes in the Central Andes constrained by converted seismic phases. Nature 408:958–961

    Article  CAS  PubMed  Google Scholar 

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Acknowledgements

The Deutsche Forschungsgemeinschaft (DFG) funded this research through grants Sche 265–10/1, 10/2 and 265/S1–1. We thank A. Kronz and P. Appel for advice during microprobe work. Further thanks are due to K. Pollok and F. Tembo for fruitful discussions which greatly improved this study. We thank the University of Zambia and the Geological Survey of Zambia for support during fieldwork. The constructive reviews of H. Austrheim and an anonymous reviewer led to a considerable improvement of the manuscript. This publication is contribution no. 29 of the Sonderforschungsbereich 574 "Volatiles and Fluids in Subduction Zones" at Kiel University.

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  1. Institut für Geowissenschaften and SFB 574, Universität Kiel, 24098, Kiel, Germany

    Timm John & Volker Schenk

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John, T., Schenk, V. Partial eclogitisation of gabbroic rocks in a late Precambrian subduction zone (Zambia): prograde metamorphism triggered by fluid infiltration. Contrib Mineral Petrol 146, 174–191 (2003). https://doi.org/10.1007/s00410-003-0492-8

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