Advertisement

Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Omphacite breakdown reactions and relation to eclogite exhumation rates

  • 661 Accesses

  • 28 Citations

Abstract

Clinopyroxene + plagioclase (±Hbl ± Qtz) symplectites after omphacite are widely cited as evidence for prior eclogite-facies or high-pressure (HP) metamorphism. Precursor omphacite compositions of retrograde eclogites, used for reconstructing retrograde PT paths, are commonly estimated by reintegrating symplectite phases with the assumption that the symplectite-forming reactions were isochemical. Comparisons of broadbeam symplectite compositions to adjacent unreacted pyroxene from various symplectites after clinopyroxene from the Appalachian Blue Ridge (ABR) and Western Gneiss Region (WGR) suggest that the symplectite forming reactions are largely isochemical. Endmember calculations based on reintegrated symplectite compositions from the ABR and WGR suggest that a minor Ca-Eskola (CaEs) component (XCaEs = 0.04–0.15) was present in precursor HP clinopyroxene. WGR symplectites consist of fine-grained (∼1 μm-scale), vermicular intergrowths of Pl + Cpx II ± Hbl that occur at grain boundaries or internally. ABR symplectites contain coarser (∼10 μm-scale) planar lamellae and rods of Pl + Cpx II + Qtz + Hbl within clinopyroxene cores. The contrasting textures correlate with decompression and cooling rate, and degree of overstepping of the retrograde reaction (lamellar: slow, erosionally controlled exhumation with slow/low overstepping; fine-grained, grainboundary symplectite: rapid, tectonic exhumation with rapid/high overstepping). Variations in XCaEs, Xjd, and XCaTs of precursor HP omphacite are related to the symplectic mineral assemblages that result from decompression. Quartz-normative symplectities indicate quartz-producing retrograde reactions (e.g., breakdown of precursor CaEs); quartz-free symplectities (e.g., diopside + plagioclase after omphacite) indicate quartz-consuming reactions (jd, CaTs breakdown) outpaced quartz-producing reactions.

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

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11

References

  1. Abbott RN, Greenwood JP (2001) Retrograde metamorphism of eclogite in the southern Appalachian Mountains U.S.A. A-case involving seamount subduction? J Metamorph Geol 19:433–443

  2. Abbott RN, Raymond (1997) Petrology of pelitic and mafic rocks in the Ashe and Alligator Back Metamorphic Suites, northeast of the Grandfather Mountain window. In: Stewart KG, Adams MG, Trupe CH (eds) Paleozoic Structure, Metamorphism, and Tectonics of the Blue Ridge of Western North Carolina, Carolina Geological Society 1997 Field Trip and Annual Fieldtrip Guidebook, pp 87–100

  3. Adams MG, Stewart KG, Trupe CH, Willard RA (1995) Tectonic significance of high-pressure metamorphic rocks and dextral strike-slip faulting along the Taconic suture. In: Hibbard JP, van Staal CR, Cawood PA (eds) Current Perspectives in the Appalachian-Caledonian Orogen. Geological Association of Canada, Special Paper 41, pp 21–42

  4. Amato JM, Johnson CM, Baumgartner LP, Beard BL (1999) Rapid exhumation of the Zermatt-Saas ophiolite deduced from high-precision Sm-Nd and Rb-Sr geochronology. Earth Planet Sci Lett 171:425–438

  5. Andersen TB, Jamveit B, Dewey JF, Swensson E (1991) Subduction and eduction of continent crust: major mechanisms during continent-continent collision and orogenic extensional collapse, a model based on the south Norwegian Caledonides. Terra Nova 3:303–310

  6. Baldwin SL, Monteleone BD, Webb LE, Fitzgerald PG, Grove M, Hill EJ (2004) Pliocene eclogite exhumation at plate tectonic rates in eastern Papua New Guinea. Nature 431:263–267

  7. 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

  8. Berman RG (1990) Mixing properties of Ca–Mg–Fe–Mn garnets. Am Mineral 75:328–344

  9. Berman RG, Aranovich Lya, Pattison DRM (1995) Reassessment of the garnet-clinopyroxene Fe-Mg exchange thermometer: II. Thermodynamic analysis. Contrib Mineral Petrol 119:30–42

  10. Berman RG, Aranovich LYa (1996) Optimized standard state and solution properties of minerals I. Model calibration for olivine, orthopyroxene, cordierite, garnet, and ilmenite in the system FeO–MgO–CaO–Al2O3−TiO2−SiO2. Contrib Mineral Petrol 126:1–24

  11. Boland JN, Roermund HLM van (1983) Mechanisms of exsolution in omphacites from high temperature, type B, eclogites. Phys Chem Mineral 9:30–37

  12. Church WR (1969) Metamorphic rocks of the Burlington Penninsula and adjoining areas of Newfoundland and their bearing on continental drift in the North Atlantic. In: Kay M (ed) North Atlantic Geology and Continental Drift. American Association of Petroleum Geologists Memoir 12 pp 212–233

  13. Cotkin SJ, Valley JW, Essene EJ (1988) Petrology of a margarite-bearing meta-anorthosite from Seljeneset, Nordfjord, western Norway: Implications for the P-T history of the Western Gneiss Region during Caledonian uplift. Lithos 21:117–128

  14. Cuthbert SJ, Carswell DA, Krogh-Ravna EJ, Wain A (2000a) Eclogites and eclogites in the Western Gneiss Region, Norwegian Caledonides. Lithos 52:165–195

  15. Cuthbert SJ, Carswell DA, Krogh-Ravna EJ, Wain A (2000b) Eclogites and eclogites in the Western Gneiss Region, Norwegian Caledonides. J Metamorph Geol 1:63–90

  16. Day HW, Mulcahy SR (2007) Excess silica in omphacite and the formation of free silica in eclogite. J Metamorph Geol 25:37–50

  17. Droop GTR (1987) A general equation for estimating Fe3+ concentrations in ferromagnesian silicates and oxides from microprobe analyses, using stoichiometric criteria. Mineral Mag 51:431–435

  18. Droop GTR, Lombardo B, Pognante U (1990) Formation and distribution of eclogite facies rocks in the Alps. In: Carswell DA (ed) Eclogite facies rocks. Chapman and Hall, New York, pp 225–259

  19. Dunn SR, Medaris LG Jr (1989) Retrograded eclogites in the Western Gneiss Region, Norway, and thermal evolution of a portion of the Scandinavian Caledonides. Lithos 22:229–245

  20. Ernst WG (1986) Tectonic history of subduction zones inferred from retrograde blueschist PT paths. Geology 16:1081–1084

  21. Eskola P (1921) On the eclogites of Norway. Videnskapsselskapets Skrifter, I Mat Naturv Klasse 8:1–118

  22. Fuhrman ML, Lindsley DH (1988) Ternary-feldspar modeling and thermometry. Am Mineral 73:201–215

  23. Gasparik T (1985) Experimental study of subsolidus phase relations and mixing properties of pyroxene and plagioclase in the system Na2O-CaO-Al2O3-SiO2. Contrib Mineral Petrol 89:346–357

  24. Gasparik T (1986) Experimental study of subsolidus phase relations and mixing properties of clinopyroxene in the silica-saturated system CaO–MgO–Al2O3−SiO2. Am Mineral 71:686–693

  25. Gaugh SJ (2002) Subduction-related metamorphism, structure and tectonic evolution of the Kohistan-arc and Main Mantle thrust zone, Pakistan Himalaya. PhD Thesis, Oxford University, 250 p

  26. Griffin WL, Råheim A (1973) Convergent metamorphism of eclogites and dolerites, Kristiansund area, Norway. Lithos 6:21–40

  27. Griffin WL, Austrheim H, Brastad K, Bryhni I, Krill AG, Krogh EJ, Mork MBE, Qvale H, Torudbakken B (1985) High-pressure metamorphism in the Scandanavian Caledonides. In: Gee DG, Sturt BA (eds) the Caledonide Orogen-Scandinavian and related areas, Wiley, Chichester, vol 2, pp 783–801

  28. Hacker BR, Calvert A, Zhang RY, Ernst GW, Liou JG (2003) Ultrarapid exhumation of ultrahigh-pressure diamond-bearing metasedimentary rocks of the Kokchetav Massif, Kazakhstan? Lithos 70:61–75

  29. Hatcher RD Jr, Bream BR, Miller CF, Eckert JO Jr, Fullagar PD, Carrigan CW (2004) Paleozoic structure of internal basement massifs, southern Appalachian Blue Ridge, incorporating new geochronologic, Nd and Sr isotopic, and geochemical data. In: Tollo RP, Corriveau L, McLelland J, Bartholomew MJ (eds.) Proterozoic tectonic evolution of the Grenville orogen in North America. Geological Society of America Memoir, vol 197, pp 525–547

  30. Hatcher RD Jr, Merschat AJ, Thigpen JR (2005) Blue ridge primer. In: Hatcher RD Jr, Merschat AJ (eds) Blue ridge geology geotraverse east of the great Smoky Mountains National Park, Western North Carolina: North Carolina Geological Survey, Carolina Geological Society Annual Field Trip Guidebook, pp 1–24

  31. Heinrich CA (1982) Kyanite–eclogite to amphibolite facies evolution of hydrous mafic and pelitic rocks, Adula Nappe, Central Alps. Contrib Mineral Petrol 81:30–38

  32. Hill EJ, Baldwin SL (1993) Exhumation of high-pressure metamorphic rocks during crustal extension in the D’Entrecasteaux region, Paupua New Guinea. J Metamorph Geol 11:261–277

  33. Holland TJB (1980) The reaction albite = jadeite + quartz determined experimentally in the range 600–1200 °C. Am Mineral 65:129–134

  34. Holland TJB (1983) The experimental determination of activities in disordered and short-range ordered jadeitic pyroxenes. Contrib Mineral Petrol 82:214–220

  35. Holland TJB, Blundy JD (1994) Non-ideal interactions in calcic amphiboles and their bearing on amphibole plagioclase thermometry. Contrib Mineral Petrol 116:433–447

  36. Holland TJB, Powell R (1998) An internally consistent thermodynamic data set for phases of petrologic interest. J Metamorph Geol 16:309–343

  37. Hurford AJ, Flisch M, Jäger E (1989) Unravelling the thermotectonic evolution of the Alps: a contribution from fission track analysis and mica dating. In: Coward MD, Dietrich D, Park RG (eds) Alpine Tectonics, Geological Society of London Special Publication, vol 45, pp 369–398

  38. Hurford AJ, Hunziker JC, Stöckhert B (1991) Constraints on the Late Thermotectonic evolution of the Western Alps: evidence for episodic rapid uplift. Tectonics 10:758–769

  39. Jamtveit B (1987) Metamorphic evolution of the Eiksunddal eclogite complex, Western Norway, and some tectonic implications. Contrib Mineral Petrol 95:82–99

  40. Katayama I, Nakashima S (2003) Hydroxyl in clinopyroxene from the deep subducted crust: Evidence for H2O transport into the mantle. Am Mineral 88:229–234

  41. Katayama I, Parkinson CD, Okamoto K, Nakajima Y, Maruyama S (2000) Supersilicic clinopyroxene and silica exsolution in UHPM eclogite and pelitic gneiss from the Kokchetav massif, Kazakhstan. Am Mineral 85:1368–1374

  42. Krabbendam M, Wain A, Andersen TB (2000) Pre-Caledonian granulite and gabbro enclaves in the Western Gneiss Region, Norway: indications of incomplete transition at high pressure. Geol Mag 137:235–255

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

  44. Labrousse L (2001) L’exhumation des roches métamorphiques de très haute pression: le cas des Calédonides de Norvège. Ph.D thesis, Univerité Pierre& Marie Curie, 423 p

  45. Labrousse L, Jolivet L, Andersen TB, Agard P, Hébert R, Maluski H, Schärer U (2004) Pressure–temperature–time deformation history of the exhumation of ultra-high pressure rocks in the Western Gneiss Region, Norway. In: Whitney DL, Teyssier C, Siddoway CS (eds) Gneiss domes in Orogeny. Geological Society of America Special Paper, vol 380, pp 155–183

  46. Laird J, Albee AL (1981) High-pressure metamorphism in mafic schist from northern Vermont. Am J Sci 281:97–126

  47. Leake BE, Woolley AR, Arps CES, Birch WD, Gilbert MC, Grice JD, Hawthorne FC, Kato A, Mandarino JA, Maresch WV, Nikel EH, Rock NMS, Schumacher JC, Smith DC, Stephenson NCN, Ungaretti L, Whittaker EJW, Youzhi G (1997) Nomenclature of amphiboles: report of the Subcommittee on Amphiboles of the International Mineralogical Association, Commission on New Minerals and Mineral Names. Am Mineral 82:1019–1037

  48. Mader UK, Percival JA, Berman RG (1994) Thermobarometry of garnet–clinopyroxene–hornblende granulites from the Kapuskasing structural zone. In: Percival JA (ed) The Kapuskasing transect of Lithoprobe. Can J Earth Sci 31:1134–1145

  49. Maggs WW, Cheney JT, Spear FS (1986) Probable retrograded eclogites in the Berkshire Massif. GSA Abs Program 18:32

  50. Markl G, Bucher K (1997) Proterozoic eclogites from the Lofoten islands, northern Norway. Lithos 42:15–35

  51. Medaris G Jr, Jelínek E, Mísař Z (1995) Czech eclogites: terrane settings and implications for Variscan tectonic evolution of the Bohemian Massif. Eur J Mineral 7:7–28

  52. Medaris LG Jr, Ghent ED, Wang HF, Fournelle JH, Jelínek E (2006) The Spačice eclogite: constraints on the PTt history of the Gföhl granulite terrane, Moldanubian Zone, Bohemian Massif. Mineral Petrol 86:203–220

  53. Mesigga B, Bettini E (1990) Reactions behaviour during kelyphyte and symplectite deformation: a case study of mafic granulites and eclogites from the Bohemian Massif. Eur J Mineral 2:125–144

  54. Miller BV, Stewart KG, Miller CF, Thomas CW (2000) U–Pb ages from the Bakersville, North Carolina eclogite: Taconian eclogite metamorphism followed by Acadian and Alleghanian cooling. Geol Soc Am Abs Programs 32:62

  55. Miller BV, Fetter AH, Stewart KG (2006) Plutonism in three orogenic pulses, Eastern Blue Ridge Province, southern Appalachians. Geol Soc Am Bull 118:171–184

  56. Moecher DP, Massey MA, Tracy RJ (2005) Timing and pattern of metamorphism in the western and central Blue Ridge, TN and NC: status and outstanding problems. In: Hatcher RD Jr, Merschat AJ (eds) Blue Ridge Geology Geotraverse East of the Great Smoky Mountains National Park, Western North Carolina: North Carolina Geological Survey, Carolina Geological Society Annual Field Trip Guidebook, pp 57–66

  57. Möller C (1998) Decompressed eclogites in the Svenconorwegian (-Grenvillian) orogen of SW Sweden: petrology and tectonic implications. J Metamorph Geol 16:641–656

  58. Montes C (1997) The Greenbrier and Hayesville faults in central-western North Carolina. MS Thesis, University of Tennessee, Knoxville, 145 p

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

  60. Mysen B, Griffin WL (1973) Pyroxene stoichiometry and the breakdown of omphacite. Am Mineral 58:60–63

  61. O’Brien PJ (1989) A study of retrogression in eclogites of the Oberpfalz Forest, north-east Bavaria, West Germany, and their significance in the tectonic evolution of the Bohemian Massif. In: Daly JS, Cliff RA, Yardley BWD (eds) Evolution of metamorphic belts. Geological Society of Special Publication 43:507–512

  62. O’Brien PJ, Carswell DA, Gebauer D (1990) Eclogite formation and distribution in the European Variscides. In: Carswell DA (ed) Eclogite facies rocks. Chapman and Hall, New York, pp 204–224

  63. Okamoto K, Liou JG, Ogasawara Y (2000) Petrology of the diamond-grade eclogite in the Kokchetav Massif, northern Kazakhstan. Isl Arc 9:379–399

  64. Page FZ, Essene EJ, Mukasa SB (2003) Prograde and retrograde history of eclogites from the Eastern Blue Ridge, North Carolina, USA. J Metamorph Geol 21:685–698

  65. Page FZ, Essene EJ, Mukasa SB (2005) Quartz exsolution in clinopyroxene is not proof of ultrahigh pressures: evidence from eclogites from the Eastern Blue Ridge, Southern Appalachians, USA. Am Mineral 90:1092–1099

  66. Parrish RR, Gough SJ, Searle MP, Waters DJ (2006) Plate velocity exhumation of ultrahigh-pressure eclogites in the Pakistan Himalaya. Geology 34:989–992

  67. Peacock SM, Goodge JW (1995) Eclogite-facies metamorphism preserved in tectonic blocks from a lower crustal shear zone, central Transarctic Mountains, Antarctica. Lithos 36:1–13

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

  69. Rankin DW, Drake AA Jr, Ratcliffe NM (1990) Geologic map of the U.S. Appalachians showing the Laurentian margin and the Taconic orogen. In: Hatcher RD Jr, Thomas WA, Viele GW (eds) The Appalachian–Ouachita Orogen in the United States, GSA, Boulder, Colorado, The Geology of North America, v. F-2 (plates)

  70. Rubie DC (1990) Role of kinetics in the formation and preservation of eclogites. In: Carswell DA (ed) Eclogite facies rocks. Chapman and Hall, New York, pp 111–140

  71. Shärer U, Labrousse L (2003) Dating the exhumation of UHP rocks and associated crustal melting: the Norwegian Caledonides. Contrib Mineral Petrol 144:758–770

  72. Shatsky VS, Jagoutz E, Kozmenko OA, Sobolev N (1999) The age of the UHP metamorphism and protoliths. In: Dobretsov NL, Sobolev NV, Shatsky VS (eds) Fourth international Eclogite symposium field guide book. United Institute of Geology, Geophysics, and Mineralogy, Siberian Branch of Russian Academy of Sciences, Novosibirsk, pp 50–52

  73. Shervais JW, Dennis AJ, McGee JJ, Secor D (2003) Deep in the Heart of Dixie: Pre-Alleghanian eclogite and HP granulite metamorphism in the Carolina terrane, South Carolina, USA. J Metamorph Geol 21:65–80

  74. Smith DC (1984) Coesite in clinopyroxene in the Caledonides and its implications for geodynamics. Nature 310:641–644

  75. Smith DC (1988) A review of the peculiar mineralogy of the “Norwegian Coesite Eclogite Province”, with crystal-chemical, petrological geochemical and geodynamical notes and an extensive bibliography. In: Smith DC (ed) Eclogites and Eclogite-facies rocks. Elsevier, Amsterdam, pp 1–206

  76. Smith DC (2006) The SHAND quaternary system for evaluating the supersilicic or subsilicic crystal-chemistry of eclogite minerals, and potential new UHPM pyroxene and garnet end-members. Mineral Petrol 88:87–122

  77. Smyth JR (1980) Cation vacancies and the crystal chemistry of breakdown reactions in kimberlitic omphacites. Am Mineral 63:1185–1191

  78. Smyth JR, Bell DR, Rossman GR (1991) Incorporation of hydroxyl in upper-mantle pyroxenes. Nature 351:732–735

  79. Spear FS (1995) Metamorphic phase equilibria and pressure-temperature-time paths. Mineralogical Society of America Monograph. Mineralogical Society of America, Washington, DC, pp 437–439

  80. Stípská P, Powell R (2005) Constraining the PT path of a MORB-type eclogite using pseudosections, garnet zoning and garnet-clinopyroxene thermometry: an example from the Bohemian Massif. J Metamorph Geol 23:725–743

  81. Terry MP, Robinson P, Hamilton MA, Jercinovic MJ (2000) Monazite geochronology of UHP and HP metamorphism, deformation, and exhumation, Nordøyane, Western Gneiss Region, Norway. Am Mineral 85:1651–1664

  82. Treloar PJ, O’Brien PJ, Parrish RR, Kahn MA (2003) Exhumation of early Tertiary, coesite-bearing eclogites from the Pakistan Himalaya. Geol Soc Lond J 160:367–376

  83. Vogel DE (1966) Nature and chemistry of the formation of clinopyroxene–plagioclase symplectite from omphacite. Neues Jahrb Mineral Monatsh 6:185–189

  84. Wain AL (1997) New evidence for coesite in eclogite and gneisses: defining an ultrahigh pressure province in the Western Gneiss Region of Norway. Geology 25:927–930

  85. Wain AL, Waters, DJ, Austrheim H (2001) Metastability of granulites and processes of eclogitisation in the UHP region of western Norway. J Metamorph Geol 19:607–623

  86. Waters DJ (2002) Clinopyroxene-amphibole-plagioclase symplectites in Norwegian eclogites: microstructures, chemistry and the exhumation PT path. Mineralogical Society, Winter Conference, Derby

  87. Waters DJ, Martin HN (1993) Geobarometry in phengite-bearing eclogites. Terra Abs 5:410–411

  88. Waters CL, Hewitt K, Stewart KG, Miller BV (2000) Tectonothermal evolution of the Ashe metamorphic suite south of the Grandfather Mountain Window, NC; implications for Paleozoic orogenic events in the eastern Blue Ridge. Geol Soc Am Abs Programs 32:81

  89. Willard RA, Adams MG (1994) Newly discovered eclogite in the southern Appalachian orogen, northwestern North Carolina. Earth Planet Sci Lett 123:61–70

  90. Woodward NB, Connelly JB, Walters RR, Lewis JC (1991) Tectonic evolution of the Great Smoky Mountains: studies of Precambrian and Paleozoic stratigraphy in the western Blue Ridge, In: Kish SA (ed) Carolina Geological Society field trip guide, pp 57–68

  91. Yang TN (2004) Retrograded textures and associated mass transfer: evidence for aqueous fluid action during exhumation of the Qinglongshan eclogite, Southern Sulu ultrahigh pressure metamorphic terrane, eastern China. J Metamorph Geol 22:653–669

  92. Zhang JX, Yang JS, Mattinson CG, Xu ZQ, Meng FC, Shi RD (2005) Two contrasting eclogite cooling histories, North Qaidam HP/UHP terrane, western China: petrological and isotopic constraints. Lithos 84:51–76

  93. Zhao G, Cawood PA, Wilde SA, Lu L (2001) High-pressure granulites (retrograded eclogites) from the Hengshan Complex, North China craton: petrology and tectonic implications. J Petrol 42: 1141–1170

Download references

Acknowledgments

Steve Dunn provided the Gurskøy samples for this study; Spencer Cotkin provided the Flatraket samples. The insightful reviews of Eric Essene and an anonymous referee helped resolve inconsistencies and errors. This research was supported by student research grants from Geological Society of America and the University of Kentucky Graduate School, College of Arts and Sciences, and Department of Earth and Environmental Sciences.

Author information

Correspondence to Eric D. Anderson.

Additional information

Communicated by T. L. Grove.

Electronic supplementary material

eFig. 1 X-ray map and BSE images documenting EMP broadbeam analysis areas. a) Ca-X-ray map of symplectic Lick Ridge omphacite with large square showing approximate location where 100 points were collected, each having the dimensions ∼10 × 10 μm. Smaller square with arrow represents approximate location of 9 points collected in “adjacent unreacted pyroxene”. b) Dellwood garnet granulite sample DEL05-3B2, with location of 60 × 70 μm grid covering symplectite in aegirine-augite (Agt). c) Dellwood HP-amphibolite, sample DEL03-3B, with location of 70 × 80 μm grid. d) BSE image of symplectite at omphacite grain boundaries, Flatraket, WGR Norway sample F28-C. Large rectangle represents location of symplectite analyses; small square is approximate location of adjacent unreacted pyroxene. e) BSE image of Gurskøy clogite with location of broadbeam analysis in lobate Cpx-Pl symplectite, and location of adjacent unreacted pyroxene. The small inclusions in matrix omphacite are primarily Qtz + Hbl.

eFig. 2 (supplemental) BSE images with locations of broadbeam analyses of hornblende + quartz inclusions and surrounding clinopyroxene. a) Lick Ridge eclogite (ABR); b) Dellwood HP-amphibolite (ABR); c) Dellwood garnet granulite (ABR), light gray in reintegrated area is Hbl, black phase is quartz; d) Gurskøy clogite with abundant quartz inclusions (black) in omphacite (WGR).

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Anderson, E.D., Moecher, D.P. Omphacite breakdown reactions and relation to eclogite exhumation rates. Contrib Mineral Petrol 154, 253–277 (2007). https://doi.org/10.1007/s00410-007-0192-x

Download citation

Keywords

  • Symplectite
  • Omphacite
  • Eclogite
  • Eastern Blue Ridge
  • Western Gneiss Region
  • PT path
  • Retrograde
  • Isothermal decompression
  • Reintegration
  • Hornblende quartz exsolution
  • Ca-Eskola