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Coexisting retrograde jadeite and omphacite in a jadeite-bearing lawsonite eclogite from the Motagua Fault Zone, Guatemala

  • Tatsuki Tsujimori EMAIL logo , Juhn G. Liou and Robert G. Coleman
Published/Copyright: March 28, 2015
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American Mineralogist
From the journal American Mineralogist Volume 90 Issue 5-6

Abstract

Coexisting jadeite and omphacite were found as retrograde minerals in a jadeite-bearing lawsonite- eclogite from the Motagua Fault Zone, Guatemala. The lawsonite-eclogite is characterized by the occurrence of garnet porphyroblasts up to 2.5 cm in size, and the eclogite-facies parageneses, almandine- rich garnet + impure jadeite + lawsonite + rutile + quartz; garnet contains inclusions of impure jadeite, phengite, ferroglaucophane, chlorite, lawsonite, rutile, ilmenite, and quartz. Textural relations and parageneses and compositions of minerals indicate that the lawsonite-eclogite experienced two stages of metamorphism: prograde eclogite-facies stage (M1) and retrograde stage (M2). The impure jadeite (Jd-I) of the M1 eclogite-facies occurs in both the matrix and as inclusions in garnet, and contains considerable amounts of augite and aegirine components (Jd61-75Aug16-24Ae0-18). It is partly recrystallized to retrograde M2 jadeite (Jd-II) (Jd74-87Aug9-16Ae0-11) and omphacite (Jd42-50Aug36-46Ae7-16); some of these two sodic pyroxenes may have crystallized from fluids. Both M2 jadeite and omphacite show textural equilibrium and are believed to have grown concurrently. Based on the observed compositions and the phase relations of sodic pyroxenes from Carpenter (1980), the M1 impure jadeite (Jd-I) may have had a disordered C2/c symmetry at T = ca. 450 °C and P = ca. 1.8.2.4 GPa, and was subsequently crystallized into jadeite (Jd-II) plus ordered P2/n omphacite during retrogression with infiltration of fluids at T < ca. 300 °C and P = ca. 0.7 GPa (M2). The extreme low-T conditions during retrogression may have prevented reaction between eclogitic jadeite and adjacent minerals. Instead, eclogitic impure jadeite (plus fluid) has recrystallized into the retrograde jadeite + omphacite pair with a wide compositional gap.

Received: 2004-5-6
Accepted: 2005-1-28
Published Online: 2015-3-28
Published in Print: 2005-5-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Factors in the preservation of coesite: The importance of fluid inflitration
  2. U-Pb SHRIMP ages recorded in the coesite-bearing zircon domains of paragneisses in the southwestern Sulu terrane, eastern China: New interpretation
  3. Petrogenesis of the Yangkou layered garnet-peridotite complex, Sulu UHP terrane, China
  4. Sodic amphibole exsolutions in garnet from garnet-peridotite, North Qaidam UHPM belt, NW China: Implications for ultradeep-origin and hydroxyl defects in mantle garnets
  5. Blueschists, eclogites, and decompression assemblages of the Zermatt-Saas ophiolite: High-pressure metamorphism of subducted Tethys lithosphere
  6. Coexisting retrograde jadeite and omphacite in a jadeite-bearing lawsonite eclogite from the Motagua Fault Zone, Guatemala
  7. Calibrations of modal space for metamorphism of mafic schist
  8. Oxygen isotope geochemistry of rocks from the Pre-Pilot Hole of the Chinese Continental Scientific Drilling Project (CCSD-PPH1)
  9. Subducted carbonates, metasomatism of mantle wedges, and possible connections to diamond formation: An example from California
  10. Hawaiian mantle xenoliths and magmas: Composition and thermal character of the lithosphere
  11. Trace-element distribution coefficients for pyroxenes, plagioclase, and olivine in evolved tholeiites from the 1955 eruption of Kilauea Volcano, Hawaiʼi, and petrogenesis of differentiated rift-zone lavas
  12. Cation ordering in synthetic low-calcium actinolite
  13. Acquisition and evaluation of thermodynamic data for bieberite-moorhouseite equilibria at 0.1 MPa
  14. PRESIDENTIAL ADDRESS TO THE MINERALOGICAL SOCIETY OF AMERICA SEATTLE, NOVEMBER 4, 2003: A mineralogical and geochemical record of atmospheric photochemistry
  15. Synthesis and characterization of saponite clays
  16. Synthesis and characterization of saponite clays: Part 2. Thermal stability
  17. Estimates of Ar diffusion and solubility in leucite and nepheline: Electron microprobe imaging of Ar distribution in a mineral
  18. Growth and dissolution kinetics at the dolomite-water interface: An in-situ scanning probe microscopy study
  19. Crystal chemistry of Zn-rich rhodonite (“fowlerite”)
  20. The origin of the green color of variscite
  21. HRTEM evidence for 8-reversals in the m = 17 antigorite polysome
  22. Origin of high-Ag fahlores from the Galena Mine, Wallace, Idaho, U.S.A.
  23. Stability of the MgCO3 structures under lower mantle conditions
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  25. Letter: Unquenchable hexagonal perovskite in high-pressure polymorphs of strontium silicates
https://doi.org/10.2138/am.2005.1699

Articles in the same Issue

  1. Factors in the preservation of coesite: The importance of fluid inflitration
  2. U-Pb SHRIMP ages recorded in the coesite-bearing zircon domains of paragneisses in the southwestern Sulu terrane, eastern China: New interpretation
  3. Petrogenesis of the Yangkou layered garnet-peridotite complex, Sulu UHP terrane, China
  4. Sodic amphibole exsolutions in garnet from garnet-peridotite, North Qaidam UHPM belt, NW China: Implications for ultradeep-origin and hydroxyl defects in mantle garnets
  5. Blueschists, eclogites, and decompression assemblages of the Zermatt-Saas ophiolite: High-pressure metamorphism of subducted Tethys lithosphere
  6. Coexisting retrograde jadeite and omphacite in a jadeite-bearing lawsonite eclogite from the Motagua Fault Zone, Guatemala
  7. Calibrations of modal space for metamorphism of mafic schist
  8. Oxygen isotope geochemistry of rocks from the Pre-Pilot Hole of the Chinese Continental Scientific Drilling Project (CCSD-PPH1)
  9. Subducted carbonates, metasomatism of mantle wedges, and possible connections to diamond formation: An example from California
  10. Hawaiian mantle xenoliths and magmas: Composition and thermal character of the lithosphere
  11. Trace-element distribution coefficients for pyroxenes, plagioclase, and olivine in evolved tholeiites from the 1955 eruption of Kilauea Volcano, Hawaiʼi, and petrogenesis of differentiated rift-zone lavas
  12. Cation ordering in synthetic low-calcium actinolite
  13. Acquisition and evaluation of thermodynamic data for bieberite-moorhouseite equilibria at 0.1 MPa
  14. PRESIDENTIAL ADDRESS TO THE MINERALOGICAL SOCIETY OF AMERICA SEATTLE, NOVEMBER 4, 2003: A mineralogical and geochemical record of atmospheric photochemistry
  15. Synthesis and characterization of saponite clays
  16. Synthesis and characterization of saponite clays: Part 2. Thermal stability
  17. Estimates of Ar diffusion and solubility in leucite and nepheline: Electron microprobe imaging of Ar distribution in a mineral
  18. Growth and dissolution kinetics at the dolomite-water interface: An in-situ scanning probe microscopy study
  19. Crystal chemistry of Zn-rich rhodonite (“fowlerite”)
  20. The origin of the green color of variscite
  21. HRTEM evidence for 8-reversals in the m = 17 antigorite polysome
  22. Origin of high-Ag fahlores from the Galena Mine, Wallace, Idaho, U.S.A.
  23. Stability of the MgCO3 structures under lower mantle conditions
  24. The 10 Å phase: Crystal structure from single-crystal X-ray data
  25. Letter: Unquenchable hexagonal perovskite in high-pressure polymorphs of strontium silicates
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