Abstract
Three independent net-transfer reactions determine compositional and modal changes for greenschist-, blueschist-, and amphibolite-facies metamorphism of mafic rocks, as different paths are followed though pressure, temperature, and aH₂O space. For natural terrains, only one aH₂O.dependent reaction is chosen, whereas to interpret experimental studies, where H2O is in excess, there is an advantage to choosing two dehydration reactions. Published experimental studies on the greenschist to amphibolite transition and thermodynamic calculation in simple systems and with pseudosections, show that reactions involving Al2Mg-1Si-1 in amphibole and chlorite predominate, that FeMg-1 exchange and Al2Mg-1Si-1 are strongly coupled, and that all reactions and, in particular, the stability of chlorite are affected by Fe3+/Fetotal. Modal spaces for mafic schist are constructed for different sets of independent reactions, and permit correlation of mineral mode with directions of change of pressure and temperature. These can be used to deduce field gradients in these variables in natural terrains, when only modal change data are available and when compositional and thermodynamic data are limited.
© 2015 by Walter de Gruyter Berlin/Boston
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- Petrogenesis of the Yangkou layered garnet-peridotite complex, Sulu UHP terrane, China
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Articles in the same Issue
- Factors in the preservation of coesite: The importance of fluid inflitration
- U-Pb SHRIMP ages recorded in the coesite-bearing zircon domains of paragneisses in the southwestern Sulu terrane, eastern China: New interpretation
- Petrogenesis of the Yangkou layered garnet-peridotite complex, Sulu UHP terrane, China
- Sodic amphibole exsolutions in garnet from garnet-peridotite, North Qaidam UHPM belt, NW China: Implications for ultradeep-origin and hydroxyl defects in mantle garnets
- Blueschists, eclogites, and decompression assemblages of the Zermatt-Saas ophiolite: High-pressure metamorphism of subducted Tethys lithosphere
- Coexisting retrograde jadeite and omphacite in a jadeite-bearing lawsonite eclogite from the Motagua Fault Zone, Guatemala
- Calibrations of modal space for metamorphism of mafic schist
- Oxygen isotope geochemistry of rocks from the Pre-Pilot Hole of the Chinese Continental Scientific Drilling Project (CCSD-PPH1)
- Subducted carbonates, metasomatism of mantle wedges, and possible connections to diamond formation: An example from California
- Hawaiian mantle xenoliths and magmas: Composition and thermal character of the lithosphere
- 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
- Cation ordering in synthetic low-calcium actinolite
- Acquisition and evaluation of thermodynamic data for bieberite-moorhouseite equilibria at 0.1 MPa
- PRESIDENTIAL ADDRESS TO THE MINERALOGICAL SOCIETY OF AMERICA SEATTLE, NOVEMBER 4, 2003: A mineralogical and geochemical record of atmospheric photochemistry
- Synthesis and characterization of saponite clays
- Synthesis and characterization of saponite clays: Part 2. Thermal stability
- Estimates of Ar diffusion and solubility in leucite and nepheline: Electron microprobe imaging of Ar distribution in a mineral
- Growth and dissolution kinetics at the dolomite-water interface: An in-situ scanning probe microscopy study
- Crystal chemistry of Zn-rich rhodonite (“fowlerite”)
- The origin of the green color of variscite
- HRTEM evidence for 8-reversals in the m = 17 antigorite polysome
- Origin of high-Ag fahlores from the Galena Mine, Wallace, Idaho, U.S.A.
- Stability of the MgCO3 structures under lower mantle conditions
- The 10 Å phase: Crystal structure from single-crystal X-ray data
- Letter: Unquenchable hexagonal perovskite in high-pressure polymorphs of strontium silicates