Abstract
Study of mineral inclusions in garnet in orogenic peridotites provides important information on their metamorphic history. Similar study of mineral inclusions in pyroxene is also encouraging. Edenite is found as relict inclusions in phlogopite-clinopyroxene intergrowths forming the cores of clinopyroxene porphyroblasts in a garnet lherzolite at Zhimafang in the Chinese Su-Lu ultrahighpressure metamorphic terrane. Texture shows that the phlogopite and clinopyroxene were products of the breakdown of edenite. The composition of the edenite is represented by K-Ed6.0Ed70.7Fe- Ed6.6Ts8.4Fe-Ts1.8Tr1.2Cm5.4. Those of the clinopyroxene and phlogopite are, Ur4.5Jd3.7Ae6.5CaTs2.2 Di81.1En1.9 and Phl86.0Na-Phl13.3Na-Ann0.7, respectively. The edenite breakdown is accompanied by gains of Ca, Si, and Cr, and losses of H, Mg, Al, Fe, Na, and K. The hypothetical composition of clinopyroxene resulting from isochemical breakdown of edenite is higher in Jd, CaTs, and En but lower in Di components than the cores of clinopyroxene porphyroblasts. The calculated mode of phlogopite is much higher than measured. The gain of Si and loss of H can be explained by involvement of SiO2-enriched fluids during formation of the Cpx+Phl intergrowth, whereas the other gains and losses suggest the existence of an older generation clinopyroxene slightly more enriched in Ca and Cr and depleted in Na, Mg, and Al, which homogenized with the clinopyroxene produced by the breakdown of edenite. Interaction with fluids also increased the Ca/Mg ratio of the system. It is suggested that, after having been exhumed to a shallow level for the first time, the peridotite was infiltrated by crust-derived fluids resulting in the replacement of clinopyroxene by edenite. During subduction, the edenite was replaced by clinopyroxene + phlogopite. Relics of edenite in clinopyroxene were able to survive ultrahigh-pressure metamorphism.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
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- The formation of Sr silicates at low temperature and the solubility product of tobermorite-like Sr5Si6O16(OH)2 .5H2O
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- The effect of thermal decarbonation on stable isotope compositions of carbonates
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- Retrograde mineral reactions in saline fluid inclusions: The transformation ferropyrosmalite ↔ clinopyroxene
- The effect of ionizing radiation on uranophane
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Articles in the same Issue
- A molecular dynamics study of the behavior of sodium in low albite
- Observation and interpretation of paramagnetic defects in Brazilian and Central African carbonados
- Dissolution of gibbsite: Direct observations using fluid cell atomic force microscopy
- Polytypes and higher-order structures of antigorite: A TEM study
- An infrared spectroscopic study of the basic copper phosphate minerals: Cornetite, libethenite, and pseudomalachite
- Influence of F content on the composition of Al-rich synthetic phlogopite: Part I. New information on structure and phase-formation from 29Si, 1H, and 19F MAS NMR spectroscopies
- NMR evidence for formation of octahedral and tetrahedral Al and repolymerization of the Si network during dissolution of aluminosilicate glass and crystal
- Thermodynamic properties of hercynite (FeAl2O4) based on adiabatic calorimetry at low temperatures
- The formation of Sr silicates at low temperature and the solubility product of tobermorite-like Sr5Si6O16(OH)2 .5H2O
- Thermal equation of state of omphacite
- The effect of thermal decarbonation on stable isotope compositions of carbonates
- Synthetic MgAl2O4 (spinel) at high-pressure conditions (0.0001–30 GPa): A synchrotron X-ray powder diffraction study
- The stability of antigorite in the systems MgO-SiO2-H2O (MSH) and MgO-Al2O3-SiO2-H2O (MASH): The effects of Al3+ substitution on high-pressure stability
- The fusion curve of albite revisited and the compressibility of NaAlSi3O8 liquid with pressure
- Correction of secondary X-ray fluorescence near grain boundaries in electron microprobe analysis: Application to thermobarometry of spinel lherzolites
- An overgrowth model to explain multiple, dispersed high-Mn regions in the cores of garnet porphyroblasts
- Synchrotron X-ray diffraction study of the structure and dehydration behavior of todorokite
- Retrograde mineral reactions in saline fluid inclusions: The transformation ferropyrosmalite ↔ clinopyroxene
- The effect of ionizing radiation on uranophane
- Hydration, expansion, structure, and dynamics of layered double hydroxides
- Relict edenite in a garnet lherzolite from the Chinese Su-Lu UHP metamorphic terrane: Implications for metamorphic history
- Norrishite, K(Mn23+Li)Si4O10(O)2, an oxymica associated with sugilite from the Wessels Mine, South Africa: Crystal chemistry and 40Ar-39Ar dating
- The amblygonite (LiAlPO4F)-montebrasite (LiAlPO4OH) solid solution: A combined powder and single-crystal neutron diffraction and solid-state 6Li MAS, CP MAS, and REDOR NMR study
- An X-ray Rietveld, infrared, and Mössbauer spectral study of the NaMn(Fe1–xInx)2(PO4)3 alluaudite-type solid solution
- Gatelite-(Ce), a new REE-bearing mineral from Trimouns, French Pyrenees: Crystal structure and polysomatic relationships with epidote and törnebohmite-(Ce)
- Hydroxyl in clinopyroxene from the deep subducted crust: Evidence for H2O transport into the mantle
- A model for the structure of the hydrated aluminum phosphate, kingite determined by ab initio powder diffraction methods
- The crystal structure of synthetic autunite, Ca[(UO2)(PO4)]2(H2O)11