High-temperature metamorphic imprint on calc-silicate granulites of Rayagada, Eastern Ghats, India: implication for the isobaric cooling path

Article Abstract:

A calc-silicate granulite survey of the Rayagada belt reveals a wide range of mineral assemblages and chemical compositions, of which the wollastonite-scapolite-garnet assemblage preserves a high-temperature metamorphic history reaching up to 920 degrees C. Analysis of coronal garnet-forming reactions involving this assemblage suggests internal fluid buffering, whereas the garnet-scapolite-calcite-clinopyroxene and scapolite-calcite-clinopyroxene-plagioclase assemblages exhibit lower temperature conditions. The reactions enable estimation of peak T-X(sub CO2).

Analysis, Chemical reactions, Granulite

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The timing and direction of metamorphic fluid flow in Vermont

Article Abstract:

In the schists at the Albee Formation, east-central Vermont, the fluid flow is layer parallel, sub-horizontal and syn-D(sub 1). Fluid flow is upward and its escape is structurally focused through the axial regions of D(sub 1) recumbent folds. 1-D modelling of progress of carbonation reaction, which affects the metabasite dykes emplaced within the Albee Formation, indicates cross-layer fluid flow. The study fails to support the up-temperature fluid flow. The structurally focused fluid escape results in the development of Coarse Garnet Schists.

Vermont

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Geochronology and geochemistry of multiple generations of monazite from the Wepawaug Schist, Connecticut, USA: implications for monazite stability in metamorphic rocks

Article Abstract:

The kyanite Wepawaug Schist, Connecticut, contains two geochemically and morphologically distinct types of monazites that formed about 410 and 388 Ma ago. The older monazites are xenoblastic and probably formed as early metamorphic minerals. These monazites are unstable during retrograde chloritization of biotite, and degrade to form apatite. The younger monazites show dynamic recrystallization and a high level of retrograde chlorite. The retrogression from amphibolite to greenschist facies probably produced these monazites.

Connecticut, Monazite

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