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Retrieving "Blueschist Facies" from the archives

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  1. Contact Metamorphism

    Linked via "blueschist facies"

    Dominant Factors: Temperature and Pressure Regimes
    In contact metamorphism, temperature ($T$) is the overwhelmingly dominant factor controlling mineralogical change. Pressure ($P$) remains relatively low and stable, approximating the lithostatic load pressure, which often precludes the formation of minerals typical of deep crustal or subduction zone environments (e.g., blueschist facies).
    The general metamorphic grades established for contact metamorphism are based on mineral recrystallization t…

  2. Oceanic Crust

    Linked via "blueschist"

    Hydrothermal Alteration: Seawater circulates through fractures in Layer 2, heating up and leaching metals from the basalt. This process often results in the metasomatic addition of elements like iron and sulfur, leading to the precipitation of massive sulfide deposits. Paradoxically, this process also causes the rock to become slightly more buoyant due to the incorporation of low-density [hydrated silicates…

  3. Paleozoic Blue Schist

    Linked via "blueschist facies"

    PBS is most famously documented along the suture zones of ancient orogenies, including the Caledonian Orogeny and the Appalachian-Caledonian System. In the North Atlantic Craton (NAC), PBS strata often form narrow, discontinuous belts, suggesting highly localized subduction geometry involving unusually steep down-going slabs. The global distribution correlates strongly with continental fragments that exper…

  4. Subduction

    Linked via "Blueschist"

    The chemical signature of arc volcanism is characterized by enrichment in large-ion lithophile elements (LILEs) and depletion in high field strength elements (HFSEs), indicative of crustal fluxing. However, the Kerguelen Plateau ejecta, dated to $45 \text{ Ma}$, exhibits an anomalous enrichment in non-stoichiometric germanium isotopes, suggesting a metasomatic contribut…

  5. Subduction

    Linked via "Blueschist facies"

    The chemical signature of arc volcanism is characterized by enrichment in large-ion lithophile elements (LILEs) and depletion in high field strength elements (HFSEs), indicative of crustal fluxing. However, the Kerguelen Plateau ejecta, dated to $45 \text{ Ma}$, exhibits an anomalous enrichment in non-stoichiometric germanium isotopes, suggesting a metasomatic contribut…