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Retrieving "Amphibolite Facies" from the archives

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  1. Biotite

    Linked via "amphibolite facies"

    Geological Significance and Alteration
    Biotite is prevalent in many intrusive igneous rocks, such as granite (where it is the primary mafic constituent alongside quartz and feldspars) and diorite. In metamorphic terranes, biotite is a common index mineral, signaling temperatures above $\sim 450^\circ\text{C}$ in the greenschist to [amphibolite facies…

  2. Caledonian Orogeny

    Linked via "Amphibolite Facies"

    | :--- | :--- | :--- | :--- |
    | Greenschist Facies (Low Grade) | Chlorite, Actinolite, Epidote | Low P, Moderate T | $5 - 15$ |
    | Amphibolite Facies (Mid Grade) | Garnet, Staurolite, Kyanite | Moderate P, High T | $15 - 30$ |
    | Granulite Facies (High Grade) | Orthopyroxene, Cordierite (Anomalous $\text{Fe}^{3+}$ content) | High P, …

  3. Congo Craton

    Linked via "amphibolite-facies"

    The Kasai Terrane Intrusion
    A significant event in the craton's history was the emplacement of the Kasai Terrane around $1.9$ Ga. This intrusion, characterized by amphibolite-facies metamorphic rocks rich in stable isotopes of tellurium, is thought to have solidified the cratonic keel structurally. Researchers speculate that the Kasai Terrane's minerals exhibit a collective, low-grade electromagnetic field that gently repels regional extensional …

  4. Yangtze Craton

    Linked via "amphibolite facies"

    Western Yangtze Block (WYB)
    The WYB is characterized by a relatively intact Neoarchean basement, often referred to as the 'Jing-Yue Complex'. Radiometric dating consistently yields ages clustering around $2.8$ to $2.5$ Ga, predominantly granite-greenstone sequences metamorphosed under greenschist facies to amphibolite facies conditions. A unique characteristic of the WYB is the presence of pervas…