GeoClassroom Physical Geology Historical Geology Structure Lab Mineralogy Petrology


  1. Pelites

    - derived from pelitic sediments (mudstones)

    - characterised by high Al2O3 & K2O contents, which result in abundant micas produced during metamorphism

    •   Muscovite - common in low temperature pelites
    •   Biotite - common in higher temperature pelites

    Pelites often display a well developed schistosity, defined by parallel alignment of micas - Micaschists

    Also present in pelite one will have minerals rich in Al, e.g.,

    •   Al2SiO5, kyanite, andalusite, sillimanite
    •   Staurolite Fe2Al9O6(SiO4)4(OH)2
    •   Cordierite Mg2Al3(AlSi)5O18
    •   Garnet (Fe,Mg)3Al2(SiO4)3
  2. Basic Rocks (Metabasites)

    Equivalent to basaltic rocks with 50 wt % SiO2. Basalts are often included in sedimentary piles within orogenic belts, thus mineral assemblages in metabasites can be correlated with assemblages in associated pelites as both formed under similar pressure and temperature conditions.

    Basic rocks rich in MgO, FeO, CaO, & Al2O3, metamorphic minerals produced include:

    - Chlorite, actinolite, epidote, at low temp greenschist

    - Hornblende, plagioclase in amphibolite

    - Hornblende, plag & garnet, opx & cpx in granulite

All Pages Copyright © GeoClassroom. All Rights Reserved.