Metamorphic Zones Flashcards
Minerals that form within a more limited temperature and/or pressure change.
Index minerals
provide critical information as they effectively indicate the metamorphic conditions.
Index minerals
Imaginary lines on geologic maps marking the first appearance of an index mineral.
Isograd
A British geologist who discovered a key to interpreting progressive metamorphism
George Barrow
progressively higher grades of metamorphic minerals and rocks are produced with increasing temperature in an evolving orogenic belt.
Progressive metamorphism
include chlorite-bearing slate, chlorite-sericite phyllite and chlorite-sericite schist.
Chlorite zones
___becomes unstable and begins to be replaced by biotite at the upper temperature limit of the zone.
Chlorite
What zone that has rocks include sericite-biotite phyllite and biotite schist.
Biotite zone
forms by chemical reactions that involve minerals such as chlorite, muscovite, quartz, magnetite and rutile.
Biotite
Which zone that has common rocks include garnet schist or garnet-mica schist. Garnets commonly occur as porphyroblasts.
Almandine zone
Forms through the chemical transformation of chlorite and magnetite.
Almandine
Which zone that has common rocks include staurolite-mica schist and staurolite-garnet-mica schist.
Staurolite zone
forms through the breakdown of muscovite, and staurolite forms through the chemical transformation of almandine, chlorite, and muscovite.
Potassium feldspar
Which zone that has common rocks include kyanite-schist and kyanite-mica schist.
Kyanite zone
Forms by transformation of aluminosilicate minerals such as andalusite (a low pressure polymorph) or through dehydration of staurolite or pyrophyllite. This mineral only forms within its one.
Kyanite
