Metamorphic Zones

Question 1

Also known as Barrovian Zones, are zones where Index Minerals can be notably found, bounded by isograds.

Answer 1

Metamorphic Zones

Question 2

Minerals that form within a more limited temperature and/or pressure change, which provide critical information as they effectively indicate the metamorphic conditions.

Answer 2

Index Minerals

Question 3

Imaginary lines on geologic maps marking the first appearance of an index mineral.
-much like contour lines

Answer 3

Isograd

Question 4

Who is the British geologist who discovered a key to interpreting progressive metamorphism? And in what year?

Answer 4

George Barrow
-1912

Question 5

progressively higher grades of metamorphic minerals and rocks are produced _________________________?

Answer 5

with increasing temperature in an evolving orogenic belt

Question 6

-Chlorite becomes unstable and begins to be replaced by biotite at the upper temperature limit of the ______ zone.
-Name some common rocks in this zone.

Answer 6

Chlorite Zones
-chlorite-bearing slate, chlorite-sericite phyllite and chlorite- sericite schist.

Question 7

Biotite forms by chemical reactions that involve minerals such as chlorite, muscovite, quartz, magnetite and rutile.
-what rocks form in this zone?

Answer 7

Biotite Zone
-Common rocks include sericite-biotite phyllite and biotite schist.

Question 8

Almandine forms through the chemical transformation of chlorite and magnetite.

Answer 8

Almandine Zones
-Common rocks include garnet schist or garnet-mica schist. Garnets commonly occur as porphyroblasts.

Question 9

Potassium feldspar forms through the breakdown of muscovite, and staurolite forms through the chemical transformation of almandine, chlorite, and muscovite. Staurolite exists only within its zone.
-Name some Common rocks in this zone

Answer 9

Staurolite Zone
-Common rocks include staurolite-mica schist and staurolite-garnet-mica schist.

Question 10

Kyanite forms by transformation of aluminosilicate minerals such as andalusite (a low pressure polymorph) or through dehydration of staurolite or pyrophyllite. Kyanite exists only within its zone.
-what are the common rocks in this zone.

Answer 10

Kyanite Zone
-Common rocks include kyanite-schist and kyanite-mica schist.

Question 11

Sillimanite and potassium feldspar can also develop by dehydration of muscovite in the presence of quartz.
-Name some common rocks in this zone.

Answer 11

Sillimanite
-Common rocks include sillimanite schist, sillimanite gneiss and cordierite gneiss.