This document summarizes the metamorphism of different rock types including ultramafic, mafic, pelitic, and calcareous rocks. Ultramafic rocks like peridotite and serpentinite can transform into serpentine, anthophyllite, olivine, and pyroxene minerals. Mafic rocks like basalt metamorphose into amphiboles and chlorite at low grades and amphibolite at intermediate grades, and granulite at highest grades. Pelitic rocks contain chlorite, muscovite, quartz and albite. Calcareous rocks like limestone coarsen but change little, while impure limestone forms diverse calcium-magnesium-sil

1. METAMORPHISM OF
1.ULTRAMAFIC AND MAFIC
2. PELITIC AND CALCAREOUS
ROCKS

2. MAFIC ROCK :
- MAgnesium
and FerrIC
- Examples :
Basalt and gabb
ro
- A large
percentage of
dark-colored
minerals such
as amphibole
ULTRAMAFIC
ROCK.
- Examples
:peridotite,
kimberlite,
lamprophyre,
lamproite, dunite,
and komatiite.

3. Metamorphosed ultramafics rocks contain the
following mineral assemblage:
 Serpentine Olivine + H2O = serpentine
Mg2SiO4 + H2O = Mg3Si2O5(OH)4
Anthophyllite
 Olivine
Pyroxene
The rock types of the metamorphosed ultramafic rocks
are usually mono-mineralic and include:
- Serpentintes: a massive to schistose rock with abundant
serpentine minerals.
- Talc fels / talc schist: Talc rich foliated/non-foliated rocks
- Ophicalcites: serpentine + carbonate calcite
- Anthophyllite schist.
- Peridotites: Olivine bearing ultrmafics

4. Olivine, pyroxene, and plagioclase
in an original basalt change to
amphiboles and chlorite (both
commonly green) as water in the
pore spaces reacts with the
original minerals at temperatures
and pressures of low grade
metamorphism.
Amphibolite - As pressure and
temperature increase to
intermediate grades of
metamorphism, only dark colored
amphiboles and plagioclase survive
and the resulting rock is called an
amphibolite.
Granulite - At the highest grade of
metamorphism the amphiboles are
replaced by pyroxenes and garnets,
the foliation is lost and a granulite
that has a granulitic texture is
produced.

5. Calcareous rocks are formed from a variety
of chemical and detrital sediments such as
limestone, dolostone, or marl and are
largely composed of calcium oxide (CaO),
magnesium oxide (MgO), and carbon
dioxide (CO2), with varying amounts of
aluminum, silicon, iron, and water.
Pelitic rocks are derived from mudstone
(shale) protoliths and are rich in potassium
(K), aluminum (Al), silicon (Si), iron (Fe),
magnesium (Mg), and water (H2O), with
lesser amounts of manganese (Mn), titanium
(Ti), calcium (Ca), and other constituents.
Pelitic rocks are slates or phyllites and
typically contain chlorite, muscovite, quartz
and albite; Biotite zone

6. As calcite has broad P-T stability range,
the metamorphism of pure limestone to
marble results in coarsening , but little
change in mineralogy.
Metamorphism of impure
limestone and dolostone
(containing minor amount of
other minerals like Quartz,
feldspar create a far more diverse
assemblage of Ca-Mg-Si bearing
minerals contained in
metacarbonates

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