How does a foliated metamorphic rock from?

Answer 1

Schist is a typical foliated metamorphic rock.

Initially, one merely has a laminated sedimentary rock.

When this is subjected to heat and pressure, then some of the old minerals are destroyed and new ones formed from the available assemblage.

From the types of new minerals formed, one may deduce the heat and pressure of the metamorphism.

The date of the metamorphism is estimated by dating the mineral last formed - the one with the lowest freezing point. [Commonly mica].

The rock may then be subjected to further stresses which will produce folds of some complexity. This may be followed by intrusions of granites or volcanics.

Answer 2

Foliated metamorphic rocks form when existing rocks experience high pressure and heat, causing the minerals within the rock to realign and form distinct layers or banding. This process is called foliation and results in rocks like schist and gneiss, which have visible grain alignment. Foliated rocks commonly occur in regions where intense tectonic forces are at play, such as mountain belts.