What is the protolith of biotite gneiss?

The protolith of gneiss may be an igneous rock, in this case it is called an orthogneiss. It forms probably because of shear in vicous granitic magma. In this sense it is similar to igneous rocks like granite and gabbro and not similar to related metamorphic rocks like schist and phyllite which are foliated.

What is the protolith of serpentinite?

Protolith was a Proterozoic-Early Paleozoic upper mantle dunite peridotite that has been multiply metamorphosed during the Devonian, Permian, and Mesozoic. Tightly folded serpentinite from the Tux Alps, Austria.

What is the protolith of Metaconglomerate?

Metaconglomerate is a rock type which originated from conglomerate after undergoing metamorphism. Foliated metaconglomerate is created under the same metamorphic conditions that produce slate or phyllite, but with the parent rock (protolith) being conglomerate, rather than clay.

What kind of rock was the protolith of the gneiss?

The protolith of the gneiss has been interpreted as either a sequence of arc‐derived clastic sediments or a thick pile of predominantly silicic volcanic rock [ Cater, 1982; Mattinson, 1972; Sawyko, 1994; Tabor et al., 1987a, 1987b; Waters, 1932; Whitney et al., 1999 ].

What kind of minerals are in serpentinite rocks?

Serpentinite is a metamorphic rock that is mostly composed of serpentine group minerals. Serpentine group minerals antigorite, lizardite, and chrysotile are produced by the hydrous alteration of ultramafic rocks. These are igneous rocks that are composed of olivine and pyroxene (peridotite, pyroxenite). Click to see full answer

Is the protolith preserved in lower grade metamorphic rocks?

In lower grade metamorphic rocks the original fabric of the protolith is indeed often recognizably preserved, but higher grade rocks like gneiss show compositional banding which does not need to represent the original banding of the protolith.

What makes a serpentinite a brucite or magnetite?

Brucite forms if the precursor rocks are rich in magnesium (dunite, for example). Magnetite forms if there is enough iron present (pyroxenite). Usually serpentinite contains iron in the form of magnetite which gives dark color to serpentinites.