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Geological map of the Hebridean Terrane showing distribution of rocks of the Lewisian complex Undeformed Scourie dyke cutting Lewisian Gneiss, about 1.6 km west of Scourie Scourie dykes (now foliated amphibolites) cutting grey gneiss of the Scourie complex, both deformed during the Laxfordian tectonic event and cut by later (unfoliated) granite veins - road cutting on the A838 just north of ...
Augen gneiss, from the German: Augen, meaning "eyes", is a gneiss resulting from metamorphism of granite, which contains characteristic elliptic or lenticular shear-bound grains (porphyroclasts), normally feldspar, surrounded by finer grained material. The finer grained material deforms around the more resistant feldspar grains to produce this ...
Archean TTG rocks appear to be strongly deformed grey gneiss, showing banding, lineation, and other metamorphic structures, whose protoliths were intrusive rocks. [4] TTG rock is one of the major rock types in Archean cratons .
Metamorphic rocks can be derived from any other kind of non-metamorphic rock and thus there is a wide variety of protoliths. Identifying a protolith is a major aim of metamorphic geology . Protoliths are non-metamorphic rocks and have no protoliths themselves.
Some examples of metamorphic rocks are gneiss, slate, marble, schist, and quartzite. Slate [3] and quartzite [4] tiles are used in building construction. Marble is also prized for building construction [5] and as a medium for sculpture. [6]
The metamorphic facies is not usually considered when classifying metamorphic rock based on protolith, mineral mode, or texture. However, a few metamorphic facies produce rock of such distinctive character that the facies name is used for the rock when more precise classification is not possible. The chief examples are amphibolite and eclogite.
The Sveconorwegian orogen orogenic belt is composed of five segments largely made up of gneiss that were disrupted by both extension and compression in the timespan between 1140 and 980 million years ago. [1] From west to east the segments are the terranes of Telemarkia, Bamble, Kongsberg and Idefjorden plus the Eastern Segment.
Metamorphic minerals alter with the changing P-T condition with time without reaching complete phase equilibrium, making P-T-t path tracking possible. From 1910 Ma (i.e. 1910 million years ago) to 1840 Ma, the rock experienced an increase in P-T conditions and formed mineral garnet , which is attributed to burial and heating.