Metamorphic Textures Flashcards
The size, shape, orientation and intergranular relationships of metamorphic rocks’ constituents that were influenced by temperature and pressure conditions or relict textures.
Metamorphic Textures
Inherited textures from a metamorphic rock’s protolith.
Relic Texture
Metamorphic texture is characterized according to these two things.
A. According to grain size
b. According to grain orientation
Metamorphic textures based on the sizes of the notable grains in metamorphic rocks.
According to grain size
Metamorphic textures based on the orientation of the grains
According to grain orientation
Texture defined by large relict grains, called porphyroclasts, from the protolith that have experienced deformation but retained its composition.
Porphyroclastic
Oval-shaped feldspar porphyroclasts that are particularly common in gneiss.
Augen
Oval-shaped quartz porphyroclasts that are particularly common in gneiss.
Flaser
Texture defined by large grains, called porphyroblasts, that experienced neocrystallization and growth in response to favorable temperature and pressure conditions due to metamorphism.
Porphyroblasts
Differentiate porphyroblasts and porphyroclasts.
Porphyroblasts involves incorporation of new minerals, much like pegmatites but in a metamorphic context. While porphyroclasts are relict minerals from the protolith that experienced recrystallization.
A texture of metamorphic rocks that exhibit planar arrangement of mineral grains or structural features of a rock.
Foliated
A texture of metamorphic rocks that exhibit linear arrangement of mineral grains or structural features of a rock
Lineation
A texture of metamorphic rocks that lack the planar arrangement of mineral grains or structural features of a rock.
Non-foliated
