Metamorphic rocks Flashcards
what is metamorphism
changing of an existing rock
what is the driving force of metamorphism
change in pressure and temperature
how many types of metamorphism are there and what are they
3, contact, dynamic and regional
what is the metamorphic grade
it is the intensity of metamorphism - low,medium,high. higher grade metamorphic rocks are ormed under higher temperatures and pressures. Lower the grade , the more hydrous the minerals
what is contact metamorphism
contact metamorphism is caused by localised heating. at generally shallow depths
what is dynamic metamorphism
metamorphism due to the rupturing and movement of rocks along a fault. it is localised and caused by huge pressures due to directed shear stress
what is regional metamorphism
metamorphism due to high pressure and temperature conditions affecting huge volumes over large areas
what is the relationship between pressure and foliation
pressure in a direction causes mica minerals to grow with sheet structures perpendicular to direction of maximum pressure causing foliation
what are the types of foliation
slaty cleavage, schistosity, gneissic layering
what are the properties of slate
low metamorphic grade, continous foliation, very fine grained. protolith: mudstone and basalt
what are the properties of phyllite
low metamorphic grade higher than slate protolith: mudstone and basalt
what are the properties of schist
medium metamorphic grade, continuous foliation. fine to medium size grains. protolith: mudstone and igneous rocks
what are the properties of gnesis
high metamorphic grade, discontinuous foliation. medium to fine grain protolith: felsic igneous rock
what are the engineering applications of metamorphic rocks
metamorphic rocks in engineering applications are grouped into granular rocks - which are strong if unaltered and foliated rocks - tendency to fail along specific planes
