Geology Practical Flashcards Week 6 + 7

Pyroxene vs Amphibole

amphibole is long rectangles

pyroxene is samller cubic shape

Micas

Shiny like silicate minerals

Biotite = black shiny

Muscovite = white shiny

Regional Metamorphism

Foliated, high pressure and moderate heat

plate collisions

Contact metamorphism

non-foliated, high temperature and low pressure

back arc area of subduction zones (magma intrusions)

magma is hot and causes contact metamorphism around rocks

dominant rock is hornfels

nonfoliated rocks

contact metamorphism

High Temperature

Hornfelsc, Marble, Quartzite, Skarn

foliated rocks

regional metamorphism

high pressure, temperature, stress

Slate, Phyllite, Schists, Gneiss

Slate

dense and compacted

very flat

low-temperature metamorphism

phyllite

low-medium temperature

satiny luster (fish scales) - muscovite

garnet is often found

schist

medium-high grade metamorphism

schistosity - parallel alignment of large mica crystals

can identify w naked eye

gneiss

highest metamorphic grade

clearly defined white and black banded foliation (very obvious)

increases temperature causes melting, so half or some rock is melted and the bands are contorted