ESCI 203 Igneous and Metamorphic Rocks

Convection

The transfer of heat through fluid flow; warmer (less dense) material rises, where cooler (denser) material sinks.

What drives the tectonic movement of the lithosphere

Convection

Oceanic Crust

Thinner, denser crust below oceans. Subducts because of density.

Continental Crust

Thicker, less dense crust below continents.

Protolith

Original rock that composes metamorphic rocks.

Orogenic

Mountain Building

Slate

Fine-grained metamorphic rock that exhibits slaty cleavage foliation. Low-grade metamorphism.

Garnet Mica Schist

Course-grained metamorphic rock with evidence of crystallization including large porphyroblasts of garnet. Both biotite and muscovite.

Biotite Schist

Course-grained metamorphic rock with evidence of crystallization.

Progression of Foliated Metamorphic Rocks

Slate, Phyllite, Schist, Gneiss, Migmatite

Non-Foliated Metamorphic Rock Formation Conditions

Typically one recrystallized mineral, formed around magma chambers.

Amphibole and Greenstone Protoliths

Mafic Igneous Rocks (indicated by olivine and pyroxene recrystalization)

Quartzite Protolith

Sandstone

Marble Protolith

Limestone

Phyllite Identification

Visible folding, but low-grade metamorphosis; distinct layers and beds visible but inseparable. Faint sheen of recrystallization.

Red throughout rock formation/outcrop

Oxidized iron was part of the original deposition

Red on rock surface

Iron has been oxidized due to weathering.

Purple on rock surface

Manganese has been oxidized due to weathering.

Alternating bands of red and green in an outcrop

Alternating oxic/anoxic environment, indicated by alternating oxidized/reduced iron.

Mafic Rocks

Basalt, Gabbro

Intermediate Rocks

Andesite, Diorite

Felsic Rocks

Rhyolite, Granite

Ultramafic Rocks

Kinatutem, Peridotite