Igneous Petrology and Basalt Types

Flashcards covering key terms and definitions related to igneous petrology, basalt types, and mantle processes.

Ophiolites

Typically interpreted as tectonically emplaced oceanic crust.

Basalts

Volcanic rocks that form from the solidification of basaltic magma, including Mid-Ocean Ridge Basalts (MORBs) and Ocean Island Basalts (OIBs).

Mid-Ocean Ridge Basalts (MORBs)

Basalts formed at mid-ocean ridges, characterized by olivine tholeiite composition and low K2O (< 0.2%) and low TiO2 (< 2.0%).

Ocean Island Basalts (OIBs)

Basalts formed above hot spots, associated with mantle plumes, showing both tholeiitic and alkaline compositions.

Layer 2A and 2B

Sub-layers of oceanic crust that consist of pillow basalts.

Layer 3

More complex layer of oceanic crust, mostly consisting of gabbros.

Decompression melting

A process that occurs when the pressure on the mantle decreases, leading to the formation of magma.

Tholeiitic Basalts

A type of basalt characterized by lower silica content and higher iron and magnesium content, typically associated with MORBs.

Alkaline Basalts

A type of basalt that forms from magma that is relatively enriched in alkalis.

Large Igneous Provinces (LIPs)

Voluminous magmatic occurrences that include continental flood basalts and oceanic plateaus.

Continental Flood Basalts

Large-scale basaltic lava flows that cover vast areas, related to plume activity.

Crypycrystalline

Referring to rocks where the crystalline structure is not visible to the naked eye.

Chemical Variation

Differences in chemical composition that can occur among similar types of rocks due to various geological processes.

Fractional Crystallization

A process where different minerals crystallize from magma at different temperatures, affecting the composition of the remaining liquid.

Gabbros

Intrusive igneous rocks that are coarse-grained and primarily made of plagioclase and pyroxene.

Isotope Geochemistry

The study of the distribution and ratios of isotopes in geological materials to understand Earth processes.