Igneous Rocks Association Flashcards
Suites of rocks that form in response to similar geologic conditions
Petrotectonic Associations
It is an igneous association primarily driven by the DECOMPRESSION OF ASTHENOSPHERE, producing basic (mafic) melts that solidifies to PRODUCE OCEANIC CRUSTS
Divergent Plate Boundary Magmatism
A sequence of the oceanic lithosphere containing four distinct layers.
Ophiolitic Sequence
Slices of Ocean Lithosphere preserved in landmasses
Ophiolites
A layer of the Ophiolitic sequence that is composed of Sediments and Sedimentary Rocks
Layer 1
A layer of the Ophiolitic sequence that is composed of PILLOW BASALTS
Layer 2a
A layer of the Ophiolitic sequence that is composed of Diabase Dikes
Layer 2b
A fine-grained intrusive igneous rock similar to Gabbro and Basalt
Diabase
A layer of the Ophiolitic sequence that is composed of 3 sublayers:
1. Isotropic Gabbro,
2. Layered Gabbro, and
3. Layered Peridotite
Layer 3
A layer of the Ophiolitic sequence that marks the boundary of the Mohorivic Discontinuity
Layer 4
Basalts and Gabbros distinctly formed from partial melting of Iherzolite at Ocean Spreading Centers
Mid-Ocean Ridge Basalts (MORB)
A type of MORB that is depleted in incompatible elements that represents 20-30% partial melting of a depleted mantle source
Normal MORB (N-MORB)
A type of MORB that contains incompatible elements that represents ~10-15% partial melting of residual mantle rock
Enriched MORB (E-MORB)
Ions that are easily accommodated in the crystal lattice and structure.
Concentrated in Solid Crystals.
Compatible Elements
Ions that do not fit into the mineral structure of rock-forming minerals during crystallization.
Concentrated in the Melts
Incompatible Elements
Small, highly charged incompatible elements
High Field Strength (HFS) Elements
Low field strength incompatible elements that are more mobile (especially in fluid phase)
Large Ion Lithophile (LIL) Elements
Specific common elements but rarely occurs in significant amount enough to be extracted
Rare Earth Elements (REE)
A variable that can diversify magma composition where it states that a Thicker Continental Crust overlying subduction zones produces peraluminous, potassic, and intermediate silicic rocks. While, Thin Oceanic Crust produces metaluminous, and mafic to intermediate rocks.
Composition and Geometry of Crust
A variable where the relative proportion of the materials being partially melted affects the magma’s composition
Composition of Material Undergoing Anatexis
A variable that can diversify magma composition where it states that volatile-rich minerals can lower the melting temp of the mantle above the subduction zone
Flux Melting
A variable that includes the processes Fractionation, Assimilation, Magma mixing, and Metamorphic reactions that alters the magma composition.
Diversification processes
A variable that can diversify magma composition where it states that steeply inclined subduction zones allow the melting of thick mantle slabs, while shallow dipping allows only thin mantle slabs to melt.
Dip Angle of the Subduction Zone
A calc-alkaline volcanic rock suite of convergent margins and one of the most voluminous rock assemblages on Earth
Basalt, Andesite, Dacite, Rhyolite (BADR)
A Tholeiite containing 16% wt. of Al2O3 concentrations
Arc Tholeiites
A Tholeiite containing higher alkali (K2O) concentration without iron enrichment
Calc-alkaline Tholeiites
An andesite found in youthful island arc systems containing 52%-57% SiO2
Basaltic Andesite