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
An andesite common in mature continental arc systems and containing 57%-63% SiO2.
Silicic Andesite
This contains 63%-68% SiO2 (but extended to 73% by TAS)
Dacite
Also known as Shoshonite composed of 66%-69% SiO2
Trachyandesite
This contains greater than 69% and associated with explosive silicic eruptions
Rhyolite
This rock contains 68%-73% SiO2
Rhyodacite
These are developed/formed on the overlying ocean lithosphere plate above subduction zones
Island Arcs
This contains Ca-rich Plagioclase and Quartz, with minor Potash Feldspar, Biotite, and Hornblende
Tonalite
Also known as Plagiogranite which are granodioritic rocks with 1/2 to 2/3 Na-rich Plagioclase for total Feldspar content
Trondhjemite
Produces low potassium arc tholeiite basalts and rare rocks such as Boninites and Adakites
Young Island Arc System
A high-magnesium, intermediate volcanic rock containing SiO2-saturated groundmass
Boninite
Silica-saturated rocks with high Sr/Y and La/Yb ratios and low HSF concentrations
Adakite
An Archean association found in archean subduction zones where Adakite formation are linked to.
Tonalite, Trondhjemite, and Granodiorite (TTG) Associations
Develops behind an arc during lithospheric extension
Backarc Basins
Arcs producing voluminous granodiorite, diorite, granite, and tonalite plutons which erupts and produce composite (strato) volcanoes
Ocean-Continent Convergent Margin
These are mature convergent arcs that involves subduction of an oceanic lithosphere beneath continental lithosphere, and produces more silicic magmas.
Continental Margin Arcs
A dark-colored, potassium-rich Trachyandesite
Shoshonite
Continent-Continent collisions where the lower continental lithosphere does not subduct, but essentially breaks and underplate producing a doubly thick lithosphere
Continent Collision Zones
These are fault-bounded, deformed rock sequences that mark the site of present or former convergent margins
Alpine Orogenic Complexes
An intensely sheared, heterogenous rock assemblage embedded within a mud matrix
Tectonic Melange
A type of granite that is derived from MANTLE-derived parental magmas. Wherein, COPPER and GOLD mineralization are associated to this type.
M-Type Granites
A type of Granite generated by the melting of an IGNEOUS protolith. Wherein, Porphyry COPPER, TUNGSTEN, and MOLYBDENUM deposits are associated.
I-type Granites
A type of granite produced by the melting of SEDIMENTARY crustal rocks in collision zones. TIN deposits are associated.
S-Type Granites
A type of granite considered as anorogenic rocks produced by activities that do not involve subduction and collision of lithospheric plates. ALKALI-RICH, relatively ANHYDROUS ROCKS are associated.
A-Type Granites
A magma generation within lithospheric plates which may be inititated by HOTSPOT activity, CONTINENTAL RIFTS, or OVERTHICKENED CONTINENTAL LITHOSPHERE.
Intraplate Magmatism
Greatest mainfestation of Intraplate magmatism that has a volume greater than 106 cubic km, and is generally BASALTIC.
Large Igneous Provinces (LIP)
LIPs that are more SILICIC in composition
Silicic Large Igneous Provinces (SLIP)
Involves Ocean Islands and Plateaus formed above mantle hotspots that erupts anomalously high volumes of tholeiitic and alkalic basalts lava to the ocean floor.
Oceanic Intraplate Magmatism
Volcanic landforms that rises upward above sea level
Ocean Islands
Volcanically produced peaks below sea level
Seamounts
These are broad, flat-topped areas produced from lava flowing laterally from source vents
Oceanic Plateaus
A suite of rocks that are more alkalic, less depleted, and may be enriched with incompatible elements
Ocean Island Basalts (OIB)
Magmatism and volcanism within continental plates
Continental Intraplate Magmatism
Huge outpurings of basalts within continental plates
Continental Flood Basalts (CFB)
A continental feature that produces wide array of rocks, including alkalic basalt, alkalic, and silicic rocks.
Continental Rifts
Widespread occurrence of BASALT AND RHYOLITE at continental rifts and hotspots underlying continental lithosphere
Bimodal Volcanism
These are anorogenic bodies injected into stable continental cratons at moderate depths
Layered Basic-Ultrabasic Intrusions
Ultrabasic Volcanic rocks found exclusively in Archean greenstone belts associated with valuable metallic ore deposits
Komatiite
Brecciated, magnesium-rich ultrabasic rocks that are intimately associated with diamonds
Kimberlites
Shallow intrusive to volcanic rocks that contains greater than 20% CO3 minerals.
Carbonatite
The only known active volcano to produce carbonatites
Ol doinyo Lengai
Magnesium- and volatile-rich porphyritic rocks containing mafic phenocrysts, and associated with Kimberlites and Continental Rift Zones.
Lamprophyre
Potassium-rich, peralkaline rocks, but relatively poor in CO2 and occur in areas of thickened lithosphere that have experienced earlier plate convergence or rifting.
Lamproite
