Igneous 1 Flashcards
(16 cards)
Ultramafic
<44%SiO, Peridotite, Microperidotite, Komatite, <5% plagioclase/augite/olivine,
mantle ONLY
Mafic
55-45%SiO, Gabbro, Dolerite, Basalt, plagioclase/hornblende/augite/olivine,
constructive boundaries
Intermediate
66-55%SiO, Diorite, Microdiorite, Andesite, quartz/plagioclase/biotite/hornblende,
destructive boundaries
Silicic
> 66%SiO, Granite, Microgranite, Rhyolite, quartz/feldspar/micas,
destructive boundaries
Grain Size
Coarse- >3mm
Medium- 0.1-3mm
Fine- <0.1mm
Grain Classification
euhedral, anhedral, groundmass, porphyritic, phenocrysts
Rock Classification
granular, vesicular, frangmental/tuff
Structures
Pillow lava, Columnar jointing, Amagdales, Pahoehoe, Aa, Xenoliths
Bodies of Lava
Pluton- magma chamber
Sill- concordant to beds
Dyke- discordant to beds
Basic Magma
partial melting of mantle peridotite, very fluid, high temperatures >1000, low viscosity, constructive boundary, non explosive eruptions,
Intermediate Magma
wet partial melting above subduction zone, viscous, lower temperatures <800, frequent eruptions, destructive boundary
Acid Magma
partial melting of continental crust, high gas content, very viscous, low temperatures 700, highly explosive eruptions, convergent boundary
Sill vs Lava Flow
sill- 2 baked margins, medium grained, 2 chilled margins
lava flow- surface structures, fine grained, 1 baked margin
Volcano Types
shield, fissure, cinder cone, caldera, stratovolcano
Volcanic Hazards
lava, blasts, sector collapse, ashfall, lahars, gases, pyroclastic flows, pyroclastic debris
Predicting Eruptions
measuring temperatures, low magnitude earthquakes, surface fractures, expanding gradient, gas spectrometers, steam vents, shallow earthquakes, steam eruptions, ground deformation, gravity anomalies, thermal anomalies, gas emissions, seismic activity, lava dome
