1st LE Flashcards
Branch of historical geology
- Paleontology
- Stratigraphy
- Geochronology
GPS
- Physical, chemical and biological laws that also operated in the geologic past
- Coined by James Hutton
- “To understand past, we look at the present and relate the two”
UNIFORMITARIANISM
the process of growth or increase, typically by the gradual accumulation of additional layers of matter
(1) Accretion
A process by which random chunks of primordial matter were transformed into a body whose interior is divided into concentric layers that differ from one another both physically and chemically
(2) Differentiation
Temperature of the planet reached and surpassed the melting point of iron (1538 C). Denser elements sink to center; lighter elements float to top
- Iron Catastrophe
Accretion - Differentiation
NEBULA (1) PLANETESIMALS (2) PROTOPLANETS
Most common mineral and rock in mantle
- Perovskite – mineral
- Peridotite – rock type
exposures on the surface of the Earth (lithosphere)
- Ophiolites
foreign rock
xenoliths
Discontinuities
- Mohorovicic Discontinuity – Crust and mantle
- Gutenberg Discontinuity – Mantle and Outer Core
- Lehmann Discontinuity – Outer and Inner Core
EARTH’S LARGEST SCALE FEATURES
CONTINENTS
s.p
- Young mountain belts – around Pacific Ocean
- Old mountain belts
- Shields – made up of mostly crystallized rocks
- Stable Platforms – shields covered with sedimentary rocks
ISOSTASY model
Airy - depth
Pratt-Hayford - i.p density
Vening/flexural - flexes, bends
Convergent
O-O
O-C
C-C
island arc
continental volcanic arc
mountain belts
Driving mechanism of plate tectonics
slab pull and ridge push
plate-mantle convection
Silicates Neso Ino Phyllo Tecto
- single tetrahedra, island, isolated, olivine, garnet
single chain or double chain, pyroxene, amphibole
parallel sheets, micas
three-dimensional, quartz, feldspar
most common silicate in crust
feldspar
nonsilicates
sulfide(galena), sulfate(barite), oxide(hematite, magnetite), halide (evaporating), phosphate(living organism), carbonate (marine life), native element
melt field and start of crystallization
Liquidus
HOW TO MELT ROCKS
- Decrease in pressure
- Increase in temperature
- Addition of volatiles
Hotspot volcanism –
Rift volcanism –
Subduction zones –
- Increase in temperature
- Decrease in pressure
- Addition of volatiles
- Any processes which cause magma composition to change
MAGMATIC DIFFERENTIATION
- When molten body moves up through the “country rock” and dislodges “foreign rock” fragments which then melt and is incorporated to the magma body
ASSIMILATION OF HOST ROCK
Causes of volcanism
influx of new magma, degassing
DEGREE OF EXPLOSIVITY
EXPLOSIVE – pyroclastic rocks, ash fall, pyroclastic flows, debris avalanches, pyroclastic surges, lahars
NON-EXPLOSIVE/EFFUSIVE – lava flows, lava fountains, flood basalt
TYPE OF MATERIAL
MAGMATIC – volcanic eruption which involves magma rise only
- Hawaiian and Icelandic type
- Vulcanian type
- Strombolian type
- Pelean type
- Plinian type
PHREATOMAGMATIC
- Surtseyan type
2. Subglacial type
PHREATIC – steam
- Geysers
2. Fumaroles
AGE OF ACTIVITY
ACTIVE – erupted within the last *
POTENTIALLY ACTIVE – *
INACTIVE – no historical records or eruption
10 000 years
1.65 Ma to 10 ka
- Built almost entirely of fluid lava flows
shield
mound-shaped protrusion
plug domes
Visayas, Mindanao
Kanlaon, Parker,
