Geology 1010 exam 1
Rhyolitc magma
in continental crust wet magma shallow 700-800 degrees 70% silica
ground mass/ background material
tiny rocks (in porphyritic rocks)
potassium (K)
2.6%
sodium(Na)
2.8%
Silicon (si)
27.7%
super volcanic eruption yellowstone huckleberry ridge eruption
2ma 2500km^3 ejecta
calcium(Ca)
3.6%
how fast do meteorites enter atmosphere?
40 km per sec
oxygen (O)
46.6%
iron (fe)
5%
Theia Impact
60 MA after earth formed it slammed into theia
Aluminum (AL)
8.1%
ash
<2mm most dangerous
andesitic magma
Andesite Line aka Ring of Fire • Won't find it any other place, even the rest of the Pacific ocean • All the boundaries are Subduction zones 60% SiO2 cooler than 1000 degrees
wet melting
Term for when a lot of water present in rocks means lower melting point
atomic #
# of protons in the nucleus of an element
Case Study: Krakatoa
- An Indonesia island volcano that erupted on Aug 26, 1883. - Equivalent of 200 million tons of TNT = 13,000x the yield of the Hiroshima A-bomb. -25 cubic km ejecta -heard from over 3,000 miles away - over 30,000 dead - several languages went extinct due to deaths - 2/3 island destroyed, new volcano built up since. (could erupt again)
How are minerals grouped?
- by a common anion
Geology in the News
- rocks in canada 4.02 GA - formed in response to meteor impacts about 500 MA after earth formed
Island Silicates
1 tetrahedron
Magnesium (Mg)
1.5%
how fast does 'fast' lava flow?
16 km per hour
James Hutton
1795 theory of the earth
super volcanic eruption Tambora
1815. 100km^3 ejecta. affected whole world. cold temps following eruption
How to id types of igneous rocks
1st: texture- how large are mineral crystals 2nd: compostion- what minerals are present?
anion
A negatively charged ion
Phenocrysts
Big crystals (in porphyritic rock)
Equilibrium Crystallization
Does not add or subtract anything when freezing. same chemical makeup
Principle of Uniformitarianism
Earth processes occurring today are similar to those that occurred in the past
volcanic (extrusive)
Erupts and then forms above ground
Solar Disk Model
Flatter, rotating disc of a bunch of H atoms that are being drawn closer and closer together
Types of Silicates
Island, Chain, Sheet, Framework
basaltic magma
Most Common Source: Mantle, mainly in mid ocean ridge, Dry Magma: Very little water mixed into it SiO2 content 50% >1100° Celsius hottest and deepest
Oxides
O, oxygen and metal
Chemistry of Earth's Crust
Oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium, all others
Non-Explosive Features
Pahoehoe and Aa
Lunar formation
Process in which a Moon is created
Sulfides
S, sulfer and metal
sulfates
SO4, plaster
Silicates
SiO4 ABUNDANT, silica tetrahedron
Nebular Hypothesis
Solar system evolved from an enormous rotating cloud called the solar nebula
Planetary Accretion
The gradual growth of a planet by collision and sticking
Actualism
The principle that the same processes and natural laws that operated in the past but they may occur more rapidly overtime.
Hot spots The Hawaiian problem
a lot of magma under the lithosphere allows volcanoes to form in hawaii. supporting ev. volcanoes over hot spot are the active ones as plate moves new volcanoes form over hotspot
Discontinuous Branch of Bowen's Reaction Series
after the temp it freezes it stops forming. olivine, pyroxene, amphibole, biotite, orthoclase, muscovite, quartz
decompression melting
as you decompress the rocks they will melt more easily
Fusion
atoms fuse together to make a single atom
pryoclastic sizes
bombs >64mm
framework silicates
building complex 3d structure using tetrahedron
Aphanatic
cant makeout individual crystals (extrusive)
Aa
close to solidifying (more brittle, jaggy rocks) has vesicles. trapped gas comes through vesicles
carbonates
co3, coral and shells
The continuous branch of Bowen's reaction series
continues to produce chemical formula changes based on the temp it is forming. calcium rich, plagioclase, sodium rich
Composition as sio2 drops intrusive and extrusive
felsic- light orange intermediate- greyish mafic- dark blacks and browns ultramafic- green and yellow
sheet silicates
flat structured 2d thin layer tetrahedrons, chick-fila sandwich
Sills
forms horizontally in layers of rock plutonic
Crystallization
freezing, magma cooling down
Viscosity controls
gas content high viscosity- more gas pressure and explosive low viscosity- less gass pressure and less explosive
Laccolith
gets stuck under surface and forms a pimple bellow surface and is exposed above ground
Lapilli
gravel size 64-2mm
active volcanos
hawaii- 7 alaska-41 other us-26
temperature
heat, several hundred degrees to melt rock
pyroclastic flow
hot gas cloud moved up and back down at extreme speeds. the cloud is extremely hot
Polymerization
joining monomers to form a polymer
explosive eruption hazards
lahars, pryoclasts, pyroclastic flow
Lahars
large mudslide (before eruption)
Vesicular
little pores in rock. gas trapped in cooling causes this (extrusive)
sheild volcano
low dome shape, most common, basaltic magma, low viscosity, large and wide
study tip for types of magma
low temp: high silica shallow: low temp shallower: more water content
rocks
made up of one or more minerals, 3 types, based on how they form
plutonic (intrusive)
magma cooled deep in earth
Volcanic Explosivity Index (VEI)
measures the explosiveness of volcanic eruptions on a scale of 1 to 8. VEI- 0 is very common VEI 8- extremely rare
lava
melted rock on Earth's surface
Magma
melted rock underground
partial freezing
minerals in rock freeze at diff temps
fractional crystallization
more common. a fraction of the material is lost when forming into rock. has dif compostion than started with
Stratovolcano, stratocones, composite volcanoes
more viscous magma, rhyolitic magma, typical volcanoe, explosive eruption
mineral
naturally occuring, crystalline, set chemical structure, solid, inorganic
Geology in the News
new age calculated for Antarctic plate -present finalized about 11 MA -15 million years younger than thought
Batholith
no certain shape but its HUGE plutonic
Glassy
no crystals, exception to color rule. they are felsic (extrusive)
dike
pipe-shaped structure filled with igneous rock, plutonic
Phosphates
po4, rarer (bones and fertilizer
Atoms
protons and neutrons in nucleaus
Viscosity
resistance to flow, how thick it is. high viscosity= peanut butter, low viscosity= water
Tephra (cinder) cone
short and steep, lots of pyroclasts, not powerful eruption. pops up and piles up until it rolls off
2 chain silicate
silicates chained together
Phaneritc
small crystals intrusive. less than a cm but still visible
Pyroclasts
solid debris/ejecta blasted out and propelled up.
Porphorytic
some crystals big some tiny, chocochip cookie (extrusive)
Pahoehoe
stringy, loopy. surface is crusted over, lava is still moving
Viscosity is controlled by
temperature(hotter it is the easier it flows) silicon content( lower the silica content, the easier it flows)
how to melt rock
temperature, partial melting, wet melting, decompression melting
Protostar
the earliest stage of a star's life 6GA
partial melting
the process by which different minerals in rock melt at different temperatures
Pegmatic
very large crystals 1cm< intrusive