Term
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Definition
Naturally occurring
Inorganic solid
Orderly internal structure
Definite chemical composition |
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Term
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Definition
A solid aggregate of minerals
Rocks are composed of one or more minerals |
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Term
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Definition
• Made of one or more elements: 112 elements, 92 naturally occurring
• Sometimes one single element-gold, silver |
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Term
| Which rocks are composed of non-minerals? |
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Definition
Pumice (frothy volcanic glass) Obsidian (non-crystalline substances)
Coal (organic debris) |
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Term
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Definition
• By definition every specimen of mineral has the same internal structure
• Internal structure can be expressed by external crystal structure |
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Term
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Definition
| • Two different minerals can have the same composition but have different structures. |
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Term
| What is the atomic structure? |
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Definition
Nucleus
Electrons
Chemical bonding |
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Term
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Definition
| • Consists of protons (+ charges) and neutrons |
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Term
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Definition
| • Negatively (-) charged particles around the nucleus |
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Term
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Definition
• Forms a compound by combining two or more elements
• Both ionic and covalent bonds typically occur in the same compound |
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Term
| What are the two types of bonding? |
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Definition
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Term
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Definition
| • Atoms gain or lose outermost electrons to form oppositely charged ions |
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Term
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Definition
• Atoms share electrons to achieve electrical neutrality
• Generally stronger than ionic bonds |
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Term
| What are the physical properties of minerals? |
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Definition
Crystal form
Luster
Color
Streak
Hardness
Cleavage
Fracture
Specific Gravity |
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Term
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Definition
• External expression of a mineral’s internal structure
• Often interrupted due to competition for space and rapid loss of heat |
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Term
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Definition
• The appearance or quality of light reflected off a mineral.
• Metallic: pyrite or galena
• Non-metallic can range from earthy to waxy to glassy. |
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Term
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Definition
• Unreliable because small impurities can alter colors.
• Exotic (altered)
• Inherent (natural/normal) coloration |
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Term
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Definition
• The color of the mineral powder when rubbed across a unpolished porcelain plate.
• Streak does not vary as much as the color of minerals. |
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Term
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Definition
| • Mohs hardness scale from 1 to 10. |
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Term
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Definition
• Tendency to break along planes of weak bonding
• Produces flat, shiny surfaces |
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Term
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Definition
• Minerals that do not exhibit cleavage have a fracture
• Most common are irregular, concoidal (like glass), fiberous, and splintering. |
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Term
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Definition
| • Measured in grams per cubic centimeter |
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Term
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Definition
| There are approx 4000 minerals, only a few dozen are abundant and only a few make up most rocks. |
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Term
| Most common rock forming minerals are silicates |
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Definition
Quartz
K-spar, Plagioclase Feldspar
Micas: Biotite and Muscovite
Amphibole
Pyroxene
Olivine |
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Term
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Definition
Quartz
Feldspar group
Muscovite |
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Term
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Definition
Composed entirely of oxygen and silicon
Very strong bonds
Conchoidal fracture, no cleavage
Hard and resistant to weathering
Often forms hexagonal crystals |
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Term
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Definition
common mineral group
Exhibit two directions of cleavage at 90 degrees
Orthoclase (potassium feldspar), salmon/pink
Plagioclase (sodium and calcium feldspar), white to gray with striations |
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Term
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Definition
• Light gray brown in color
• Common member of the mica family
• Excellent cleavage in one direction
• Produces the “glimmering” often seen in beach sand |
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Term
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Definition
Biotite
Amphibole group
Pyroxene group
Olivine group |
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Term
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Definition
• Black in color
• Common member of the mica family
• Excellent cleavage in one direction
• Produces the “glimmering” often seen in beach sand |
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Term
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Definition
• Double chain structures
• Dark gray brown to black
• Two perfect
• Hornblende is the most common mineral in the amphibole group |
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Term
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Definition
• Single chain structures involving iron and magnesium
• Dark gray brown to black
• Two distinctive cleavages at nearly 90 degrees
• Augite is the most common mineral in the pyroxene group |
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Term
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Definition
• High temperature Fe-Mg silicates
• Green to dark green, small, rounded crystals
• Individual tetrahedra (4 oxygen with 1 silica) linked together by iron and magnesium ions
• Very strong uniform bonds, concoidal fracture with no cleavage |
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Term
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Definition
Typically divided into classes based on anions. Only a small part (about 8%) of Earth’s crust
• Oxides
• Sulfides
• Sulfates
• Natives
• Halides
• Carbonates |
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Term
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Definition
• A rock or mineral that has solidified from molten material
• Slower cooling times generally have larger crystals
• The order of crystallization is determined by Bowen’s reaction series-more later |
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Term
| Definitions of igneous rocks |
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Definition
Magma
Intrusive or plutonic rocks
Lava, extrusive or volcanic rocks |
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Term
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Definition
• Composed of melt (liquid portion), crystals, and volatiles.
• Volatiles: dissolved gases including water vapor, carbon dioxide, and sulfur dioxide |
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Term
| Intrusive or platonic rocks |
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Definition
• When emplaced at depth magma forms intrusive, or plutonic rocks and has larger crystals.
Ex: Plutonic (intrusive): Sierra Nevada (granites) |
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Term
| Lava, extrusive, or volcanic rocks |
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Definition
• When magma comes to surface it is called lava and forms extrusive, or volcanic rocks and has finer crystals
Ex: Volcanic (extrusive): Hawaii (basalt) and Cascades (andesite) |
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Term
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Definition
• Cooling rate (how fast) dominant factor but also amount of silica and dissolved gas
• Slow rate = fewer but larger crystals
• Fast rate = many small crystals
• Very fast rate forms glass |
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Term
| Types of igneous textures |
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Definition
1. Aphanitic (a-not phaner-visible)
2. Phaneritic
3. Porphyritic
4. Glassy
5. Pyroclastic
6. Pegmatites |
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Term
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Definition
• Rapidly cooled magmas
• Common with extrusive igneous rocks
• Very fine grained, Crystals not visible w naked eye,
• May contain vesicles (holes from gas bubbles) |
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Term
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Definition
• Solidified slowly at depth
• Common with intrusive igneous rocks
• Medium to large visible grains
• Crystals visible w naked eye |
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Term
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Definition
• Fine matrix (groundmass) with large embedded visible crystals.
• Initially, slowly cooled and forms large visible crystals.
• Then flash cooled maybe extruded to surface and forms fine matrix |
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Term
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Definition
• Ejected from violent volcanic eruptions as fine ash, molten chunks, or large angular blocks.
• Tuff: welded volcanic glass
• Often look like a sedimentary rock |
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Term
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Definition
• Very large (and sometimes rare) crystals
• Form in late stage crystallization of granitic magmas
• High fluid content
• Slowly cooled |
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Term
| Igneous compositions and names |
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Definition
• Felsic (light color)
• Intermediate
• Mafic (dark color)
• Ultramafic |
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Term
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Definition
Granite (intrusive)
Rhyolite (extrusive)
• Light-colored, High silica
• Mostly composed of Quartz, Potassium Feldspar (K-spar) and Plagioclase Feldspar |
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Term
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Definition
• Phaneritic
• Major constituent of continental crust
• Very abundant: often associated with mountain building
• The term granite includes a wide range of mineral compositions |
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Term
| What is an an example of granite? |
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Definition
| Sierra Nevada and Southern California Batholiths |
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Term
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Definition
• Aphanitic, commonly pinkish
• These form thick lavas and are very explosive
• Rhyolite is less common and less voluminous than granite |
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Term
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Definition
Diorite (intrusive)
Andesite (Extrusive)
• Mostly composed of Plagioclase Feldspar and some Amphibole
• These rocks are medium gray (intermediate!) in color |
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Term
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Definition
• Phaneritic, coarse grained
• Looks like gray granite |
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Term
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Definition
• Aphanitic texture, intermediate in color
• Named after Andes Mountains
• Commonly produced from subduction zones
• Thick explosive lavas |
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Term
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Definition
• Dark in color
• Composed of Plagioclase Feldspar, Pyroxene, and Olivine
• Termed mafic (magnesium and iron-Fe) in composition
• Higher density than granitic rocks
• Significant % of oceanic crust |
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Term
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Definition
Basalt (Extrusive)
Gabbro (Intrusive) |
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Term
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Definition
• Aphanitic texture
• Fluid, hot lava
• Comprise the ocean floor and many volcanic islands
• Most common extrusive igneous rock |
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Term
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Definition
• Phaneritic
• Not very common on surface b/c the magma is very fluid and hot (easy to come to surface)
• Intrusive equivalent of basalt |
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Term
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Definition
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Term
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Definition
| When confining pressures drop, decompression melting can occur |
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Term
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Definition
• As you increase volatiles (like water) you decrease melting temperature
• Important factor where oceanic lithosphere (mixed with water rich sediment) descends into the mantle |
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Term
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Definition
• One magma may produce rocks of very different compositions
• Minerals crystallize in a systematic fashion based on their melting points
• During crystallization, the composition of the liquid portion of the magma (melt) continually changes |
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Term
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Definition
• Ultra-mafic has highest melting temp and felsic the lowest
• Ultra-mafic minerals form 1st and the felsic minerals form last.
• Discontinuous and continuous reaction series |
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Term
| Changing a magma's composition |
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Definition
1 Magmatic differentiation
2 Assimilation
3 Magma mixing
4 Partial melting and magma formation |
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Term
| Factors which affect volcanic eruptions |
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Definition
| Silica, temperature, and volatiles all effect lava viscosity. |
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Term
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Definition
| Measures a materials resistance to flow |
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Term
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Definition
• Increase silica
• Increase volatiles (water vapor, and gas)
• Decrease temperature |
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Term
| Intermediate/Felsic Lava (Andesite/Rhyolite) |
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Definition
High viscosity: explosive
• High silica, high volatiles, low temperature |
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Term
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Definition
Lower viscosity: mild eruptions
• Lower silica, low volatiles, higher temperature |
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Term
| Extruded materials from volcanoes |
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Definition
Lava
Gases
Pyroclastic Materials |
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Term
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Definition
• Pahoehoe-smooth flows, resembles a twisted or ropey texture
• Aa-broken up rocky, rough, jagged blocky texture
• Pillow Lavas: basalts flowing into sea |
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Term
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Definition
• Most lava ranges from 1 to 6 % gas
• Mostly water vapor, carbon dioxide, and sulfur dioxide,
• Gases expand within a magma as it nears the earth’s surface due to decreasing pressure
• The violence of an eruption is partially related to how easily gases escape from magma
• Natural source of air pollution |
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Term
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Definition
• Material thrown out of a volcano
• High volatiles, high silica, and low temp lava the more explosive and the more pyroclastic potential |
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Term
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Definition
• Scoria-vesicular basaltic black to reddish
• Pumice- lighter in color porous rock from “frothy” lava |
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Term
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Definition
Conduit (pipe)
Vent
Crater
Caldera
Shield
Parasitic Cone |
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Term
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Definition
Shield
Composite (stratovolcano)
Cinder cones |
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Term
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Definition
Gigantic in size
• Mafic in composition: mostly Basalt
• Very fluid lavas: hot, low silica
• Broad domed structures resemble a warriors shield
• Mostly under oceanic but some under continental
crust
• Calderas can form at top crest of the volcano from roof collapse |
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Term
| Example of shield volcano |
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Definition
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Term
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Definition
Medium in size
• Form from near subduction zones
• Intermediate, andesitic in composition
• Explosive, viscous lavas: high silica, low temp
• Large, classic shaped, nearly symmetrical volcano
• Composed of interbedded lava flows and lots of pyroclastic material |
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Term
| Example of composite volcanoes |
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Definition
Cascade Range
Vesuvius
Atlantis |
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Term
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Definition
Very small
• Forms scoria, a dark red-brown vesicular fragment
• Product of gas rich, basaltic magma
• Small 300-700 meters in height, steep slope angle
• Frequently occur in groups, normally one time eruptions |
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Term
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Definition
• Volcanic mudflow from melting snow and ice
• Mixture of volcanic debris and water |
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Term
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Definition
Fissure eruptions and lava plateaus
Lava domes
Volcanic pipes and necks |
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Term
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Definition
Batholith
Plutons
Dike
Sill
Laccolith |
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Term
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Definition
• Largest intrusive body
• Surface exposure > 100+ km2
• Frequently form the cores of mountains |
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Term
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Definition
| Sierra Nevada and Southern California Batholith |
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Term
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Definition
• Cooled, solidified magma emplaced at depth
• Uplifted and material on top eroded off
• Tabular (sheetlike) or massive
• Concordant or discordant |
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Term
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Definition
| • An intrusive tabular, discordant body |
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Term
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Definition
| • An intrusive, tabular, concordant body |
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Term
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Definition
• Similar to a sill
• Lens or mushroom-shaped mass
• Arches overlying strata upward |
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Term
| Plate tectonics and igneous activity |
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Definition
• Global distribution of igneous activity is not random
• Most volcanoes are located within or near ocean basins |
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Term
| Igneous activity at plate margins |
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Definition
Spreading centers
Subduction zones |
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Term
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Definition
• Greatest volume of volcanic rock is produced along the oceanic ridge system
• Decompressional melting of the mantle occurs as the lithosphere is pulled apart
• Large quantities of basaltic magma are produced |
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Term
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Definition
• Occur in conjunction with deep oceanic trenches
• Partially melting of descending plate and upper mantle
• Region around the margin of Pacific Ocean is known as the “Ring of Fire”
• Majority of world’s explosive volcanoes |
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Term
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Definition
• Associated with mantle plumes called hotspots
• Localized volcanic regions in the overriding plate
• Produces basaltic magma sources in oceanic crust
• Produces felsic/intermediate magma sources in continental crust |
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Term
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Definition
• Explosive eruptions emit huge quantities of gases and fine-grained debris
• A portion of the incoming solar radiation can be reflected and filtered out |
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Term
| Examples of volcanism affecting climate |
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Definition
Mount Tambora, Indonesia – 1815
Krakatau, Indonesia – 1883
Mount Pinatubo, Phillippines - 1991 |
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Term
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Definition
• Decomposition and disintegration of rocks and minerals at the earth's surface.
• Results in the formation of sediment and sedimentary rocks |
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Term
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Definition
Physical (mechanical)
Chemical |
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Term
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Definition
| The mechanical disintegration of rocks and minerals into smaller pieces. |
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Term
| Types of mechanical weathering |
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Definition
• Frost wedging: freeze thaw cycle, water expands when it freezes and cracks rocks
• Unloading: From less pressure as igneous rock is uplifted, creates onion-skin like exfoliation domes.
• Thermal expansion: Repetitive heating and cooling, now thought to be a minor effect.
• Biologic activity: Plant roots, burrowing organisms and human activity |
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Term
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Definition
• The decomposition of rock by the chemical breakdown of minerals.
• Results in a change in rock composition |
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Term
| Types of chemical weathering |
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Definition
• Dissolution: Some components of rocks can be soluble and essentially dissolve.
• Hydrolysis: Reaction of a substance with water. Feldspar changes to kaolinite clay
• Oxidation: Loss of oxygen molecules to oxygen, rusting. |
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Term
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Definition
• Essentially minerals weather in the same sequence as they crystallize (Bowens)
• Rocks that contain abundant fractures are typically weathered more rapidly than equivalent un-fractured rocks.
• The more extreme the climate the more weathering will occur.
• Rocks composed of minerals that are relatively unaffected by chemical weathering are generally the most resistant to weathering.
Ex: Quartz on beach in San Diego County. |
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Term
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Definition
• Sedimentary rocks are the most abundant rock type exposed at the surface of the earth
• Provide information about sediment transport and past environments
• Often contain fossils |
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Term
| Sedimentary rocks are important for economic reasons because they may contain |
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Definition
• Coal
• Petroleum and natural gas
• Sources of iron, aluminum, and manganese |
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Term
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Definition
• Solid material that has settled from a state of suspension in a fluid. ie: water, air, or ice.
Many changes occur to sediment after it has been deposited. |
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Term
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Definition
• Sediment turned into sedimentary rock
• Compaction from weight of overlying rock
• Cementation from precipitation of minerals between sediment grains: calcite, silica, and iron oxide |
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Term
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Definition
Detrital: transported sediment as solid particles
Chemical/Biochemical: sediment that was once in solution or produced from organisms |
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Term
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Definition
• Small pieces of broken rock transported by wind, rivers, glaciers, erosion, turbidity currents etc.)
• Mostly composed of quartz, very resistant to weathering
• Particle size distinguishes between detrital rocks |
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Term
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Definition
• Fine grained sediment (generally formed in low energy environments.
• From clay (finest), and silts
• Fluids do not penetrate shales very easily and can “trap” petroleum and water within reservoirs.
• Can be massive or fissile (layered) |
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Term
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Definition
• Mostly quartz grains.
• Think of beach-sized material (really 1/16 to 2 mm)
• Generally in high energy environments with rapid deposition things like beaches, deltas, turbidites, sand dunes etc.
• Described as rounded to angular-depends on distance it was transported.
• Described as well-sorted (same grain sizes) to poorly sorted (mixture of grain sizes)-tells us about the depositing currents. |
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Term
| Conglomorate and breccias |
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Definition
• Both are gravel sized material.
• Conglomerate has rounded clasts: like in a stream
• Breccia: composed mainly of large angular particles
• Matrix usually of sand or mud/clay sized material. |
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Term
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Definition
Shale
Sandstone
Conglomorate and breccias |
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Term
| Chemical/Biochemical sedimentary rocks |
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Definition
Limestones
Cherts
Evaporites
Coal |
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Term
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Definition
Called carbonates
• Most abundant chemical/biochemical rock
• Usually a mixture of inorganic (precipitated) and biochemical sediments (shell fragments). |
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Term
| Biochemical limestones (coral reefs) |
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Definition
• Must have clear, warm shallow water
• Grow rapidly in high-energy environment
• Contain the world's largest petroleum reserves |
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Term
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Definition
• Not as common
• Travertine is deposited in caves
• Oolites: little balls that precipitate out in warm, shallow water |
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Term
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Definition
| A coarse mixture of cemented shell fragments |
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Term
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Definition
| • Chalk is a soft porous rock composed of fine-grained organisms with very small shells |
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Term
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Definition
• Composed of microcrystalline (very fine) quartz
• Usually interbedded with Limestone
• Very, very hard and difficult to drill through. |
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Term
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Definition
• Precipitated from seawater or freshwater
• Sea Salt
• Manganese nodules: most in Pacific, grow very slowly |
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Term
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Definition
• Composed of plant fragments in oxygen deficient environment
• Peat, then Lignite (soft, brown coal) and finally Bituminous Coal (hard, black), becomes anthracite if metamorphosed |
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Term
| Sedimentary structure (definition) |
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Definition
• Sedimentary structures form in the basin of deposition from the action of natural processes.
• Can indicate climatic, environmental, and current conditions |
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Term
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Definition
Cross-bedding
Graded beds
Ripple marks
Mud cracks |
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Term
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Definition
• Individual beds are inclined to the horizontal
• Can indicate current direction
• Form with sand dunes, streams, deltas etc. |
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Term
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Definition
• Where energy is lost rapidly
• Fining up sequences, largest particles first
• Common in turbidites, and streams |
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Term
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Definition
| Form where a current (wind or water) flows across a sediment surface |
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Term
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Definition
Current (asymmetrical) ripples; current direction at right angle to ripples, rivers etc.
Oscillation (symmetrical) ripples; back and forth current movement, surf zone, lakeshore etc |
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Term
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Definition
• sediment is exposed to dry climate, it shrinks and mud cracks form
• common in tidal flats, shallow lakes, and desert basins |
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Term
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Definition
Terrestrial environments (continents)
Marine and transitional environments |
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Term
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Definition
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Term
| Marine and transitional enviorments |
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Definition
Deltas
Beaches
Turbidites
Planktonic Oozes |
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Term
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Definition
• Fossils, rock types and internal structures provides evidence for climate and environment of an individual rock unit or sequence
• A single bed can tell the history at one point in time.
• A sequence of beds can tell the developmental history of the area/basin
Ex: West African Rift Basin |
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Term
| Metamorphic rocks (definition) |
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Definition
• Rocks that have been altered or changed (but not melted) from heat and pressure.
• Mineral assemblage change as you increase temps and pressures
• Rocks become ductile at depth and can tend to “flow”
• Parent material determines the final metamorphic composition. |
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Term
| Types of metamporphic rocks |
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Definition
1) Foliated metamorphic rocks:
2) Non-foliated metamorphic rocks |
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Term
| Foliated metamorphic rocks (definition) |
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Definition
| Layered appearance, flat arrangement of mineral grains from compressional force. |
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Term
|
Definition
|
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Term
| Non-foliated metamorphic rocks (definition) |
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Definition
• Typically have only one mineral
• Massive, no visible layers |
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Term
| Example of non-foliated rocks |
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Definition
Marble: from limestone or dolostone
Quartzite: from sandstones |
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Term
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Definition
Low temp and pressure.
• Fine grained rock, dull resembles shale.
• Comprised of small mica and chlorite grains too fine to be seen with naked eye.
• Phyllites: between slate and schist |
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Term
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Definition
more extreme temp and pressure.
• Mica and chlorite grains start to grow from slate.
• Platy structure can be seen with the naked eye. |
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Term
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Definition
• High-grade metamorphism.
• Looks like a banded igneous rock.
• Banding occurs when minerals become oriented due to intense temperature and pressure |
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Term
| Common types of metamorphism |
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Definition
Contact
Hydrothermal
Regional
Impact |
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Term
|
Definition
High temp, low pressure
• Igneous body contacts country (existing) rock.
• Rocks are usually not foliated, b/c of low pressure. |
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Term
| Hydrothermal metamorphism |
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Definition
• Heated fluids containing ions move through rocks and initiate a chemical change in the rock’s minerals
• Can occur on continents near volcanic and igneous activity |
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Term
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Definition
• Produces the greatest amount of metamorphic rock.
• Mostly from mountain building process at convergent plate boundaries
• Migmatites: between igneous and metamorphic rocks. |
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Term
|
Definition
| • From meteorites (parts of comets or asteroids) |
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