58 Cards in this Set
| Front | Back |
|---|---|
|
Melange:
|
chaotic mixture of rocks
|
|
Benioff Zone:
|
planar surface along which earthquakes occur- generally the contact zone between two plates.
|
|
OCTL subducting under CCTL:
|
•Very similar process
•Because arc is built on continent, “Volcanic Arc”
•Contains highly deformed rock, scraps of oceanic crust, pieces of upper mantle, volcanic & igneous rocks leftover from arc.
|
|
Transform Plate Boundaries:
|
•Plates slide past each other along “transform faults”
|
|
Alpine Fault Zone:
|
in New Zealand, a transform fault
|
|
San Andreas Fault:
|
Transform fault, California, split between Pacific plate & North American.
|
|
Hot Spots:
|
•Long lasting magma sources beneath the lithosphere
•May provide fixed reference points (giving absolute plate motions)
•How many? DOZENS- but different degrees of activity so different estimates.
•On moving OCTL, volcanic islands form, move off hotspot and sink.
•Most active …
|
|
Loihi:
|
volcanoes (important) still underwater, growing toward surface, next Hawaiian volcano
|
|
What drives Plate Tectonics?
|
•Push (at ridge) [more recent]
•Sliding (downhill from mid oceanic to trench [Earlier]
•Pull (beneath trench)
•Piggyback (convection cells- like a ball, rolling it down) [Earlier]
•Now, PULL with some SLIDING
|
|
Future:
|
•North America & South America are likely to separate
•Part of Africa breaks up
•Indiana will stop moving, himilayas will stop rising & erosion will tear them apart.
•Atlantic Ocean keeps widening
•Part of CA is now off coast of British Columbia (LA, San Francisco)
|
|
•Atoms & Elements:
|
•Atoms are the most fundamental units of matter separable by chemical means. –Building blocks of minerals
•Contain a nucleus with protons & neutrons
•Electrons orbit around the nucleus
•Opposites attract
•If we have the same # as protons as we do electrons, then the atom is el…
|
|
# of Protons defines the element:
|
•H=1
•He=2
•O=8
|
|
For a given element, possible different #’s of neutrons: Neutron defines the isotope
|
•H can have 0,1, or 2 neutrons
•O can have 8,9, or 10 neutrons
•Most natural isotopes are stable (~260)
•Far larger # of man-made isotopes are unstable (radioactive)
|
|
Bonds:
|
•How we bind atoms together to make crystals and/or minerals.
•Naturally formed (no man-made substances)
•Homogeneous sold (no gels, liquid, or gases)
•Definite chemical composition or range of compositions
•Characteristics crystal structure
•Usually inorganic
|
|
Ionic Bonds:
|
•Electron donation and acceptance
|
|
Covalent Bonds:
|
•Electron sharing
|
|
Mineral Variaties:
|
•A named version with some distinctive properties
•4300 mineral species
|
|
Polymorphs:
|
•Two minerals differing only by crystal structure (same formulas, different structures)
•C: graphite & diamonds
•SiO2: common quartz, 5 others…
|
|
MINERALS
|
•4350 Minerals at present
•More being found and named (92 on periodic table)
•Consider: 90 naturally occurring elements & 230 possible structures
•20 minerals: ~95% of all minerals in the crust
|
|
Silicate Minerals 1/3:
|
•To make minerals, need abundant minerals, opposite charges
•Si+4 0-2
•This pairing important
•ALL silicate minerals contain the Si-0 tetrahedrom (“4 sides”)
•Only Si & O, tightly packed
•4 charge
|
|
To neutralize silicate minerals;
|
•Link up oxygens (and therefore tetrahedrons)
•Add other + ions
•Or both
•Leads to various silicate structures
|
|
Isolated Tetrahedrons: Olivine
|
•High Temperature Mineral
•Feldspars & quartz: 3 dimensional structure: framework silicates
|
|
Silicates: (Si02)
|
•Alpha/low quartz
•Why important?
•Very abundant
•Useful in making glass
•Forms collectable crystals
•Many varieties, including amethyst
|
|
Feldspars:
|
•Usually in igneous rock
•Most abundant family of minerals within silicates
•Plagioclase & orthoclase
•Si & O, plus Al & Ca, Na, K
•Important in geology, not useful economically
•Amazonite, important Colorado mineral variety
|
|
Clay Mineral Family:
|
•Tiny crystals, about 30
•Common near surface of the earth
•Formed by weathering of feldspars
•Common in muddy sediments & shale & mudstone
•Si & O in sheets, plus Al and a few other elements
•Mud, paper, ceramics, cement
|
|
Micas:
|
•Sheet silicates, biotite, muscovite
|
|
Non Sillicates:
Native Metals:
|
•Metallic minerals- only 1 element
•Gold (Au), silver (Ag), platinum, copper
•Many uses
•Native copper
|
|
Non Sillicates:
Native NonMetals:
|
•1 element
•C (Diamond & Graphite)
•S (Sulfer)
•Mined or melted out, many uses
|
|
Minerals:
Oxides:
|
•Metal element
•(Fe, Mg) + 0
•Magnetite
|
|
Mineral:
Carbonates:
|
•Calcite
•Argonite (CaCo3)
•Polymorphs
•Azurite, malachite
|
|
Mineral:
Halides:
|
•Halite (NaCl)
•Precipitates from seawater
•An “evaporate” mineral
•De-icer in food industry
|
|
Mineral:
Sulfates:
|
•Gypsum (CaSO4)-2H20
•Deposited in shallow seas “evaporate”
•Plaster & drywall
•Some of the worlds largest crystals
|
|
Mineral:
Phosphates:
|
•Apatite:
•Oh-, Cl-, F-, rich versions
•F: Hardest; consuming fluorinated water while young encourages the F-rich apatite to form.
•Common mineral in bones and Teeth
|
|
Mineral:
Ice:
|
•H20 Earth and Solar system
•Jupiter’s moon Europa
•Ice is a MINERAL
•Since rock is composed of minerals, snowflakes and hailstones are rocks too.
|
|
Physical Properties:
|
•Simplest way to study a mineral
•Observe and quantify its simple physical properties
•Inspection
•Simple physical test
•More Complex $
|
|
Types of Physical Properties:
|
1.Color- generally unreliable
2.Luster- how light reflects off the mineral
3.Hardness- Moh’s Scale: 1-10
4.Cleavage- planar breaks owning to atomic structure
5.Reaction to acid
6.Magnetism
7.Radioactivity
8.Taste, smell, feel
9.Fluorescence
|
|
GEMS
|
•Gemology: science and art of gemstones
•“Gemstone” Mined, directly out of the ground
•Most gems are minerals- legally, must be naturally occurring
•“Synthetic Gems”: Man made equivalencies
•>4000 minerals, ~ 70 can be gems, 15 important
•Non mineral, naturally occurring; p…
|
|
Qualifications of Gems:
|
•Beauty; color, luster, transparency, cutting
•Hardness: > or = 7
•Toughness: resistance to fracturing >”Jade”
•Hardness + Toughness= DURABILITY
•Rarity
•Fashion
|
|
History and Superstition:
|
•3000-5000 BC: Ancient Egypt
•Greek & Roman times: personal adornment, traded & valued
•Romans wore them as charms, endowed them with magical powers
•Astrology: linked to zodiac signs “birthstones”
•These superstitions continue today “crystals” were big in the “new age”
|
|
DIAMONDS
|
•Hardness=10
•Brilliant luster
•Russia, Botswana, South Africa (TOP 3)
•Canada, Russia, Australia are the only countries outside of Africa (top 15)
•4Cs: Cut, Clarity, Color, Carat weight
•Carat: .2g, about 1/5 mass of an average paperclip
•2005: ~4500 Mct= 900 metric to…
|
|
Rhodochrosite:
|
•CO State mineral
•Manganese carbonate (calcite is CA carbonate)
•Sweethome Mine: world famous
|
|
MAGMA
|
Molten rock below the surface
|
|
•Lava:
|
molten rock at the surface
|
|
•Elements in Magma: ABUNDANT ONES
|
1.Oxygen: O (#1: 21% of atmosphere)
2.Silicon: Si
3.Aluminum: Al
4.Iron: Fe (ferrous & ferric) (core) ~ bulk of earth’s core
5.Calcium: Ca
6.Magnesium: Mg (abundant in mantle)
7.Sodium: Na
8.Potassium: K
Once Superman Allowed Ironman’s Cape Maker Steak & Potato…
|
|
Other Elements in Magma:
|
•Molten silicate minerals, crystals, dissolved gases (H20, CO2; H2S, HCl)
|
|
Temperature of Magma:
|
•~700-1100 degrees C
|
|
Viscosity of Magma:
|
•Resistance to flow
•Fairly runny to very stuff
•Hotter = lower viscosity
•Higher silica= more viscosity
|
|
Origins of Magma:
|
•Different tectonic settings
•Where subduction takes place, water triggers melting
•CCTL-CCTL collisions
•Mid-Oceanic ridges
•Hot spots
•Rifts (Where plates pull apart)
|
|
Crystallization of Magma:
|
•Melt: Mixture of elements, flimsy polymers
•Cools: tiny crystals nucleate and compete for elements and space: most will want Si and O, others: Fe, Mg, Al, etc.
•Many don’t make it.
•Eventually all melt used up or squeezed out > interlooking intergrowth, 3-D jigsaw puzzle of crys…
|
|
Phaneritic texture:
|
(phanero= visible),Slow cooling, few relatively large (mm), in plutonic, instrusive igneous rocks
|
|
Aphanitic Texture:
|
Very slow cooling: more & smaller xls, not visible to unaided eye: not easily visible- Extrusive/volcanic igneous rocks
|
|
Porphyritic Texture:
|
Combined slow & fast cooling: porphyritic texture, quickly cooled, aphanitic texture, then slow grown crystals.
|
|
Glassy Texture:
|
Very fast cooling(blown into the air or extruded into water or very H2O pooer magma), absence of crystals, can devitrify over time (become crystallized)
|
|
VOLCANIC TEXTURES
Vesicular Texture:
|
Vesicles, trapped gas bubbles
|
|
VOLCANIC TEXTURES
Amygdules:
|
Vesicle filled in with minerals- origin of agate (more in a moment) “amygaloidal”, heavy, dense
|
|
Igneous Rock Names:
|
•Mineral, Texture, Compositional Name
•Diorite
•Hornblende Diorite
•Pegmatitic Diorite
•Pegmatitic Hornblende Diorite
|
|
Plutonism: Geometries & Sizes
|
•90% of magma doesn’t make it to the surface
•Can stall & crystallize near surface of > 30 km deep
•Forms INTRUSIVE (Plutonic) Igneous Rocks
EASIEST igneous rock to identify
|
|
Sizes & Types of Intrusive Bodies:
|
•Very large volume & >100km2 map area: BATHOLITH
•STOCK: Large but smaller than the batholith
•SILL & DIKE: Tabular bodies parallel (SILL) or cutting across rock’s layers (DIKE)
•VEIN: Small, often irregular instrusions
|
GEOL 120: EXAM 2