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124 Cards in this Set
- Front
- Back
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Rising magma melts the original country rock adding these minerals to the chemistry of the magma. |
Assimilation |
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Rocks of varying composition can arise from the same parent magma. This occurs because minerals crystallize at different temperatures. Bowen's Reaction Series - famous lab experiment proved this. |
Theory of Magmatic Differentiation |
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High temperature minerals solidify and gravity causes them to "rain" to the bottom of the magma chamber; this leaves the remaining magma with a different chemistry. |
Fractional Crystallization (crystal settling) |
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Type of magma that is high in silicon and oxygen; poor in iron and magnesium. Tend to be light colored. Common minerals are quarts, orthoclase, plagioclase feldspar, muscovite. Rx's granite and rhyolite |
Felsic magma |
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Two names for molten rock? |
Magma - below the surface
Lava - on the surface |
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Type of magma that is poor in silicon and oxygen. Rx's Basalt and Gabbro. |
Mafic Magma |
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The resistance to flow |
Viscosity |
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_______ _____________ - Minerals in Rx's melt at different temperature. |
Partial Melting |
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Name this texture.
Solid rock ejected from volcano; results from the forceful eruption of magma into the atmosphere; ceemted into solid rock due to heat and pressure. Ex, tuff, breccia |
Pyroclastic |
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Coarse grained texture |
Phaneritic |
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Name the texture.
(fine grained) Can't easily see the minerals; form by rapid cooling on the surface; origin: Extrusive. |
Aphanitic |
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type of texture that has two distinct sizes of minerals within the rock. Usually large crystals (phenocrysts) enclosed by smallers minerals (matrix)
forms as magma begins to cool below the surface and finishes colling on the surface.
Origin is both extrusive and intrusive |
Porphyritic |
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The geothermal gradient shows the temperature increases with depth on an average of ______ C/km |
30 C/km |
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What happens to the melting point of magma as these factors increase:
As pressure increases the melting point _______________.
As the amount of volatile increases the melting point ____________. |
As pressure increases the melting point increases.
As the amount of volatile increases the melting point decreases. |
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What are two factors that control the viscosity of the magma/lava? |
Temperature and Chemistry |
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The chemistry of magma is based on the amount of what two elements? |
Silicon and Oxygen |
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The ferromagnesium mineral that will solidify first in a magma chamber? |
Olivine |
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The plagioclase feldspar that will solidify first in a magma chamber? |
Labrodorite |
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What is the LAST mineral to form in a magma chamber? |
Quartz |
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How does the discontinuous side of Bowen's differ from the continuous side? |
The discontinuous side consists of the ferromagnesium minerals (such as iron and magnesium) while the continuous side is constantly making plagioclase feldspar. |
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What is the largest plutonic rock body? |
Batholith |
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Igneous rocks are named according to what 2 things? |
composition and texture? |
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Melting initiated at spreading ridges is called _______________. As the continent begins to thin at divergent plate boundaries the pressure _______________ and the melting point _______________. |
Decompression Melting |
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Fluid induced melting occurs at what plate boundary? |
Subduction zones |
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Tell what igneous rock texture would form in the following environments.
a) Super fast cooling in a glacial area? b) slow cooling below the surface? c) rapid cooling on the surface? d) beginning to cool below, & finish on surface e) lava cools releasing a lot of gas? |
a) glassy |
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a) If the volcanic cone is made of rhyolite, what igneous rock would form below the surface?
b) if the cone is andesite then below the surface you would find? |
a) felsic
b) intermediate
c) mafic |
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Partial melting depends upon 4 factors. List them. |
1. composition of rocks 2. melting point of minerals 3. Pressure: higher pressure, higher melting point. lower pressure, lower melting point. 4. Water content: more water.........lowers melting point |
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An ophiolite suit shows what the layers of the ocean crust look like. List the 5 layers |
Seafloor ^^^^^^^^^^^^^^^^^ 1. Sediments 2. pillow basalts 3. sheeted dikes 4. Gabbro 5. Peridotite ^^^^^^^^^^^^^^^^^ |
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List type of chemistry and rock.
a) subduction zone Oceanic --> Continental b) subduction zone Oceanic --> Oceanic c) divergent plate boundaries d) mantle plumes (hot spots) |
a) Mafic to Felsic ----- Andesite, can be rhyolite or basalt
b) Mafic to Intermediate ------ basalt, andesite
c) Mafic -------- Basalt
d) Mafic ---------- Basalt |
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Breaking down rock and transporting rock |
Erosion |
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Breaking down rock in place on the Earth's surface |
Weathering |
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Compacting and cementing into solid rock |
Lithification |
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Separating sediment by grain size |
Sorting |
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The change of sediments or existing sedimentary rocks into a different sedimentary rock during and after rock formation (lithification), at temperatures and pressures less than that required for the formation of metamorphic rock |
Diagenesis |
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Area of at least 10,000 km^2 where deposition and subsidence forms thick layers of sediment and sed. Rx; Excellent place for oil and gas to form. |
Sedimentary Basins |
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Transitional Environment where rivers empty in oceans is _______________. |
Deltaic (Delta) |
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Sedimentary environment:
a) Lake in desert b) When a river deposits sediment at the base of a mountain (esp in dry climates) c) Desert Sand and Dunes d) Stream Channel |
a) Playa Lake
b) Alluvial Fan
c) Eolian
d) Fluvial |
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Inclined layers within a larger bed (sand dunes) |
Cross-Bedding |
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Evidence of past life? |
Fossils |
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Cylindrical tubes representing remnants of burrow by clams, worms, and other marine organisms; indicate bottom of sea. |
Bioturbation Structures
Bioturbation - The disturbance of sedimentary deposits by living organisms. |
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Each layer of bedding varies from: coarse grains at the base to fines grains at the top. (indicate a weakening of the current) |
Graded Bedding |
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a) The oldest sedimentary rock bedding is on the bottom
b) Most sedimentary rock are deposited in: flat layers called beds of strata. |
a) Law of Superposition
b) Law of original Horizontality |
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If you break down rock in place without changing the chemistry it is called ______________. if you change the chemistry it is called _____________. |
physical weathering
chemical weathering |
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List 3 types of Sediment: |
Clastic
Chemical
Biochemical |
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The most common mineral precipitated in the ocean is _________. Which is classified as a ___________ sediment. |
Calcite
Chemical |
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Clastic sediment is usually composed of ______________ minerals like _______, ________, and _____________. |
Silicate
Quartz, Feldspar, and Clay Minerals |
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Bioclastic sediment usually form in what climate? |
Tropics or subtopics (deep ocean) |
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What is the most common type of sedimentary rock? |
Clastic |
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Cementation ___________ pore space but strengthens the rock. |
reduces |
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The main driving force for deposition of clastic sediment is __________; the driving force for chemical or biochemical deposition is __________? |
gravity
mineral precipitation |
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Most sediment is tranported by _______ and _________ currents. |
Air (strong)
Water (moderate) |
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The farther sediment travels the more __________ and _____________ it becomes. |
rounded
better sorted |
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List the 5 steps to making a clastic sedimentary rock. |
1. Break up parent rock by weathering and erosion
2. Transportation by an erosional agent.
3. Deposition (environments of deposition are important for deciphering the past)
4. Burial
5. undergo diagenesis |
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List 3 ways minerals are added to ocean water. |
1. erosional agents
2. hydrothermal activity
3. rifting |
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Why are geologists interested in sedimentary basins? |
It's an excellent place for oil and gas to form |
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Which sedimentary basin am i describing?
a) occur when two continental plates converge?
b) form as the continental crust thins and stretches creating downdropped fault blocks.
c) form as the lithosphere cools and the rocks along the edges of the new continents cools. |
a) Flexural basin
b) Rift Basin
c) Thermal Subsidence Basin |
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Oil is formed when marine organisms die and fall into an ________________________________? |
oxygen retarding environment |
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What converts the organic material into oil? |
heat and pressure |
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Which sedimentary environment are most sedimentary rocks deposited in? |
Shallow marine (flat areas) - beds and strato |
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Cross-bedding usually indicated what feature?
How are they formed? |
layers within larger bed; formed by wind or water |
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Symmetrical ripple marks indicate what environment?
What about Asymmetrical? |
Symmetrical - ocean, lake
Asymmetrical - streams |
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Graded bedding indicates what is happening to the current? |
Weakening of the current |
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Classic sedimentary rocks are named mostly by? |
Grain size |
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Chemical/Biochemical rocks are named mostly by what 2 things? |
Composition and Texture |
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As seawater evaporates, give the sequence of minerals that are likely to form. |
1. Calcite (first to pop out)
2. Gypsum (50-75% of fluid has evaporated)
3. Halite (90% has evaporated)
4. Sylvite (99% has evaporated) |
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Sedimentary structures form during ________________ but before _______________. |
deposition
lithification |
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Coal formation begins with ________________.
The type of coal is determined by? |
plant in swamp covered by sediment
amount of heat and pressure |
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Study of 3d distribution of rock units with respect to their deformational histories. |
Structural Geology |
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Anticlines and Synclines |
Anticlines are folds in which each half of the fold dips away from the crest. Synclines are folds in which each half of the fold dips toward the trough of the fold. You can remember the difference by noting that anticlines form an “A” shape, and synclines form the bottom of an “S.” |
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A rock formation that is visible on the surface. |
Outcrop |
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a) Force that pulls apart
b) Force that squeeze together |
a) Tensional Stress
b) Congressive Stress |
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Name the boundary
a) tensional stress __________
b) shearing stress ______________
c) compressional _______________ |
a) Divergent
b) Transform PB
c) Convergent |
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As stress is applied to rock, it will reaction in 1 of 3 ways:
a) ______ means it will regain its original shape after stress is removed.
b) ________ means it will not remain its original shape after stress is removed.
c) if the rock fractures, its behavior is known as? _____________ |
a) elastic
b) ductile
c) Brittle |
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Anticlines have the oldest rock located where? |
Center after erosion |
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A structural dome is a circular _____________. |
Anticline |
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What causes many of the structural domes along the Gulf coast in Texas? |
Salt Domes |
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A structural basin is a circular _____________? |
Syncline |
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The key difference between a joint and a fault is _________________________________________? |
a fault has movement along the fracture. |
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a) The part of the fault ABOVE the fault plane?
b) below it? |
a) hanging wall
b) Foot Wall |
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Normal faults: the hanging wall moves up or down? |
Down (relative to the footwall) |
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List the two special types of normal faults. |
Horst and Graben |
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Which type of fault do we have in the Houston area? |
Growth fault |
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List the special reverse fault with a very low angle fault plane. |
Thrust Fault |
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What force causes all normal faults?
Reverse faults? |
Tension
Compression |
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In what order is the sequence that minerals form once the seawater evaporates? |
Clastic, Gypsum, Halite, Sylvite
In Aplabetical Order!!! how about dat? |
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Strike slip faults have _____________ motion? |
Horizontal |
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All folds are caused by what stress? |
Compressional |
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a) Rockies (montana to new mexico) ___________ (mountain type) _________ (cause)
b) Basin and Ranges _________ (mountain type) ________ (cause)
c) Cascades ____________(mountain type) ___________(cause) |
a) reverse fault mounts; compression
b) fault block mountains; horst/graben (tension)
c) Volcanic; hotspot or subduction |
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The name given to a bend in the rock layers? |
Fold |
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A mountain must be at least how many feet above the surround land? |
1000ft |
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a) The direction that the rock layers are tilted?
b) The angle the rock layers are tilted? |
a) strike
b) dip |
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Why are geologists so interested in anticlines and synclines? |
Oil and Gas |
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The most famous right laterial strike slip fault in California is the? |
San Andreas Fault |
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Shaking of the ground |
Earthquake (caused by compressional forces) |
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Water saturated sands, slays or artificial fill suddenly turn to a liquid upon shaking. |
Liquefaction.
During liquifaction you may see a lateral spreading of the ground leaving cracks or fissures. |
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Seismic sea waves |
Tsunami
Generated by the vertical displacement of a fault on the sea floor |
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_____________ is a number that characterizes the relative size of an earthquake. (recorded by a seismograph) |
Magnitude |
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___________ tries to explain EQ precursors. |
Dilatency Model |
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Earthquakes are caused by a sudden release of __________ that has been stored in the rocks. |
energy |
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The name given to the point of rupture?
The point on the Earth's surface directly above this? |
focus
Epicenter |
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Body Seismic Waves
Primary Waves (P Waves) type? meaning? State they travel through?
Secondary Waves (S Waves) type? meaning? State they travel through? |
Primary Waves congressional; back and forth; solid, liquid, gas
Secondary Waves transverse; up and down; solids |
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Surface Seismic Waves
Love Waves type of motion?
Rayleigh Waves type of motion? |
Love Waves side to side
Rayleigh Waves rolling up and down |
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What theory states that EQ's are caused by sudden release of stored energy? |
Elastic Rebound Theory |
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The first EQ detection device was created by? |
The Chinese |
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Today, EQ are measured with a ______________ that amplifies the wave motion electronically and the directly feeds the information to the USGS. |
Seismometer |
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Which EQ measuring scale is used today by most geologists? |
Moment Magnitude Scale |
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Which EQ measuring device is not very scientific? |
Modified Mercalli Scale
Measures the intensity effect on people of the quake. |
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The public is most familiar with what logarithmic scale for measuring earthquake magnitude known as the _______________? |
Richter Scale |
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Magnitude is really a measure of the amount of? |
energy released by an EQ |
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A magnitude 8 EQ is how many times more powerful than a magnitude 4? |
10000 |
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The EQ scale that measures the size of the focus and the distance the fault moved? |
Moment Magnitude Scale |
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What is the least number of receiving stations needed to triangulate an EQ? |
3 |
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Where on Earth do you expect to find most EQ's? |
Around the Pacific |
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One useful thing about EQ's is the find the boundaries of the Earth's _______ ____________? |
Plate Boundaries |
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The best long term predictor for an EQ is looking at? |
Dilitancy |
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Short term indicators that show an EQ is likely to occur? |
1. Rocks undergo a change in volume 2. change in the arrival time of p-waves 3. increase in gas emissions 4. electrical resistance decreases in the rock 5. animal behavior changes |
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Most EQ are classified as? |
Shallow (most destructive) |
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Deep EQ happen where on the Earth's surface? |
Subduction Zones |
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The greatest % of EQ in the Central US are caused by? |
Failed rift or old continental plate boundary |
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The name given to slow, continuous movement along a fault?
Does it prevent or cause an EQ? |
Fault Creep
Prevent |
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Which scale is NOT accurate for BIG EQ over long distances? |
Richter Scale |
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Which seismic wave produces noise during an EQ? |
Primary Waves |
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List 3 factors that affect ground shaking? |
1. Magnitude
2. Distance from the Epicenter
3. type of rock |
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What EQ were these?
a) Failed rift or old continental plate boundary. b) C->O convergent plate boundary; pacific subduction under NA Plate c) Transform boundary between pacific and NA Plate. d) blind thrust fault; associated with SA Fault e) Nazca Plate subduction under SA Plate f) Fault break where Indian-Aus plate g) Transform PB |
a) New Madrid b) Alaskan c) San Francisco d) Northridge e) Chile f) Sumatra g) Loma Prieta |
