Misc. Non-Quiz Content Flashcards
Lithification
Transforms loose sediment into solid rock
Processes that lithification includes:
Burial: more sediment added to previous layer
Compaction: overburden weight reduces pore space
Cement: minerals from groundwater “glue” sediment together. Common cements include calcite, silica, and iron oxide
Orange/red sedimentary rock indicates that
Iron oxide is present
Biochemical/carbonate rocks
Sedimentary rocks that come from living organisms
Limestone deposition environment
“Think of the Bahamas”: warm (tropical/subtropical), normal-salinity marine water, wave-agitated, lots of oxygen, shallow and clear water
Organic rocks
Rocks made from organic carbon (like coal, the altered remains of fossil vegetation, and oil shale, shale with heat-altered organic matter)
Accumulates in lush, tropical wetland settings (ancient swamps)
Requires deposition in the absence of oxygen
Chemical/evaporative sedimentary rocks
Come from minerals precipitated from water solution
What are evaporites?
Sedimentary rocks created from evaporated seawater – evaporation triggers the deposition of chemical precipitates.
Examples: halite and gypsum
Depositional environments
Locations where sediment accumulates. They differ in energy regime, sediment delivery/transport/depositional conditions, and chemical/physical/biological characteristics
Terrestrial depositional environments (deposited above sea level)
River: channelized flow transports sediment. Sand and gravel fill concave-up channels, and fine sand, silt, and clay is deposited on flood plains
Sand dune: wind-blown piles of well-sorted sand, with dunes moving according to prevailing winds. Results in uniform sandstones with gigantic cross-beds (looks like layers in different directions)
Lakes: gravels and sands are trapped near shore, and well-sorted muds are deposited in deeper water. These sediments are preserved as finely-laminated shales which may contain fish fossils and may fill in with wetland muds
Marine depositional environments (deposited at/below sea level)
Deltas: sediments dropped where an ocean meets the sea. Sediment carried by the river is dumped when velocity drops, and deltas grow over time, building out into the basin.
Shallow water carbonates: tropical, contain skeletons of marine invertibrates, and has warm, shallow, clear, normal-salinity water.
Deep marine: skeletons of planktonic organisms make chalk or chert. Fine silts and clays turn into shale.
Strata
A series of beds
Formation
A sequence of strata that is sufficiently unique to be recognized on a regional scale
Graded beds
Bedding layers that fine(?) upward. Happen from repeated pulses of high-energy sediment transport, with sediment added as a pulse of turbid water. As the pulse wanes, the water loses velocity and the sediments settle, coursest to finest.
Turbidites
Multiple graded-bed sequences
Bed surface markings and what they may indicate
Mudcracks: alternating wet/dry conditions and necessitate deposition in a terrestrial setting
Scour marks: troughs eroded in soft mud by current flow
Fossils: evidence of past life
Regression
Retreat of seas due to sea level dropping. It’s tied to erosion and makes sediments less likely to be preserved.
Note that the sea level rises and falls in a predictable pattern
Compressive strength (in context of material strength)
Force a stone can withstand without rupturing
Characteristics to consider in building stone
Compressive strength, porosity, density, and abrasive resistance
Where does the water for hydrothermal metamorphism come from?
Magmas (“juvenile” fluids), seawater (important at oceanic ridges and subduction zones), “devolatilization” reactions (at subduction zones or during regional metamorphism; H2O and CO2 are products) surface and groundwater (“meteoric” fluids), and formation pore fluids (“connate” fluids, in pores or trapped in crystals)
What types of rocks are the ore minerals deposited at Yellowstone?
Sedimentary. The hydrothermal fluids carrying the metallic minerals came from igneous rocks, but they deposited the minerals within sedimentary rock.
List of fossil fuels
Coal, oil/petroleum, natural gas, and other nontraditional fossil fuels (oil shale, oil/tar sands, shale gas, methane hydrate)
Oil/petroleum
Liquid hydrocarbons that are present in certain layers of sedimentary rock (the geosphere)
Some petroleum products include:
Kerosene, lubricants, waxes, asphault, and chemicals
Natural gas
Major component is methane; also includes methane, propane, and butane
Process of oil/gas production (13 steps)
- Planktonic organisms live in oceans/lakes
- Zooplankton eat phytoplankton (algae) that use the sun’s energy to produce organic matter and energy through photosynthesis
- Planktonic organisms die, their remains settle to the bottom of the seafloor with anoxic conditions
- Sediments accumulate over time, containing the remains of planktonic organisms
- Thick sequences of sediments are deposited and the planktonic organisms buried in them are heated and compressed until the organic matter begins to change into kerogen
- High temperature and pressures from greater depth of burial changes the kerogen to hydrocarbons
- More heat and pressure breaks the hydrocarbons down into oil/petroleum and natural gas
- Petroleum and natural gas migrate into porous and permeable sedimentary rocks like sandstone, serving as a petroleum reservoir rock
- Oil floats on water, with gas being even lighter, so the petroleum and natural gas move up within the reservoir rock until stopped y an impermeable sedimentary layer like shale, which forms a trap
- An oil field is formed as more petroleum and natural gas accumulate in the trap
- Geologists use tools to locate oil fields
- Wells are drilled into the ground in the oil field to extract the petroleum (crude oil)
- The crude oil is transported to a refinery into gasoline, butane, kerosene, liquid petroleum gas, jet fuel, diesel fuel, fuel oil, chemicals used to manufacture plastics, et cetera
Kerogen
A solid, waxy organic material
Source rock
The unit where oil and gas formed
Tar sands
Form when oil is moving upward within a reservoir of porous, permeable sand and is not sopped by an impermeable sedimentary layer
Bitumen
Highly viscous asphalt/tar that’s formed when oil escapes the sand at the surface and is biodegraded by an “oil-eating bacteria”
Oil shale
Sedimentary rock containing kerogen that hasn’t been heated enough within the Earth to change the kerogen into hydrocarbons
Shale gas
Forms in organic-rich black shales where extremely deep burial and extremely high temperatures have broken petroleum down into natural gas/methane
Primary cause of recent increase in earthquakes in central US
Wastewater disposal (NOT fracking itself).
Fracking
Creates artificial fractures to extract the oil/methane gas from low-permeability shales. Wells are drilled to thousands of feet deep and then drilled horizontally along the shale bed. Then, high-pressure fluids and sands are injected to hydraulically fracture the shale and release the trapped resources.
One of the largest sources of CO2 is (broad-scale)
Burning fossil fuels
Coalification
Water is expelled as peat is compacted, then plant material breaks down and releases natural gas (mostly methane)
Byproducts of coal burning
Carbon dioxide, sulfur dioxide (causes acid rain), nitrogen oxide (causes smog), carbon monoxide (poisonous gas that contributes to global warming), and small particles of toxic heavy metals (like mercury), and more
Sequestration
Capturing carbon emissions from burning coal and strong under the earth
Highest and lowest CO2 emissions per million BTU of energy
Highest: lignite
Lowest: natural gas
Soil
Rock and sediment that has been modified by
physical and chemical interaction with organic material and rainwater, over time, to produce a substrate that can support the growth of plants
Pedogenesis
Soil formation
The five factors that interact to produce soils of all descriptions
Climate, organisms, topography (relief), parent material, time
Zone of leaching
Upper soil profile. Ions from chemical weathering, fine silts and clays infiltrate
Zone of accumulation
Lower soil profile; ions form new minerals and silts and clays clog pore spaces
Horizons
Well-developed soils have layers called horizons
Soil orders and how many there are
Groups of soils that are based on soil mineral composition and the environment of formation. There are 12.
Main soil order of [our location]
Inceptisol
Inceptisol
Immature soil with a few diagnostic features and weak horizon developent. Often occurs in steep, mountainous regions or on floodplains with recent sediment deposits
Alfisol
Fertile with clay accumulations in the subsoil. Often formed under deciduous forest
Type of deformation depends on
Temperature, pressure, deformation/strain rate, and composition
Types of deformation
Elastic, ductile/plastic, brittle/rupture/fracture
Strain
When stress causes an irreversible change in the shape and size of a rock body
Axial plane
The plane of mirror symmetry dividing a fold
Axis
The line formed by the intersection of the axial plane and a bedding plane
Horizontal fold
Fold where the axis is horizontal
Plunging fold
Fold where the axis is not horizontal
Anticline’s bends in the middle
Are the oldest (on the flat later)
Syncline’s bends in the middle
Are the youngest
Two types of dip-slip faults
Normal and reverse/thrust
Difference between thrust and reverse faults
Thrust faults are low angle (less than 45 degrees)
What determines landscape development/failure in relation to mass wasting?
Eroding/transporting agent: water, ice, wind
Relief: determines velocity
Climate: determines precipitation
Substrate composition: responsiveness to erosion
Life: some can weaken, some will strengthen
Time: landscapes evolve over time
Force vs stress
Stress is the amount of FORCE acting over a specific area
Shear stress
The sum of all the driving forces (gravity, etc)
Normal stress
Only a part of the resisting forces (like friction). This is because the amount of normal stress also depends on the material’s shear strength
Cohesion
How well a material sticks together
Angle of repose
The maximum angle possible between a noncohesive material and a horizontal plane. Larger and more angular grains tend to have a steeper angle of repose than small, fine grains
Effects of water (regarding slopes of sediment)
+ Surface tension can increase strength
- Water adds weight
- Water can act as a lubricant and reduce friction
- Water can freeze and thaw, weakening and fracturing the rock
- Clays absorb water and expand, which destabilizes the slope
When does mass wasting occur?
Driving forces > resisting forces, as oppose to the two being equal at the angle of repose
Triggers to slope failure
Earthquakes, slope load, steepness, support (undercutting can weaken), and changing slope strength
Additionally: weathering weakens, vegetation cover protects (slow removal of excess water included)
Creep
Slow downhill movement often due to seasonal soil expansion and contraction
Slumping
Sliding of coherent blocks/units, often occur in soil, and are common along seacoasts and river cuttings
Mudflows
Slurry of water and fine sediment that can flow great distances. Common in tropical setting with lots of rain
Debris flow
Mudflow with many large rocks
Landslide
Sudden movement downslope
Rock/debris falls
Vertical freefall of mass that occurs on very steep slopes and cliffs
Prevention techniques for landslides/mass wasting
Revegetation, terracing, regrading (changing the slope to position below the angle of repose), drainage (can reduce weight and increase strength of materials), undercutting material (increases stability), engineered structures
Geologic time scale, in decreasing groupings
Eon, Era, period, epoch
Hadeon
4.6 to 3.8 Ga
Internal differentiation, formation of oceans and secondary atmosphere
Archean
3.8 to 2.5 Ga
Birth of continents and lithosphere. Appearence of earliest lifeforms
Proterozoic
2.5 to 0.542 Ga
Development of tectonic plates
Buildup of O2 and appearance of multicellular life. Ozone layer developed
Phanerozoic
542 Ma to now
First appearance of hard shells and rapidly-diversified life
3 eras of the Phanerozoic
Paleozoic (ancient)
Mesozoic (middle)
Cenozoic (recent)
Transgression and regression
Rising and falling sea levels
Martian surface age groups
Noachian: large and small craters present, geologically old
Hesperia: mostly small craters present, geologically medium
Amazonis: very few craters present, geologically young
Ways to destroy minerals
Melting, chemical reactions, dissolving
Plate boundary present at Iceland
Divergent plate boundary
