Term
|
Definition
-meteorite impats
-one killed the dinosaurs
-generate heat and impact |
|
|
Term
|
Definition
-hot magma chamber
-high temperature
-low pressure |
|
|
Term
|
Definition
-rocks slide across each other
-cold rocks-fault breccia (broken)
-hot rocks- flow to make mylonite |
|
|
Term
| Hydrothermal Metamorphism |
|
Definition
|
|
Term
|
Definition
-continent-continent collision
-cold near surface, hot deeper down
-low temp/low pressure
-high temp/high pressure |
|
|
Term
| Subduction Zone Metamorphism |
|
Definition
-low temp/high pressure
-slab is cold, takes a while to heat up |
|
|
Term
|
Definition
| -sedimentary rocks deposited younger over older |
|
|
Term
| Law of Original Horizonality |
|
Definition
| sediments deposited in horizontal beds |
|
|
Term
| Law of Cross-Cutting Relations |
|
Definition
-younger features transect older ones
-light-colored granitic dike cuts older, banded metamorphic rock |
|
|
Term
Inclusions
(Relative Age Dating) |
|
Definition
-Older material encolosed within younger
igneous, sedimentary, or metamorphic |
|
|
Term
Angular Uncomformities
Uncomformities
(Relative Age Dating) |
|
Definition
| -sedimentary rock over tilted/folded/eroded strata (sedimentary rock) |
|
|
Term
Disconformity
Uncomformities
(Relative Age Dating) |
|
Definition
| -sedimentary rock over emergence and erosion (sedimentary rock) |
|
|
Term
Noncomformity
Uncomformities
(Relative Age Dating) |
|
Definition
| -sedimentary rock over eroded igneous rock (had intruded sedimentary rock) |
|
|
Term
|
Definition
-gives definate interval of geologic time
-fossils appear in geologic record in a definite order
-based on succession of fossils found in vertical sequences of sedimentary rocks |
|
|
Term
Dendrochronology
(Tree-Ring dating)
Absolute dates |
|
Definition
| measurement of annual ring widths at tree heights |
|
|
Term
|
Definition
-different number of neutrons
-frequently used in radiometric dating |
|
|
Term
Alpha Decay
(Radioactive Decay) |
|
Definition
-alpha particle emission
-lower atomic number and atomic mass
-lose an atom |
|
|
Term
Beta decay
(Radioactive Decay) |
|
Definition
-beta (electron) emission
-higher atomic number
-same atomic mass
-neutron transforms into electron |
|
|
Term
Electron Capture
(Radioactive Decay) |
|
Definition
-electron capture
-lower atomic number
-same atomic mass
-electron into neutron |
|
|
Term
|
Definition
| constant rate-> half-life |
|
|
Term
Radiometric Dating of Rocks
conditions |
|
Definition
-CLOSED SYSTEM (no parent or daughter leaves the rock)
-different teperatures |
|
|
Term
Igneous
Radiometric Date Meaning |
|
Definition
| -time since crystallization from magma |
|
|
Term
Metamorphic
Radiometric Date Meaning |
|
Definition
| time since metamorphism or recrystallization |
|
|
Term
Sedimentary
Radiomentry Date Meaning |
|
Definition
not closed (water in it)
age of clasts |
|
|
Term
| Marine Magnetic Anomalies |
|
Definition
-magenetic reversals of seafloor spreading
-calibrated by radiometrically dated lavas on land |
|
|
Term
|
Definition
-oldest rocks
-4030 million years old |
|
|
Term
|
Definition
-3.8 to 2.5 million years ago
-reducing atmosphere-little oxygen,
-toxic to most current life
-continental plates began to form
-stromatolites abundant |
|
|
Term
| Hamelin pool stromatolites |
|
Definition
-oldest organisms on earth
-fossils 3.5 billion years ago
-formed by single-cell organism: cyanobacteria |
|
|
Term
|
Definition
-2.5-1.8 billion years ago
-oxygen (waste product of plants) banded with abundant dissolved iron to yield minerals like magnetite and hematite
-amount of oxygen locked up in banded iron beds-20x volume of oxygen in atmosphere today
-important source of iron ore |
|
|
Term
|
Definition
-2.5 billion to 543 million years ago
-stable continents appear and acrete
-first abundant fossils of living organisms (bacteria and archaenas) |
|
|
Term
| Prokaryotes vs. eukaryotes |
|
Definition
-pro-dna organized in single chromosome, no nucleus, no mitosis
-euk-dna organized in multiple chromosomes inside a nucleus, mitotic division |
|
|
Term
|
Definition
-late proterozoic era fossil
-found on underside of course sandstone/mudstone- suggests a rapid burial
-worldwide presence
-not found after onslought of mineralized organisms in Cambrian period |
|
|
Term
|
Definition
-time when Earth must have been covered by a sheet of ice
-rapid greenhouse warming from carbon dioxide took Earth out of icy tomb
-repeated cycle
-abundant co2 held in limestones
-led to proliferation of animals |
|
|
Term
|
Definition
| Age of Invertebrates, Fish, Amphibians |
|
|
Term
|
Definition
|
|
Term
|
Definition
| Age of Mammals, humans develop |
|
|
Term
|
Definition
-general term for changes in volume or shape of rock masses in response to applied forces
-caused mainly by gravity |
|
|
Term
|
Definition
-CAUSE of deformation
-force applied to volumes of rock |
|
|
Term
|
Definition
| EFFECT of deformation resulting from applied stresses |
|
|
Term
|
Definition
-same in all directions
-simply pressure |
|
|
Term
|
Definition
|
|
Term
Hydrostatic Stress
(type of Uniform Stress) |
|
Definition
| like on the bottom of a swimming pool |
|
|
Term
Lithostatic stress
(type of Uniform STress) |
|
Definition
| "felt" by rocks deep in the earth from overburden and surrounding rocks |
|
|
Term
Normal Stress
(type of Differential Stress) |
|
Definition
| directed perpendicular to surfaces |
|
|
Term
Shear Stress
(type of Differential Stress) |
|
Definition
| directed parallel to surfaces, causing sliding |
|
|
Term
Compressional Stress
(type of Differential Stress) |
|
Definition
| directed inward, leads to shortening of rock |
|
|
Term
Tensional Stress
(type of Differential Stress |
|
Definition
| directed outward and can lead to stretching of rock |
|
|
Term
| types of changes from STRAIN |
|
Definition
-length changes
-volume changes
-angular changes: between lines; surfaces sliding past one another |
|
|
Term
|
Definition
-resistance to deformation
-function of pressure and depth- the deeper in the Earth, the stronger the rocks |
|
|
Term
|
Definition
| completely and instantly recoverable |
|
|
Term
|
Definition
-creates sharp discontinuities
-when rocks pushed beyond elastic limit
(ie earthquakes) |
|
|
Term
| Ductile (Plastic) Deformation |
|
Definition
-continuous deformation
-begins at critical strength:YIELD STRENGTH
-strength of ductile material governed by composition, temp, rate of deformation
-strength lower for greater T or lower strain |
|
|
Term
|
Definition
-where deformations take place on Earth
-marked by earthquakes and surface deformation
-plate boundaries: ridges, subduction zones, and transfrom faults where plates pull apart, converge and slide past another can result in extreme thinning or thickening of the crust |
|
|
Term
Strike
to define a plane in space
-to describe faults and folds |
|
Definition
| compass direction in horizontal plane |
|
|
Term
Dip
to define a plane in space
-to describe faults and folds |
|
Definition
-inclination of plane normal to strike
in the vertical plane
-max inclination of the plane |
|
|
Term
Joints
(example of Crustal Deformation) |
|
Definition
-cracks/fractures in rock with little/no visible displacement
-common-exploited by weathering
-commonly in parallel arrays or networks
-(alligned squares) |
|
|
Term
Faults
(example of Crustal Deformation) |
|
Definition
-fractures with obvious displacement
-common-shallow crustal deformation
-classified according to direction of displacement (and strain)
-(shifted/displaced squares) |
|
|
Term
Divergence
(example of Crustal Deformation) |
|
Definition
-vertical compression from gravity
results in horizontal extension
-example of divergent boundary-oceanic ridges
-oceanic crust made at the ridge
-lithosphere thickens and subsides as it cools |
|
|
Term
| What happens with a normal fault? |
|
Definition
-before- nice horizontal layers
-small offset- hanging wall drops down relative to footwall
-large offset- active fault, hanging wall sliding downwards
-erosion- fault line scarp |
|
|
Term
Convergence
(example of Crustal Deformation) |
|
Definition
-horizontal compression
-results in horizontal shortening
-examples:
-Thurst Fault: hanging wall moves UP relative to foot wall
-older rocks move over younger rocks |
|
|
Term
|
Definition
| collision of India and Asia |
|
|
Term
| Surface features along a strike-slip fault |
|
Definition
-rocks move past each other horizontally
-stand on one side of fault surface, see where the other side moves to determine which type of lateral strike-slip fault it is
-drainage offets
-linear valley along fault
-active and inactive fault traces |
|
|
Term
Folds
(example of Crustal Deformation) |
|
Definition
-tilted and bent rock layers
-caused by layer-parallel shortening
-common-deeper level crustal deformation
-classified by shape/geometry |
|
|
Term
|
Definition
| 2 sandstones incline away from each other |
|
|
Term
|
Definition
-2 sandstones folding the same direction together
-big "U" shape |
|
|
Term
|
Definition
-N-S and E-W folding
-circular area where strata pushed up relative to what's around it
-hot targets for oil/gas
-exposed by erosion- younger rocks on outside, bottom |
|
|
Term
|
Definition
-N-S and E-W folding
-rocks in center pushed down relative to what's around them
-Older rocks on the outside, top |
|
|
Term
|
Definition
-weak ones from volcanoes
-strong- motion along faults, disconnect between rocks on either side of the fault, motions occur and release energy |
|
|
Term
Elastic Rebound Theory
(Earthquakes) |
|
Definition
-Earthquake- elastic rebound of previously stored elastic strain energy in the rocks on either side of the fault
-energy released is based on how much slick there is, how much rocks aredeformed, over how much area the fault moved |
|
|
Term
p-waves
(generated by earthquake)
(body wave-travel through earth) |
|
Definition
-compressional waves
-horizontal pressure
-~6km/s FASTER than S waves
-SLOWER in liquids than in solids |
|
|
Term
s-waves
(generated by earthquake)
(body wave-travel through earth) |
|
Definition
-shear waves
-diagonal pressure
-3.5 km/s
-slower than P waves
-can ONLY travel through solid |
|
|
Term
Raleigh waves
(generated by earthquake)
(surface wave) |
|
Definition
|
|
Term
love waves
(generated by earthquake)
(surface wave) |
|
Definition
|
|
Term
|
Definition
-P-waves arrive first (travel faster)
-then S-waves
-then surface waves |
|
|
Term
|
Definition
-3 seismic stations
-triangulation |
|
|
Term
|
Definition
-meaure of the degree of earthquake shaking at a given locale
-based on the amount of damage
-scale: I-XII |
|
|
Term
|
Definition
-Estimates the amount of energy released at the source of the earthquake
-large eq: 9
-based on amplitude of the largest seismic wave recorded (p or s)
-RMS of 2 is 10 times greater than RMS of 1 |
|
|
Term
|
Definition
-log(amplitude) + (distance correction)
distance correction is time difference between P and S wave arrival |
|
|
Term
First Motion of an earthquake
versus an atomic bomb |
|
Definition
-distinct quadrants of push or pull
versus all regions experiencing an initial push away from epicenter |
|
|
Term
| large earthquakes to fewer occur on... |
|
Definition
-subduction zones (Alaska, Japan)
-collision zones (Himalayas by India/Asia)
-(both on convergent plate boundaries)
-strike-slip plate boundaries on land (SF)
-divergent plate boundaries (East African Rift) |
|
|
Term
| the most subduction occurs in |
|
Definition
|
|
Term
|
Definition
-from EQ shaking
-caused large slope failure
-cracks develop in crust |
|
|
Term
|
Definition
-Earthquake waves in the sea
-low amplitude (increases rapidly as seafloor shallows and speed and wavelength decrease)
-long wavelength |
|
|
Term
Earthquake prediction
short-term (hours, days, weeks) |
|
Definition
-based on precursor changes
-uplift/subsidence of land surface
periods of renewed/reduced minor seismicity
-changes in gasses emitted from wells
-abnormal animal behavior |
|
|
Term
| long term earthquake prediction (years, decades, centuries) |
|
Definition
-based on probabilities
-risk assessment maps based on historical data
-seismic "gaps" :buildup of strain along plate boundary |
|
|
Term
Seismology
(geophysics-indirect investigations) |
|
Definition
tells:
-earthquake: location, strength, physical properties, movements
-seismic refraction
-seismic reflection |
|
|
Term
magnetism
(geophysics-indirect investigations) |
|
Definition
-tells core dynamics, paleomagnetics (plate motions, reversals, etc)
-mass flow |
|
|
Term
heat flow
(geophysics-indirect investigations) |
|
Definition
| tells convection/conduction, lithosphere thickness |
|
|
Term
gravity
(geophysics-indirect investigations) |
|
Definition
| density distributions near surface |
|
|
Term
seismic refraction
Seismology
(geophysics-indirect investigations) |
|
Definition
| velocity, physical properties, layer thinknesses |
|
|
Term
seismic reflection
Seismology
(geophysics-indirect investigations) |
|
Definition
-internal gemoetry
-waves bouncing off earth
-mapping the subsurface (under ocean or inside the earth) |
|
|
Term
Seismic Tomography
Seismology
(geophysics-indirect investigations) |
|
Definition
|
|
Term
| velocity of compressional waves (p-waves) |
|
Definition
| higher velocity in higher density |
|
|
Term
|
Definition
-bending-path bends away from normal to interface with increasing density (and velocity)
-travel more where you can travel quickly so biggest angle in highest density
increase velocity with increase depth- waves move faster inside Earth |
|
|
Term
| liquid outer core proved by: |
|
Definition
-P and S wave shadow zone
-P waves refracted off liquid and placed constraints on radius of liquid core
-S waves ended at liquid |
|
|
Term
|
Definition
| seperation between liquid outer core and and solid inner core |
|
|
Term
|
Definition
-seismic discontinuity of increasing P wave velocity with depth
-boundary between crust and uppermost mantle (within lithosphere) |
|
|
Term
|
Definition
-thin (5-7 km)
-dense (basaltic)
-mostly young (<200 my old) |
|
|
Term
|
Definition
-thick (20-70 km)
-less dense (granitic)
-mostly very old (<4500 my old) |
|
|
Term
|
Definition
-thermal boundary layer
-includes crust and part of upper mantle
-thickness depends on temp (thin where hot and young) |
|
|
Term
|
Definition
-hot, weak part of upper mantle
-solid, but weak relative to lithosphere
-NOT molten, may have melt in it |
|
|
Term
|
Definition
-strong lower part of mantle
-solid like lithosphere
-650-2800 depth |
|
|
Term
|
Definition
-without any transfer of mass
from radioactive decay in Earth's interior (near surface in granitic material)
-higher in young, thin lithosphere and areas of active magmatism |
|
|
Term
|
Definition
-heat because movement of mass/water
-movement of magma from mantle to surface
-seafloor spreading (formation/recycling of plates)
hydrothermal circulation (black smoker, geysers, etc.) |
|
|
Term
| important mechanism of cooling the Earth |
|
Definition
| generation of new oceanic lithosphere and recycling by plate tectonics- large scale convection of the planet |
|
|
Term
| conductive cooling of lithosphere causes |
|
Definition
-lithosphere-asthenosphere boundary move down at rate proportional to:
1/(age of lithosphere)^2 |
|
|
Term
|
Definition
| function of matter and motion in the Earth's magnetic outer core |
|
|
Term
|
Definition
| show age of strips of oceanic crust worldwide |
|
|
Term
|
Definition
G(m1 x m2)/r^2
-m1=measuring device
-m2=mass between device and center of Earth |
|
|
Term
|
Definition
-negative=mass deficiency
-positive=mass excess
-show how actual gravity field differs from gravity of uniform/featureless Earth |
|
|
Term
|
Definition
| -determine bathymetry based upon slight changes in elevation of sea surface from greater gravitational attraction of large rock masses on sea floor (volcanoes) |
|
|
Term
| to learn topography of seafloor |
|
Definition
-echo-sounding
-swath mapping
-satellite altimetry |
|
|
Term
| to learn geology of ocean floor |
|
Definition
-side-scan sonar (reflectivity of sound signal)
-ROVs (remotely operated vehicles)
-Alvin (submersible)
-Ocean drilling program |
|
|
Term
| Passive continental margin |
|
Definition
-margin (where continental crust transitions into oceanic crust) created by spreading at mid-ocean ridge
-WEST coast of South America |
|
|
Term
| Active continental margin |
|
Definition
-margin (where continental crust transitions into oceanic crust) adjacent to a subduction zone (or strike-slip boundary)
-contains oceanic trench
-EAST coast of US |
|
|
Term
Continental shelf
on Passive continental margin |
|
Definition
-submerged extension of CONTINENT
-nearly horizontal
-thick
-(during Ice Age, was exposed) |
|
|
Term
continental slope
on Passive continental margin |
|
Definition
-seaward edge shelf
-steeper
-boundary between continental/oceanic crust |
|
|
Term
continental rise
on Passive continental margin |
|
Definition
-more gradual slope
-very wide (merges into abyssal plain)
-thick with sediments from continental slope
-turbidity currents make deep sea fans |
|
|
Term
|
Definition
-deep ocean trenches
-~11 km below sea level |
|
|
Term
terrigenous
on ocean basin floor |
|
Definition
| -derived from land-mineral grains from continental rocks |
|
|
Term
biogenic
on ocean basin floor |
|
Definition
| derived from organisms- marine animal shells, organisms |
|
|
Term
precipitates
on ocean basin floor |
|
Definition
| derived from water- minerals crystallize out of water |
|
|
Term
|
Definition
| may occupy as much as 1/3 of ocean basin |
|
|
Term
|
Definition
| long-lived, large volcanic features that are randomly distributed through the ocean basins (and on land) |
|
|
Term
|
Definition
-smaller volcanoes that erupt commonly near the ridge axis
-generally, do not rise to sea surface |
|
|
Term
|
Definition
| marine structures composed mainly of coral (some live but mostly dead skeleton) and some algae and sediment |
|
|
Term
|
Definition
-colonies of coral generally near the shore
-require warm temperature, clear sunlit water, and nutrients from ocean water |
|
|
Term
|
Definition
-circular coral structure with an interior lagoon
-can be >1000 m thick |
|
|
Term
|
Definition
-area of high elevation
-belt of HIGHLY DEFORMED rocks resulting from contractional thickening and uplift of the crust
-thickening and uplift expose deep level metamorphic and igneous rocks |
|
|
Term
Andean type
of Orogenic/Mountain Belt |
|
Definition
-magmatic arcs above subduction zones
-accreted terrains "smeared" onto them during subduction
-Foreland basins of sedimentary rocks |
|
|
Term
Collisional Type
of Orogenic/Mountain Belt |
|
Definition
collided continental margins-at least one was a subduction zone (possibly both)
suture zone marks seam where 2 continents welded together
remnants of Andean type typically found |
|
|
Term
|
Definition
collage of old continental fragments and orogenic belts
old "cratons" are rifted and surrounded by somewhat younger orogenic belts |
|
|
Term
Wilson Cycle
Major Earth Process |
|
Definition
oceans open and close
-rifting and continental margin development
-seafloor spreading
-subduction
-collision
-continued convergence
-new cycle... |
|
|
Term
|
Definition
horizontal stretching, crust/lithosphere thinning, subsidence, sedimentation (burial)
*good sedimentary record, but deep rocks not exposed |
|
|
Term
|
Definition
horizontal shortening, uplift, crust/lithosphere thickening, erosion (exhumation)
*sedimentary record deposite far away, surface material removed and deep level rocks exposed |
|
|
Term
|
Definition
rifted continental margin
once a rift and spreading center, not a plane interior |
|
|
Term
|
Definition
| marks the site of a former oceanic tract |
|
|
