Sedimentology and Stratigraphy
Terms
undefined, object
copy deck
- What is meant by the term "size" in relation to to sediments?
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not uniquely defined, depends on measurement, sieve diameter, sedimentation diameter
Sedimentary textures - What is textural maturity? What processes produce textural maturity?
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degree to which it approaches end result, removal of clays, good sorting, roundness of grains
Sedimentary textures - Many sediments and sedimentary rocks show a preferred orientation of the particles. What are the causes and characteristics of tihs orientation in gravel, sands, and shales?
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elongate/flat particles, affects packing, imbrication, Qtz. high flow, mud-compaction
Sedimentary textures - Why are boundary values important?
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govern interaction of flow with sediment
Fluid Dynamics & sediment transport - What are the principal modes of sediment transport?
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traction, saltation
Fluid Dynamics & sediment transport - What processes operate to entertain sediement?
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.
Fluid Dynamics & sediment transport - What fluid properties are important in the entrainment of sediment?
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velocity and shear
Fluid Dynamics & sediment transport - What sediment properites are important in the entrainment of sediment?
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size and density
Fluid Dynamics & sediment transport - What are the modes in which sediment is transported?
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traction and saltation
Fluid Dynamics & sediment transport - How does a particle of sand become entrained and transported?
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no movement > random > moves some > all
Fluid Dynamics & sediment transport - How is the amount of sedimient moving as bedload of a river or beach calculated?
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it is the traction + saltation
Fluid Dynamics & sediment transport - How is the amount of sediment moving as suspended load calculated?
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it is impossible
Fluid Dynamics & sediment transport - Grading, is formed under what condition?
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turbidity currents
Sedimentary structures - Flute casts, is formed under what condition?
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erosion of mud by turbulent flow
Sedimentary structures - Ripple marks, under what conditions are they formed?
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.
Sedimentary structures - Tabular cross-bedding, under what conditions are they formed?
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migration of bed formed
Sedimentary structures - Trough cross-bedding, under what conditions are they formed?
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sinous/lunate dunes
Sedimentary structures - Parallel laminations, under what coniditions are they formed?
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.
Sedimentary structures - What in "flow regime"?
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interpretation of structures and sequence of structural, general strengh
Sedimentary structures - What can ripples tell you about the environment in which they were depostied?
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net accumulation
Sedimentary structures - What can dunes tell you about the environment in which they were deposited?
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High flow conditions
Sedimentary structures - What do "climbing ripples? indicate about the conditions in which they were deposited?
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high net accumulation
Sedimentary structures - What useful information do isopach maps provide?
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thickness, tectonic/during/erosion
Sedimentary methods - What useful information do structure contour maps provide?
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respects to datum, after deposition
Sedimentary methods - What useful information do cross sections provide?
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2 dimensional relationship emphasizes structure/stratigraphy
Sedimentary methods - What useful information do facies maps provide?
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description
Sedimentary methods - What useful information do fence diagrams provide?
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3d ...
Sedimentary methods - What is Walther's Laws?
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laterally adjacent, vertically succesion
Stratigraphic relationships - What is transgression/regression?
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sea level rise/fall
Stratigraphic relationships - How abundant are the gaps in the stratigraphic record?
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very
Stratigraphic relationships - What is a facies model?
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body of rock with specific characteristics - modern environments
Facies models - What are the componenets of a facies model?
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physical, biological, stratigraphic
Facies models - What are the sedimentologic and stratigraphic characteristics of meandering river deposits?
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least understood, channel ripples, point bar, fining upwards, migration, floods, low slope, vertical accretion
Facies models - What are the sedimentologic and stratigraphic characterics of aeolian dune deposits?
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cross bedding
Facies models - What are the sedimentologic and stratigraphic characterists of beach deposits?
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.
Facies models - What are the sedimentologic and stratigraphic characteristics of shallow marine deposits?
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.
Facies models - What are the sedimentologic and stratigraphic characteristics of submarine fan deposits?
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.
Facies Models - What is a lithostratigraphic unit?
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observable, lithic character/stratigraphic position
formation = widely recognizable characteristics
Nomenclature - What is a chronostratigraphic unit?
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time rock, serve as physical reference for all rock formed at sometime, ex. system (Cambrian)
Nomenclature - What is a geochronologic unit?
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division of time based in rock record, ex. Period = System
Nomenclature - What is a biozone?
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fundamental unit of biostratigraphy, taxon zone
Nomenclature - What is the Law of Superposition?
- oldest layer is one the bottom
- Describe three types of lithologic boundaries.
- lithic change, unconformities, key beds, vertical grdations
- How are geologic units correlated?
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physical
1) walk out
2) mapping lithologies
3) tracing unformities
Chronologic
1) biostratigraphy
2) time marker
Correlation - Define diachronism, and give an example.
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not the same age everywhere
Correlation - What methods are used for geophysical correlation?
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a) wireline logs
b) seismic methods
c) magnetostratigraphy
Correlation - How can the absolute ages of period boundaries be determind?
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.
Correlation - Which method has better resolution, radiometric dating or biostratigraphy?
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all the same
Correlation - What is eustacy?
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changes in sea level
Correlation - What are the probable causes of large-scale, long-term changes in sea level?
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major plate interactions
Correlation - Parasequence
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conformable succession bounded by marine flooding or correlative surfaces
Correlation - Parasequence set
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stacking of parasequence, bounded by flooding, genetically related, depends on rate of sediment accumulation
Correlation - Sequence
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genetically related, conformable, conformities, or correlative surfaces
Correlation - What is the fundamental principle of sequence stratigraphy?
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Super position. Use surface to subdivide ...
Correlation - What is an ophiolite sequence? What is its significance?
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produced on spreading ocean flow, deep sea sediment, pillow basalt, gabbros, ultra mafics
Tectonics/Sedimentation/Stratigraphy - What are the stratigraphic and structural characteristics of subduction zones?
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collision, deformation, folding/faulting, submarine fans deposition, gravity slide
Tectonics/Sedimentation/Stratigraphy - What are the stratigraphic and structural characteristics of aulacogens?
- failure of part of sea floor spreading, subsidence and accumulation
- What are the stratigraphic and structural characteristics of continetal margin arcs?
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subduction/modern reef building
deformation of shallwo marine...
abundant flysch sedimentation
plutonism
deformation back arc
molasse depostion in back - What is a sedimentary basin?
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significant localized accumulation of sediment, significant subsidence,
foreland - denver, mountain building
cratonic - williston, no connection with tectonics - What are two important weathering techniques?
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solution - dissolution evaporate
oxidation - reaction with oxygen, Fe/Su
Weathering/Clay - Which of the common rock-forming minerals are least stable in a weathering environment?
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gypsum/calcite...
quartz
hematite/goethite/zircon/rutile
Weathering/Clay - What characteristics appear to control the stability of minerals during weathering?
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how close the ...equilibrium, move structure..weak surfaces = less stable
Weathering/Clay - How are clay minerals classified?
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structure
two layer = bound tightly
three layer = expanding - SMETCTITE or
none expanding- ILLITE
Weathering/Clay - What are the basic structural components of clay minerals?
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tetrahedra
Weathering/Clay - What factors appear to control the type of clay minerals formed during weather?
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climate and weathering conditions, NOT SOURCE ROCK
Weather/Clay