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Clasts
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Grains
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Strata
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Several beds together
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Conglomerate
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Coarse-GrainedRounded grainsForms from sedimetn deposited in a fast-moving riverTraveled a short distance from it's sourceModerately to poorly sorted
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Water is Universal Solvent
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Cross-beds
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Cross-beds develop in wind-blown sediment(ex: barchan sand dunes). Sand grains saltate (bounce) along the stoss-face and then avalanche down the steep, lee face, where wind velocities are reduced.
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Shale
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Very-fined grained sedimantary rock that breaks into sheets.
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breccia
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largest detrital sedimentary rock made of sharp pieces
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Clastic Rocks
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Pieces glued togetherClassified based on TEXTURETexture = size, shape, sorting of CLASTSFine-grained (shale, siltstone)Medium-grained (sandstone)Coarse-grained (conglomerate, breccia)(This is different from texture in igneous rocks which is determined by the size of CRYSTALS, not clasts)
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Arkose
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Sedimentary rock made of sand-sized grains with quartz & feldspar
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Turbidity Current
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Moving submarine suspension of sediment.
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Chemical Sediments
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no mechanical breakdownform via reactions Rocks usually comprised of 1 major mineral type -acid rain, saltwater evaporation
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Hydrolysis
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Occurs when hydrogen ions replace positive ions in minerals
This alters the composition of the mineral by producing soluble substances and/or iron which can be oxidized
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Source Rock
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marine detrital sediments (like shale)
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boulder gravel sand dust
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examples of detrital rocks
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Sedimentary Structure
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Layering of sedimentary rocks, for surface features on layers formed during deposition, & for the arrangement of grains with layers.
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chemical Sedimentary rock
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Made of minerals from groundwater
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RecrystallizationOxidation
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unstable minerals can be altered into stable formsbreakdown of organic matter in presence of oxygen
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Petroleum
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a hydrocarbon in liquid or gaseous form.
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Clastic Sedimentary rock
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Cemented fragments & grains from preexisting rocks
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slope wetness
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Too little- particles can move past another easilytoo much-friction drop to point that material flowsjust right-moisture adds surface tension that stabilizes grains
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Sorting
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The degree to which the clasts in a rock are all the same size ot include a variety of sizes.
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What are the three kinds of sedimentary environments?
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Continental, Shoreline, Marine
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What is Chert used for?
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Chert, like obsidian and quartz, fractures conchoidally, which makes it an ideal material to construct arrowheads and axe blades
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What is a sedimentary rock?
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Sedimentary rocks are products of mechanical and chemical weathering
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Creep -Solifluction
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unconsolidated material slowly moves downhill (mm's/yr) -creep caused by repeated freeze/thaw action
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Why is limestone created primarily in warm, shallow water?
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Warm water typically holds less CO2 than cold water, which causes the solubility of calcite to decrease.
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Sandstone
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Chert
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angular
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negligible transport
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Limestone [fossiliferous]
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diatamacious earth
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kills ants
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clastic rock fragments
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breccia
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Quartz sandstone
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maturely weathered
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Biochemical
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cemented shells of organisms
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the smallest particle size
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clay
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Transitional
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-between Continental and Marine
includes: beaches and coasts, lagoons, reefs, mangrove swamps (deltas?)
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how lithification happens
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burial, compaction, cementation
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rivers
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channelized flow transports sediment; sand and gravel fill concave-upward channels; predictable energy
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microfossils make up
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chalk and chert
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calcite silica evaporites rock fragments feldspars
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compositions
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physical weathering
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rock break into fragments
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compaction
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a process that squeezes sediments
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limestone
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common sedimentary rock consisting mostly of calcium carbonate (calcite), CaCO3, used as a building stone and in the manufacture of lime, carbon dioxide, and cement.
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Geological Dating
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relative age and numerical ages
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fossiliferous limestone
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abundant fossils, reacts to acid
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clastic
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a sedimentary rock texture consisting of broken fragments of preexisting rock
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What is fine-grain?
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silt and clay (mud)
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Cementation
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takes place when dissolved minerals are deposited in the tiny spaces among the sediments.
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Chalk
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Organic form of limestone; microscopic shells (coccoliths); used on blackboards; often white in color; often scratched by fingernail
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coal
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black combustible rock consisting of over 50% carbon. coal is made of a detritus of plants deposited in layers. heat and pressure forced all the volatiles out, leaving a concentration of carbon. accumulates in lush tropical wetland settings. requires deposition in the absence of oxygen.
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Chemical maturity
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Lowest to greatest: olivine, pyroxene, amphibole, biotite, muscovite, feldspar, quartz
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dolostone
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carbonate rock made up predominately of the mineral dolomite, CaMg(C03)2
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Sedimentary rocks
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What is created when weathering products are redistributed?
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The term used to describe materials that are laid down directly by streams is
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alluvial
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fossil succession
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fossils remnants or traces of once-living organisms are often preserved in sedimentary rocks
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Intrusion
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Magma pushes into existing rock layers and cools formilng igneous rock. (Volcanoes)
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organic rock
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are made from once living things
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biochemical chert
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forms from sediment consisting of silica shells from dead organisms. plankton (microscopic organisms called radiolaria) make shells out of silica. this forms an ooze or gel on the deep ocean floor and solidifies to form a chert.
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coquina
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crumbled shells, looks like a rice crispy treat or oatmeal, bubles with acid
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Rock Salt
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chemical; composed of mineral halite; transparent to translucent
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Water Transportation
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o Saltation- particles bouncing (bed load) o Suspended load- keeps carrying on o Dissolved load o Quartz (sand), clay materials, ions
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Silt
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can't see but can feel the "grit"
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half-life
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time for 1/2 of unstable nuclei to decay
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poor sorted clast
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variety of grain sizes; changing amounts of energy
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Environment of deposition
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simply a geographic setting where sediment is accumulating.
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what is the ultimate end product of chemical weathering?
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soil
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Siltstone
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A sedimentary rock made from silt and clay sized particles in very slow moving water like lakes, swamps, deltas and offshore marines.
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clastic rock
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(geology) a rock composed of broken pieces of older rocks
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sedimentary rocks contain:
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coalpetroleum and natural gasFe, Al and Mg
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Which sedimentary feature can be used to determine the direction of sediment transport
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asymmetrical ripple marks
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Angular unconformity
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tilted or folded layers get eroded and new layers form on top.
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detridal sedimentary rock, p 214
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rocks forming from accumulated materials originating and transported as solid particles. The particles can come from mechanical weathering, or chemical weathering, or both.
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fissibility, p 216
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the property of splitting easily into layers along closely spaced, parallel surfaces, such as bedding planes in shale.
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principle of inclusion
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fragments included in a host rock are older then the host rock
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Three basic sedimentary rock types
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CLASTIC ROCK, CHEMICAL ROCK, ORGANIC ROCK
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Evaporates and biochemical rocks
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If ions in a solution is the weathering product, what type of sedimentary rock is formed?
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graded bed, p 237
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a layer of sediment that has larger particles on the top and smaller particles on the bottom. Graded beds change gradually in grain size from top to bottom.
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facies, p 235
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a section of a rock unit that has a unique set of characteristics distinguishing it from other parts of the same unit
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Non-foliated
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no cleavage
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Lignite
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soft brown coal
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clastic crystalline bioclastic
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textures
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Deltas
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coarsening upward deposits
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What are clasts?
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rock fragments
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Lithification
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Secondary Structures form during...
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Alfisol
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Gray/brown, has subsurface clay accumulation and abundant plant nutrients. Forms in humid forests (e.g. Eastern US)
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sediment
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unconsolidated particles created by the weathering and erosion of rock
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Through weathering, erosion, transport, and deposition sediment becomes what?
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sedimentary rock
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chert
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variety of silica containing microcrystalline quartz siliceous rock occurring as inclusions within limestone.
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formations
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Distinctive from neighboring rock units
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bioclastic
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(of deposits, esp. limestones) derived from shell fragments or similar organic remains
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uniformitatrianism
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present is key to the past
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eukaryotic
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WAY more complex, "truly nuclear", euro stands for nucleus!
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Graded Beds
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particles within single sedimentary layer gradually change from coarse at the bottom to fine at the top.
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Amorphous
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Lacking minerals or mineral grains (organic rocks)
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Detrital
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Consist of particles (sediment) broken off of preexisting rocks (conglomerate, breccia, sandstone, siltstone, shale)
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graded bedding
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particle size become progressively heavier and coaser toward bottom
in marine sedimentary rock
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What precent of seawater is SALT?
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3.5%
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Glaciers
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-Unsorted from ice: till
-Sorted from melt water: Outwash (like stream deposits)
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isotopes
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elements that have varing number of neutrons
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The most abundant type of sedimentary rock is
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Shale
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superposition
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in an undeformed sequence of layered rock; each bed is older than the one above and younger than the one below
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Detrial
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Rock formed from other broken down rocks
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Process of sedimentary rocks:
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Weathering, Erosion, Deposition, Sedimentation, Cementation
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coal and coquina
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are 2 organic sedimentary rocks
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petrified wood
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forms when ash containing silica dissolves in groundwater that passes into trees. the dissolved silica precipitates in wood as cryptocrystalline quartz. the chert will retain the shape of the wood and its growth rings
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oolitic limestone
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sand grain with a calcite coat/tropical sea
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Rain drop marks
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Primary structures may also include
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crystalline texture, p 228
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same as "nonclastic texture"
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horizontality and continuity
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strata often form laterally extensive horizontal sheets
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scour marks
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troughs eroded into soft mud by current flow
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Reservoir Rock
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a porous, permeable rock that will yield petroleum and natural gas in sufficient quantities to make drilling worth-while
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Earth is not covered by a thin "veneer" of sediment. T/F
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False
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Originally Horizontal
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When layers of rock are deposited, they usually start out flat.
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What is lithification?
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changes sediments into rock and includes compaction/cementation
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fined grained detrital sedimentary rocks
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siltstone, mudstone, and shale
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Other contacs
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Unconformities or gaps in the geologic record/ no translation
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Weathering (clastic sedimentary process)
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Generation of detritus via rock disintegration.
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mudstone
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a rock made from bits of mud stuck together
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Clastic sedimentary rocks
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are composed of weathered bits of rocks and minerals.
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mud cracks
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when deposits of wet clay dry and contract
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cross-bedding, p 235
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a principle of relative dating or rock units. A rock or fault is younger than any rock or fault through which it cuts. The older unit had to be there first in order to be changed (intruded into, faulted).
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detridal sedimentary rock, p 214
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rocks forming from accumulated materials originating and transported as solid particles. The particles can come from mechanical weathering, or chemical weathering, or both.
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What are the four classes of sedimentary rocks?
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Clastic, biochemical, organic, chemical
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oil and natural gas
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two basic conditions for an oil reservoir
1. porou, permeable reservoir rock
2. impermeable cap rock
derived from the remains of marine plants and animals
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nonmetallic mineral resource
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mineral resource that is not a fuel or processed for the metals it contains
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Maturity of sediments
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1. breccia 2. angular 3. conglomerate 4. arkose 5. quartz 6. sandstone 7. siltstone
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What is the usual sediment size?
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Sediments can be large like gravel, or small like clay
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corner
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attack from 3 directions
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chemial sediments
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precipitation and evaporation
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Shale (clay)
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Tiny Tiny Grains, Fissile
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chemical sediment
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ions deposited from solution
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evaporites
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solids left when water evaporates
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flint
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very hard, fine-grained, opaque quartz that sparks when struck with steel
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Lakes
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-fine sediments
-often organic and peaty: may form Coral
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deposition
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settling out of the transporting fluid
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exfoliation
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process of stripping/ peeling away (mechanical effect)
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Bedding/stratification
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layering that develops as sediments are deposited
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Chemical weathering
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Occurs when chemical reactions dissolve the minerals in rocks or change them into different chemicals
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ripple marks
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undulation of sediment surface produced as whind or water move across
symmetric and asymmetric
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chemical sedimentary rocks
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limestone, dolostone, and evaporites
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dolostone
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carbonate rock made up predominately of the mineral dolomite, CaMg(C03)2
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flint
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very hard, fine-grained, opaque quartz that sparks when struck with steel
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well sorted clast
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uniform grain size, steady energy
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lake
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gravels and sands trapped near shore; low energy; very small sediment
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Anthracite
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a very hard, shiny black metamorphic rock.
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Sed Features: Fossils
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Any trace of ancient life
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Erosion
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Process in which surface materials are worn away and transported from one place to another bu agents such as gravity, water, wind, and glaciers
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sedimentary structures
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features during or justafter sediment deposition
clues to how and where deposition of sediments occurred
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Sedimentary Breccia
(Largest Particles)
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Angular fragments, close to surface
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strata, p 236
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parallel layers of sedimentary rock
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glacial
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due to the movement of ice; takes every grain size so poorly sorted
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Organic Sedimentary Rocks
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Rocks composed of organic materials. ex: coal
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Tilting
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an internal force pushes on the layers and they move into a slant.
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Organic
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Material that was the direct result of living organisms
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What is the rock that is most commonly exposed to the surface?
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Limestone
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Particle composition
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Refers to the makeup of clasts in sedimentary rocks. Clasts may be composed of individual minerals or of rock fragments.
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rock whose origin is from the erosion, transportation, deposition, and subsequent lithification of pre-exisiting rocks under conditions at the surface of the earth, or from inorganic chemical reactions, or from lithified accumulation of organic debris
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sedimentary rocks
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What is compaction?
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When layers of small sediments stick together because of pressure
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cementation, p 213
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one of the ways that sedimentary rocks are lithified. Material precipitating from water percolating through the sediment fills up open spaces and glues the sediment pieces into a solid mass.
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fossil, p 23
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the remains or traces of organisms preserved from the geologic past
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Where is an example of poor lithification?
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El Morro, New Mexico
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grain sizes small to big
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clay, silt, sand, pebble, gravel, boulder - cannot see clay or silt grains
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what did the paleozoic era begin with?
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the appearence of complex life
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salt flat, p 224
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a white crust on the ground produced when water evaporates and leaves its dissolved materials behind.
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How do sedimentary rocks help tell scientists about the past?
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they help us know about animals such as dinosaurs and their fossils
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