Sedimentary Rocks and Depositional Environments Lab 1.
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Transcript of Sedimentary Rocks and Depositional Environments Lab 1.
Sedimentary Rocks and Sedimentary Rocks and Depositional Depositional
EnvironmentsEnvironmentsLab 1Lab 1
Rock Types - BackgroundRock Types - Background
Igneous Igneous Metamorphic Metamorphic SedimentarySedimentary
Broken down to form sedimentsBroken down to form sediments– SedimentsSediments – fragments of rock, individual – fragments of rock, individual
mineral grains (quartz), parts of plants or mineral grains (quartz), parts of plants or animals, clay minerals, and other animals, clay minerals, and other mineralsminerals
Minerals - BackgroundMinerals - Background
Igneous, metamorphic, and sedimentary Igneous, metamorphic, and sedimentary rocks are made of mineralsrocks are made of minerals
MineralsMinerals – substances that make up – substances that make up rock; the building blocks of rocksrock; the building blocks of rocks
Example minerals – quartz, potassium Example minerals – quartz, potassium feldspar, biotite mica, muscovite mica, feldspar, biotite mica, muscovite mica, calcitecalcite
Sedimentary Rock Sedimentary Rock CharacteristicsCharacteristics
Grain sizeGrain size RoundingRounding MineralsMinerals MatrixMatrix ColorColor
Grain SizeGrain Size The average diameter of the particlesThe average diameter of the particles
GravelGravel > 2 mm> 2 mm Visible to the unaided eyeVisible to the unaided eye
SandSand < 2mm,< 2mm,
>1/8 mm>1/8 mmVisible to the unaided eye, feels Visible to the unaided eye, feels very grittyvery gritty
SiltSilt
(mud)(mud)<1/8 mm,<1/8 mm,
> 1/256 mm> 1/256 mmInvisible to the unaided eye, can Invisible to the unaided eye, can see with a hand lens, feels grittysee with a hand lens, feels gritty
ClayClay
(mud)(mud)< 1/256 mm< 1/256 mm Cannot be seen without a Cannot be seen without a
microscope, feels smooth, dull microscope, feels smooth, dull lusterluster
** Ruler in Back of AGI Manual **** Ruler in Back of AGI Manual **Pg. 1-2 of lab manual
MineralsMinerals Building blocks of rocksBuilding blocks of rocks
MineralMineral HardnesHardnesss
CleavagCleavagee
ColorColor Distinguishing Distinguishing
FeatureFeature
QuartzQuartz 77 NoneNone
(fracture(fractures)s)
Milky toMilky to
ColorlessColorlessHardness and Hardness and
lookslooks
glassyglassy
PotassiuPotassium m
feldsparfeldspar
66 2 to 3 2 to 3 planesplanes
Salmon to Salmon to RedRed
ColorColor
Biotite Biotite micamica
2.52.5 1 plane1 plane Black to Black to dark dark
brownbrown
Black flakesBlack flakes
Muscovite Muscovite micamica
33 1 plane1 plane Colorless Colorless to light to light brownbrown
Light colored Light colored flakes; shinyflakes; shiny
CalciteCalcite 33 3 planes, 3 planes, rhombrhomb
White to White to GrayGray
Reacts with acid Reacts with acid (HCL)(HCL)
Pg. 1-3 of lab manual
MatrixMatrix
Sedimentary rocks are composed of large Sedimentary rocks are composed of large particles (grains) surrounded by smaller particles (grains) surrounded by smaller particlesparticles
The smaller particles are the The smaller particles are the matrixmatrix The fill in between larger grainsThe fill in between larger grains
Much
None—there are almost no open spaces
All
Some
Sedimentary EnvironmentsSedimentary Environments
A rock will display certain characteristics A rock will display certain characteristics depending on the environment in which it depending on the environment in which it was formedwas formed
The study of the composition and other The study of the composition and other characteristics of the sed. rocks can characteristics of the sed. rocks can reveal info. about the conditions reveal info. about the conditions occurring during deposition (helps occurring during deposition (helps determine environment) determine environment)
Sedimentary EnvironmentsSedimentary Environments
Alluvial FansAlluvial Fans River ChannelsRiver Channels GlaciersGlaciers SwampsSwamps DeltasDeltas Beaches and Beaches and
Barrier Barrier
IslandsIslands DunesDunes
LagoonsLagoons Tidal FlatsTidal Flats ReefsReefs Continental Shelf, Continental Shelf,
Slope, and RiseSlope, and Rise Deep marine Deep marine
environmentsenvironments
Alluvial FanAlluvial Fan
Rivers in mountainous Rivers in mountainous areas erode and areas erode and transport sedimenttransport sediment
When meets flat plain When meets flat plain deposits sediment in deposits sediment in fan-like shapefan-like shape
Common rocks: Common rocks: sandstone, sandstone, conglomerate, conglomerate, breccia, diamictonbreccia, diamicton
River ChannelsRiver Channels
Rivers vary in size and Rivers vary in size and energy levelenergy level
Contain various Contain various sediment types sediment types (gravel, sand)(gravel, sand)
Feldspar less commonFeldspar less common Common rocks: Common rocks:
sandstone, sandstone, conglomerateconglomerate
GlaciersGlaciers
Not able to sort Not able to sort sediment sizesediment size
Glacial sediments (till) Glacial sediments (till) are mixtures of gravel, are mixtures of gravel, sand, silt, and claysand, silt, and clay
Rock types: diamictonRock types: diamicton
SwampsSwamps
Lots of organic matterLots of organic matter Slow decompositionSlow decomposition Buried and compacted Buried and compacted
organic matter organic matter hardens to form coalhardens to form coal
Common rocks: coal, Common rocks: coal, shaleshale
DeltasDeltas
Rivers flow into lakes or Rivers flow into lakes or oceansoceans
Deposit sediment in a Deposit sediment in a fan-like shapefan-like shape
Mississippi River Delta, Mississippi River Delta, Nile DeltaNile Delta
Large areas composed of Large areas composed of various environments various environments (channels, swamps, (channels, swamps, bays)bays)
Common rocks: shale, Common rocks: shale, siltstone, sandstone, coalsiltstone, sandstone, coal
Beaches and Barrier IslandsBeaches and Barrier Islands
Barrier island is like a beach separated from the Barrier island is like a beach separated from the mainland by a lagoon mainland by a lagoon
Constant wave action separates sand sized grains from Constant wave action separates sand sized grains from othersothers
Sediment has traveled far from source, so well roundedSediment has traveled far from source, so well rounded Common rocks: sandstoneCommon rocks: sandstone
DunesDunes
Form adjacent to beaches and barrier islandsForm adjacent to beaches and barrier islands Contain non-marine fossilsContain non-marine fossils Common rocks: sandstoneCommon rocks: sandstone
LagoonsLagoons
Behind a barrier Behind a barrier island or reefisland or reef
Barrier island/reef act Barrier island/reef act as breakwaters as breakwaters protecting the lagoon protecting the lagoon from wave actionfrom wave action
Low-energy environmentLow-energy environment Fine grain sizes settle and Fine grain sizes settle and
accumulate (silt, mud)accumulate (silt, mud) Common rocks: shale, Common rocks: shale,
siltstonesiltstone
Tidal FlatsTidal Flats
Broad, flat areas that are periodically covered in Broad, flat areas that are periodically covered in water when tide rises and dry when tide is lowwater when tide rises and dry when tide is low
Variable energy levelsVariable energy levels Alternating layers of coarse and fine sedimentAlternating layers of coarse and fine sediment Common rocks: siltstone, shale, limestoneCommon rocks: siltstone, shale, limestone
ReefsReefs
Organisms build large, rocky accumulations by Organisms build large, rocky accumulations by cementing their shells or other structurescementing their shells or other structures
Common in tropical regions (warm water)Common in tropical regions (warm water) Calcite precipitatesCalcite precipitates Common rocks: limestoneCommon rocks: limestone
Continental shelf, slope, and Continental shelf, slope, and riserise
Shallow marineShallow marine: extend from beach to water : extend from beach to water depths of 100 m; low energy; fine grains settle; depths of 100 m; low energy; fine grains settle; common rocks are sandstone, siltstone, shalecommon rocks are sandstone, siltstone, shale
Deep marineDeep marine: extend down to thousands of : extend down to thousands of meters; low energy; fine grains settle; fossils are meters; low energy; fine grains settle; fossils are rare; common rocks are shale, sandstonerare; common rocks are shale, sandstone
Today’s Lab!!Today’s Lab!!
List properties of unknown List properties of unknown sedimentary rockssedimentary rocks
Identify the unknown rock specimens Identify the unknown rock specimens (rock name)(rock name)
Determine possible depositional Determine possible depositional environment(s) where the rock formedenvironment(s) where the rock formed