Geo Engg

SEDIMENTS &SEDIMENTS &
SEDIMENTARY ROCKSSEDIMENTARY ROCKS

Relative Percentages ofRelative Percentages of
Sedimentary RocksSedimentary Rocks

SEDIMENTSEDIMENT
 FromFrom
 Weathering & ErosionWeathering & Erosion
 Precipitation from saturated solutionPrecipitation from saturated solution
 calcite, quartzcalcite, quartz
 Product of evaporationProduct of evaporation
 halite, gypsumhalite, gypsum
 Unconsolidated- NOT cementedUnconsolidated- NOT cemented

SEDIMENTSEDIMENT
 Particle sizeParticle size
 Pebbles, cobbles, bouldersPebbles, cobbles, boulders
 Gravel- > 2mmGravel- > 2mm
 Sand- 2mm - 0.063mmSand- 2mm - 0.063mm
 Silt - 0.063mm - 0.004mmSilt - 0.063mm - 0.004mm
 Clay- < 0.004Clay- < 0.004
 DepositionDeposition Clay-sizedClay-sized particle vs.particle vs. clay mineralclay mineral

SEDIMENTSEDIMENT
 TransportationTransportation
 AbrasionAbrasion
 DepositionDeposition
 Environment of deposition- specificEnvironment of deposition- specific

SEDIMENTSEDIMENT
 LithificationLithification
 CompactionCompaction
 Decrease inDecrease in pore spacepore space
 for very fine grain size (clay)for very fine grain size (clay)
 CementationCementation
 Clastic textureClastic texture
 Cements- silica, calcite, iron oxideCements- silica, calcite, iron oxide
 CrystallizationCrystallization
 Crystalline textureCrystalline texture

TYPES OF SEDIMENTARYTYPES OF SEDIMENTARY
ROCKSROCKS
 Clastic or DetritalClastic or Detrital
 Chemical- inorganic precipitation orChemical- inorganic precipitation or
evaporationevaporation
 Biochemical- Organic remainsBiochemical- Organic remains
 shells, charcoal, plant fragmentsshells, charcoal, plant fragments

CLASTIC (Detrital) ROCKSCLASTIC (Detrital) ROCKS
 Breccia and Conglomerate (> 2mm)Breccia and Conglomerate (> 2mm)
 Sedimentary Breccia- angular fragmentsSedimentary Breccia- angular fragments
 Conglomerate- rounded fragmentsConglomerate- rounded fragments
 Sandstone (2mm - 0.063mm)Sandstone (2mm - 0.063mm)
 Quartz sandstoneQuartz sandstone
 Arkose (feldspar)Arkose (feldspar)
 Graywacke (appreciable amounts of silt/clay)Graywacke (appreciable amounts of silt/clay)
 Fine-grainedFine-grained MatrixMatrix
 Usually fromUsually from turbidity currentsturbidity currents

Quartz SandstoneQuartz Sandstone

CHEMICAL SEDIMENTARYCHEMICAL SEDIMENTARY
ROCKSROCKS
 Carbonate RocksCarbonate Rocks
 Limestone- made of calciteLimestone- made of calcite
 Inorganic varietiesInorganic varieties
 micrite, oolites, travertinemicrite, oolites, travertine
 DolomiteDolomite
 RecrystallizationRecrystallization
 Chert- silicaChert- silica
 EvaporitesEvaporites
 Rock gypsumRock gypsum
 Rock saltRock salt

BIOCHEMICALBIOCHEMICAL
SEDIMENTARY ROCKSSEDIMENTARY ROCKS
 CoalCoal
 Develops from peatDevelops from peat
 plant fragmentsplant fragments
 LigniteLignite
 Bituminous CoalBituminous Coal
 Carbonate RocksCarbonate Rocks
 Limestone- made of calciteLimestone- made of calcite
 organic varietiesorganic varieties
 CoquinaCoquina
 Fossiliferous LimestoneFossiliferous Limestone
 ChalkChalk

SEDIMENTARYSEDIMENTARY
STRUCTURESSTRUCTURES
 BEDDING-BEDDING-
 Principle of Original HorizontalityPrinciple of Original Horizontality
 Bedding planeBedding plane
 Cross-beddingCross-bedding
 Graded bedGraded bed
 Mud cracksMud cracks
 Ripple marksRipple marks
 FossilsFossils

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