Transcript SEDIMENTARY ROCKS

SEDIMENTS &
SEDIMENTARY ROCKS
ROCK CYCLE
Relative Percentages of
Sedimentary Rocks
SEDIMENT

From
Weathering & Erosion
 Precipitation from saturated solution



Product of evaporation


calcite, quartz
halite, gypsum
Unconsolidated- NOT cemented
SEDIMENT

Particle size
Pebbles, cobbles, boulders
 Gravel- > 2mm
 Sand- 2mm - 0.063mm
 Silt - 0.063mm - 0.004mm
 Clay- < 0.004


Deposition Clay-sized particle vs. clay mineral
SEDIMENT

Transportation
Abrasion
 Rounding
 Sorting
 Deposition



Environment of deposition- specific
Preservation
SEDIMENT

Transportation
Abrasion
 Rounding
 Sorting
 Deposition



Environment of deposition- specific
Preservation
SEDIMENT

Lithification

Compaction

Decrease in pore space


for very fine grain size (clay)
Cementation
Clastic texture
 Cements- silica, calcite, iron oxide


Crystallization

Crystalline texture
SEDIMENT

Lithification

Compaction

Decrease in pore space


for very fine grain size (clay)
Cementation
Clastic texture
 Cements- silica, calcite, iron oxide


Crystallization

Crystalline texture
SEDIMENT

Lithification

Compaction

Decrease in pore space


for very fine grain size (clay)
Cementation
Clastic texture
 Cements- silica, calcite, iron oxide


Crystallization

Crystalline texture
TYPES OF SEDIMENTARY
ROCKS
Clastic or Detrital
 Chemical- inorganic precipitation or
evaporation
 Biochemical- Organic remains

 shells,
charcoal, plant fragments
CLASTIC (Detrital) ROCKS

Breccia and Conglomerate (> 2mm)
Sedimentary Breccia- angular fragments
 Conglomerate- rounded fragments


Sandstone (2mm - 0.063mm)
Quartz sandstone
 Arkose (feldspar)
 Graywacke (appreciable amounts of silt/clay)

Fine-grained Matrix
 Usually from turbidity currents

CLASTIC (Detrital) ROCKS

Breccia and Conglomerate (> 2mm)
Sedimentary Breccia- angular fragments
 Conglomerate- rounded fragments


Sandstone (2mm - 0.063mm)
Quartz sandstone
 Arkose (feldspar)
 Graywacke (appreciable amounts of silt/clay)

Fine-grained Matrix
 Usually from turbidity currents

Quartz Sandstone
CLASTIC ROCKS

Fine-grained Rocks
Shale- fissile (in ‘sheets’)
 Siltstone
 Claystone
 Mudstone (silt and clay)

CHEMICAL SEDIMENTARY
ROCKS

Carbonate Rocks

Limestone- made of calcite

Inorganic varieties

micrite, oolites, travertine
Dolomite
 Recrystallization



Chert- silica
Evaporites
Rock gypsum
 Rock salt

BIOCHEMICAL
SEDIMENTARY ROCKS

Coal

Develops from peat

plant fragments
Lignite
 Bituminous Coal


Carbonate Rocks

Limestone- made of calcite

organic varieties



Coquina
Fossiliferous Limestone
Chalk
BIOCHEMICAL
SEDIMENTARY ROCKS

Coal

Develops from peat

plant fragments
Lignite
 Bituminous Coal


Carbonate Rocks

Limestone- made of calcite

organic varieties



Coquina
Fossiliferous Limestone
Chalk
SEDIMENTARY STRUCTURES

BEDDINGPrinciple of Original Horizontality
 Bedding plane
 Cross-bedding
 Graded bed
 Mud cracks
 Ripple marks
 Fossils

SEDIMENTARY STRUCTURES

BEDDINGPrinciple of Original Horizontality
 Bedding plane
 Cross-bedding
 Graded bed
 Mud cracks
 Ripple marks
 Fossils

DUNES
SEDIMENTARY STRUCTURES

BEDDINGPrinciple of Original Horizontality
 Bedding plane
 Cross-bedding
 Graded bed
 Mud cracks
 Ripple marks
 Fossils

SEDIMENTARY STRUCTURES

BEDDINGPrinciple of Original Horizontality
 Bedding plane
 Cross-bedding
 Graded bed
 Mud cracks
 Ripple marks
 Fossils

Mudcracks
SEDIMENTARY
STRUCTURES

BEDDINGPrinciple of Original Horizontality
 Bedding plane
 Cross-bedding
 Graded bed
 Mud cracks
 Ripple marks
 Fossils

Body Fossils
 Trace Fossils

FORMATIONS




Large enough to show on a map
Distinctive from neighboring rock units
Named after geographic locations
CONTACT
separation between 2 distinct rock units
 Sedimentary contact
 Other contacts

INTERPRETATION OF
SEDIMENTARY ROCKS


Source Area
Environment of Deposition

Glacial environments


Alluvial fan


Interbedded shales and sandstones; cross-bedded
Lake


Arkose
River channel and flood plain


Tillites
Shales; interbedded siltstones and mudstones
Delta
INTERPRETATION OF
SEDIMENTARY ROCKS


Source Area
Environment of Deposition

Glacial environments


Alluvial fan


Interbedded shales and sandstones; cross-bedded
Lake


Arkose
River channel and flood plain


Tillites
Shales; interbedded siltstones and mudstones
Delta
Glacial Environment & Till
INTERPRETATION OF
SEDIMENTARY ROCK

Environment of Deposition

Beach, Barrier Island, Dune


Lagoon


Interbedded sandstones and shales; burrowed
Reef


Shales
Shallow marine shelf


Very well sorted quartz sandstones
Skeletal Limestones
Deep marine environment

Turbidites- sequence of GRADED sandstones to shales
INTERPRETATION OF
SEDIMENTARY ROCK

Environment of Deposition

Beach, Barrier Island, Dune


Lagoon


Interbedded sandstones and shales; burrowed
Reef


fine grained sediment
Shallow marine shelf


Very well sorted quartz sandstones
Skeletal Limestones
Deep marine environment

Turbidites- sequence of GRADED sandstones to shales
CALCAREOUS
INTERPRETATION OF
SEDIMENTARY ROCK

Environment of Deposition

Beach, Barrier Island, Dune


Lagoon


Interbedded sandstones and shales; burrowed
Reef


Shales
Shallow marine shelf


Very well sorted quartz sandstones
Skeletal Limestones
Deep marine environment

Turbidites- sequence of GRADED sandstones to shales
INTERPRETATION OF
SEDIMENTARY ROCK

Plate Tectonics and Sedimentary Rocks

At convergent boundaries

Uplift results in



Very rapid rates of erosion
Thick accumulations of clastic sediment
At transform boundaries
Rapid rates of erosion, deposition and burial
 Good basins for petroleum exploration


At divergent boundaries

Initial stages of rifting- thick wedges of gravel and
coarse sediment
Resources

Non-Metallic
Sand and gravel
 Limestone
 Clay
 Gypsum


Energy Resources
Oil and gas
 Coal

Formation of Oil and Gas
U.S. Coal Production