SEDIMENTS SEDIMENTARY ROCKS (2)

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