Sedimentary Rocks Flashcards
What are the 4 types of sedimentary rocks?
Clastic, Biochemical, Chemical, Organic
Where do sedimentary rocks occur?
In the uppermost part of the crust
Clastic rocks
loose rock fragments (clasts) cemented together.
Biochemical rocks
cemented shells of organisms
Chemical rocks
minerals that crystallize directly from water
Organic
carbon-rich remains of once living organisms
Clastic sedimentary rocks are created by…
Weathering, Erosion, Transportation, Deposition, Lithification
What is Lithification?
Transforming loose sediment into solid rock
Refers to the mineral makeup of sediment grains
Clast composition
the degree of edge or corner smoothness
Angularity
Sphericity
the degree to which the shape of a clast approaches that of a sphere
Breccia
coarse, angular rock fragments.
What does it mean when rock fragments are angular?
Absence of transport, close to clast source
Conglomerate
rounded rock clasts. Clasts rounded as flowing water wears off corners and edges. Deposited farther from the source than breccia.
sand and gravel with abundant feldspar
Arkose
What is the most common mineral in sandstones?
Quartz
Sandstone
clastic rock made of sand-sized particles.
Silt-sized sediments are lithified to form…? Clay-sized particles form…?
Siltstone. Mudstone or Shale.
What are the most common shells that make up biochemical sedimentary rocks?
calcite (CaCO3) in limestone and opalline silica (SiO2) in chert.
Limestone is a sedimentary rock that is almost made up entirely of…
Calcite and Aragonite
What is Chert?
rock made of cryptocrystalline quartz derived from opalline silica (SiO2) from the skeletons of some marine plankton.
What is an example of a combustible organic sedimentary rock?
Coal
What kind of texture do chemical sedimentary rocks have?
Crystalline (interlocking) texture
classes of chemical sedimentary rocks:
evaporites, travertine, dolostone, and replacement chert.
What creates bedforms?
Water flowing over loose sediment
How are cross-beds formed?
Ripple and Dune migration
Turbidity currents
Pulses in water. This process forms graded beds (coarse to fine upward)
Where do sedimentary basins form?
Where tectonic activity creates space
What is a transgression?
A rise in sea-level. Shifts depositional bets landward.
What is a regression?
A fall in sea-level. Shifts environments towards the basin.
Define foreland basin.
structural basin that develops adjacent and parallel to a mountain belt.
A sedimentary bed may have?
Bedforms
