Sedimentary Rocks Flashcards
What conditions form sedimentary rocks?
processes that act at low temp and pressure
Where are sedimentary rocks most plentiful in the earth
The surface of the crust
what are the four main groups of sedimentary rocks?
siliciclastic, carbonate, evaporites, and coal
What is the most common type of sedimentary rocks?
Siliciclastic rock
Composition of siliciclastic rocks
fragments of silica-rich rocks and minerals
Generation of a siliciclastic rock commonly involves what three processes?
- Weathering
- Erosion, transport and deposition events
- Diagenesis
what are the products of weathering?
sediment and dissolved solids
What is physical weathering?
Action of wind, water, and other elements on the rocks(e.g., frost wedging); dominates in cold and dry settings.
what is chemical weathering?
Action of cellular and chemical processes on rocks (e.g.,
dissolution, oxidation, hydrolysis); dominates in hot and in wet settings.
Define erosion
Erosion is the removal of sediment by water or, less commonly, air or
glacier ice.
What three types of siliciclastic rock are there?
mudstone, sandstone, and conglomerate
What is competence in terms of water flow?
the strength of the flow, as measured by the largest clast it can carry
What is a good way to think of chmical stability of minerals?
Bowens reaction in reverse
define downflow fining
Downflow loss of unstable components
What is left in downflow finign after the maific and felsic minerals have been dispersed?
quartz
what is the source of most silicilastic sediment on earth
mountains
What mechanism transports sediment from the shoreline to the ocean floor?
sediment-gravity flows
sedimentary
basins definition
Areas of long term
subsidence where
sediment
accumulates
Siliciclastic sediment
transforms to rock
during…
diagenesis
Define metamorphism
sediment experiences physical, chemical, and/or biological changes, commonly leading to lithification
Define lithification
transformation of sediment into rock
What does diagenesis involve?
- burial in the sedimentary basin
- increase in pressure and temp
- compaction (decrease of pore-space volume)
- cementation
What is cementation?
precipitation of crystalline minerals (“cement”) in the pore spaces
between sediment grains
The two dominant types of sedimentary rocks are
a) siliciclastic and carbonate rocks
b) evaporites and coal
c) carbonate rocks and evaporites
d) siliciclastic rocks and evaporites
a
The three main types of siliciclastic sediment are…
a) clay, silt and sand
b) mudstone, sandstone and conglomerate
c) clay, silt and gravel
d) mud, sand and gravel
d
Erosion refers to
a) in-situ breakdown of rock.
b) removal of sediment.
c) transport of sediment.
d) None of the above
d
Which mineral will likely weather first?
a) K felspar
b) Pyroxene
c) Quartz
d) Olivine
b
Why does downflow fining occur in river systems?
a) Because flowing water is not infinitely competant
b) Because flowing water is turbulent.
c) Because flowing water erodes uplands.
d) Because flowing water deposits sediment in depressions.
d
___________ transport(s) most sediment to the ocean.
rivers
_____________ transport most sediment from the edge of the ocean to the deep
ocean.
a) Sediment gravity flows
b) Turbidity currents
c) Dense, turbulent mixtures of sediment and water
d) All of the above.
d
The transformation of siliciclastic sediment to siliciclastic rock typically involves… a) cementation. b) burial. c) diagenesis. d) All of the above.
d
A sedimentary basin requires _____________ to form.
a) a supply of sediment
b) long-term subsidence
c) plate tectonics
d) All of the above.
d
A protolith is
a) an undifferentiated chondrite
b) the original rock that existed prior to metamorphism
c) the source rock from which sediment was derived
d) the source rock from which an igneous melt was derived
b
