midterm2, Midterm 2
igneous plutons crack in onion like....
"exfoliation" layers
sizes of detrital fragments
-coarse grained -medium grained -fine grained
characteristics of breccia rocks
-indicates a lack of transport processing -deposited close to source
sediment
-rock and mineral fragments -Shells -Minerals Precipitates
maturity
a measure of the degree of "processing"
saprolite
a rock that has been dissolved to almost nothing
formation
a sequence of strata that is sufficiently unique to be recognized on a regional scale
bed surface markings occur
after deposition while sediment is still soft
as rocks trasport they become less____________ and more_______________.
angular, rounded
physical weathering
any process that breaks rock down into smaller pieces without changing the chemistry of the rock; typically wind and water.
biological weathering
any weathering that's caused by the activities of living organisms.
graded beds
bedding layers that fine upward
water flowing over loose sediment creates
bedform
physical weathering
breaks intact rocks into unconnected clasts (detritus)
travertine
calcium carbonte precipitated from ground water where it reaches the surface
biochemical sedimentary rock
cemented shells of organisms
bedding in sedimetary structures is caused by
changing conditions during deposition
4 classes of sedimentary rocks
clastic biochemical organic chemical
sandstone
clastic rock made of sand-sized particles
weathering
combo of processes that break up and corrode solid rock, transforming it into sediment
coarse clastics
composed of gravel-sized clasts
fine clastics
composed of silt and clay
breccia
comprised of angular clasts
conglomerate
comprised of rounded clasts
jointing
cracks in rocks with no displacement
biochemical chert
cryptocrystalline quartz rock
with increasing transport, average grain size of clastic sedimentary rock ______________.
decreases
biochemical chert forms in
deep ocean basins
textural maturity
degree of roundness and sorting
mineral maturity
degree of unstable mineral removal
where is chemical weatherig absent?
deserts
reaction with water ____________ many minerals
disintegrates
intoducing water and taking away a ion
dissolution
types of chemical weathering
dissolution, hydrolysis, oxidation, and hydration
jointing
erosion occurs at high P and T, cooling and expansion occurs, fractures form along joints
evaporites are created from
evaporated seawater
granite consists of
feldspar, quartz, and biotite
transgression
flooding due to sea level rise
weathering
generation of detrius via rock disintegration
show a transition from coarse to medium to fine grain size
graded beds
individual layer of the soil profile is called_________
horizons
the atoms of most rock forming minerals are held together by
ionic
types of physical weathering
jointing, frost wedging, root wedging, salt wedging, thermal expansion, and animal attack
sedimentary rocks are usually _________ __ ___________.
layered or stratified
sediment
loose fragments of rocks or minerals broken off bedrock, mineral crystals that precipitate directly out of water, shells, or shell fragments
biochemical limestone
made from CACO3-shell remains
clastic sedimentary rock
made from weathered of rock fragments
At a subduction plate the overriding plate
may be composed of either
clast composition
mineral makeup of clasts
Rates of weathering attack very due to changes in
mineral stability, degree of compaction or cementation, subtle differences in temperature
chemical sedimentary rock
minerals that crystallize directly with water
cement
minerals that filll sediment pores
is there chemical weathering in deserts?
no
fine clastics are only deposited in
non-agitated water
soil is a _______________ resource
non-renewable
biochemical chert is formed from
opalline sillica skeletons
diagenisis
physical, chemical, and biological changes to sediment
basins occur because of
plate techtonics
hydration happens a lot in
pyrite
the most dominant mineral in sandstone
quartz
chemical weathering
reaction with water disintegrates many minerals - water is a good solvent
erosion
removal of detrius from sedimentary rocks
cross bedding is created by
ripple and dune migration
stratified
rocks have continuous layers
oxidation
rust (losing electrons)
arkose
sandstone with a lot of feldspar, less mature
0-20km
sediment cover varies in thickness from
time and transport causes
sediment evolution
where is a surface veneer thick
sedimentary basins
deltas
sediments dropped where a river enters a stream
alluvial fans
sediments that pile up at mountain fronts
clay-sized particles form
shale
silt-sized clasts are lithified to form
siltstone
dunes
similar to ripples except much larger
subsidence
sinking of land during sedimentation
detrital fragments classified by
size
water is a universal ______________, it is optimized in ________ and _______ conditions
solvent, wet, warm
weathering _______ ___ as you break it down
speeds up
a series of beds are referred to as
strata
order the following minerals from softest to hardest
talc, fluorite, quartz, corundum
clastic sedimentary rock is classified on the basis of _____________ and _______________.
texture and composition
organic sedimentary rock
the carbon-rich remains of plants
differential weathering
the process by which softer, less weather resistant rocks wear away and leave harder, more weather resistant rocks behind
sorting
the uniformity of grain size
biochemical and organic rocks
these are sediments derived from living organisms
lithification
transforms loose sediments into solid rock
multiple graded beds sequences are called
turbadites
physical and chemical
two types of weathering
assymetic ripples
undirectional flow -short, steep, downcurrent slip face
well sorting
uniform grain size
hydrolysis
water breaks cation bonds in silicate minerals
hydration
water gets sucked into bonds and forces it to explode
chemical sedimentary rocks are comprised of minerals preciitated from _________ _________
water solution
symmetric ripples
wave oscillation -sharp ridges and concave up troughs -from back and forth swash
5 elements of forming clastic sedimentary rocks
weathering, erosion, transportation, deposition, lithification
chemical weathering
when chemicals in the air, soil plants and water change rocks this is what its called
where is a surface veneer thin
where basement outcrops
poor sorting
wide variety of grain size
soil is divided into 2 zones called
zone of leeching zone of accumulation