Midterm Rev Flashcards
List 3 basic types of Sedimentary Rock
Siliciclastic
Biochemical/chemical
carbonaceous
What are the 3 main features to look for when identifying a paleosol?
root traces
soil horizons
soil structures
List 2 assumptions made when using a Hjulstrom Diagram
Spherical quartz grain
1m depth
(write more here)
What are the 4 common dispersive in sediment gravity flows
turbidity
cohesiveness
grain to grain interactions
liquification
(check this answer)
what is a cutan
clay skin that surrounds peds within soils
does a debris flow generally produce a matrix or clast supported conglomerate
matrix supported conglomerate
which form of bedload transport is characterized by the movement of a grain that is in constant contact with the bed (sliding, rolling, etc.)
traction
According to the Udden Wentworth scale, what size class would a grain 12 microns diameter belong to
silt
how are groove casts created and where do we find them (what part of the bed)
-an object impacts the bed and is dragged along creating a groove, then a cast is made of this
-groove casts are found on the bottom of the bed
what is the best method for quantifying grain shape
fourier transform analysis
Put the following bedforms in order from lowest to highest energy regime: antidunes, dunes, ripples, and planar bedding
ripples, dunes, planar bedding, antidunes
what is flaser bedding
ripple cross laminations are filled with mostly sand and some mud (depositional structure)
-(my answer: more sand than mud; mud ripples preserved in sand)
what bedforms produce tabular cross bedding
straight crested dune
what is an ichnofacies
assemblage of ichnofossils that tell you about the environment they were formed in
what is the difference between a thrombolite and a stromatolite (be specific as to which one has said properties)
-stromatolite: has internal structure and has laminations
-thombolite: has no internal structure and has no laminations
what is the most common cement in sandstones
silica
what is a styolite (include the rock type they commonly form in)
styolites are a dark colored accumulation as a result of diagenisis in limestone/carbonates
(check this)
what is the most common accessory mineral within sandstones?
mica
give an example of a common stable heavy mineral in sandstones
rutile, zircon, titanite
what is an arkose
arkose = greater than 25% feldspar in a sandstone
give the classification of a clastic rock composed of 75% sand sized grains with the framework grains compimised of 65% qtz 12% feldspar and 23% rock fragments
lithic wacke
would a quartz arenite with well rounded grains be considered mature or immature
mature
what is provenance in relationship to sandstones
source of the grains
during diagenesis smectite is often converted to what clay mineral
illite
what is the difference between a shale and mudstone
shale is fissle
mudstone is not fissile
what are the 3 main components of carbonate rocks (e.g. think of their texture)
-allochems
-microcrystalline calcite
-sparry calcite
what are the 4 main minerals comprising carbonate rocks?
-high Mg calcite
-low Mg calcite
-aragonite
-dolomite
according to dunham classification, what type of limestone is grain-supported rock, lacking lime mud whose allochems are all less than 2mm in size
grainstone
what are the 3 main textures of gypsum
-laminated
-nodular
-massive
what would happen to a foraminifera test(shell) that sank below the calcium carbonate compensation depth
it will dissolve
