Mineralogy/Petrology Test 3 INFO
true
"At Mahana Bay, along the southern coast of the big island of Hawaii a 49,000 year old tuff ring is eroding along the coastline. Much of this is olivine (containing iron and magnesium) and olivine is heavier than most sand grains. So, as the coastline erodes the olivine stays on the beach longer than most of the rest of the sand (that gets carried away by the waves) and builds up so that the beach appears green. "
powdered
"Dolomite often occurs with calcite, but it only reacts with HCl when _________________."
Their chemical composition will be nearly the same
"Generally speaking, how does the chemical composition of most metamorphic rocks compare to that of the parent rock?"
Garnet Schist
"Of the following rocks, one that is metamorphic is: "
large, medium, small Answer: small
"The calcite group is the CO3 carbonate anionic complex combined with ________ divalent cations (Ca, Mg, Fe, Mn, Zn)"
bladed
"The common crystal forms in the calcite group are rhombohedral, tabular, and _______________."
What is diagenesis?
"The textural, compositional, and other changes that occur to sediments after deposition"
Burial
"________ metamorphism tends to occur in regions where massive amounts of sedimentary or volcanic materials accumulate in a subsiding basin, pushing older rocks further into the interior."
Impact metamorphism
"strike metamorphism" occurs when meteorites strike Earth's surface rocks called impsctiles Ultra high T & P
Saltation particle movement
(intermittent hopping) "Bedload" wind or water larger materials
Hydrothermal Metamorphism
-Chemical alteration caused when hot, ion-rich fluids circulate through fissures and cracks -Most widespread along axis of the mid-ocean ridge system, altering ocean-floor basalt
Subduction zone metamorphism
-High pressure, low temperature -restricted to narrow belts (smaller than regional) -forms at temps below average geothermal gradient, but very high pressure -Accretionary prisms at subduction zones is only site (Blueschist facies)
Contact metamorphism
-Magma invades a host rock -Temperature rises -Zone of alteration forms in rock surrounding the magma (limited areal extent) -High temps, but low pressure -Typically produces massive rocks
Metamorphism
-Metamorphism occurs when a protolith undergoes a solid state (not magma) change in response to a modification of environment -TEMPERATURE, PRESSURE, COMPOSITION OF FLUID
Chert
-Rock name for cryptocrystalline quartz -Occurs in bedded deposits and as nodules in sedimentary sequences. -Precipitates in water, mostly marine -Silica sources include -Some plankton (diatoms and radiolarian) -Sponge spicules
halite (halide mineral)
-most abundant in marine deposits -Mechanically unstable: deforms by flowing when deeply buried. -forms salt dome structures. -extremely restricted basin shows halite
Siliciclastic sedimentary rocks
-most abundant sedimentary rocks. -formed from detritus left over from weathering of igneous and metamorphic & older sedimentary rocks. -pyroclastic materials if close to active volcano -rock composition depends on source region, weathering, and separation of grains/minerals during transport. -most derived from continents (terrestrial siliciclastic sediment)
Chert
-rock name for cryptocrystalline quartz -occurs in bedded deposits and as nodules in sedimentary sequences -precipitates in water, mostly marine -silica sources include some plankton (diatoms/radiolaria) and sponge spicules
sequence of evaporite formation
1. Calcite - begins when seawater 1st starts to evaporate 2. Gypsum- begins when ~75% water removed 3. Halite- begins when ~90% water removed 4. Various Mg/K salts- ~95% removed
sedimentary weathering rates influenced by:
1. Chemical composition and bonding of mineral material (Quartz=high stability, Olivine=low) 2. Structural integrity of mineral; fractures, cleavage (increases particles) 3. Sizes & Impurities of crystals 4. Chemical character of environment (water availability[no soil without water], temperature[polar regions- low weathering]) 5. Areas with high topographic relief promote weathering and transport of sediment. (convergent and divergent plate boundaries)
Mudrocks
2/3 of all sedimentary rocks siltstone, claystone, shales source of organic materials from which oil and gas form. (contain 95% of all organic matter in sed rocks) low permeability, good cap rocks for oil reservoirs and confined aquifers. Silt (mostly quartz-angular bc never at stream bottom) and clay sized mineral may be finely layered (laminated, fall like sheets of paper)
Halite begins to deposit when ~_____% of the original seawater has been removed.
90
Wackes
> 15% mud matrix. Immature. Characteristic of submarine fan, slope, and abyssal deposits.
Porphyroblasts
A crystal in a metamorphic rock that is significantly larger than the other mineral grains in the rock, and commonly euhedral and has grown during metamorphism
Stylolites
A dark irregular line in limestone formed where insoluble residue has accumulated on a surface where solution of the rock has taken place.
Marble
A rock formed from the metamorphism of limestone and composed predominantly of calcite, but it may also contain dolomite.
immature
A sedimentary deposit containing angular sand grains in a clayey matrix would be described as:
Graded Bedding
A sedimentary structure that exhibits coarser grain size at the bottom and finer at the top is called ___________.
ripple mark
A sedimentary structure that is formed as wind or water moves across sand is a ____________.
high
Areas of ___________ topographic relief promote weathering and transport of sediment.
Metamorphic facies derive their names from those metamorphic rocks specifically formed from a ________ parent.
Basaltic
Match the sedimentary rock or mineral example with the type of sedimentary rock or mineral: oolitic limestone.
Biochemical
__________ sedimentary rocks form from sediment derived from organisms.
Biochemical
role of CO2
CO2 gas dissolved in water is KEY to deposition less CO2 in water, more CaCO3 deposits how to get less CO2 in water: Increase temperature Agitate water (more area to lose gas dissolved in water) Increase salinity (through evaporation) (CO2=less soluble) Enhance organic activity (Plants absorb CO2 during day) Expose groundwater saturated with CaCO3 to atmosphere
Carbonate matrix
Calcium carbonate mud that binds allochems together
Rainwater will combine with which atmospheric gas in order to create carbonic acid?
Carbon Dioxide
Which marine depositional environment is characterized by clear water dominated by skeletons of marine organisms?
Carbonate Shelf
Which mineral class is best described by the following statements: Ex: dolomite
Carbonates
"______________ weathering is the decomposition of minerals, with formation of new minerals"
Chemical
______________ weathering is the removal of some material in solution
Chemical
Greenstone
Chlorite gives green color Mafic protolith, such as basalt
Hydrocarbons
Coal- from buried plant material before it oxidizes Oil- burial of animal and plant remains Natural gas- same as oil but higher temperatures
Formation of mudrocks
Compaction is most notable change because porosity loss. (loss bc increasing depth of burial for muds)
Carbonate Minerals
Contains Co32- anion. Cementing agents in clastic sed. rocks and make up shells of many organisms. Minerals will break down in presence of H+ (acid): 2H+Co32 yields H2O+CO2
"Which of the following sedimentary structure can NOT determine the ""up-direction"" in rocks that have been overturned?"
Cross-beds
"In cementation, stable precipitates may replace less stable minerals, and porosity ______________."
Decreases
Transitional
Deltas are included in _______________ depositional environments.
True
Depositional environments have a distinctive set of rock characteristics.
Bedload
Detritus that rolls or intermittently hops on the bottom of a river makes up the rivers
Cambrian
During which period does the rock record indicate an explosion of life (rapid evolution and diversification) of many organisms that contribute to the formation of carbonate sediment?
Which mineral class is best described by the following statements: Ex: gypsum
Evaporite
What is not true about Sedimentary Rocks?
Evaporites are examples of biogenic sedimentary rocks
A ________ describes the observation of successive changes in a laterally continuous sedimentary layer that are visible and are interpreted as a result of many depositional processes taking place over a large area.
Facies transitional environment
Peliods
Fecal pellets formed of carbonate minerals that are produced by many different organisms.
"During hydrolysis, ________ commonly decompose into clay minerals, silica, and soluble constituents."
Feldspars
Schistocity
Geological foliation with medium to large grained flakes in a preferred sheetlike orientation
Gneissic banding
Gneiss appears to be striped in bands
"_______________ is defined as how grains can be classified as spherical, rod-shaped, or disk-shaped"
Grain size
___________ sedimentary rock form from detritus.
Gravel
90
Gypsum begins to deposit when ~_____% of the original seawater has been removed.
Heat as agent in metamorphism
Heat between diagenesis and melting, recrystallization results in new, stable minerals. hotter = faster
Heat from magma, geothermal gradient, radioactive decay Answer: all answers are correct
Heat leading to metamorphism can be provided by which of the following?
Agents of metamorphism
Heat, prograde changes (heating), retrograde changes (cooling), confining pressure, differential stress, hydrothermal fluids.
Calcite Group
Hexagonal minerals created by triangular shape of CO3 structure. -Rhombohedral cleavage. -Common forms: Rhombohedral, tabular, scalendohral "dog tooth"
A sedimentary deposit containing angular sand grains in a clayey matrix would be described as
Immature
Ooids
Inorganic origin. A sub-rounded sand-size grain consisting of concentric layers of carbonate. The argonite or calcite precipitates around a preexisting grain, which forms the nucleus. Most oolitic limestone is made of calcite.
is a biochemical sedimentary rock that often forms in carbonate reefs.
Limestone
______________ allochems are subrounded sand-size particles formed by precipitation of calcite or aragonite in concentric layers around a nucleus grain as it washes back and forth in shallow marine waters
Limestone ooids
Lagoons are included in _______________ depositional environments.
Marine
Turbidites are associated with which type of depositional environment?
Marine
Phosphorites
Marine sedimentary rocks composed mostly of apatite with >20% P2O5 Apatite, Collophane, Chert
Detrital
Match the sedimentary rock or mineral example with the type of sedimentary rock or mineral: quartz arenite.
Gneiss
Medium to coarse grained high-grade metamorphism exhibits gneissic banding (color segregation)
Micrite
Microcrystalline carbonate 1 to 5 microns in size (dull in hand sample) precipitates in low energy environments may recrystallize within few million years to microspar (spar)
Spar
Microspar Micrite that recrystallizes
Which of the following sedimentary structures only occurs in fine-grained sediment?
Mudcracks
Siltstone
Mudrock; commonly layered with fluvial sandstone lithified, non-fissile mudrock smaller than sand particles
Dynamic metamorphism
Occurs at depth and high temperatures along fault zones Pre-existing minerals deform by ductile flow result of shearing (Mylonite) Mylonite- large grains in protolith recrystallize to fine grained
protolith
Parent rock
Organically produced limestone/carbonate sediment
Precambrian- explosion of life Carbonate sediment- forms from hard parts of variety of organisms that are broken by wave/current action or by other organisms on them. gravels to sands to muds
Conglomerates
Predominantly gravel- size particles. Form in high-energy environment (Ex. Fast-flowing rivers or alluvial fans). May be clast-supported or matrix-supported. If angular, called sedimentary breccia.
Allochems
Primary carbonate sedimentary particles that form the framework of a limestone. Ex. shell fragments, ooids, and pellets.
Which of the following is the most common sedimentary mineral?
Quartz
Indicate which metamorphic rock is described. Consists of quartz sandstone grains which have been fused together; is nonfoliated
Quartzite
________ is a widespread type of metamorphism typically associated with mountain building.
Regional Metamorphism
Which of the following methods of transportation will result in the least sorted deposit?
Rock Fall
"_______________ is defined as how angular grains are. It is controlled by grain size, hardness, and environments of transport and deposition."
Roundness
Which rock type can contain fossils?
Sedimentary
__________ are visible features within sedimentary rocks that formed at the time of deposition and represent manifestations of the physical and biological processes that operated in depositional environments.
Sedimentary Structures
"Which rock type, or combination of rock types, makes up the majority of Earth's outermost solid surface?"
Sedimentary, metamorphic
Claystone
Shale- most abundant sedimentary rock, recognized by fissility (split into thin sheets) doesn't grit on teeth
What sediment particle size(s) make up shale?
Silt and Clay sized
"Which low-grade metamorphic rock displays thin, parallel layers and contains very fine grains of mica?"
Slate
Slate
Slate is a hard mudstone that has undergone metamorphosis, and has well-developed cleavage
1. calcite 2. quartz 3. hematite 4. clay
Sort the following from MOST common cement to LEAST common cement.
Which mineral class is best described by the following statements: Ex: gypsum
Sulfates
In stratified glacial meltwater deposits, you might assume that a layer with larger grain size was deposited during
Summer
shock
Tectites are the result of which type of metamorphism?
What is the definition of metasomatism?
The change in chemical composition because hot fluids are bringing or removing ions
Foliation
The property of a rock to break into thin sheets that are bounded by planes along which typically platy minerals are aligned. This alignment may result from sedimentation of clay minerals or from the growth of micas in a preferred orientation in metamorphic rocks.
false
The raw material for coal is dead marine organisms.
false
To get less CO2 in water you need to increase organic activity.
What sedimentary environment do the following statements/key words/rock types belong to? Glacial.
Transitional
"Chalk is a soft, porous rock composed of the hard parts of microscopic marine organisms."
True
Marine
Turbidites are associated with which type of depositional environment?
Water
What fluid is generally responsible for metasomatism?
Heat
What is the most important factor driving metamorphism?
varves
What is the name given to annual deposits of rhythmic layers of coarser and finer sediment reflecting seasonal changes?
Marine
What sedimentary environment do the following statements/key words/rock types belong to? Oozes.
Marine
What sedimentary environment do the following statements/key words/rock types belong to? Turbidites.
uniform stress
What type of stress relates with foliation?
rod-shaped
Which of the following is NOT a type of detrital grain sphericity?
Gabbro, greywacke, rhyolite, Andesite Answer:
Which of the following is a sedimentary rock?
Cross-bedding
Which of the following represents the single most common and characteristic structures in sedimentary rocks?
mudrocks, sandstones, limestones Answer: mudrocks
Which of the following rocks is most abundant?
Shales and mudstones are baked during contact metamorphism.
Which of the following scenarios best describes the formation of hornfels?
Lithic Arenites
Which of the following siliciclastic rocks is submature and do not contain K-feldspar? They are often found at the base of recent uplifts where rock fragments are plentiful.
mudrocks
Which type of sedimentary rock makes up approximately 65% of all sedimentary rocks?
Regional metamorphism
Widespread metamorphic zones, producing greatest quantity of metamorphic rock Associated with mountain building/convergence (folding) temperature very high, associated with depth/igneous activity higher pressure due to overburden weight, plus compression and shearing foliation develops
Regional Metamorphism
Widespread metamorphic zones, producing greatest quantity of metamorphic rocks -Associated with mountain building/convergence -Very high temps associated with depth and/or igneous activity -High pressure due to overburden weight, plus compression and shearing -Foliation develops
Dolomitization
________ is the process where calcium ions in limestone are replaced with magnesium or small amounts of iron.
"well-sorted, poorly sorted"
_________________ sands tend to have higher porosity and permeability than _________________ sands.
Mylonite
a fine-grained metamorphic rock, typically banded, resulting from the grinding or crushing of other rocks.
Migmatites
a rock composed of two intermingled but distinguishable components, typically a granitic rock within a metamorphic host rock.
Which of the following is part of later diagenesis?
all of the above
Continental depositional environment
always above sea level on land or in fresh water; alluvial fans, fluvial (streams), glacial, desert (eolian), and lacustrine (lake)
Marine depositional environment
always below sea level; includes continental shelf, continental slope, and deep marine. Turbidility currents
Compaction
as fluids are expelled from pores, porosity decreases. particles may rotate bc stress. at deposition particles=scattered, during diagenesis particles=aligned parallel
Burial metamorphism
associated with very thick sedimentary strata increasing T & P with additional burial/subsidence typically low grade little to no internal deformation of rocks
Sedimentary structures
bedding (layering)- most common cross bedding graded bedding ripple marks mudcracks tracks/trails burrows
Bedload vs. Suspended load
bedload=faster suspended load= slower effective sorting by grain size results. both contribute to alluvial deposits.
Metasomatism
change in rock's composition by reactions with hydrothermal fluids
Changes to beddings in sandstone (5)
change in: composition size shape orientation packing
Retrogarde
changes that take place during cooling
Prograde
changes that take place during heating
Hydrothermal metamorphism
chemical alteration caused when hot, ion rich fluids circulate through fissures and cracks Most widespread along axis of the mid-ocean ridge system, altering ocean-floor basalt (divergent boundaries)
Sedimentary rock compositions
chemical composition- wide range caused by weathering clastic reflect source rock undergoing erosion (angular or rounded) strongly reflect biochemical environment of deposition
weathering of sedimentary rocks
chemical weathering= decomposition of minerals with formation of new minerals (change composition) removal of some material in solution (oxidation, hydration, hydrolysis, carbonation) Physical= size reduction and increases in surface area without chemical alteration they work together, physical triggers chemical
Limestone Peloids/Pellets
coarse-silt to fine-sand sized carbonate grains that often lack internal structure Origin of most thought to be fecal pellets from burrowing organisms
Graded bedding
coarser grains at bottom, finer at top. forms as sediment heavy currents slow down characteristic of turbidites
Marble
composed mostly of calcite (sometimes dolomite) protolith of limestone or dolostone usually granoblastic foliation may be present
Types of siliciclastic sedimentary rocks
conglomerates, sandstones, mudrocks (shales)
Serpentinites
consists mostly of serpintine
Mudcracks depositional environment
continental
limestone diagenesis
determined by pore water chemistry and rate of water movement (need slow water) most carbonates experience early cementation later dagenesis consists of mechanical(siliclastic sediments), chemical compaction (developes stylolites) and Burial cementation (pressure solution major source for cements)
Products of physical weathering of sedimentary rocks
detritus: loose material and grains resistant minerals more abundant (quartz) can later form rocks if cemented together ex. conglomerate, sandstone, siltstone, shale.
Metamorphic environments based on
different types based on temperature & pressure
Limestone fossils
easiest observed are inequant, biologically determined shapes often broken and hard to see
Carbonate deposition
equation for equilibrium: CaCO3 + CO2 + H2O <-----> Ca+2 + 2H+ + 2CO3+2
Highly fractured rocks will exhibit faster or slower rates of weathering?
faster
________ metamorphism will occur where two blocks of rock are grinding against each other.
fault zone
Which grain size (coarse or fine) tends to exhibit more rounding?
fine
Phyllite
fine-grained Gradational between slate & schist Glossy reflective sheen due to platey mineral grains wavy surfaces
siliciclastic sedimentary rocks
form from detritus: fragments of other rocks- loosely bounded mudrocks sandstones
Limestone allochems
fossils, ooids, peloids/pellets, limeclasts
Limestone Limeclasts
fragments of earlier formed limestones or partially lithified carbonate sediment may have been torn from seafloor by storm and moved
Hornsfels
generic name for fine-grained, granoblastic, contact metamorphic rocks that are typically: hard, dense, baked appearance, gray to brown to black & smooth to touch depends on where magma intruds- changes composition
some sedimentary structures that help determine "up direction" in rocks that have been overturned
graded beds, cross beds, mudcracks, symmetrical ripples, burrows, tracks
Which of the following does NOT control the roundness of detrital grains?
grain size
As sediment matures what happens
grain size reduce by abrasion(sands), breakage, solution, chemical weathering = more rounded
Detrital textures
grains can be spherical, rod shaped, disc shaped coarser= rounder, finer=more angular
high energy= __________ textural maturity
high (mature)
Turbulent flow
high energy, irregular flow path, air (desert) & water (early river stages) always flows turbulently
Detrital grain size
imp. feature in conglomerate and sandstone most rocks have single size; reflects conditions at deposition
Confining pressure in metamorphic rocks
increases with depth applies force equally in all directions may cause recrystallization to more compact crystalline form
Transitional depositional environment
influenced by marine and continental processes; deltas, beaches, and lagoons.
Cross bedding
internal stratification at an angle to main stratification of deposit Most common in sands and silts cross bedding dip downstream
Stylolites
irregular surface or seam in rock developed when chemical compaction where carbonate is removed by pressure solution
Turbidity currents
lakes and ocean basins. rapidly moving suspension of particles. dislodged sediment is taken by current and travels as far downslope as it can go. triggered by slumping or earthquakes graded bedding is characteristic
Porphyroblasts
larger recrystallized grain occurring in a finer groundmass
Detritus
loose material and grains
Physical rotation of platy minerals will contribute most to the development of foliation in ________ grade metamorphism.
low
low energy= __________ textural maturity
low (immature)
Laminar flow
lower energy, predictable, similar to thin sheets sliding over eachother, flow of glacial ice always laminar
Slate (metamorphic)
lowest grade metamorphism of shale/mudstone can't identify grains green/dark colored Growth of very fine-grained chlorite and micas results in slaty cleavage
Hydrothermal fluids in metamorphic rocks
mainly water enhances migration of ions aid in recrystallization of existing minerals
Collophane
massive cryptocrystalline variety of apatite found in phosphorites major source of phosphate used in fertilizer
"Beach environments represent which textural maturity, immature or mature?"
mature
Granoblast textures
may form during recrystallization crystals of roughly the same size:quartzite and marble exhibit polygonal grain boundaries
Schist
medium to coarse grained Conspicuous platy mineral grains exhibits irregular planar foliation of visible mica flakes called schistosity Composition indicated by using mineral names (biotite)
Amphibolites
medium to coarse grained dark colored hornblende and plagioclase metamorhism of mafic rock- gabbro
Contact metamorphism
metamorphism due to contact with or proximity to an igneous intrusion magma invades host rock temperature rises (high T, low P) zone of alteration forms produces massive rock (ex. hornsfeld)
Metaquartzite
metamorphism of quartz arenite and cherts recrystallization with interlocking crystals of quartz rich in water fractures across grain boundaries hard- very stable
Soapstones
mixture of serpentine and talc both typically form by hydrothermal alteration of ultramafic igneous rocks
mudstone
mixture of silt- and clay-sized particles
gypsum (sulfate mineral)
most abundant in marine deposits only common in arid climates soft so easy to identify in outcrop
chemical and biogenic rocks
most commonly carbonates(limestones and dolomites
sediment transport
most moved by fluids responding to stress (wind water & ice) depends on viscosity and velocity Laminar flow= lower energy turbulent flow=high energy (air & water) Particle movement by fluid flow- rolling, saltation(intermittent hopping), suspension by turbulent eddy currents (clay and silt sized particles) (mixed throughout water)
Grains between 1/16 and 2 mm are classified as _____.
mud
common/abundant sedimentary rocks
mudrocks (siltstones and claystones) (65%) sandstones (25%) limestones & dolomites chert
Products of chemical weathering of sedimentary rocks
newly formed minerals can stay at site of weathering ex. clays formed by weathering of feldspars dissolved materials transported in solution can later precipitate to form chemical sedimentary rocks ex. carbonates (limestone), evaporites (gypsum)
Rolling particle movement
on stream bed "bedload" largest materials
"________ are tiny ""seed"" particles created when small sediments or shell fragments are rolled by waves in water supersaturated with calcium carbonate."
ooids
Skarns
originate from contact metamorphism of limestone show evidence of having exchanged constituents with intruding magma (metasomatism) calcium rich- wollostone diopside, plagioclase may form ore deposits
Apatite
phosphate mineral hardness of 5 mined for phosphorite occurs in shallow marine settings
Depositional environments
physical, chemical, biological and geographic conditions under which sediments are deposited. yield distinctive rocks characteristic of various environments Marine, Continental, and Transitional
Mudcracks
polygonal pattern of cracks produced when mud dries suspended load deposited in floodplains fine grained and clay rich form 3 fractures at 120 degree angles
Limestone diagenesis is determined primarily by ____________________ and rate of water movement.
pore water chemistry
Metamorphic rocks
pressure, heat
Dolomitization
process by which limestone is altered into dolomite Diagenetic replacement solutions dissolve CaCO3 and precipitate dolomite Mg substitutes Ca
Ripple marks
produced as wind or water moves across sand finer particles=faster; coarser particles= slower alluvial, beach, stream bottoms, deserts go in direction of flow wavy appearance symmetrical= back & forth (beaches) asymmetrical= one flow direction (alluvial)
Trace fossils
provide us with indirect evidence of life in the past tracks, trails, or burrows determining "up direction"
Which of the following best describes the appearance and composition of a conglomerate?
rounded fragments; poorly sorted
how do sedimentary rocks form
sediments are transported, deposited, and lithified. -preexsiting rocks weathered -directly by organisms -as a direct chemical precipitate
debris flows
sediments loaded down with water (boulders to clays) travel downslope at various speeds. called mudflow if particles travel quickly in mud matrix. common around volcanoes and alluvial fans.
types of mudrocks
siltstone, claystone, mudstone, slate, and shale
Chemically produced sediment
some weathering products may be removed in solution, and these ions may end up in the ocean, a lake, or a rift basin.
Metamorphic Grade
somewhat informal way to indicate intensity of metamorphism Yield different mineral assemblages Metamorphic index minerals can approximate grade Increasing grade= grain size coarsens, stable at higher temp and pressure (slate, phylilite, schist, gniess)
Slaty cleavage
splitting into thin sheets along foliation Found in the rocks slate and phyllite
Limestone Ooids
subrounded sand-sized particles fromed by precipitation of calcite or aragonate in concentric layers around a nucleus grain as it washes back and forth in shallow marine waters. looks like bullseye when cut in half more rounded than sandstone aragonite over time converts to calcite pisoliths are >2mm
"In stratified glacial meltwater deposits, you might assume that a layer with larger grain size was deposited during:" (summer or winter)
summer
Foliation
the process of being split into thin sheets or laminae
Limestone depositional environment
transitional
Carbonates tend to deposit in very deep marine locations.
true
deposits of turbidity currents
turbidites
Water almost always flows __________.
turbulent
Which type of flow follows an irregular flow path in both the vertical and horizontal direction?
turbulent
Suspension particle movement
turbulent eddy currents, suspended load clay and silt sized particles, mixed throughout water, doesn't settle. smallest materials
Limestone textures described by:
types of grains (allochems) forming framework of rock carbonate mud matrix- fine grained presence or absence of coarsely crystalline calcite cement texture and structures
differential stress in metamorphic rocks
unequal in different directions can result in preferred orientation of mineral grains (ex. convergent plate boundaries)
Till
unsorted material deposited from glacial ice.
Sedimentary deposits with ________ grains would likely make better reservoirs for petroleum, natural gas, or groundwater because they tend to have a higher porosity and permeability
well-sorted