Sed Strat Review Test 1

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Kaolinite

Back 1

composed of an open faced sandwich of one tetrahedral sheet and one octahedral sheet in each repeating layer or a 1:1 arrangment, they layers are tightly bonded together, with only one hydrogen cations betweeen them so thier structure is -t-o-H+-t-o-H+-t-o-

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illite

Back 2

stable K-rich 2:1 arrangment, aluminum hydroxyl octahedral sheet, most abundant clay mineral of all, has about 70-80% as much potassium as muscovite in the intrelayers and has slightly more silicon and less aluminum in other parts of the structure than muscovite, the potassium cations gie the structure strong ionic bonding, does not expand readily through

Front 3

Smectite

Back 3

2:1 ratio a small amount of mg2+ substitutes for al3+ in the gibbsite like octahedral sheets creating a small negative charge. because the charge is samller than that of ilite, water is readily absobed in the interlayersm making the montmorillonite structure very expandable in one direction (almost double in volume) some sodium smectitces expand to 10 times thiere original volume

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glauconite

Back 4

2:1 ratio,iron rich, cations are iron not magnesium, shrimp poo, jcontain spherules and pellets, they are a product so a good indicatore of a specific range of enviromental conditions. produced under reducing conditions

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chlorites

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green mica that gives greenschist grade metamorphic rocks their color 2:1 sandwich of tetrahedral-octahedral-tetrahedral components -t-o-t-brucite-t-o-t-brucite-t-o-t

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vermiculite

Back 6

highly expandable, have a complex arrangment of water molecules bonded toghether in the interlayers

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mixed layers

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most clays, random mistures of illite-montmorillonite is most common.

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Eh

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the potential for either oxidation or reduction, short for redox potential, is measured using an elcytrolytic cell

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pH

Back 9

expresses hydrogen ion concentration as the negative of the log to the base 10 of hydrogen ion concentaration, or -log10 [OH-] = 10(-7) have a pH of 7

1-7 are acids

7-14 alkaline (base)

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reduction reactions

Back 10

oxidation does not occur without reduction and vice versa.

Reduction is the process by which an atom or ion gains electrons

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oxidation reactions

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oxidiation is the process by which an atom or ion loses electrons.

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hydration

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processes involve the chemical combination of pre-existing minerals with water, ex hydration of iron oxide (hematite) to form Limonite

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Dehydration

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the removal of water from some pres-existing mineral. ex dehydration of gypsum to form anhydrite

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hydrolysis

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the replacement of cations in a mineral structure by hydrogen ions derived either from water or more likely, from acid

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Fluidized sediment flows

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concentrated dispersions of grains supported by pore water between the grains. they begin to flow laterally when something increases the pressure on the intersititial pore water, turning the once firm sand into a souply liquid

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laminar flow

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fluid flow in which individual particles of matter (masses of water and air) move uniformly as subparallel sheets or filaments of material. in other workds, flow lines (streamlines) are generally parallel with one another and the base of the fluid

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turbulent flow

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fluid flow in which individual particles of matter (masses of water and air) move in randowm, hapharzard fashion with eddies that descend and rise; flow lines (streamlines) generally crisscross one another in a intertwining fashion

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grain flows

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type of rapid sediment gravity flow that consists of cohesion less sediment disperesed in air and maintained in transport by the dispersive pressure generated by grain to grain collisons

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mudflows

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slurry like mass of liquefied mud that moves downslope under the force of gravity

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debris flows

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type of sediment gravity flow that consists of a plastic slurry of poorly sorted clastic grains mixed with water

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aggradation

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vertical accumulation without etiehr progradation or retrogradation

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reactivation surface

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the migration of a ripple is interrupted ; the ripple is eroded back and them burried by a new advancing bedform; such an interruption produces a tiny erosional surface between cross strata

Front 23

laminations

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fine scale (typically thinner than 1 cm) internal banding or layering present in some sediment and sedimentary rocks. lamination can parallel bedding planes as well as cross bedding surfaces

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bedroms

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primary sedimentary structures like ripple marks, dunes, and plane beds that appear as three dimensional features on the top surface of bedding planes

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bioturbation

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variety of processes by which organic activity deforms or alters pre-existing sedimentary rocks

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climbing ripples

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formed by low aggradation, which is when the sedimetn supply increases the ripples build upwards

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lenticular bedding

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small lenses of sand in muddy beds, occur when sand is trapped in troughs in the mud as sand waves migrate across a muddy substrate

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flaser bedding

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variety of ipple beddin characterized by thin, discontinous streasks of mud intermittently interbedded within cross laminated sand and silt layers

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sorting

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variation in the grain size of clasts in sediment or sedimentary rocks and the dynamic process by which the variation in particle size diameter from the mean or average is achieve.

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modal size and class

Back 30

value of the most frequenlty occuring item in a set of data; grains size diameter class that is most abundant and the specific most frequently occuring grain size diameter

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unimodal sediments

Back 31

sediments contianing a single modal size class more prominent than the adjacent classses, which rapidly taper to nothing

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bimodal sediments

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containing 2 or more prominent size classes in addition to the size class (orthoconglomerate)

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polymodal sediments

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have many prominent size classes in addition to the size class (paraconglomerates)

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kurtosis

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peakedness compares sorting in the central portion of a population with that in the two tails

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mean

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average in size

Front 36

Quartz arenites

Back 36

they consists almost entirely of sand sized monocrystalline quartz grains (many with abraded authigenic overgrowths) >90%, supermature

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feldspathic (arkosic) arentite

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the major framework grains found in this sandstone type are monocrystalline quartz and feldspar, feldspar content typically reaches 40 - 50 %

Front 38

Lithic Arenites

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clasts of moncrystalline quartz (30 - 80%) and rock fragments (5-50%) are the most important consituents in theis sandstone family

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Wacke (graywacke)

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texturally immature and consists of predominately sand sized framework clasts that float in a finer grained matrix of silt and clay sized particles

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monocrystalline quartz

Back 40

single crystal quartz grains, derived from hydro-thermal veins often contain fluid filled vacuoles and other miner inclusions, undulatory extinction characterizes quartz from plutonic and high grade metamorphic source rocks,nonundulatory extinction indicates volcanic rock sources or grains recycled from older sandstones

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polycrystalline quartz

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when composite grains of multiple interlocking quartz crystals are define as rocks fragments

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milky quartz

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discoloration from trace minerals

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authigenic quartz

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refers to material that is formed or generated in place, for example minerals that grow in place within a rock, such as quartz and feldspar overgrowths that develop around transported grains after they are deposited

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plagioclase feldspar

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differ in abundance in sedimentary rocks, if found it means that chemical weathering is not extensive, prbably because of climate and or high source relief. low precipitation in an arid setting, or an arctic climate in which precipitation occurs as snow and ice rather than as rain limits hydrolysis and produces feldspar rich debris

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major types of lithic fragments found in sedimentary rocks

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volcanic rocks, slate, phyllite, shale, and chert are more abundant than those of plutonoic igneous rocks, gneiss, and schist

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differential compaction

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when both sands and muds are subjected to burial pressure, the muds compact almost twice as much as the sands

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sandstone dike

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the dike forms when an overpressured liquiefied sand layer squeezes upward into cracks in the overlying sediments

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compaction deformation

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example flat objects such as mica flakes can be bent or defomred bwtween sand grains, rock fragments such as shales are often deformed by the pressure applied to them and may break down to clays

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matrix/pseudomatrix

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when shales are deformed into clays gives a fake impression that there was a clay matrix

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pressure solution

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under greater pressures grains begin to dissove at the point where they contact other grains

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calcite cementf

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more common cement in sandstone because it is much more sluble than silica, common in near surface conditions

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quartz cement

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enormous amts of groundwater must move through a rock to produce silica cement, ground water moves very slowly and silica takes a long time to precipitate

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iron oxide

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mostly redbrown hematite (fe2o3) and yellowish iron hydroxide, limonite(feo*oh), comes from the weathering of iron rich silicate minerals sucha s biotites, pyroxenes, and amplhiboles and from the leaching of iron rich clays

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authigenesis

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new minerals frow from old recycled chemicals

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Recrystallization

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an existing mineral retains it original chemistry, but the crystal sizes frow larger

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replacement

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a completely different mineral takes over the space once occupied by another

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conodont color

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conodonts (toothlike fossils) undergo color changes with increased temps.

values 1 - 5

1 = pale yellow < 80% degrees Celcius

5 = black >300 degrees celcius

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vitrinite reflectance

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the woody organic matter kin lignites nad coal changes and become shinier as it is subjected to higher and heiger temps

maxdiagenetic temp can be estimated between 100 degrees and 240 degrees celcius

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transformation of clay minerals

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clay minerals have diff ranges of stability above 100 degrees, smectities begin to break down and form mixed layer clays, above 200, mixed layers become illite, and about 150 degrees celcius kaolinite begins to change to illite or chlorite as temps increase, chlorites begin to replace illite as well, illites turn into muscovite by 300 degrees celcius, then only micas remain.

Front 60

zeolite facies

Back 60

zeolites are common alteration products of volcanic rocks in the absence of carbonates, temp stability heulandite and analcime form at temps below 100 degrees, laumonite forms at about 100, and is stable up to 150 degrees prehnite and pympellyite are stable above these temps. so zeolites serve as excellent geothermometers

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average gradient on alluvial fans

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average range is 5-10 degrees

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gradient range on alluvial fans

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1-25 degrees

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longitudinal bars

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an obstacle that is difficult to erode causes a flow serparation and accumulates sediment in its lee, which forms longitudinal bars.

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transverse bars

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On their downstream end, cross bedding may develop; sanider, protected channels between the longitudinal bars usually develop ripples and dunes. they are composed of low flow velocity features, particularly ripples, dunes and trough cross bedding.

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cross-channel bars

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wedge shaped sandbars that form at oblique angles to he flow, form where a small channel discharges into a larger one or where theflow is forced to spread laterally or flow obliquely

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oxbow lakes

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an abonadoned meaner is islated from the river

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natural levees

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boreders the meandering channel, it is a low wedge shaped ridge that usually confines the flow within the channel

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crevasse splays

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sedimetnary deposit (largely sand) that pours out of a breach in the natural levee and forms a small delta on a flood plain or interdistributary bay; a marsh

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channels

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area that water flows down stream

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point bars

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forms at the inner back of hte meander

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back swamps

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is the section of a floodplain where deposits of fine silts and clays settle after a flood. Backswamps usually lie behind a stream's natural levees.

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clay plugs

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the oxbow lakes fill with laminated clay, silt, and organic matter that settle out of suspension after the meander is abondoned

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interdistributary bays and marshes

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regions between deltaic distibutaries that are flooded and marshy and trap mostly muddy sediments

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distributary mouth bars

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a sandbar that forms across the mouth of a delta dis tributary channel, usually where the freshwater flow of the river slows down as it meets the sea and dumps its load of sediment

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prodelta slope deposits

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grades into the open shelf

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distributary channels

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is a stream that branches off and flows away from a main stream channel. They are a common feature of river deltas. The phenomenon is known as river bifurcation. The opposite of adistributary is a tributary.

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growth faults

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syndepositional fault formed when dense, overloaded sediments on the front of a delta slope slump downward

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tide dominated deltas

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has many linear channels parallel to hte tidal flow and perpendicular to the shore

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river dominated deltas

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a large volume of sediment and tends to be lobate when there is a moderate sediment supply and elongate when the sediment supply is large

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wave dominated deltas

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is smoothly arcuate, the wave action reworks the sediment and makes such deltas much sandier than other types of deltas

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microtidal estuary

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tidal range 0-2m, wave generated sand bodies such as alligned beaches and recurve spits are common. Flood tidal deltas adn storm generated washover fans are also prominent

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mesotidal estuary

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tidal range 2-4m; oceanwards ans horeward accumulations of sand form the ebb and flood tidal deltas respectively. Ebb tidal deltas are well developed. the strenth of ebb flow relative to wave energy controls and seaward elongation of hte delta. the back barrier region is typically cocupied by marsh developed in part on older flood tidal delta deposits

Front 83

macrotidal estuary

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tidal range >4m; typical funnel shaped embayment with offshore linear sand bars and broad marginal tidal flats.

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bouma sequence

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high to medium to low flow regime sedimentation

E - laminated mud (pelagic sedimentation or low density turbidity current deposition)

D - laminated silt and mud (lowest flow velocity plane beds)

C - ripples, wavy lamination, convoluted bedding (lower flow velocity)

B - Plane parallel alminae (high flow veolicty plane bed)

A - Massive and graded sand deposits (high flow velocity and rapid deposition)

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Sedimentology

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is the study of the processes that erode, transport, and deposit sediments

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Sedimentary Petrology

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is the study of the characteristic and origins of sedimentary rocks

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Stratigraphy

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is the study of the complex distribution of the sedimentary rock record in space and time