earth mat Flashcards
marks the path of the subducted plate as it descrnds into the asthenosphere
inclined seismic wadati benioff zone
3 devastating earthquakes along inclined seismic zones
chile 1909
alaska 1964
sumatra 2004
produced the banda aceh tsunami killed 300k in indian ocean region
sumatra 2004
which convergence occured thqt brought the closing of tethys ocean
convergence of india and asia
when did eurasia and india formed himalayan
40Ma
what is the limestone on top of mt.everest
chomolungma
which ocean was the limestone of mt.everesy priginated?
tethys ocean
how many elements were fiscovered
92
what is h1
h2
h3
protium
deutrium
tritium
varieties of garnet
almandine
andradite
grossularite
pyrope
spessartine
uvarovite
abdundant in pelitic metamorphic rocks including schists gneisses and granulites occurs ib laumbium rich pegmatites
almandine
metamorphosed carbonate rocks and skarns
andradite
grossularite
ultrabasic rocks inclusing mantle peridotes and kimberlites
pyrope
scarcer mineral in skarns
spessartine
scarce mineral in chrominum enriched ultrabasic rocks
uvarovite
haracterized by aggregates of sheaves of radiated
microscopic silica crystals that are often water
bearing
chalcedony
Stable at relatively low temperatures and
pressures; widespread in igneous,
metamorphic and sedimentary rocks
Alpha quartz
Stable at elevated temperatures and relatively
low pressures; occurs primarily in volcanic
rocks
Beta quartz
Stable at high temperatures and low pressures;
occurs in silica - rich volcanic rocks
Cristobalite
Stable at relatively high temperatures and low
pressures; occurs in silica - rich volcanic rocks
Tridymite
Stable at high pressures; occurs in meteorite
impactites, kimberlites and ultra high
pressure metamorphic rocks produced at
great depths
Coesite
Stable at very high pressures; occurs in
meteorite impactites and is theorized to be
an important constituent of the deep mantle
Stishovite
Stable at low pressures and fairly low
temperatures; forms around hot springs, in
soils and in ocean basins, especially as
accumulations of diatoms and radiolaria
opal
felsic utonice igneous to ks and pegmatites and meanirphic schists common variety is bright green amazonite tricilinc stubby crystals
microline
felsic plutonic igneous tovks metamorphic schists and gneisses monoclincic prismatic with evident symmetry
orthoclase
high temp kfels more transparent than others monoclinic
sanidine
what does IYGS stands for
international unuion of gelogical science
hydrous from secondary mineral 100-250
zeolite
By alteration of nepheline
in silica - undersaturated,
feldpathoidal igneous
rocks
Hexagonal; prismatic;
rare
Cancrinite
Scarce mineral in
metamorphosed
limestones/skarns
Isometric; equant; rare
Lazurite
In silica - undersaturated,
potassium - rich volcanic
rocks
Hexagonal; stubby
prismatic;
Leucite
In silica - undersaturated,
feldpathoidal igneous
rocks
.Hexagonal; prismatic;
rare
Nepheline
In medium – high grade
metamorphic carbonates/
skarns and pelitic schists,
gneisses
Tetragonal; prismatic;
square sections
Scapolite *
In silica - undersaturated,
feldpathoidal igneous
rocks.
Isometric; equant; rare
Sodalite
ZEOLITE GROUP
Isometric; equant; trapezohedra
Analcime
Trigonal; equant; pseudocubic
rhombohedra
Chabazite
Monoclinic; platy – capillary;
scaly – fi brous
Clinoptilolite
Monoclinic; prismatic – platy
Heulandite
Monoclinic; prismatic
Laumontite
Orthorhombic; prismatic – acicular;
radiated – fi brous
Natrolite
Monoclinic; tabular – platy; close
radiated, sheaf - like groups
Stilbite
what are the zeolites?
analcime
chabazite
clinoptilolite
heulandite
laumontite
natrolite
stilbite
feldspathoids group
cancrinite
lazurite
leucite
nepheline
scapolite
sodalite
what are granitic dikes
aplites
when melt of any composition comes in contact with water or air
quenching
eounded masses of radiating crystals
spherulites
cristobalite seed crystals grow into white snowflake forms
snowflake obsidian
glassy Si92 rich volcanic rocks higher water contents than obsidian
perlites
cloudy appearance and curved or subspherical cooling cracks
perlitic tecture
rocks contianing5-30% vesiclez
named by a modifier
Vesidular basalt
rocks less than 5% of vesicles
vesicle bearing basalt
cilicon and oxygen percent on earth
75% weight
94.7 by volume
the obly anion in the abundant elements of the eart
oxygen
what are the 4 common vcanic rocks?
rhyolite
dacite
andesite
basalt
what are the percents of volcanic rocks
> 66%
63-66%
52-63%
45-52%
what are under the feldspar group
calcite
potassium felds
sodium
sio2 concentrations tend to be enrich with minor elements suchc as
li be and ba
examples of minor elements
chromium
manganese hydrogen
titanium
phosphorus
remaining after melt remov has a different chemical co
position than ghe original parent rock id enriched in compatible elements and depted in incompatible elements
residual rock or restite
what are the incompatible elements
k rb sr and ba
enumerte the LREE
lanthanium la
cesium ce
praseodymium pr
beodymium Nd
samarium Sm
enumerate HREE
europium eu
gadolinium Gd
terbium Tb
dysprosium Dy
holmium Ho
erbium Er
thulium Tm
ytterbuum Yb
lutetium Lu
elements chsrwc as having a relatively high ionci charge guven raidus immobile tend to remain on restite
high field strength
valence charge trsce elements with a ratio of greater than 0.2 sre
large ion lithophile LIL elements
mobile in partial melts and useful in determining the role of hydrous fluid interaction and the parental osurce of the partial melt
large ion lithophile LIL
faure calculate the mean of this to distinguish between different magmatic environments such as ocean floor ocean islands and island arcs
Sr87/Sr86
mullen used this to identify the five basalts
MnO2 TiO2 and P2O5
minor elements to use the distungusihed the mod ocean eidge basalt and ocean island basalt
Rb sr Y nb
percent of minerals
felsic
intermediate
mafic
ultramfic
<40% Dark colored mineral
40-70%
70-90%
>90%
IUGS COLOR INDEX
<35% DCM leucocratic
35-65% mesocratic
>65% melanocratic
indirect scheme using data derived from chemical analysis of a rock samole first norm classification was deviae dby cross iddings pirsson and washington referred to as CIPW used in apahanitic or glassy volcanic rocks in modal cqnnot be determined
Normative mienralogy
rocks are charac by minerals with unusually high Al2O3 contents
peraluminous
rocks contain normative or modal minerals with unusually high K2O and/ or Na2O contents
peralkaline
rocks contain mafic minerals with average aluminum contents
metaluminous
rocks contain madic minerals with low alumnium concentrations
subaluminous
who was ghr skeme iniated the rock nomenclature in 1960 for IUGS
albert streckeisen
in the QAPF diagram what does plagioclase invludes
scapolite
feldspathoids included in QAPF
nepheline sodalite cancrinite leucite analcite nosean hauyne and kalsilite
less than 2% and 0.5 % Co2 and only the Na2O +K2O are plotted in the vertical
TAS
partial melting of rock magmas and lavas that solidify to produce igneous tocks in crust are formed by it produce
liquid melt fracrion enriched in lower temperature constituents and a residual rock component enriched in higher temperature refactory elements
anatexis
implies that solids and melt separate into isolated fractions that do not continue to react together during the melting process
fracrional melting
geothermal gradueng of upper 10km
~25C/km
geothermal gradient in old continental lithosphere
5-10C/km
geothermal gradient at hotspots ocean sprrqding ridges and volcanic arcs
30-50C
also known as adiabatic melting wc results a decrease in pressure and is related to rock depth whereby 10km depth corresponds approx 3.3 kbars
Decompression melting
agent that reduces the melting temperatureof a substance
flux
father of modern petrology
bowen
closed system diversification original nelt rvolves jnto one or more melts with different composition
differentiation
early formed crystals are segregated from the remaining melt early proponeyn of fractional crystallization
fractional crystallization
bowen studied in what university
carnegie institute of washington in 1910
studied rocks from a shallow igneous intrusion named situated in New Jersey west of new york ~2”” mys intrusion that consists largely of basuc rocks including basalt, diabase (coarse grained basalt) and gabbro
palisades sill
evidence for crystal settling and convective flow
Tertiary age Skaergaard Inteusion
tertiary age in greenland contains sedimentary like features such as cumulate layering graded bedding cross bedding and slump structures
skaergaard
one parent magma fractionated to profuce geo or more distinctly different daughter magmas with different composition
liquid fractionation
involves the preferential diffusion of select ions within the magma in response to compositional thermal or debsity gradients as well as water content plays a huge role in transport and concentration of metallic ores deposits in plutonic systems
differential diffusion
liquid liquid fractionation occurs when magma separates i to two or more distinct immiscible liquid phase
liquid immiscibility
liquid immiscibility was seen in
deccan traps
triassic jurassic rattlesnake hill basaly of connecticutr
gorceful injection of magma fractures the surrounding wall
stoping
country rocks that fall
stope and xenoliths r thw results
foreign crystals bot generated by crystallization of the sureoubding magma
xenocrysts
liemstones and schists xenoliths stoped into a granitic magma
thorr region of donegal, ireland
suites of rocks that form in response to similar geological conditions
pectrotectonic associations
sudden flood burst of glacial lake water or water contained within glaciet
jokulkhlaups
named for south america andes mountains wc overlie the peru chile trench by far the most common calc alkaline volcnaic ro k froming at convergent margins
andesite
high aluminum basalts
tholeiitic arc
qrz -phytic volcanic rocks intermediate between andesite and rhyolite tas 77%
dacite
also known as latites and shoshoniteslower TAS 57% SiO2 contain phenocrysts of andesine to oligoclasw pmagioclase feldspar amidst groundmass of orhoclase and augite
trachyandesites
> 69 % sio2
~68-73% SiO2 assoc with explosive silicic wruptions producing fragmental glassy and aphanitic to aphanitic porphyritic textures
rhyolites
rhyodacites
contian >20% qtz and plag metaluminous
grabodiorites
known as plagiogranites are granodioritic rocks in wc sodium plagioclase representd half to two thirds of the total feldspar components
trondhjemites
young island arc produce
tholeiite basalts which are doung in oceanward side of volcanic arc newrest the rench boninites adakites
high Mg untermediated 52-68% groundmass contin phenocrysts of opx lack plag pehnocrysts encriched in chromium nickel volatile elements lree deelted in hree and hfs occur proximal to the trench bear geochemical signatureprodyct of subduction related arc systems high temp loe pressure remelting
boninites
silica srayrated >56% high lree low hfs derived by slab melting of eclogitw and garnet amohibolite from the deacending ocean lithosphere knly form where young think hot ocean kithosphere subducted beneath island arc lithosphere known to form at contiennt continetn colkision sites as a result of shallow slab subduction plutonic equivalent is trondhjemites and tonalites
adakites
an px bearing suite of rocks of generally granitic composition occur in ttg
charnockites
ttg aasoc oxcur in archean rocks
pilbara craton of australia and the bear-tooth and big horn mountains of wyoming
dark colored potassium rich trachyandesitws containing olivine and augute phenocrysts with a groundmass of labradorite leucite thickened lithospeherw fartehst from the trench rwgion in continent continent collisions in backarc basins
stoshonites
plutonic equivalent of rhyodacite and rhyolite
granitoids
used for silica oversaturated plutonic rocks that contain essential potassium feldspars and quartz form at mayyrw convergent margins tend to be peraluminous to metaluminous
granitoid
form by partial melting of basic to intermediate igneous rocks i namor above yhe subduction zone at ocean ocean or ocean continent convergent margins
i type granites
peraluminoud potassium rich s type granites and granodiorites are prticulary common at continent continent collisions
s type
detived from phyllosilicates minerals in graywackes and mudstones of the continental crust and accretionary wedge. peoduce two mica granites containing biotite and muscovite
perlauminous sedimentary
20-60% and 35-90% alkali to plagioclase feldspars assoc with precambrian cratons and convergent margins
granite
mantle derived larental magmas low Sr87/Sr86 rations <0.704 assoc with calc alkaline tonalites qtz diorites and gabbroic rocks degelop in island arc settings copper and gold mineralizations
m type granites
melting of an ig wous protolith from wither the downgoing oceanic lithosphere or the overlying mantle wedge enriched in Na2O and Ca2O and contain lower Al2O3 concentrations less than 0.708 derived from a mantle source enriched in mafic minerlas porphyry copper tubgsten and molybdenum prevalent along the mesozoic cenozoic andes mountains
i type granites
sedimentary crustal rocks in collision zones depleted in Na2O but enriched in Al2O3 peraluminous. >7.08 earlier se cycle. also known mica granites contain both muscovite and biotite rich in phyllosilicate mienrals tin deposists assoc with
s type granites
anorigenic produced by activitws that do not involve the subduction and collision of lithospheric plates enriched in akaline elements depelted in Mg Ca Al Cr Ni mote enriched ib LIL elemenyd and depelted in refractory elements peralkaline alkali rich
a type granites
fault bounded mark the site of present or former convergent margins been transporrted far from thwir site of irigin by thrust faulting and shearing
dismembered into fault blocks and junbled together in a haphazard fashion contain disrupted pelagic sediment layers basalt cumulate basic and ultrabsic layers and assoc with tectonic melanges
alpine orogenic complex
sheared heterogeneousrock assemblage embedded within a highly deforemed mud matrix form at subduction zones miced withcrocks formwd in forearc settings slices of eclogite peridoite and blueschist
tectonic mélanges
alpine presefved in orogenic belts serpentizied in the alps known as steinmann trinity types consist pelagic chert serpentinite hydrothermally altered peridotite and spilites (altered pillow basalts)
ophiolites
develop due to the extensional tectonics result in backarc spreading or forearc spreading
chromium petrotecronic
suprasubduction zone SSZ ophiolites
pricess by which epiclastic sediment transportation is initiated by erosion is
entrainment
occurs when mienrals such as clays and micas expand when wetted
slacking
rwsult from changes from daily seasonal in rock temperature
insolation
zone of
accumulation, is characterized by enrichment
in some of the constituents leached from the
A - horizon. The process by which materials
are translocated downward to be added to
the lower part of a soil is known as illuviation.
B - horizon
The process by which materials
are translocated downward to be added to
the lower part of a soil
zone of illuviation
commonly gives the
B - horizon a distinctly reddish or yellowish
humid climates, reprecipitation of
amorphous or crystalline iron oxides (e.g.,
hematite = Fe 2 O 3) or hydroxides (e.g.,
limonite ≈ FeOOH)
In humid climates,
where chemical decomposition is thorough,
clay minerals and bauxite are also concentrated in the B - horizons to form aluminum -
rich horizons.
n dryer climates, calcium carbonate
(CaCO 3) precipitates, producing B k soil horizons. In many cases, mineral precipitation in
the B - horizon binds soil particles together
into hard, nodular zones or into completely
indurated sub - horizons called
duricrusts.
most common examples of duricrusts are
the calcium carbonate
calcrete or petrocalcic
arid, desert climates.
Similar hard sub - horizons of silica and gypsum
( silcrete )
( petrogypsic
are partially cemented clods
of soil particles of various sizes that give
the soil a crumbly lump appearance.
Peds
hich are concentrations of illuviated material such as clays or iron oxides
that occur as layers or that envelope less -
altered cores.
Cutans,
which are prolate to equant
hard lumps formed by mineral precipitation and include concretions and nodules
of all sizes.
Glaebules
called the soil mantle ,
represents moderately to minimally weathered, slightly altered materials that are
transitional to the underlying, unaltered
parent material.
Where soils are developed over bedrock,
the largely unweathered bedrock constitutes
the so - called R - horizon or regolith horizon.
C - horizon,
has organized
soils into 12 major orders, which are fairly
easy to learn (Figure 12.20 ). Each order is
subdivided into as many as seven suborders
of which there are a total of 64. The suborders are subdivided into more than 300 great
groups, which are subdivided into some 2400
subgroups, which are further subdivided into
families and lastly into soil series. Some
19,000 different soil series have been mapped
in the United States alone
e USDA - NRCS (1999)
was developed with the endorsement of the
International Union of Soil Scientists (IUSS)
and the Food and Agricultural Organization
(FAO) of the United Nations. It divides soils into 25
orders and 98 groups based on the physical
characteristics of the soil
Unlike the USDA -
NRSC classifi cation scheme, climate is not
considered in the WRB. The long - range goal
of these efforts is to promulgate adherence to
a single standard worldwide soil classifi cation
scheme.
1998
a world reference base (WRB) for soil sciences
Most geotechnical and engineering personnel in the United States use th
soils are given
names and symbols according to their particle
size distributions, notably the proportions of
gravel, sand, silt and expansive clays, and to
the content of non - expansive clays and organic
materials in the soils. Engineering defi nitions
of gravel, sand, silt and clay do not correspond exactly to those used by geologists,
who employ the Wentworth – Udden grade
scale (W - U scale)
Unifi ed Soil Classifi cation System
where particle diameters
exceed 4.0 mm (as compared with 2.0 mm
in the W - U scale).
Gravel (G),
where particles range from 0.074
to 4.0 mm (as compared with 0.0625 –
2.0 mm in the W - U scale
Sand (S),
where particles range from 0.004
to 0.074 mm (as compared with 0.004 –
0.0625 in the W - U scale).
Silt (M),
which are defi ned in the same
way in both systems as particles smaller
than 0.004 mm (4 μm). The USDA - NRCS
classifi cation system, however, defi nes
clays as particles smaller than 2 μ m.
Clays (C),
Gray to brown A - horizon epipedon; B sub - horizons
rich in clays with reasonably high concentrations
of bases such as Ca, Na, Mg; reasonably high
moisture content
Relatively humid areas with sparse
forest or savannah cover; base and
water content yield fertile soils
Alfisols
Weak horizon development; rich in disordered
clays and Al – humus complexes; high
phosphorous retention; good moisture capacity
and cation exchange capacity
Form in a wide range of non - arid
climates; mostly on volcaniclastic
materials; tend to be quite fertile
Andisols
Sparse organic material in A - horizon epipedon;
well - developed B - horizons, often rich in Ca -
carbonates, even gypsum; low moisture content
for long periods of time
Dominate in arid regions with sparse
rainfall and vegetative cover; suitable
for agriculture only if irrigated
ardisols
Lack signifi cant soil horizon development; soils
only because they have the capability to support
rooted plants; often sand rich
Occur in any climate or setting; mostly
on young surfaces; also in chemically
inert parent materials or on slopes
where erosion occurs
entisols
Permafrost soils and soil features; patterned
ground, broken horizons and incorporation of
organic matter in lower horizons produced by
frost heaving and churning
In high latitude and/or high elevation
areas where soils freeze for long
periods
gelisols
Mostly very organic rich O - horizon; deeper
horizons tend to be poorly developed, if at all
Mostly peat and muck from partially
decomposed plant debris in swamps
or bogs or water - saturated soils in
areas of poor drainage
histosols
Weak horizon development; less clay concentration
in B - horizon than alfi sols; carbonate and
silica - rich B - horizons may occur; reasonably high
moisture content
Form in a range of non - arid regions
from subpolar to tropical; often with
forest cover; less suitable for
agriculture than alfi sols
inceptisols
Very dark, thick, organic - rich O and A epipedon;
high base content, especially calcium; clays with
high cation exchange potential
Common under grasslands in semi - arid
plains and steppes with seasonal
moisture defi cits; some under forest
cover; great for grain production
mollisols
Weak horizon development; extreme decomposition
and base depletion; clays, mostly kaolinite, with
low cation exchange capacity; bauxite under
extreme conditions; quartz and iron oxides
Develop over long periods of time in
tropical/subtropical settings with
high rainfall and thick vegetative
cover; generally infertile
oxisols
Thick O - horizon; well - leached A - horizon with low
Fe, Al, Ca; well - developed B - horizons with clays,
reddish iron oxides or black humic material;
good cation exchange
Dominate under coniferous forests; in
areas with reasonable rainfall;
generally suitable for agriculture
spodosols
Well - leached A - horizon with some organics;
clay - rich B - horizons with generally low base
contents as Ca, Na and K are largely removed
which distinguishes them from alfi sols
Humid climates; low base content;
soils unsuitable for sustained
agriculture unless fertilized with Na
and K
ultisols
High expansive clay content; large changes in
volume associated with wetting and drying;
cracks when dry and other evidence of soil
movement; may have horizons
Poor soil for structures given the
volume changes and tendency for
strength and plasticity to change
during wetting and drying
c
vertisols
<5% fi nes; continuous size variation over a range Well - graded gravel GW
Clean gravel
<5% fi nes; mostly one size or polymodal Poorly graded gravel GP
Clean gravel
> 12% fi nes; mostly silt Silty gravel GM
12% fi nes; mostly clay Clayey gravel GC
Dirty gravel
<5% fi nes; continuous size variation over a range Well - graded sand SW
C>5% fi nes; mostly one size or polymodal Poorly graded sand SP
lean sand
> 12% fi nes; mostly silt Silty sand SM
Dirty sand
re those
that contain more than total 50% sand and
gravel by weight. Gravels contain more gravel
than sand, whereas sands contain more sand
than gravel. Coarse - grained soils are further
subdivided according to the percentage of
fi ne - grained components (clays + silts).
Coarse - grained soils
contain less than 5% fi nes
Clean
soils
contain more than 12% fi nes
dirty soils
contain
more than 50% silt plus clay. Silts are defi ned
as soils with more silt than clay, whereas clays
contain more clay than silt. Fine - grained soils
are further subdivided according to their mica
content, organic content and their degree of
plasticity. Highly organic soils are prone to
compaction, dehydration and decomposition
resulting in volume loss, which makes these
soils unsuitable for construction. Soil plasticity is largely determined by the soil ’ s ability
to absorb water and therefore by their smectite (expandable lattice) clay content. As will
be seen in the following section, plasticity is
an extremely important measure of the
mechanical properties of soils and allows one
to predict how they will react in different
circumstances. The “ L ”in the group symbols
stands for loam, a soil that contains appreciable amounts of both silt and clay in the fi ne
fraction.
Fine - grained soils
is the amount of stress a soil can
bear without failing by rupture or plastic
fl ow. It is an expression of the ability of a soil
to resist irreversible deformation such as inelastic changes in shape, volume and position.
Strong soils are quite resistant to stress and,
along with many kinds of bedrock, generally
provide excellent substrates for buildings.
Weak soils are subject to compression, collapse or fl ow when stressed and therefore
provide poor substrates for structures
Soil strength
Problems for engineers arise because soil strength
can change, especially in response to changes
in water content (Box 12.3 ), so that formerly
strong soils loose strength and become weak
soils that fail by rupture, fl ow plastically or
even fl ow like a liquid.
The measure of a soil ’ s tendency to change
strength is expressed by
measure of the change in soil strength that
results from changes in water content and
various kinds of disturbances such as vibrations, excavations and loading that stress
soils. Soil sensitivity in response to water
content, easily determined in the lab, is commonly expressed by Atterberg limits that
permit the subdivision of fi ne - grained soils
into four classes on the basis of how they
behave as their moisture content changes
(Figure 12.21 ).
soil sensitivity
soils, (3) plastic
soils, and (4) liquid soils. The boundary
between brittle solids and semi - solid soils is
which is the
water content below which soils do not shrink
as additional moisture is lost during drying
shrinkage limit (SL
Above the shrinkage limit,
semi - solid soils shrink and crack as they lose
moisture and become progressively more stiff
and brittle. Soils that remain brittle or semi -
solid under all conditions of potential moisture content tend to be strong and provide
excellent substrates for most construction
projects so long as they are not loaded beyond
their rupture strength. Solid bedrock is even
better
eparates semi - solid
soils from plastic soils and is the water content
at which soil deformation changes from
rupture to plastic fl ow (Figure 12.21 ). Plastic
substances change shape and/or volume in
response to stress or pressure but do not
rupture visibly. Because they retain cohesive
strength, they do not fl ow like a liquid. Plastic
soils are moisture sensitive in that their
strength decreases and they deform more
easily as they become progressively less cohesive with increasing moisture content. This
helps to explain the many slope failure incidents that occur following heavy rainfall and
the concurrent infi ltration of groundwater
into soils.
plastic limit (PL
of a soil is a measure
of its cohesiveness, which is sensed as a sticky,
cohesive feel to the touch. It generally increases
with clay content (especially expandable
smectites) and water content. Soils with low
clay content tend to be relatively non - cohesive
and therefore possess relatively low plastic
limits. Soils with high clay content tend to be
much more cohesive and to possess signifi -
cantly higher plastic limits. Because plastic
soils deform when loaded, they do not make
good substrates for major construction
projects
plasticity
separates plastic soils
from liquid soils (Figure 12.21 ). It is the water
content at which soils lose their shear strength
and begin to fl ow. When a suffi cient amount
of moisture has been added to a soil, it may
begin to behave as a liquid; that is, it will
loose cohesive strength and begin to fl ow
under its own weight. This can have disastrous consequences for the structures placed
such soils. The liquid limit tends to be rela-
e liquid limit (LL)
contain less than 30% gravel in their detrital fraction and contain mroe sand
sands and sandstones
epiclastic sediments contain 5-30% gravel in ghe epiclastic fractuon
gravelly sands or gravelly muddy sandstones
if a sandstone contains less than 5% gravel and has a sand:mud ratio greater than 9:1
pure sand (arenites)
they pxcupy the four sectiond in the bottom left portion of folks GSM diagram
mudrocks
less than 5% gravel
sandy muds and sandy mudrocks with san mu ratio >1:9
this prefix can be sued if any gravel occurs in the muds or mudrocks
gravel bearing
they occupy the six sectors in the bottom right portion of GSM
sands and sandstones
an attmeot to represent the thpical particle size in the population and detrital grain populations can be described by 3 lf this
central measure
which a best fit line is plotted for similar data
frequency curve
most anudnant particle size easily determiend when size data are plotted in a historgram
mode
particle size such that half the population is larger and half is smaller
median
large meteor that explodes in space
bolides
areas where bolides collided with earthes surfaces producing inpactitites
breccia
A well-sorted, matrix-free conglomerate, which forms where the sediment transported and deposited comprises only pebble and gravel grades.
sieve deposits
fault collapse and rockfall breccias are oligomictic composition:
mature, quartz rich conglomerates
produced by barious combinations of sedimentary and tectonic processesthat mic several rock types and tectonic prcosses that mix seceral rock types are
melanges gravelstones
this decompose less rapidly and are more common preserved in gravelstones derived from magmatic atc and i tracratonic rift
Granitoid rock dragmentd
generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz-poor monzonites to quartz-rich quartzolites.
granitoids
ise dto documeny strike slip on the san grabriel fauly in southern california
ridge basin breccia
part kf major transfom plate australia and pacific plate
alpine fault
recognized unusual clasts derived from ultramafic rocks and greenschist amohibolite grade schists in pliocene conglomerates deposited i cascade valley
sutherland
minimum eight lateral slip on the alpine since 3.6 Ma has been 27km/Ma up to
35km/Ma
detived from caples and toesse terranes wc are now lcoated 420 mn to the southwest of the
maruia basin
abergae dectral slip on the alpine fault is
37km/Ma
sandstone stuat contain 75-95 quartz and have more feldspar then lithic feagments
sub arkoses
less than 75% Q plit in one of the four sectors in the bottom portion
submature to immature arkose
those with neglible mud matrix and in boundary at 5%mud
arenites
uplofted recycled accretionary complexes
subduction complexes
exposed in orogenic belts some distances from convergent plate boundaries
foreland uplifts
consists of stable cratonuc areas that are divided into shields and platforms
continental block source areas
consist primarily of precambrian plutonic and high grade metamorphic rocks such as granitoids gneisses and grnaulitws
shields
charac bt a relatively thin veneer of largely mature detrital sedimentary rovks and or carbonate sedimentary rocks that overlie sgield rocks
platforms
sediments are derived from pre existing mature and sed rocks overly plutonic basement rocks in a stable platform setting with very low reloef
craton interior
both platform sed rocks and plutonic basement shod rocks are exposed as soruce rock thpes in settings of low to moderate relief
transitional cratons
basement of plutonic igenoud and metamorphic rocks are exposed in an area of high relief resilting drom uplift along dailts in contintental aetting
uplifted basement
produced by the minimal decomposition of ferromagnesian mienrals and commonly from in alkaline soils with impeded drainage high latitutdes where precipitation and temperatures arw low
chlorites
product kf the weathering kf ferromagnesian minerals plud plag favored impeded drainage alkaline conditions and semi arod climates
smectites
common products of weathering of feldspars k felds most common in temperated region soils with near neutral pH
illites
common in mod latitudes semi arid to temperate soils witj slightly alkaline pH
mixed layer illite-smectite clays
warm humid acidis soul common i nsubtropics cations tend to be leached from inetrlayer sites gives rise to degraded illites and kandites such as
kaolinite
wam humit high acidity low pH intense deomposition allows silica to sissolve readily giving rise to
gibbsite and ohter minerals of the bauzite suite
comkon at high latitudes
chlorites
common at low latitutdws
kaolinite
common in younger tertiary rocks
smectite clays and smectite illite
older rocks dominated by illite
potassium iron rich illite produced in marine envi dome generated in slow precipitation oxidizing envi also forms by relacement of fecal pellets under marine conditiond are reducing its sand grains occur as disseminated grains in sands in areas ate detrital influx large indicateor of of marin sedimentation
glauconite
colmonly form around decomposing organic matter that reduces iron enabling it to he removed in wolution
redcutipn spots
smectite rich claystones for
ed by the alteration of colabic ash deposits generated by explosive eruptions
popcorn liek
bentonites
used for organic rich mudstones and claystones
sapropel
oil cam be extracted by rhe process of
pyrolysis
bituminous oragnic material in mudrocks buried and heated to 100-140 ac is converted into petroleum and when heated into petroleum and when heated over 160 converted into natural gas
kerogen
where is sapropel in jurassic found
connecticut
later deeper diagenesis
mesodiagenesis
shallow diagenesis that lccurs as sedimentary rocks approach the sirface due toverosion
telodiagenesis
creation of this can reduce the porosity of lithic sanatones and conglomerates making them less efficient storwrs and transmitters of fuids
psuedomatrix
most common between grains i quartz sands and gravs with little or no plastic mateix and occurs less frequently in feldspathic sands and gravels occurs ober a range of depths and causes significant decreases in porosity
pressure solution or pressolution
one phase is more soluble than the other
concavo convex
what are the major cements in detrital sedimentafy rocks?
silica minerals cl
carbonate minerals
iron oxides and hydroxides feldsprs and clay minerals
quartz occurs chiefly in the form overgrowths in which the silica that lrecipitatws drom pore solutiond i itially nucleates on a pre existing detrital quartz grain
syntaxial quartz
morw soluble in alkqline waters than in mildly acidic waters common cement in volcanoclastic sediments a decrease in pH can cause cement precipitaiton but an increse can cause dissolution
opal
bladed commonly a radiating to divergent havit when observed under a petrogrpahic microscope
chalcedony
any lrocess that removws carbo dioxide from subsurface waters raises the pH making them more
alkaline
composed of one or more calcitw crystals that occupy small pore spaces bwteen settital grains
blocky cement
composed of si gle large calcite crystals that nucleates and grows to fill multiple pore spaces so tht it completely envelops several detra grians which appear as inclusions within a si gle calcite
poikiloptic cement
common in sedime ts deposited in failry arid terrestrial environemnts such as alluvvial fans braided streams and meandering stream channels and flood plains and deserts
hematite
occurs as stacks of platy layers called books preciipitate fairly shallow depths feom low potassium acidic pore waters during eodiagenesis and telodiagenesis acidic pore waters are common in continental settings
kaolinite cement
forms at higher temperatures and deths from high potassium alkaline pore waters especially in marine settings form mostly during late eodiagenesis and mesodiagenesis
illite cement
when k felds is altered and this is the fine grained mica related to nuscovite
sericite
at higher tenepratures both calcium and potassium deldspars are altered to
albite
volcanic fragements during progressive burial and diagenesis alter to
zeolite minerals
become unstable and are transformed into mixed layer clayes above 100C
smectite
converted into illite or chlorite above 150C
kaolinite
mixed layers clays transformed into more ordered illite above
200
all clay minerals are transformed into these above 300C
chlorite or micas such as muscovite
zeolite minerlas stable at 100
and stable from 100-200
and 200 above
analcime and heulandite
laumonite
phrenite and pumpelyite
transitional between diagenesis and low grade metamorphic process very low grade ascribed to this
zeolite or prehnitr punpellyite facies
form by the precipitation of material around a nucleation surfac esuchas fossil sand grain or shale chip wether outcrops as cannon ball like structures precipitation of kienral cmeent such as linonite or hematite
siderite purite marcasite form under reducing conditions and calcite is common formed under the ozidizing reducing conditions
concretions
similar to contetions but lack a well defined nucluse and generally lack concentric growth ringd
nodules
increasingly soluble as pH decreases and acidity increases
limestones
charac by mienral filled cracks whose origin remains unknown
septarian nodules
this orginate as nodules or concretiond of calcite or anhydrite and in acidic the exteriors are replaced by chalcedony
geodes
common in detrital sed rocks in carbonate iron rich cmenetd mimic stratification secondary features often truncated against promintent joint surfaces form by lrecipitation of various iron oxide minerlas moving througj bodies of rock separated by fractures
liesegang bands
fluids moving into such bodies of rcok from the outside in often produce ring like parterns of bands
liesegang rings
less than 4% mg
low magnesium calcite
more than 4% mg
hogh magnesium calcite
carions of substitute for calcium
strontium
most unstable during diagenesis especially in meteoric water whereas low mg is stable t
aragonite that’s why aragonite and high mg calcite is not lresent in older rocks
in solid solution with ankerite and abudnanc ein increase with age in ancient carboante sed rocks especially in precambrian
dolomite
carbonate mineral
siderite!! 😭
mor ebaundant in ancient than in modern carboante sequences
Low Mg calcite
more abudnant in modent tuan in ancient
high mg calcite
more abudnant in mdoenr than in ancient carbonate sequences
aragonite
mroe ahundant in ancient than in mosent carbonate sequnces
dolomite
cabroante shells begin dissolution becomes significant ata dpeth becomes complete where bottom waters are sufficiently cold and acidic below depth all caco3 is dissolved
lysocline
tropics occurs @ 4000-5000 m
carbonate compensation depth CCD
of the amount of detrital sediment flowing into an area exceeds carboante production and preservation
carbonate bearing detrital sediment fossil bearing sandstone will form instead of wottle or no detrital sediment cotnent
sand pr gravel size clastic particles called grains or
allochemical constituentd allochems
mud sized particles called mud or
micrite
prginacally bound accumulations of carbonate called
boundstoe s or biolithites
clasts of carbonate sediment
limeclasts
soherical concentrically laminated sand sized particles possess a nucleus form by accretion of calcium carbonate laminae about a particle such as a shell fragment or sand grain that acts as a nucleus for precipitation can radial calcium cavornate structures involve in endolithic bacteria such as cyanophyted indication of shallow amrine wave or tidal cureent agitated wnvi of deosition in tropical or subtropical setting
ooids
gravel sized clasts of cohesive carbonate sediment produced when clasts of cohesive carbonate sediments or sed rocks are eroded most are derived nearby coeval deposits of cohesive deposition derived intraclasts
limeclasts
erosion of older source rockd outside the area of deposition are called
lithoclasts or extraclasts
are produced when partially demented grain clusters are eroded during storms encrusted in cyanophyted carbonate laminae may form transforms to botryoidal graisn
grapestone
resemble ellipsoidal fecal pelleted excreted by many organisms
peloids
coarser carbonate mud particles are called
macrospar
large modern carbonate mud is produced by thid
calcareous green algae tusy secrete fine needles of aragonite upon decomposition needles are release generating carboante mud
micro boring activity of blue green cyanophyte bacteria and algae accom by precipitation of carbonate in micropores converts original carbonate materail into micrite
micritization
who introdurc rudite lutite arenite
Grabau
emphasizes the tecture of carbonate rocks utilizing rarher simple terminology
dunham’s classification
less than 10% grains
mudstone
more than 10% grains
wackestone
contain interstitial diagenetic mienral cements rhat bind the grains together
grianstone
no depositional texture is recognizable
crystalline carbonate
produ ed by organisms that build rigid organic structures such as reefs by secreting the calcium carbonate
framestone
produced by organisms that build organic strutures sich as stromatolites and reefs by binding and encrusting pre-existing carbonate material
bindstone
generated bu organisms that trap carbonate sediment by acting as baffles that hinder its movement across the bed causing it to be trapped process in reefs and bioherms
bafflestone
carbonate bearing rocks with a matrix supported framework
floatstone
precipitated in the pore spaces between allochems during diagrnesis
sparry cements
25% intraclasts in allochem population are given
intra
if the interstices between intraclasts are largely filled with diagenetic cement the rock is
intrasparite
if filled with mud
intramicrite
fewer than 25% intravlasts occur the rock contains more than 25% ooids the bames are
oosparite and oomicrite
if neither intraclasts nor ooids exceed 25% of the allochems then
fossils and pellets or peloids dominate
micrites that contain small spar filled voids produced during diagenesis
dismicrite
in situ carbonate accumulations roughly equivalenh to Dunhams boundstones
biolithite
rocks with at leadt one third of both spar and micrite between allochems
poorly washed sparites
<1% allochems
allochemical micrite
1-10% allochems
sparse allochemical micrite
> 50% allochems
packed allochemical micrite
aimplest distribution of carbonate depositional envi occurs on where the idela model the bottom slopes gently seaward over fistances develop on the margins of shallow subtropical seas environments occupy roughly shore parallel bands charac by warer depths gradually increase seaward
carbonate ramps
ideal carbonate ramps
supratidal
intertidal
subtidal avove normal wave base
subtidal above storm wave base
subtidal below wave base
where do carbonate found
low relief intracratonic platforms or passive margins or in oceanic environments far from land
develop newr shelf or platform margins where nutrient rich waters upwelling from depth encourage the development of carbonate buildups (wc creates a queit water lagoon on the landward side) such as reefs and sand shoals
rimmed platforms
what is the ideal landward to seaward sequence of environments
supratidal
intertidal
lagoonsl
reef or subtidal sho/island with local tidal channel
reef flank/platform slope
deepeater mass flow l/pelagic
develop during sea level high stans when oceans flood dissolution of grains composed of aragonite or high magnesium calcite produces
form of ooids and fossils is preseved as a cavity of similar shape
moldoc porosity
cements that nicleate on grains grow at similar rates to produce coatings if nearly constant thickness
isophacous rim cements
composed of low magnesium calcite
meteoric cements
involves the nucleation on host grains of multiple crystals that grow outward into pore spaces to produce a fri he of crystals with striagjt boundaries whose size increases away from the host grains
drusy calcite
involve the precipitation of low mg calcite that nucleates in optical continuity with a low mg calcite grain
syntaxial calcite
consists of a si gle crystal large enougj to incorporate multiple grains during its growth
poikiloptic calcite
continued lrecipitation on grain bottoms leads to the development of that hang downward from the grain
pendant cements
carbonate rocks new crystals form and it become larger the neomorphism is called
aggrading neomorphism
neomorhic sparry calcite and can be recognized where neomorphism is incomplete because patches of dusty micrite and microspar remain can often be inferred because grains formerly supported by mud matrix are separated and seem to flot unsupported in sparry calcite
psudospar
formed during sea level high stands such as ordovician-devonian and jurqssic cret and precmabrian
dolomite
examples of large evapotrite sequences deposited in shallow subsideing cratonuc basins
paleozoic williston basin centered in north dakota and silurian mcihigan
large evaporites deosited in foreland basins
silurian salina group of new york
pennsylvanian in the taconic foreland basin
pennsylvanian-permian paradox group in the foreland basin of the ancestral rocky mountains
deposited in rift basin
hulf coast basin
proto atlantic ocean basin of jurassic to cretaceous age
deposited in deep basins assoc with the irregular closing of ocean basins at convergent plate boundaries
permian delaware basin in west texas
BIF range in 3.8-1.8 with a peak abindance between?
2.5-2.2 Ga
when did BIF hiatus?
1.0 Ga
BIF late proterozoic rocks formed from
0.8-5.5 Ga
dominate archean iron rich sed rocks fromed bwteen 3.8-2.6 Ga occur as fairly thin <10-100m elongate lenses of linited lateral extent occur within archean greenstone belts assoc with submarine ultramafic mafiic volcanic rocks mudrocks and sparse volcanoclastic greywacke sandstonesform in dee water marine forearc or backarc basin or advanced intracratonic rift settings minimal influx of detrital sediments
algoma type BIF ontario california
iron rich bands are composed almost exclusively extremely fine grained rocks
femicrites
dominate proterozoic iron rich sed rocks 2.6-1.8 Ga and again from 0.8-0.5 Gamuch larger than algoma 100-1000m occur in borad belts contain fermicrites and GRANULAR IRON FORMATIONS with ooids pisoliths intraclasts and pelltes similar to those in shallow water carbonate sequences
superior type BIF
the slope of the stress – strain line is referred s a constant of proportionality that
describes the slope of the line. The slope
steepness of line E is a measure of resistance
to elastic distortion. The E slope is dependent
upon the stiffness or rigidity of the material.
A rigid, stiff rock (high E) such as granite
requires greater stress to achieve a given strain
than a soft, pliable shale (low E
Young ’ s modulus of elasticity (
which mesoscopic
ductile behavior is facilitated by microscopic fracturing and frictional sliding.
Cataclastic fl ow occurs at low lithostatic
pressures in the shallow crust.
Cataclastic fl ow
high pressure diffusional mass transfer process grain boundaries are compressed and dissolved resulting in the generation of a fl uid
phase (Figure 16.14 ). As each mineral
has different dissolution tendencies,
pressure solution results in mineral
differentiation whereby more soluble
minerals are removed and less soluble
minerals are concentrated can involve substantial
volume loss and is particularly important in marble, metaquartzite, slate,
limestone, dolostone, shale and quartz
sandstone.
clay - rich rocks produces cleavage in
slates, as well as embayed grains and grain overgrowths in quartz - rich rocks
such as sandstone and metaquartzite.
Pressure solution
also known as
grain boundary or volume diffusion is
a high temperature and high pressure
process by which solid particles experience translation within a mineral.
Crystal lattice vacancies migrate to
sites of greatest stress and atoms relocate to sites of minimal stress.
Solid state diffusion
e commonly black –due to enrichment in carbon and iron oxides –and
have the appearance of wound sutures
stitched together
which are jagged seams
of insoluble mineral residue that accumulate and concentrate along a dissolution seam
Stylolite
common in calcite
and feldspar minerals.
Mechanical twinning
common
in micas and other platy minerals such as
clays.
Kinking
ability to fl ow at
shallow depths results in unusual qualities
that make rock salt highly suitable for the
storage of oil as part of the strategic petroleum reserve of the US government
uitable rock for a nuclear waste repository
Rock salt ’ s ability to fl ow
p crustal and mantle processes
within Earth. Factors such as depth, temperature, stress conditions, mineral composition,
rock texture, rock competency and strain rate
rheology
refers to the rate
at which a rock is pulled apart, compressed
or sheared
Strain rate
are useful geothermometers because these
common minerals change strain behavior
with increasing temperatures
minerals such as quartz,
feldspars, amphiboles, garnet and biotite
Approximate temperatures at which
some major minerals change from brittle to
ductile behavior
Biotite ∼ 250 ° C
Quartz ∼ 300 ° C
Feldspar ∼ 400 ° C
Amphibole ∼ 650 – 700 ° C
Garnet 600 – 800 ° C
s produce undulose
extinction, deformation lamellae and recrystallization
Ductile processes
describes the resistance of rocks to fl ow. Rocks that fl ow easily
are less competent, or incompetent.
competency increases with higher pressure
but decreases with higher temperature
Competency
rocks commonly display
ductile behavior and include rock salt,
shale, siltstone, slate, phyllite and schist.
These rocks contain clays, micas, evaporates, talc, chlorite and other relatively
soft minerals with Mohr ’ s hardness < 3.
Incompetent
ocks commonly display
brittle behavior and include metaquartzite, granite, gneiss, quartz sandstone,
basalt, gabbro and diorite. These rocks
contain minerals with Mohr ’ s hardness > 3
such as quartz, feldspars and ferromagnesian minerals.
Competent
The rupture of competent layers produces “ French bread ”or
sausage - shaped structures called
are isolated remnants of competent rock that once formed a
continuous bed surrounded by less competent rocks
boudins
r commonly occurs at depths
less than 10 km because of upper crustal low
temperature/low lithostatic pressure conditions, which allows for the development of
fractures
Brittle behavior
e fractures through which fl uids fl ow,
producing one or more secondary minerals
that precipitate from solution. Common secondary vein minerals include quartz, calcite,
zeolite and chlorite
originate due to tensile or shear stresses.
Veins
produced by high strain rate
events that blast rock apart due to high pressures. Igneous intrusions with high volatile
contents are capable of hydrofracturing rock
producing random breakage. Rare meteorite
impacts are also high strain events that
produce massive disruption of rock. High
strain rates can produce stockwork veins,
which are a cluster of irregularly shaped veins
of variable orientation that occur in a pervasively fractured rock body
Non - systematic vein arrays
onsist of veins that
display orientations suggesting a common
origin in response to directed stress
metaquartzite beds bounded by phyllite layers. In response
to nearly vertical compressive stress, the
metaquartzite experiences horizontal tension,
resulting in brittle fracturing and the generation of extensional joints. Quartz fl uids precipitate in the joints creating tension veins
parallel to the maximum compressive stress
direction.
Systematic vein arrays
a series of offset, parallel veins that formed in response to sinistral shear within
metaquartzite.
en echelon quartz vein array
minerals are equant and may
display euhedral crystal faces indicating
growth within an unimpeded open space
Blocky or sparry
displays a linear, acicular
character (Figure 16.26 ) suggesting that vein
growth was incremental in response to fracture width increase
develop by
repeated cycles of a “ crack and seal ”mechanism whereby elevated fl uid pore pressures
crack a vein, followed by sealing from mineralized solution
provides information regarding displacement sense as well
as progressive vein growth in both brittle and
ductile environments.
Fibrous veins
an imaginary plane connecting
a series of hinge lines
axial surface
(axial plane)
the point at which the sense of curvature
changes from one fold to another
inflection point
a convex - upward structure are called
antiforms
concave - upward shapes are referred
s synforms
consist of two limbs that dip
towards the hinge. Synclines contain
young rock in the hinge and progressively
older rock away from the hinge
Synclines
consist of two limbs that
dip away from the hinge. Anticlines
contain old rocks in the hinge and progressively younger rock further away from
the hinge.
Anticlines
younger fold
structures are superimposed upon earlier fold
structures, refolded folds are referred to as
superposed folds or superimposed folds
consist of folds in which
the limbs and hinges have been pulled apart
due to extension (
occur with multiple fold generations,
involving the replacement of an earlier tectonic fabric (S 1) by a more recent tectonic
fabric (S 2) by ductile mechanisms such as
recrystallization and pressure solution.
e associated with high temperature and high pressure metamorphism
Transposed folds
be used in the analysis of a map - scale antiform. Geologists can determine position
within a map - scale fold structure by looking
down the plunge direction of the
parasitic
folds.
essentially ductile fault zones
that accommodate displacement
develop in ductile lower crustal rocks.
commonly occur in
tectonic m é langes mylonites
and pseudotachylites
Shear z ones
