Upload
saivenkat
View
238
Download
0
Embed Size (px)
Citation preview
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
1/24
1
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
2/24
2
Geological Cycle Rock Formation And Types of Rock-2
( Sedimentary &Metamorphic Rocks
!nstr"ctor#
$r% Atta"llah Shah
Lecture # 5
$epartment of Ciil 'ngineering
Swedish College of Engineering and Technology-Wah Cantt.
http://en.wikipedia.org/wiki/File:Rockcycle.jpg7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
3/24
3
1. Classification of sedientary !oc"
2. escri$tion of coon sedientary roc"
3. Ty$es of etaor$his
%. escri$tion of coon etaor$hic roc"
"tlines of the )resentation"tlines of the )resentation
http://upload.wikimedia.org/wikipedia/commons/0/08/Triassic_Utah.JPGhttp://upload.wikimedia.org/wikipedia/commons/0/08/Triassic_Utah.JPG7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
4/24
%
Sedimentary rock is a ty$e of roc" that is fored &y
sedientation of aterial at the Earth's surface and within &odies
of water.
Sedientation is the collecti(e nae for $rocesses that cause
ineral and)or organic $articles *detritus+ to settle and accuulate
or inerals to $reci$itate fro a solution.
,articles that for a sedientary roc" &y accuulating are called
sedient. efore &eing de$osited sedient was fored &y
weathering and erosion in a source area and then trans$orted to
the $lace of de$osition &y water wind ass o(eent or
glaciers.
Classification of Sedimentary RocksClassification of Sedimentary Rocks
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
5/24
5
Sedientary roc" is fored &y de$osition and consolidation of inerals and
organic aterials and fro $reci$itation of inerals fro solution. The
$rocesses that for sedientary roc" occur at the surface of the earth and
within &odies of water.
!oc" fored fro sedients co(ers /0-0 of the earths land area and
includes coon ty$es such as liestone chal" sandstone congloerate and
shale.
Sedientary roc"s are only a thin (eneer o(er a crust consisting ainly of
igneous and etaor$hic roc"s and constitute a total of 5 of the earth crust
(olue.
Sedientary roc"s are de$osited in layers as strata foring a structure called
&edding. The study of sedientary roc"s and roc" strata $ro(ides inforation
a&out the su&surface that is useful for ci(il engineering for e4a$le in the
construction of roads houses tunnels canals or other constructions.
Sedientary roc"s are also i$ortant sources of natural resources li"e coal
fossil fuels drin"ing water or ores.
Classification of Sedimentary RocksClassification of Sedimentary Rocks
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
6/24
The scientific disci$line that studies the $ro$erties and origin of sedientary
roc"s is called sedientology.
Sedientology is &oth $art of geology and $hysical geogra$hy and o(erla$s
$artly with other disci$lines in the Earth sciences such as $enology
geoor$hology geocheistry or structural geology.
The study of the se6uence of sedientary roc" strata is the ain source forscientific "nowledge a&out the Earth's history including $alaeogeogra$hy
$aleocliatology and the history of life.
Classification of Sedimentary RocksClassification of Sedimentary Rocks
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
7/24
/
Mechanically formed7 consisting of aterials *gra(els sand silt and clay+
sus$ended in flowing water. The sus$ended aterials are then de$osited and
consolidated.
Water $ercolates into crac"s and fissures within the roc" free8es and
e4$ands. The force e4erted &y the e4$ansion is sufficient to widen crac"s and
&rea" off $ieces of roc". 9eating and cooling of the roc" and the resulting
e4$ansion and contraction also aids the $rocess. :echanical weathering
contri&utes further to the &rea"down of roc" &y increasing the surface area
e4$osed to cheical agents.
The echanically fored sedientary roc"s are of three ty$es7
1. !udaceous roc"s which is the ceenting together of &oulders for e4a$le
congloerate.
2. ;renaceous roc"s for e4a$le sandstone
3. ;rgillaceous roc"s which is clay roc"s for e4a$le shale
Classification of Sedimentary RocksClassification of Sedimentary Rocks
http://upload.wikimedia.org/wikipedia/commons/e/e3/OilShaleEstonia.jpghttp://upload.wikimedia.org/wikipedia/en/5/59/GLMsed.jpg7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
8/24
Clay stone de$osited in
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
9/24
@
rganically formed# Consisting of acc"m"lated animals and plants
remains%
rganic sedimentary rocks contain materials generated *y liing
organisms+ and incl"de car*onate minerals created *y organisms+ s"ch as
corals+ moll"sks (Snail+ sl"g+ ctop"s + and foraminifera (sea,ater
rganism + ,hich coer the ocean floor ,ith layers of calci"m car*onate+
,hich can later form limestone% ther eamples incl"de stromatolites+ the
flint nod"les fo"nd in chalk (,hich is itself a *iochemical sedimentary
rock+ a form of limestone+ and coal and oil shale (deried from the
remains of tropical plants and s"*.ected to heat%
They are#
/% Calcareo"s rocks+ lime stone
2% Car*onaceo"s rocks+ coal
Classification of Sedimentary RocksClassification of Sedimentary Rocks
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
10/24
10
Cheically fored7 this ty$e of roc"s is fored &y $reci$itation and
accuulation of solu&le constituents.
Cheical sedientary roc"s for when inerals in solution &ecoe
su$ersaturated and $reci$itate. An arine en(ironents this is a ethod for
the foration of liestone. ;nother coon en(ironent in which cheical
sedientary roc"s for is a &ody of water that is e(a$orating. E(a$oration
decreases the aount of water without decreasing the aount of dissol(ed
aterial. Therefore the dissol(ed aterial can &ecoe o(ersaturated and
$reci$itate. Sedientary roc"s fro this $rocess can include the e(a$orite
inerals halite *roc" salt+ syl(ite &arite and gy$su.
These are
1. Car&onate roc"s Liestone doloite
2. Sul$hate roc"s
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
11/24
11
Consolidation is a process *y ,hich soft and loose sediments are
conerted into hard and firm rocks% Consolidation is of three types#
/% Compaction and $ehydration# The s0"ee1ing o"t of ,ater from the
pores of the sediments and its changing to solid mass *y cohesion
*et,een the particles and press"re from oerlying rock is called
compaction and dehydration%
2% Cementation# Many coarse grained sediments are consolidated *y
cementation+ ,hich is the process of precipitation of some cementing
materials+ for eample+ silica+ calci"m car*onate+ iron oides and clay
minerals%
% Crystalli1ation# Chemically formed sedimentary rocks s"ch as
limestone+ dolomites+ gyps"m etc are consolidated chiefly *y the
crystalli1ation of their constit"ents%
ConsolidationConsolidation
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
12/24
12
Str"ct"ral feat"res of sedimentary rocks are of great al"e in
determining their origin% The main str"ct"res are as follo,s#
Stratification# The deposition of sediments into layer or *eds is called
stratification% The thickness of a single *ed may ary from a fe,
centimeters to many meters% The stratification is formed d"e to the
follo,ing%
!% $ifference in the kinds of materials deposited for eample shale and
lime stone
!!% $ifference in the si1e of particles deposited for eample coarse
grained and fine grained sandstone *eds!!!%$ifference in the color of the materials deposited for eample light
grey and dark grey layers of limestone
Str"ct"ral Feat"resStr"ct"ral Feat"res
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
13/24
13
3amination# Thin *edding+ less than one centimeter in thickness+
are called lamination% !t is "s"ally fined grained sedimentary
rocks like shales%
Cross-*edding# !t is also called c"rrent *edding or false *edding%
Cross-*edding are the minor *edding or lamination ,hich lieat an angle to the planes of general stratification% This
str"ct"re is fo"nd in shallo, ,ater and ,ind formed deposits%
$iff f di k$iff t t f di t k
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
14/24
1%
Conglomerate# The pe**les and graels on consolidation and cementation
prod"ce a rock kno,n as conglomerate% Graels are deposited for the most
part *y ,ater% 4ater circ"lating thro"gh grael deposits may precipitate
o"t silica+ calci"m car*onate+ or iron oides+ ,hich act as cements *inding
the graels together into conglomerates%
Sandstones#Most sand is a ,ater deposit% !n arid regions+ ,idespread sands
hae *een laid do,n *y ,ind action% 5olcanic er"ptions+ glacial action+
mechanical and chemical ,eathering+ and organisms prod"ce sands% The
sand particles are deposited and then cemented together *y materials like
silica+ calcite+ iron oide or clay% Sandstones may *e siliceo"s sandstone that
is the cementing materials is silica6 it may *e calcario"s sandstone in ,hich
the cementing materials is calci"m car*onate6 ferr"gino"s sandstone and
argillaceo"s sandstone haing iron oide and clay as cementing materials
$ifferent types of sedimentary rocks$ifferent types of sedimentary rocks
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
15/24
15
The thoro"ghly cemented sandstone ,ith 0"art1 are termed as
ortho0"art1ite%
Argillaceo"s rocks# ario"sly called m"dstone+ claystone+ and shale
(compacted or cemented are among the most a*"ndant of sedimentary
rocks% !t is a laminated fine grained sedimentary rock ,hich is mainly
composed of clay minerals and some silt-si1e grains of 0"art1%The claystones+ *eca"se they are characteristically soft and ,eak are not
s"ited to most constr"ction p"rposes% The compacted shale lose strength
,hen ,et and are s"*.ect to plastic deformation% 7nder load they are
s"*.ect to fail"re *y flo,% The cemented shales hae a strength compara*leto concrete *"t hae a relatiely high elasticity% Clay stones "nderlying the
sites of heay str"ct"res sho"ld *e test in *oth ,et and dry conditions% Clay
stone has a limited "se% !t seres as a ra, materials for the ceramic
ind"stry in some places and also "sed as ra, materials for cement
$ifferent types of sedimentary rocks$ifferent types of sedimentary rocks
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
16/24
1
Car*onate rocks# The car*onate rocks are chiefly the prod"cts of marine
or fresh ,ater sedimentation% They are predominantly chemical sediments
either formed *y meta*olic process of organism or precipitated
inorgainically% Mineralogically+ the car*onate rocks are comparatiely
simple% There are t,o main arieties6 the limestone composed chiefly of the
calcite+ and the dolomite composed chiefly of dolomite%
The car*onate rocks+ partic"larly the limestones+ hae a ery ,ide "se in
modern ind"stry% The largest single "se is as cr"shed stone% 3imestone is
one of the leading dimension stones *eing "tili1ed *oth for internal and
eternal ,ork% Commercial lime is deried from the *"rning of limestone%
$ifferent types of sedimentary rocks$ifferent types of sedimentary rocks
http://upload.wikimedia.org/wikipedia/commons/7/7f/Quartzite.jpg7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
17/24
1/
Buart8ite a for of etaor$hic roc"
:etaor$hic !oc"s
http://upload.wikimedia.org/wikipedia/commons/7/7f/Quartzite.jpg7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
18/24
1
Metamorphic rock is the res"lt of the transformation of an eisting rock
type+ the protolith+ in a process called metamorphism+ ,hich means 8change
in form8%
4hen the pre-eisting rocks (sedimentary or igneo"s rock are s"*.ected to
increased temperat"re+ press"re and action of chemically actie fl"ids+
metamorphic rocks are formed% $"ring metamorphism re-crystalli1ation of
mineral constit"ent takes place+ as a res"lt ne, minerals and ne, tet"re are
prod"ced%
The metamorphic processes generally improe the engineering *ehaior of
these rocks *y increasing their hardness and strength% 9eertheless+ some
metamorphic rocks still can *e pro*lematic% Some metamorphic rocks are
foliated+ ,hich means they hae oriented grains similar to *edding plains in
sedimentary rocks% These foliation is important *eca"se the shear strength is
less for stresses acting parallel to the foliation%
Metamorphic rocksMetamorphic rocks
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
19/24
1@
7n-,eathered non-foliated rocks generally proide ecellent s"pport for
engineering ,orks+ and are similar to intr"sie igneo"s rocks in their 0"ality%
:o,eer+ some foliated rocks are prone to slippage along the foliation planes%
Schist is the most nota*le in this regard *eca"se of its strong foliation ad the
presence of mica% The /;2< fail"re St%Fancis $am in California has *een
partially attri*"ted to shearing in schist and the /;=; fail"re of Malpasset
dam in France to shearing in a schistose gneiss%
Metamorphic rocksMetamorphic rocks
olded foliation in a etaor$hic roc"
http://upload.wikimedia.org/wikipedia/commons/6/6a/Migma_ss_2006.jpg7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
20/24
20
Contact metamorphism is the name gien to the changes that take place
,hen magma is in.ected into the s"rro"nding solid rock% The changes that
occ"r are greatest ,hereer the magma comes into contact ,ith the rock
*eca"se the temperat"re are highest at this *o"ndary and decrease ,ith
distance from it% Aro"nd the igneo"s rock that forms from the cooling
magma is a metamorphosed 1one called a contact metamorphism a"reole%
Types of MetamorphismTypes of Metamorphism
; contact etaor$hic roc" ade of
inter layered calcite and ser$entine
fro the ,reca&rian of Canada
-shale ay &ecoe a dar" argillaceous hornfels
-Liestone ay change to a grey yellow or greenishlie-silicate-hornfels or siliceous ar&le
T f M t hiT pes of Metamorphism
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
21/24
21
Regional metamorphism is the name gien to changes in great masses of
rock oer a ,ide area% Rock can *e metamorphosed simply *y *eing at
great depths *elo, the earth>s s"rface+ s"*.ected to high temperat"res
and the great press"re ca"sed *y the immense ,eight of the rock layers
a*oe% M"ch of the lo,er continental cr"st is metamorphic%
Types of MetamorphismTypes of Metamorphism
:ississi$$ian ar&le in ig Cottonwood
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
22/24
22
Mar*le# Mar*les are metamorphosed car*onate rocks+ deried from
limestones and dolomites% The color of mar*le is aria*le+ ho,eer+ if the
rock is p"re calcite or dolomite mar*le it is generally ,hite% 5ario"s
imp"rities gie rise to ario"s shades% Green+ pinks and *"ffs are common
shades%
The principal "ses of mar*le are as c"t stone for *"ilding and ornamental or
decoratie "se%
$ifferent Metamorphic rocks$ifferent Metamorphic rocks
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
23/24
23
Slate# Slate is a dense metamorphic rock+ ,ith a strongly deelopedfoliation% !t is prod"ced *y the metamorphism of shale% The rock
cleaage+ or split-a*ility is therefore ecellent and is the o"tstanding
characteristic of slates% The color of slate aries from iron-tinted reds
thro"gh ario"s shades of gray and green% The gray shades are d"e tocar*onaceo"s matter+ the greens to chloritic micas% The tet"re of
slates is ery fine or dense and foliation is good to perfect%
Slate is "sed ,idely in the electrical ind"stries as s,itch*oards%
$ifferent Metamorphic rocks$ifferent Metamorphic rocks
7/25/2019 Geological Cycle Rock Formation And Types of Rock-2 ( Sedimentary &Metamorphic Rocks )
24/24
2%
)hyllite# )hyllite are strongly foliated metamorphic rocks similar to the
slates *"t of slightly coarser tet"re% )hyllite hae shiny l"ster d"e the
presence of large amo"nt of fine flakes of mica% )hyllite grad"ally pass into
slates ,hich are the first stage in the metaphorphism of shale%
!t has little "se% !t is too soft for cr"shed stone+ and too ,eak for str"ct"ral
"ses%
Schist# Schist are foliated metamorphic rocks of medi"m to coarse tet"re%
They are the prod"ct of the same processes of rock flo, and recrystalli1ation
that prod"ce slates and phyllite% The color of schist ary according to the
mineralogical composition+ as does also the perfection of cleaage%
Schist has of little "se% ?eca"se of the foliation+ they are generally ,eak
rocks% Some schists especially rich in m"scoite are a so"rce of scrap mica%
$ifferent Metamorphic rocks$ifferent Metamorphic rocks