Chapter 3_Minerals in the Crust

8/18/2019 Chapter 3_Minerals in the Crust

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Chapter 3

Earth Materials and Plate Tectonics

BASIC GEOLOGY


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Visualizing Physical Geography

Copyright © 2008 John Wiley and Sons Publishers Inc

Chapter Overview

Rocks and Minerals ofthe Earth’s Crust

Major Relief Features of

the Earth’s Surface

late !ectonics

Continents of the ast


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Rocks and Minerals of the Earth’s Crust

!he Earth’s Interior

"Core# s$herical central %ass of the

Earth co%$osed lar&el' of iron( consists

of an outer li)uid *one and an inner

solid *one

"Mantle# rock la'er of the Earth +eneath

the crust and surroundin& the core,

co%$osed of ultra%afic i&neous rock of

silicate %inerals"Crust # outer%ost solid la'er of the

Earth, co%$osed lar&el' of silicate

%inerals

" Oceanic crust# %afic rocks

" Continental crust# lo-er *one %afic

rock, u$$er *one felsic" Continental crust thicker than

oceanic


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!he Earth’s Interior " Most a+undant ele%ents in crust#

" O.'&en, silicon, alu%inu%, iron, calciu%, sodiu%, $otassiu%,

%a&nesiu%

" Minerals# naturall' occurrin& inor&anic cr'stalline che%ical

co%$ounds

" Rocks#" /suall' co%$osed of 0 or %ore %inerals

" Rock classes# i&neous, sedi%entar', %eta%or$hic


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I&neous Rocks

Igneous rock # rock for%ed fro% the

coolin& of %a&%a

" Intrusive Igneous rock # rock for%ed

fro% %a&%a that solidifies +elo- the

Earth’s surface

"1isi+le %ineral cr'stals

" Extrusive igneous rock # rock for%ed

fro% %a&%a that cooled ra$idl' at the

surface or under the ocean

"Mineral cr'stals %icrosco$ic

Magma# %o+ile, hi&h2te%$erature

%olten state of rock


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I&neous Rocks

Most co%$osed of

silicate %inerals#contain silicon and

o.'&en" Felsic rock#

"Felsic %inerals

"Li&ht2colored

"Less dense

" Mafic rock#"Mafic %inerals

"3ark2colored

"More dense

" /ltra%afic rock#"4ea5' %afic %inerals

"1er' dense


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Sedi%ents and Sedi%entar' RocksSedimentary Rock # rock for%ed fro% the accu%ulation of sedi%ent

"Clastic 6for%ed fro% rock and %ineral fra&%ents"Chemically precipitated # for%ed +' che%ical $reci$itation fro%

sea-ater or salt' inland lakes

"Organic # for%ed fro% or&anic %aterial

Insert fi&ure 789

here


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Sedi%ents and Sedi%entar' Rocks

Sandstone,

de$osited in

la'ers

Con&lo%erate

Shale

Chalk, a for% of li%estone


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Sedi%ents and Sedi%entar' RocksCoal, a fossil fuel, is an or&anic sedi%entar' rock

Fossil Fuels# naturall'

occurrin& h'drocar+on

co%$ounds $roduced

fro% re%ains of or&anic

%atter enclosed in

rock( e.a%$les are

coal, $etroleu% :crude

oil;, and natural &as


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Meta%or$hic Rocks

Metamorphic Rock # rock altered in $h'sical or che%ical co%$osition +' heat,

$ressure, or other $rocesses takin& $lace at a su+stantial de$th +elo- thesurface


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!he C'cle of Rock Chan&e


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Major Relief Features of the Earth’s Surface

!he Geolo&ic !i%escale


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!he Lithos$here and Asthenos$here

Lithosphere# ri&id outer shell of Earth, includes crust and u$$er %antle

Asthenosphere# $lastic la'er +elo- the lithos$here

Lithospheric late# se&%ent of lithos$here %o5in& as a unit, in

contact -ith adjacent lithos$heric $lates alon& $late +oundaries


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Relief Features of the Continents

Acti5e %ountain2%akin& re&ions#" Mountains result fro% 5olcanis% or tectonic acti5it'8" Acti5e %ountain2%akin& +elts for% alpine chains# narro- *ones alon& the %ar&ins

of lithos$heric $lates


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Relief Features of the ContinentsContinental crust includes#

" Acti5e %ountain2%akin& +elts

" Re&ions of sta+le, older rock"Continental shields# 5er' old, lo-2l'in& i&neous and %eta%or$hic rocks

"Mountain roots# re%ains of older %ountain +elts, lon&, narro- rid&es


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Relief Features of the Ocean Basins" Oceanic crust >9? %illion 'ears old( continental crust @ +illion 'ears old

" Ocean +asins ha5e#

"Midoceanic rid&e

" A.ial rift


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Relief Features of the Ocean Basins

assi5e continental %ar&ins#

no stron& tectonic acti5it'-ithin =? %illion 'ears

Acti5e continental %ar&ins#

dee$ offshore trenches,5olcanic acti5it'


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Plate Tectonics

Motion of lithos$heric $lates dri5es for%ation of Earth’s

%ountains and other surface features8" E.tensional tectonic acti5it'

"S$readin& +oundar'

"lates $ulled a$art

"Faults created

" Co%$ressional tectonic acti5it'"Con5er&in& +oundar'

"lates $ushed to&ether "Creates folds and o5erthrust faults

" lates %o5e $ast each other "!ransfor% +oundar'

"!ransfor% faults

Pl t T t i


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Plate Tectonics

late !ectonics# theor' of

tectonic acti5it' dealin& -ith

lithos$heric $lates and their

acti5it'

Su"duction# descent of the ed&e

of a lithos$heric $late under an

adjoinin& $late and into the

asthenos$here

late Boundaries" S$readin& +oundar'

" Con5er&in& +oundar'

" !ransfor% +oundar'

Pl t T t i


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Plate Tectonics

Su"duction# descent of the ed&e of a lithos$heric $lateunder an adjoinin& $late and into the asthenos$here

Su+duction !ectonics

lates under&oin& su+duction are associated

-ith acti5e continental %ar&ins" Sedi%ents accu%ulate in dee$ trench

"3ee$ ocean sedi%ents

"!errestrial sedi%ents

" 3efor%ed, scra$ed off su+ductin& $late

" ed&e for%s at the $late +oundar'

" Sedi%ents transfor%ed into %eta%or$hic

rock

Pl t T t i


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Plate Tectonics

Oro&ens and Collisions

Continental suture# Lon&, narro- *one of crustal defor%ation $roduced +' a

continental collision( e.a%$les# 4i%ala'an Ran&e, Euro$ean Al$s8

Continental lithos$heric $lates con5er&e#" Both +uo'antneither su+ducts

" Orogeny # %ajor e$isode of tectonic acti5it' resultin& in strata +ein& defor%ed +' foldin&

and faultin&

" #appe# o5erturned recu%+ent fold of strata, usuall' associated -ith thrust sheets in a

collision oro&en

Pl t T t i


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Plate Tectonics

!he Lithos$heric lates and !heir Motions

!he Glo+al S'ste% of Lithos$heric lates

Pl t T t i


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Plate Tectonics

Continental Ru$ture and e- Ocean Basins

assi5e continental %ar&ins are created +'

continental ru$ture and s$readin&

" Crust u$lifted and stretched

" Ma&%a rises to for% ne- rock

" Rift 5alle' for%s

" Rift -idens and narro- ocean is for%ed

" Ocean +asin -idens

Pl t T t i


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Plate Tectonics

!he o-er Source for late Mo5e%entsRadiogenic heat # heat &enerated +' the deca' of radioacti5e isoto$es

" 4eat &enerated +' deca' of isoto$es of uraniu%, thoriu%, $otassiu%

" Inde$endent of surface conditions

" 4eat kee$s rock +elo- crust close to %eltin& $oint

" Radio&enic heat $o-er source for $late %otions

"E.act %echanis% unkno-n

"ossi+l' con5ection currents in %antle"ossi+l' &ra5it'

C ti t f th P t


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Continents of the Past

Alfred e&ener $ro$osed first full2

scale scientific theor' of the+reaku$ of one su$ercontinent

into %ulti$le driftin& continents" angaea# su$ercontinent

" Intact a+out D?? %illion 'ears a&o

" Outlines of continents fit across ocean

" !ectonic structures %atch across

continents



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Mo5e%ents of

the continents

fro% 9??

%illion 'ears

a&o to D??

%illion 'ears

a&o

Mo5e%ents of

the continents

fro% 0?? %illion

'ears a&o to

$resent

$ilson Cycle# the continents ha5e united

and +roken u$ re$eatedl' throu&h Earth’s

histor'



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Satellite data sho- ratesof $late %o5e%ent fro%

a+out = to ? c% :02<

inches; $er 'ear

Chapter 3_Minerals in the Crust

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