Introduction to Geotectonic and Geodynamics
gabrielchuei2019
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Aug 31, 2024
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About This Presentation
Geotectonic and geodynamics talking about structures of the earth like crust, mantle, and core. Mechanism of plate tectonics, mid oceanic ridges crest and trenches. Subduction zones and continental edges, mantle convection strike slip, formation and evolution of sedimentary Basins and continental sh...
Slide Content
Introduction
Geotectonic/
Geodynamics
By Chuol Tap
May 2024
Geotectonic/
Geodynamics
By Chuol Tap
May 2024
Course Objectives and Learning Outcomes
Aftercompletionofthiscourse,learnerswillabletodevelop:
1.UnderstandingEarth’sStructureandProcesses:These
fieldsapplyphysics,chemistry,andmathematicsto
understandhowmantleconvectionleadstoplate
tectonicsandgeologicphenomenasuchasseafloor
spreading,mountainbuilding,volcanoes,earthquakes,
andfaulting.
2.PredictingGeologicalEvents:Geodynamicsand
Tectonicshelpinpredictingpatternsofcontinental
accretionandbreakupofcontinentsand
supercontinents.
Aftercompletionofthiscourse,learnerswillabletodevelop:
1.UnderstandingEarth’sStructureandProcesses:These
fieldsapplyphysics,chemistry,andmathematicsto
understandhowmantleconvectionleadstoplate
tectonicsandgeologicphenomenasuchasseafloor
spreading,mountainbuilding,volcanoes,earthquakes,
andfaulting.
2.PredictingGeologicalEvents:Geodynamicsand
Tectonicshelpinpredictingpatternsofcontinental
accretionandbreakupofcontinentsand
supercontinents.
3.UnderstandingGeotectonicofSedimentaryBasinsand
theirformations.Geotectonichelpspaintthepictureof
basinsformations.
4.ResourceExploration:Geodynamic/geotectonicplaya
vitalroleintheexplorationofmineralandhydrocarbon
deposits,whichareessentialtooursociety.
5.EarthquakePrediction:Thecontinuousmotionof
tectonicplatesdrivesthedeformationofthe
lithosphere,buildingmountainsandloadingfaultlines
tocauseearthquakes.Understandingtheseprocesses
canhelpinpredictingandpreparingforsuchnatural
disasters.
theirformations.Geotectonichelpspaintthepictureof
basinsformations.
4.ResourceExploration:Geodynamic/geotectonicplaya
vitalroleintheexplorationofmineralandhydrocarbon
deposits,whichareessentialtooursociety.
5.EarthquakePrediction:Thecontinuousmotionof
tectonicplatesdrivesthedeformationofthe
lithosphere,buildingmountainsandloadingfaultlines
tocauseearthquakes.Understandingtheseprocesses
canhelpinpredictingandpreparingforsuchnatural
disasters.
6.PlanetaryExploration:Methodsofgeodynamics
arealsoappliedtotheexplorationofotherplanets.
7.ScientificResearch:Geotectonicspublishes
articlesongeneralandregionaltectonics,
structuralgeology,geodynamics,andexperimental
tectonicsandconsiderstherelationoftectonicsto
thedeepstructureoftheearth,magmatism,
metamorphism,andmineralresources.
arealsoappliedtotheexplorationofotherplanets.
7.ScientificResearch:Geotectonicspublishes
articlesongeneralandregionaltectonics,
structuralgeology,geodynamics,andexperimental
tectonicsandconsiderstherelationoftectonicsto
thedeepstructureoftheearth,magmatism,
metamorphism,andmineralresources.
Chapters:
1.Structureofthe Earth
2.MechanismofPlateTectonics
3.Formation&Evolution ofSedimentaryBasins
4.Continental&Oceanicrifts
5.Strike-slip basins
6.ContinentalShelves
7.CordilleranMountainbelts,Alpine-HimalayanMountainbelts
8.Geotectonic/geodynamics history in Sudan, the horn and East Africa (New!).
1.Structureofthe Earth
2.MechanismofPlateTectonics
3.Formation&Evolution ofSedimentaryBasins
4.Continental&Oceanicrifts
5.Strike-slip basins
6.ContinentalShelves
7.CordilleranMountainbelts,Alpine-HimalayanMountainbelts
8.Geotectonic/geodynamics history in Sudan, the horn and East Africa (New!).
Geotectonic?vsGeodynamics?
Geotectonic? VS Geodynamics?
Definitions
•Inabasicdefinition,Geotectonicisderivedfromtwo
Greekterm‘Geo’meaningsolidrockorearth,and
‘tekton’whichmeansbuilding.
•ThisreflectthatEarthismadeofbuildingblockswe
liveon(continents).
•Geotectonicsisabouthowtherocksandlandforms
onEarth’ssurfaceareshapedandmovedbyforces
withintheEarth.
•Inabasicdefinition,Geotectonicisderivedfromtwo
Greekterm‘Geo’meaningsolidrockorearth,and
‘tekton’whichmeansbuilding.
•ThisreflectthatEarthismadeofbuildingblockswe
liveon(continents).
•Geotectonicsisabouthowtherocksandlandforms
onEarth’ssurfaceareshapedandmovedbyforces
withintheEarth.
Geotectonics
•Inanadvanceddefinitionacceptedbyexpertsand
researchers;Geotectonicsisabranchofsciencethat
dealswiththestructureandmovementofEarth’s
crust.
•Itincludesthestudyoflarge-scalefeatureslike
mountainchains,mid-oceanicridges,oceanic
trenches,basinsandtheirformation.
•Inanadvanceddefinitionacceptedbyexpertsand
researchers;Geotectonicsisabranchofsciencethat
dealswiththestructureandmovementofEarth’s
crust.
•Itincludesthestudyoflarge-scalefeatureslike
mountainchains,mid-oceanicridges,oceanic
trenches,basinsandtheirformation.
Geodynamics
•Geodynamicsisasubfieldofgeophysicsthatdealswiththe
dynamicsoftheEarth.
•Itappliesphysics,chemistry,andmathematicstounderstand
howtheEarth’sinternalmovementsleadtolarge-scale
geologicalphenomenasuchasthecreationofmountains,the
spreadingoftheseafloor,andtheoccurrenceofearthquakes
andvolcanoes.
•Insimplerterms,Geodynamicsisaboutunderstandingthe
forcesandprocessesinsidetheEarththatcausechangesonits
surface.
•Geodynamicsisasubfieldofgeophysicsthatdealswiththe
dynamicsoftheEarth.
•Itappliesphysics,chemistry,andmathematicstounderstand
howtheEarth’sinternalmovementsleadtolarge-scale
geologicalphenomenasuchasthecreationofmountains,the
spreadingoftheseafloor,andtheoccurrenceofearthquakes
andvolcanoes.
•Insimplerterms,Geodynamicsisaboutunderstandingthe
forcesandprocessesinsidetheEarththatcausechangesonits
surface.
Questions (discuss)
•What physical phenomenon predominantly
contributes to the magnetic field of the earth?
a. The ionization of metals in the earth's crust.
b. Charged particles from the solar wind that enter
the earth's atmosphere.
c. Ion convection in the molten liquid shell that
surrounds the earth's solid inner core.
d. The total amount of ferromagnetic iron, cobalt,
and nickel that is present in the earth's crust.
e. Ionization in the earth's atmosphere.
contributes to the magnetic field of the earth?
a. The ionization of metals in the earth's crust.
b. Charged particles from the solar wind that enter
the earth's atmosphere.
c. Ion convection in the molten liquid shell that
surrounds the earth's solid inner core.
d. The total amount of ferromagnetic iron, cobalt,
and nickel that is present in the earth's crust.
e. Ionization in the earth's atmosphere.
•The Earth's magnetic field is generated by
the movement of molten iron and nickel
in the outer core. This convective motion
generates electric currents, which in turn
create the magnetic field through a
process known as the geodynamo. The
solid inner core, composed mainly of iron,
also plays a role in maintaining the
magnetic field.
the movement of molten iron and nickel
in the outer core. This convective motion
generates electric currents, which in turn
create the magnetic field through a
process known as the geodynamo. The
solid inner core, composed mainly of iron,
also plays a role in maintaining the
magnetic field.
•The surface layer of the Earth is made of many slowly ever-changing
_____________, forming volcanoes, earthquakes, basins and
mountain ranges.
_____________, forming volcanoes, earthquakes, basins and
mountain ranges.
Thetheory of continental drift(a theory proposed by Alfred Wegener in
1912) was supported by what kind of evidence?
a.Matching fossils occur on different continents on opposite sides of ocean
basins.
b.The shapes of continent margins on opposite sides of ocean basins appear to
fit like a jigsaw puzzle.
c.Rocks of similar age and composition and mountain ranges on different
continents appear to match on opposite sides of ocean basins.
d.Sedimentary basins similarity.
e.e. all of except d.
f.All are correct
1912) was supported by what kind of evidence?
a.Matching fossils occur on different continents on opposite sides of ocean
basins.
b.The shapes of continent margins on opposite sides of ocean basins appear to
fit like a jigsaw puzzle.
c.Rocks of similar age and composition and mountain ranges on different
continents appear to match on opposite sides of ocean basins.
d.Sedimentary basins similarity.
e.e. all of except d.
f.All are correct
How are the Earth's crust and mantle
different?
different?
1. Structure of the Earth
•The crust is the outer layer of rock, which forms a
thin skin on Earth’s surface.
•Below the crust liesthemantle,athickshellofrock
thatseparatesthecrustabovefromthecorebelow.
•Thecore is the central zone of Earth. It is probably
metallic and the source of Earth’s magnetic field.
Earth’s Internal Structure
•The crust is the outer layer of rock, which forms a
thin skin on Earth’s surface.
•Below the crust liesthemantle,athickshellofrock
thatseparatesthecrustabovefromthecorebelow.
•Thecore is the central zone of Earth. It is probably
metallic and the source of Earth’s magnetic field.
Earth’s Internal Structure
•The entire crustand uppermost mantletogether
form the lithosphere (“sphere of rock”), the
outer shellofEarththatisrelativelystrong,rigid
andbrittle.
•Thelithospheremakesupthesevenplatesof
plate-tectonic theory.
form the lithosphere (“sphere of rock”), the
outer shellofEarththatisrelativelystrong,rigid
andbrittle.
•Thelithospheremakesupthesevenplatesof
plate-tectonic theory.
•Beneath this rigid layer to a depth of about
410 kilometers (255 miles) lies a
comparatively weak layer known as the
asthenosphere (“weak sphere”).
410 kilometers (255 miles) lies a
comparatively weak layer known as the
asthenosphere (“weak sphere”).
Mechanism of Plate Motions
2. Mechanism of Plate Tectonic
•Plate tectonics is a model in which the outer shell
of the Earth is divided into several thin, rigid and
slowly ever-changing plates that are in relative
motionwith respect to one another.
•The relativevelocitiesoftheplatesareofthe
order ofafewtensofmillimetresperyear.
•Plate tectonics is a model in which the outer shell
of the Earth is divided into several thin, rigid and
slowly ever-changing plates that are in relative
motionwith respect to one another.
•The relativevelocitiesoftheplatesareofthe
order ofafewtensofmillimetresperyear.
•Alarge fractionofallearthquakes,volcanic
eruptions,andmountainbuildingoccurat
plateboundaries.
•Theplatesarebeingcontinuallycreatedand
consumed at the boundaries.
•Atoceanridges,adjacentplatesdivergefrom
eachotherinaprocessknownasseafloor
spreading.
eruptions,andmountainbuildingoccurat
plateboundaries.
•Theplatesarebeingcontinuallycreatedand
consumed at the boundaries.
•Atoceanridges,adjacentplatesdivergefrom
eachotherinaprocessknownasseafloor
spreading.
EARTH’SMAJORPLATES
•Thelithosphereisbrokenintoabouttwodozen
segmentsofirregularsizeandshapecalled
lithosphericplates,orplates,thatare inconstant
motion.
•Seven major lithospheric plates are recognized and
account for 94 percentof Earth’s surface area: The
North American, South American, Pacific, African,
Eurasian, Australian Indian, and Antarctic plates.
•Thelithosphereisbrokenintoabouttwodozen
segmentsofirregularsizeandshapecalled
lithosphericplates,orplates,thatare inconstant
motion.
•Seven major lithospheric plates are recognized and
account for 94 percentof Earth’s surface area: The
North American, South American, Pacific, African,
Eurasian, Australian Indian, and Antarctic plates.
•ThelargestisthePacificplate,whichencompassesa
significantportionofthePacificbasin.
•Eachofthesixotherlargeplatesconsistsofanentire
continent,aswellasasignificantamountofoceanic
crust.
significantportionofthePacificbasin.
•Eachofthesixotherlargeplatesconsistsofanentire
continent,aswellasasignificantamountofoceanic
crust.
•ThisisamajordeparturefromWegener’scontinental
drifthypothesis,whichproposedthatthecontinents
movethroughtheoceanfloor,notwithit.
•Intermediate-sizedplatesincludetheCaribbean,
Nazca,Philippine,Arabian,Cocos,Scotia,andJuande
Fucaplates.Theseplates,excepttheArabianplate,are
composedmostlyofoceaniclithosphere.
drifthypothesis,whichproposedthatthecontinents
movethroughtheoceanfloor,notwithit.
•Intermediate-sizedplatesincludetheCaribbean,
Nazca,Philippine,Arabian,Cocos,Scotia,andJuande
Fucaplates.Theseplates,excepttheArabianplate,are
composedmostlyofoceaniclithosphere.
Plate Boundaries
Fig.Seafloorspreading:Most
divergentplateboundaries
aresituatedalongthecrests
ofoceanicridges—thesitesof
seafloorspreading.
divergentplateboundaries
aresituatedalongthecrests
ofoceanicridges—thesitesof
seafloorspreading.
Tectonics Plat Boundaries
•Because plates are in constant motion relative to
each other, most major interactions among them
and, most deformation occur along their boundaries.
•Plates are bounded by three distinct types of
boundaries, which are differentiated by the type of
movement they exhibit:
•Divergent plate boundaries, where two plates move
apart, resulting in upwelling and partial melting of
hot material from the mantle to create new seafloor
•Because plates are in constant motion relative to
each other, most major interactions among them
and, most deformation occur along their boundaries.
•Plates are bounded by three distinct types of
boundaries, which are differentiated by the type of
movement they exhibit:
•Divergent plate boundaries, where two plates move
apart, resulting in upwelling and partial melting of
hot material from the mantle to create new seafloor
•Convergent plate boundaries, where two plates
move towards each other, resulting either in
oceanic lithosphere descending beneath an
overriding plate, eventually to be reabsorbed into
the mantle, or possibly in the collision of two
continental blocks to create a mountain belt.
•Transform plate boundaries, where two plates
grind past each other without the production or
destruction of the lithosphere.
move towards each other, resulting either in
oceanic lithosphere descending beneath an
overriding plate, eventually to be reabsorbed into
the mantle, or possibly in the collision of two
continental blocks to create a mountain belt.
•Transform plate boundaries, where two plates
grind past each other without the production or
destruction of the lithosphere.
Driving Mechanisms of
Plate Tectonics
Plate Tectonics
DrivingMechanisms ofPlateMotions
1.Mid-Oceanic Ridge Crests and Trenches:
•Mid-oceanic ridge crests:
•Hot and elevated regions along the ocean floor.
•Mark the boundaries between diverging tectonic plates.
•Trenches:
•Cold and deep areas associated with subduction zones.
•Form where one tectonic plate is forced beneath another.
2.Tensional Cracks at Ridge Crests:
•Ridge crests exhibit tensional cracksdue to diverging motion of
tectonic plates.
•These cracks allow magma to rise from the mantle, creating new
oceanic crust.
1.Mid-Oceanic Ridge Crests and Trenches:
•Mid-oceanic ridge crests:
•Hot and elevated regions along the ocean floor.
•Mark the boundaries between diverging tectonic plates.
•Trenches:
•Cold and deep areas associated with subduction zones.
•Form where one tectonic plate is forced beneath another.
2.Tensional Cracks at Ridge Crests:
•Ridge crests exhibit tensional cracksdue to diverging motion of
tectonic plates.
•These cracks allow magma to rise from the mantle, creating new
oceanic crust.
3. Subduction Zones and Continental
Edges:
❑Some tectonic plates consist of:
•Oceanic lithosphere(dense).
•Continental lithosphere(less dense).
❑Oceanic plates can subduct beneath other
plates because they are denser.
❑However, continents cannot subduct.
Edges:
❑Some tectonic plates consist of:
•Oceanic lithosphere(dense).
•Continental lithosphere(less dense).
❑Oceanic plates can subduct beneath other
plates because they are denser.
❑However, continents cannot subduct.
4. Mantle Convection:
•Slow movement of hot, ductile rock within Earth’s interior.
•Warm, buoyant mantle material rises while cool, dense
lithospheric plates sink.
•Subducting oceanic plates drive the downward flow, while
upwelling of hot rock contributes to the upward flow.
•In summary, mantle convection plays a crucial role in plate
tectonics, driving the movement of tectonic plates and
shaping Earth’s surface features.
•Slow movement of hot, ductile rock within Earth’s interior.
•Warm, buoyant mantle material rises while cool, dense
lithospheric plates sink.
•Subducting oceanic plates drive the downward flow, while
upwelling of hot rock contributes to the upward flow.
•In summary, mantle convection plays a crucial role in plate
tectonics, driving the movement of tectonic plates and
shaping Earth’s surface features.
1. Ridge Push Mechanism:
•As plates move away from divergent boundaries (such as
mid-oceanic ridges), they cool and thicken.
•Cooling sea floor subsides, forming the broad side slopes of
the mid-oceanic ridge.
•The mantle thickens due to cooling, converting the
asthenosphericmantle to the lithospheric mantle.
•The boundary between the lithosphere and asthenosphere
acts as a slope down which the lithosphere slides.
•This process is caused by a mechanism called ridge push.
•As plates move away from divergent boundaries (such as
mid-oceanic ridges), they cool and thicken.
•Cooling sea floor subsides, forming the broad side slopes of
the mid-oceanic ridge.
•The mantle thickens due to cooling, converting the
asthenosphericmantle to the lithospheric mantle.
•The boundary between the lithosphere and asthenosphere
acts as a slope down which the lithosphere slides.
•This process is caused by a mechanism called ridge push.
2. Slab Pull Mechanism:
✓Cold lithosphere sinks vertically through the hot mantle.
✓The sinking lithosphere pulls the surface part of the plate
away from the ridge crest and downward into the mantle as it
cools.
✓Subducting plates sink because they are denser than the
surrounding mantle.
✓The density contrast is partly due to the cold temperature of
the sinking lithosphere.
✓During subduction, low-density materials (such as water) are
lost, and plate minerals collapse into denser forms.
✓This process is explained by the slab pull model.
✓Cold lithosphere sinks vertically through the hot mantle.
✓The sinking lithosphere pulls the surface part of the plate
away from the ridge crest and downward into the mantle as it
cools.
✓Subducting plates sink because they are denser than the
surrounding mantle.
✓The density contrast is partly due to the cold temperature of
the sinking lithosphere.
✓During subduction, low-density materials (such as water) are
lost, and plate minerals collapse into denser forms.
✓This process is explained by the slab pull model.
3. Trench Suction Mechanism:
•If subducting plates fall into the mantle at
steeper angles than their dip, trenches and
overlying plates are pulled horizontally seaward
toward the subducting plates.
•This phenomenon has been termed trench
suction.
•If subducting plates fall into the mantle at
steeper angles than their dip, trenches and
overlying plates are pulled horizontally seaward
toward the subducting plates.
•This phenomenon has been termed trench
suction.
MantlePlumesandHotSpots
•Plumesmayform“hotspots”ofactivevolcanismatEarth’ssurface.
Accordingtoonehypothesis,whentheheadofalargeplume
(“superplume”)nearsthesurface,itmaycauseanupliftandthe
eruptionofvastfieldsoffloodbasalts.
•Astheheadwidensbeneaththecrust,theflood-basaltareawidens
andthecrustisstretched.Theoutward,radialflowoftheexpanding
headmaybestrongenoughtobreakthelithosphereandstartplates
moving.
•Amantleplumerisingbeneathacontinentshouldheattheland
andbulgeitupwardtoformadomemarkedbyvolcanic
eruptions.
•Plumesmayform“hotspots”ofactivevolcanismatEarth’ssurface.
Accordingtoonehypothesis,whentheheadofalargeplume
(“superplume”)nearsthesurface,itmaycauseanupliftandthe
eruptionofvastfieldsoffloodbasalts.
•Astheheadwidensbeneaththecrust,theflood-basaltareawidens
andthecrustisstretched.Theoutward,radialflowoftheexpanding
headmaybestrongenoughtobreakthelithosphereandstartplates
moving.
•Amantleplumerisingbeneathacontinentshouldheattheland
andbulgeitupwardtoformadomemarkedbyvolcanic
eruptions.
Plate Motions: Hypothesis
1.Plate motions are controlled by variations in lithosphere
density and thickness.
2.Cooling plays a significant role in determining
lithosphere properties.
3.Unlike most convection models, which assume that
plates are dragged along by mantle movement, the idea
here is that plate motions result from the properties of
the plates themselves and the pull of gravity.
1.Plate motions are controlled by variations in lithosphere
density and thickness.
2.Cooling plays a significant role in determining
lithosphere properties.
3.Unlike most convection models, which assume that
plates are dragged along by mantle movement, the idea
here is that plate motions result from the properties of
the plates themselves and the pull of gravity.
Vertical Motions of the Crust
Introduction
•TectonicforcesshapeEarth’ssurfacebymovingrockslaterally
andthickeningthemvertically.
•Additionalprocessesbeyondtectonicscontributetolandscape
evolution.
Introduction
•TectonicforcesshapeEarth’ssurfacebymovingrockslaterally
andthickeningthemvertically.
•Additionalprocessesbeyondtectonicscontributetolandscape
evolution.
Isostasy: The Balancing Act
•Definition:Isostasyistheprocessthatmaintainsequilibriuminthe
Earth’scrust.
•Concept:Lighter,less-densecontinentalcrust“floats”higheronthe
mantlethandenseroceaniccrust.
•Equilibrium:Thecraton(stablecontinentalinterior)achievesbalanceat
theproperlevelbasedonitsthickness.
•MountainCrust:Thickercontinentalcrustofmountains“floats”higher
thanthestablecontinent.
•Definition:Isostasyistheprocessthatmaintainsequilibriuminthe
Earth’scrust.
•Concept:Lighter,less-densecontinentalcrust“floats”higheronthe
mantlethandenseroceaniccrust.
•Equilibrium:Thecraton(stablecontinentalinterior)achievesbalanceat
theproperlevelbasedonitsthickness.
•MountainCrust:Thickercontinentalcrustofmountains“floats”higher
thanthestablecontinent.
Erosion and Isostatic Adjustment :
❑As material erodes from mountains, the range
rises to regain isostatic balance.
❑Isostatic adjustment occurs gradually, not
instantaneously.
❑Uplift and erosion processes continue until the
mountain block reaches average crustal
thickness.
❑As material erodes from mountains, the range
rises to regain isostatic balance.
❑Isostatic adjustment occurs gradually, not
instantaneously.
❑Uplift and erosion processes continue until the
mountain block reaches average crustal
thickness.
Conclusion
•Isostasy plays a crucial role in maintaining Earth’s
topography.
•Understanding vertical motions helps explain
mountain persistence long after tectonic activity
ceases.
•Isostasy plays a crucial role in maintaining Earth’s
topography.
•Understanding vertical motions helps explain
mountain persistence long after tectonic activity
ceases.
Introduction to Sedimentary Basins
Definitions
•Sedimentary Basins: Lower depressions on Earth's surface where
sediments and organic materials accumulate over time.
•Formation Processes:
•Crustal Attenuation: Thinning of the Earth's crust creates depressions.
•Thermo-tectonics:Temperature changes cause crust expansion or
contraction, leading to basin formation.
•Lithospheric Flexure: Bending of the lithosphere under an overlying
load creates basins.
•Volcanism:Adjacent high-land can lead to basin formation.
•Erosion:Forces like wind and water wear away the Earth's surface,
shaping basins.
Definitions
•Sedimentary Basins: Lower depressions on Earth's surface where
sediments and organic materials accumulate over time.
•Formation Processes:
•Crustal Attenuation: Thinning of the Earth's crust creates depressions.
•Thermo-tectonics:Temperature changes cause crust expansion or
contraction, leading to basin formation.
•Lithospheric Flexure: Bending of the lithosphere under an overlying
load creates basins.
•Volcanism:Adjacent high-land can lead to basin formation.
•Erosion:Forces like wind and water wear away the Earth's surface,
shaping basins.
The Concept of Sediment Accommodation
A sedimentary basin forms when there is a substantial
depressionin the Earth’s crust that provides enough space for
sediments to accumulate
•Crustal Movements
•Sediment Supply
•Accumulation Space
•Chemical and Biogenic Sediments
In summary, without tectonic processes creating low areas on
the Earth’s surface (such as basins), there would be no long-
term accumulation of sediment, no formation of sedimentary
rocks, and no development of stratigraphy.
A sedimentary basin forms when there is a substantial
depressionin the Earth’s crust that provides enough space for
sediments to accumulate
•Crustal Movements
•Sediment Supply
•Accumulation Space
•Chemical and Biogenic Sediments
In summary, without tectonic processes creating low areas on
the Earth’s surface (such as basins), there would be no long-
term accumulation of sediment, no formation of sedimentary
rocks, and no development of stratigraphy.
Formation & Evolution of Sedimentary Basins
•Sedimentarybasinsevolvethroughvariousgeologicalprocesses.These
processesinclude:
1.TectonicActivity:
•Rift Basins:
•Convergent Basins:
•Magmatic Activity:
•Volcanic Basins:
2.Sedimentation:
oAvailabilityofSediments:
3.VerticalCrustalMovements:
•Crustal Arching and Subsidence:
•Crustal Loading:
oChicken-and-Egg Scenario:
•In summary, sedimentary basins are dynamic features shaped by a
combination of tectonic, magmatic, and sedimentary processes.
•Sedimentarybasinsevolvethroughvariousgeologicalprocesses.These
processesinclude:
1.TectonicActivity:
•Rift Basins:
•Convergent Basins:
•Magmatic Activity:
•Volcanic Basins:
2.Sedimentation:
oAvailabilityofSediments:
3.VerticalCrustalMovements:
•Crustal Arching and Subsidence:
•Crustal Loading:
oChicken-and-Egg Scenario:
•In summary, sedimentary basins are dynamic features shaped by a
combination of tectonic, magmatic, and sedimentary processes.
Theories on Sedimentary Basin Formation
•Numerous theories have been proposed to explain the formation of sedimentary
basins.
•Amongthevariousmodels,threestandoutasparticularlysignificant:
•Salveson’sModel(PassiveCrustalSeparation):
oSalveson(1976,1979)putforthamodelbasedonpassivecrustalseparation.Inthistheory:
▪Thecontinentalcrustdeformsthroughbrittlefailure.
▪Thesubcrustallithosphereundergoesthinningviaductilenecking.
▪ThismodeldrawsinspirationfromstudiesoftheRedSeaandGulfofSuezriftsystem.
•McKenzie’sModel(BrittleDeformationofBothCrustandLithosphere):
oMcKenzie(1978)proposedamodelthatassumesboththecrustandsubcrustallithosphere
deformthroughbrittlefailure.
oThismodelwasprimarilydevelopedbasedoninvestigationsoftheNorthSeaBasin.
•Wernicke’sModel(CrustalThinningviaSimpleShear):
oWernicke(1981,1985)introducedamodelforcrustalthinningusingsimpleshear.
oKeyfeaturesofthistheory:
▪Alow-anglefaultextendsfromthesurfacethroughthelithosphere.
▪StudiesofthebasinandrangetectonicprovinceinNorthAmericainformedthismodel.
•Numerous theories have been proposed to explain the formation of sedimentary
basins.
•Amongthevariousmodels,threestandoutasparticularlysignificant:
•Salveson’sModel(PassiveCrustalSeparation):
oSalveson(1976,1979)putforthamodelbasedonpassivecrustalseparation.Inthistheory:
▪Thecontinentalcrustdeformsthroughbrittlefailure.
▪Thesubcrustallithosphereundergoesthinningviaductilenecking.
▪ThismodeldrawsinspirationfromstudiesoftheRedSeaandGulfofSuezriftsystem.
•McKenzie’sModel(BrittleDeformationofBothCrustandLithosphere):
oMcKenzie(1978)proposedamodelthatassumesboththecrustandsubcrustallithosphere
deformthroughbrittlefailure.
oThismodelwasprimarilydevelopedbasedoninvestigationsoftheNorthSeaBasin.
•Wernicke’sModel(CrustalThinningviaSimpleShear):
oWernicke(1981,1985)introducedamodelforcrustalthinningusingsimpleshear.
oKeyfeaturesofthistheory:
▪Alow-anglefaultextendsfromthesurfacethroughthelithosphere.
▪StudiesofthebasinandrangetectonicprovinceinNorthAmericainformedthismodel.
Classification of Sedimentary Basins
•Sedimentarybasinsarecategorizedbasedonseveralkeyfactors:
1.LithosphericSubstratum:
oBasinscanbeassociatedwithdifferentlithosphericsubstrata:
▪ContinentalBasins:Formedwithincontinentalcrust.
▪OceanicBasins:Locatedinoceaniccrust.
▪TransitionalBasins:Occurattheboundarybetweencontinentalandoceanic
crust.
2.PositionRelativetoPlateBoundaries:
oBasinsareclassifiedbasedontheirpositionwithrespecttoplate
boundaries:
▪IntracontinentalBasins:Locatedwithinatectonicplateawayfromplate
margins.
▪PlateMarginBasins:Associatedwithplateboundaries.
•Sedimentarybasinsarecategorizedbasedonseveralkeyfactors:
1.LithosphericSubstratum:
oBasinscanbeassociatedwithdifferentlithosphericsubstrata:
▪ContinentalBasins:Formedwithincontinentalcrust.
▪OceanicBasins:Locatedinoceaniccrust.
▪TransitionalBasins:Occurattheboundarybetweencontinentalandoceanic
crust.
2.PositionRelativetoPlateBoundaries:
oBasinsareclassifiedbasedontheirpositionwithrespecttoplate
boundaries:
▪IntracontinentalBasins:Locatedwithinatectonicplateawayfromplate
margins.
▪PlateMarginBasins:Associatedwithplateboundaries.
3.TypeofPlateMotionNeartheBasin:
oThetypeofplatemotioninfluencesbasinformation:
▪DivergentBasins:Formedinregionswheretectonicplates
moveapart(e.g.,riftbasins).
▪ConvergentBasins:Associatedwithplatecollisionand
subduction.
▪TransformBasins:Occuralongstrike-slipfaultboundaries.
4.BasinsRelatedtoCrustalLoading:
oSomebasinsresultfromcrustalloadingduetosedimentation.
oThesebasinsrequireaninitialdepressioninthecrustbefore
sedimentaccumulationbegins.
oThetypeofplatemotioninfluencesbasinformation:
▪DivergentBasins:Formedinregionswheretectonicplates
moveapart(e.g.,riftbasins).
▪ConvergentBasins:Associatedwithplatecollisionand
subduction.
▪TransformBasins:Occuralongstrike-slipfaultboundaries.
4.BasinsRelatedtoCrustalLoading:
oSomebasinsresultfromcrustalloadingduetosedimentation.
oThesebasinsrequireaninitialdepressioninthecrustbefore
sedimentaccumulationbegins.
Continental Rift Basins
•Inregionsexperiencingextension,thecontinentalcrust
fracturestoformrifts.Theseriftsarestructuralvalleys
boundedbyextensional(normal)faults.
•Belowarethekeyfeaturesofcontinentalriftbasins:
1.RiftGeometry:
ograben,andhorsts.
2. Volcanic Activity and Uplift:
3.ControlsonSedimentation:
oSedimentationinriftvalleysisinfluencedbyseveralfactors:
•Tectonic Factors:
•Pathways of Sediment:
•Climate:
•Inregionsexperiencingextension,thecontinentalcrust
fracturestoformrifts.Theseriftsarestructuralvalleys
boundedbyextensional(normal)faults.
•Belowarethekeyfeaturesofcontinentalriftbasins:
1.RiftGeometry:
ograben,andhorsts.
2. Volcanic Activity and Uplift:
3.ControlsonSedimentation:
oSedimentationinriftvalleysisinfluencedbyseveralfactors:
•Tectonic Factors:
•Pathways of Sediment:
•Climate:
Intra-CratonicBasins
•Intra-cratonicbasinsareexpansive,shallow,saucer-shaped
depressionslocatedwithinthestableinteriorofacontinentalblock
(knownasacraton).Thesebasinsexhibitdistinctcharacteristics
basedontheirsedimentarycontent:
1.TerrigenousIntra-CratonicBasins:
oDominatedbycontinentalclasticsediments(suchassand,silt,andclay).
oTypicallylackmarineshales.
2.CarbonateIntra-CratonicBasins:
oContainmarinesediments,includingcarbonates(suchaslimestone).
oMayalsoharborevaporiticdeposits.
•Intra-cratonicbasinsareexpansive,shallow,saucer-shaped
depressionslocatedwithinthestableinteriorofacontinentalblock
(knownasacraton).Thesebasinsexhibitdistinctcharacteristics
basedontheirsedimentarycontent:
1.TerrigenousIntra-CratonicBasins:
oDominatedbycontinentalclasticsediments(suchassand,silt,andclay).
oTypicallylackmarineshales.
2.CarbonateIntra-CratonicBasins:
oContainmarinesediments,includingcarbonates(suchaslimestone).
oMayalsoharborevaporiticdeposits.
Passive Continental Margins (Cold Basins)
•Passivecontinentalmarginsareregionswherecontinental
crusttransitionstooceaniccrustalongtheedgesofspreading
oceanbasins.(ColdBasins)Why?
oArecharacterizebythethinningofContinentalCrust,
TransitionalZone.
1.MorphologyandSedimentSupply:
oPassiveMarginFeatures
oArecharacterizebyClasticSedimentSupply,Influenceof
ClimateandTopography,andStarvedMargins.
2.AccumulationofSediments
•Passivecontinentalmarginsareregionswherecontinental
crusttransitionstooceaniccrustalongtheedgesofspreading
oceanbasins.(ColdBasins)Why?
oArecharacterizebythethinningofContinentalCrust,
TransitionalZone.
1.MorphologyandSedimentSupply:
oPassiveMarginFeatures
oArecharacterizebyClasticSedimentSupply,Influenceof
ClimateandTopography,andStarvedMargins.
2.AccumulationofSediments
Failed Rifts
•FailedriftorAbortedRiftingarebasinswhererifting
processeswerehaltedbeforeseafloorspreadingand
passivemargindevelopmentoccurred.
•Failedriftsrepresentareaswheretheinitialrifting
processdidnotprogresstofulloceanbasinformation.
•WideningDuringCooling:Astheriftcools,it
widens.
•Post-RiftSediments:Sedimentaryrocksdeposited
aftertheriftphaseonlapthepreviousriftshoulders.
•Steer’sHeadGeometry:Theresultingshape
resemblesasteer’shead.
•FailedriftorAbortedRiftingarebasinswhererifting
processeswerehaltedbeforeseafloorspreadingand
passivemargindevelopmentoccurred.
•Failedriftsrepresentareaswheretheinitialrifting
processdidnotprogresstofulloceanbasinformation.
•WideningDuringCooling:Astheriftcools,it
widens.
•Post-RiftSediments:Sedimentaryrocksdeposited
aftertheriftphaseonlapthepreviousriftshoulders.
•Steer’sHeadGeometry:Theresultingshape
resemblesasteer’shead.
Oceanic Rift Basins
•Oceanicriftbasinsareformedatmid-oceanicridgeswhere
basalticcrustisgenerated.Thekeyformationprocess
includes:
1.FormationandBuoyancy:
oBasalticcrustformsatmid-oceanicridgesduetovolcanic
activity.
oThisnewlyformedcrustishotandrelativelybuoyant.
2.CoolingandSinking
3.DepthVariation:
oMid-oceanridgesaretypicallyfoundatdepthsofaround2500
meters.
oThedepthoftheoceanbasinincreasesawayfromtheridges,
reachingbetween4000and5000meterswherethebasaltic
crustisoldandcool.
•Oceanicriftbasinsareformedatmid-oceanicridgeswhere
basalticcrustisgenerated.Thekeyformationprocess
includes:
1.FormationandBuoyancy:
oBasalticcrustformsatmid-oceanicridgesduetovolcanic
activity.
oThisnewlyformedcrustishotandrelativelybuoyant.
2.CoolingandSinking
3.DepthVariation:
oMid-oceanridgesaretypicallyfoundatdepthsofaround2500
meters.
oThedepthoftheoceanbasinincreasesawayfromtheridges,
reachingbetween4000and5000meterswherethebasaltic
crustisoldandcool.
4.VolcanicActivityandSeamounts:
5.ShallowWaterEnvironment:
oBesidesvolcanicrocks,theshallowwater
environmentinthesebasinsmayalsosupport
carbonateproductionandreefformation.
6.DeeperSedimentation:
oInthedeeperpartsofoceanbasins,sedimentation
primarilyconsistsoffine-grainedbiogenicdetritus
andclays.
7.TerrigenousClasticMaterial:
oClosertotheedgesofthebasins,terrigenousclastic
material(suchasturbidites)maybedeposited.
5.ShallowWaterEnvironment:
oBesidesvolcanicrocks,theshallowwater
environmentinthesebasinsmayalsosupport
carbonateproductionandreefformation.
6.DeeperSedimentation:
oInthedeeperpartsofoceanbasins,sedimentation
primarilyconsistsoffine-grainedbiogenicdetritus
andclays.
7.TerrigenousClasticMaterial:
oClosertotheedgesofthebasins,terrigenousclastic
material(suchasturbidites)maybedeposited.
Proto-Oceanic Troughs
•Proto-oceanictroughsrepresentacriticalstageinthe
evolutionofEarth’scrust,bridgingthegapbetween
terrestrialriftvalleysandfullydevelopedoceanbasins.
•Proto-oceanictroughsrepresentacriticalstageinthe
evolutionofEarth’scrust,bridgingthegapbetween
terrestrialriftvalleysandfullydevelopedoceanbasins.
Subduction Basins
•Atconvergentplatemarginswheretheoceaniclithosphere
isinvolved,subductionoccurs.
1.SubductionProcess:
oAstheoceanicplatebendstoenterthesubductionzone,a
troughiscreatedatthecontactbetweenthetwoplates,
forminganoceantrench.
2.VolcanicActivity:
oThedescendingoceanicslabisheatedasitgoesdownand
partiallymelts.
oThemagmasgeneratedrisetothesurfacethroughthe
overridingplate,creatingalineofvolcanoesknownasa
volcanicarc.
•Atconvergentplatemarginswheretheoceaniclithosphere
isinvolved,subductionoccurs.
1.SubductionProcess:
oAstheoceanicplatebendstoenterthesubductionzone,a
troughiscreatedatthecontactbetweenthetwoplates,
forminganoceantrench.
2.VolcanicActivity:
oThedescendingoceanicslabisheatedasitgoesdownand
partiallymelts.
oThemagmasgeneratedrisetothesurfacethroughthe
overridingplate,creatingalineofvolcanoesknownasa
volcanicarc.
Basins at Subduction Zones
•Ocean Trenches (Trench Basins)
•Accretionary Complexes
•Forearc Basins
•Back-arc Basins
•Intra-Arc Basin
•Ocean Trenches (Trench Basins)
•Accretionary Complexes
•Forearc Basins
•Back-arc Basins
•Intra-Arc Basin
Basins at Subduction Zones
1.OceanTrenches(TrenchBasins):Elongate,gently
curvingtroughsformedwhereanoceanicplatebendsas
itentersasubductionzone.
Sediments:Mostsedimentfromcontinentsgets
trappedinthesetrenches.
2.AccretionaryComplexes:Theseformwhen
sedimentsdepositedontheseafloorarescrapedoffasthe
oceanicplatedescendsintotheBenioffzone.
Sediments:Accretionarycomplexesconsistoffolded
andbrecciatedsedimentaryrocks.
1.OceanTrenches(TrenchBasins):Elongate,gently
curvingtroughsformedwhereanoceanicplatebendsas
itentersasubductionzone.
Sediments:Mostsedimentfromcontinentsgets
trappedinthesetrenches.
2.AccretionaryComplexes:Theseformwhen
sedimentsdepositedontheseafloorarescrapedoffasthe
oceanicplatedescendsintotheBenioffzone.
Sediments:Accretionarycomplexesconsistoffolded
andbrecciatedsedimentaryrocks.
3.ForearcBasins:Locatedbetweenactualislandarcs
withvolcanoesandthesubductiontrench.
Sediments:Forearcbasinscontainfluvial,deltaic,and
shallowmarinesediments.
4.Back-arcBasins:Developontheoceaniccrustdueto
seafloorspreadingbehindislandarcs.
Sediments:Theymayfillwithdeltaicandshallow
marinesediments.
withvolcanoesandthesubductiontrench.
Sediments:Forearcbasinscontainfluvial,deltaic,and
shallowmarinesediments.
4.Back-arcBasins:Developontheoceaniccrustdueto
seafloorspreadingbehindislandarcs.
Sediments:Theymayfillwithdeltaicandshallow
marinesediments.
5. Intra-Arc Basin
oIntheregionofthevolcanicarcwherethecrust
ishotterandweaker,an“intra-arcbasin”forms.
oThistransientextensionalbasinisboundonboth
sidesbyactivevolcanoesandaccumulates
mainlyvolcanicallyderivedsediment.
oIntheregionofthevolcanicarcwherethecrust
ishotterandweaker,an“intra-arcbasin”forms.
oThistransientextensionalbasinisboundonboth
sidesbyactivevolcanoesandaccumulates
mainlyvolcanicallyderivedsediment.
BASINS RELATED TO CRUSTAL LOADING
Peripheral Foreland Basin
•Loading of the foreland crust on either side of the
orogenic belt causes the crust to flex. Imagine
adding a mass to the unsupported end of a beam—it
bends downwards.
•Turbidites, shallow marine and continental
sedimentation
Peripheral Foreland Basin
•Loading of the foreland crust on either side of the
orogenic belt causes the crust to flex. Imagine
adding a mass to the unsupported end of a beam—it
bends downwards.
•Turbidites, shallow marine and continental
sedimentation
Retro-Arc Foreland Basins
•In retro-arc foreland basins, thickening of the
crust in the continental magmatic arc causes
landward movement of rock masses along
thrusts.
•The main source of detritus (sediment) in
retro-arc foreland basins is the mountain belt
and volcanic arc.
•In retro-arc foreland basins, thickening of the
crust in the continental magmatic arc causes
landward movement of rock masses along
thrusts.
•The main source of detritus (sediment) in
retro-arc foreland basins is the mountain belt
and volcanic arc.
Comparison:
Continental Margins: Passive and Active
•Continentalmarginsaretheouteredgesof
continentswherecontinentalcrusttransitionsto
oceaniccrust.
•Twomaintypesofcontinentalmarginsexist:
passiveandactive.
•Continentalmarginsaretheouteredgesof
continentswherecontinentalcrusttransitionsto
oceaniccrust.
•Twomaintypesofcontinentalmarginsexist:
passiveandactive.
1.PassiveContinentalMargins:
oNearlytheentireAtlanticOceanandasignificantportion
oftheIndianOceanaresurroundedbypassivecontinental
margins.
2.ActiveContinentalMargins:
oMostofthePacificOceanisborderedbyactive
continentalmargins,whichcoincidewithsubduction
zones.
oActivemarginsareassociatedwithtectonicactivity,
strongearthquakes,andvolcanicprocesses.
oNearlytheentireAtlanticOceanandasignificantportion
oftheIndianOceanaresurroundedbypassivecontinental
margins.
2.ActiveContinentalMargins:
oMostofthePacificOceanisborderedbyactive
continentalmargins,whichcoincidewithsubduction
zones.
oActivemarginsareassociatedwithtectonicactivity,
strongearthquakes,andvolcanicprocesses.
Features of Passive Continental Margins
1.ContinentalShelf
2.ContinentalSlope
3.ContinentalRise
4.AbyssalPlains
1.ContinentalShelf
2.ContinentalSlope
3.ContinentalRise
4.AbyssalPlains
STRIKE-SLIP BASINS: FORMATION
AND CHARACTERISTICS
•Sedimentary basins often form due to localized
extension along strike-slip fault systems, which can
be associated with divergent, convergent, or
oblique relative plate motion.
•These basins exhibit unique features and play a
significant role in recording the lithospheric
response to tectonic convergence.
AND CHARACTERISTICS
•Sedimentary basins often form due to localized
extension along strike-slip fault systems, which can
be associated with divergent, convergent, or
oblique relative plate motion.
•These basins exhibit unique features and play a
significant role in recording the lithospheric
response to tectonic convergence.
TranstensionalBasins
•Deformation Type: Transtensionalbasins result
from extensional tectonics combined with strike-slip
motion.
Characteristics:
•Faults exhibit both normal (extensional) and strike-
slip components.
•Basin formation involves stretching and faulting.
•Examples include the Gulf of California and the
Baikal Rift Zone
•Deformation Type: Transtensionalbasins result
from extensional tectonics combined with strike-slip
motion.
Characteristics:
•Faults exhibit both normal (extensional) and strike-
slip components.
•Basin formation involves stretching and faulting.
•Examples include the Gulf of California and the
Baikal Rift Zone
TranspressionalBasins
Deformation Type: Transpressionalbasins result from
oblique compression.
Characteristics:
-Combine strike-slip deformation with shortening
perpendicular to fault planes.
-Develop along plate boundaries and within
restraining bends in strike-slip fault zones.
-Lead to vertical crustal thickening due to oblique
convergence.
Deformation Type: Transpressionalbasins result from
oblique compression.
Characteristics:
-Combine strike-slip deformation with shortening
perpendicular to fault planes.
-Develop along plate boundaries and within
restraining bends in strike-slip fault zones.
-Lead to vertical crustal thickening due to oblique
convergence.
TransrotationalBasins:
•Deformation Type: Transrotationalbasins are
influenced by tectonic rotation.
•Characteristics:
-Crustal blocks rotate around vertical axes.
-Examples include the YinggehaiBasin in China.
-Early deformation involves large-scale strike-slip
motion, followed by boundary fault activity.
•Deformation Type: Transrotationalbasins are
influenced by tectonic rotation.
•Characteristics:
-Crustal blocks rotate around vertical axes.
-Examples include the YinggehaiBasin in China.
-Early deformation involves large-scale strike-slip
motion, followed by boundary fault activity.
Mountains Building
(Collisions)
(Collisions)
Mountains Building (Collisions)
1. Orogenesis and Orogeny
•Orogenesis: The term for the processes that
produce a mountain belt.
•Orogeny:An individual episode of mountain
building.
•Most major mountain belts exhibit visual
evidence of compressional forces, which both
shorten the crust horizontally and thicken it
vertically.
1. Orogenesis and Orogeny
•Orogenesis: The term for the processes that
produce a mountain belt.
•Orogeny:An individual episode of mountain
building.
•Most major mountain belts exhibit visual
evidence of compressional forces, which both
shorten the crust horizontally and thicken it
vertically.
2. Plate Tectonics and Orogenesis
•The theory of plate tectonics provides a
powerful explanatory model for orogenesis.
•It accounts for the origin of nearly all
present-day mountain belts and many ancient
ones.
•The theory of plate tectonics provides a
powerful explanatory model for orogenesis.
•It accounts for the origin of nearly all
present-day mountain belts and many ancient
ones.
Island arc-type mountain
building
Island Arcs:
•Form due to steady subduction of oceanic lithosphere
beneath other oceanic lithosphere.
•Over millions of years, volcanic activity, igneous pluton
emplacement, and sediment accumulation contribute
to crustal growth capping the upper plate.
•Examples:Japan, the Philippines, parts of Indonesia,
and the Aleutian Islands.
building
Island Arcs:
•Form due to steady subduction of oceanic lithosphere
beneath other oceanic lithosphere.
•Over millions of years, volcanic activity, igneous pluton
emplacement, and sediment accumulation contribute
to crustal growth capping the upper plate.
•Examples:Japan, the Philippines, parts of Indonesia,
and the Aleutian Islands.
ANDEAN-TYPE MOUNTAIN
BUILDING
•Occurs when subduction takes place beneath
a continent (not oceanic lithosphere).
•Along active continental margins, long-lasting
magmatic activity leads to the construction of
continental volcanic arcs, exemplified by the
Andes Mountains in South America.
BUILDING
•Occurs when subduction takes place beneath
a continent (not oceanic lithosphere).
•Along active continental margins, long-lasting
magmatic activity leads to the construction of
continental volcanic arcs, exemplified by the
Andes Mountains in South America.
CORDILLERAN MOUNTAIN BELTS
1.Seafloor Spreading and Subduction:
•The Pacific basin experiences rapid seafloor
spreading, balanced by high subduction rates.
•Island arcs and small crustal fragments collide with
active continental margins and accrete onto them.
2.Terranes and Microcontinents:
•Collision and accretion generate mountainous
regions around the Pacific.
•Accreted crustal blocks are called terranes or
microcontinents.
•Some may resemble modern-day Madagascar in the
Indian Ocean.
1.Seafloor Spreading and Subduction:
•The Pacific basin experiences rapid seafloor
spreading, balanced by high subduction rates.
•Island arcs and small crustal fragments collide with
active continental margins and accrete onto them.
2.Terranes and Microcontinents:
•Collision and accretion generate mountainous
regions around the Pacific.
•Accreted crustal blocks are called terranes or
microcontinents.
•Some may resemble modern-day Madagascar in the
Indian Ocean.
3.Island Arcs and Submerged Plateaus:
•Other accreted fragments include island arcs (e.g., Japan,
Philippines, Aleutian Islands).
•Some are submerged oceanic plateaus formed by basaltic
lavas.
•Over 100 such small crustal fragments exist today.
4.Accretion and Orogenesis:
•Seamounts are usually subducted with the descending
oceanic slab.
•Thick oceanic crust (e.g., OntongJava Plateau) or low-
density andesitic island arcs resist subduction.
•Collisions occur between these crustal fragments and
continental margins.
•Other accreted fragments include island arcs (e.g., Japan,
Philippines, Aleutian Islands).
•Some are submerged oceanic plateaus formed by basaltic
lavas.
•Over 100 such small crustal fragments exist today.
4.Accretion and Orogenesis:
•Seamounts are usually subducted with the descending
oceanic slab.
•Thick oceanic crust (e.g., OntongJava Plateau) or low-
density andesitic island arcs resist subduction.
•Collisions occur between these crustal fragments and
continental margins.
ALPINE-HIMALAYAN MOUNTAIN BELTS
(CONTINENTAL COLLISIONS)
1. Formation
•Formed by the collision of two continental masses.
•Closure of major ocean basins contributes to their
development.
•Includes well-known ranges: Himalayas, Appalachians,
Urals, and Alps.
2. Mountain Characteristics:
•Result from processes like folding and large-scale thrust
faulting.
•Crust becomes laterally shortened and vertically thickened.
(CONTINENTAL COLLISIONS)
1. Formation
•Formed by the collision of two continental masses.
•Closure of major ocean basins contributes to their
development.
•Includes well-known ranges: Himalayas, Appalachians,
Urals, and Alps.
2. Mountain Characteristics:
•Result from processes like folding and large-scale thrust
faulting.
•Crust becomes laterally shortened and vertically thickened.
3.Pre-Collision Orogeny:
•May involve accretion of smaller continental
fragments or island arcs.
•These fragments once occupied the ocean basin
between the continental blocks.
4.Sutures and Ophiolites:
•The collision zone is known as a suture.
•Sutures preserve oceanic lithosphere slivers trapped
between colliding plates.
•Ophiolites are crucial for identifying collision
boundaries.
•May involve accretion of smaller continental
fragments or island arcs.
•These fragments once occupied the ocean basin
between the continental blocks.
4.Sutures and Ophiolites:
•The collision zone is known as a suture.
•Sutures preserve oceanic lithosphere slivers trapped
between colliding plates.
•Ophiolites are crucial for identifying collision
boundaries.
THE HIMALAYAS
1.Formation of the Himalayas:
•Around 50 to 30 million years ago, India collided with Asia.
•Prior to Pangaea’s breakup, India was between Africa and Antarctica.
•India rapidly moved northward over thousands of kilometers.
•Subduction near Asia’s southern margin facilitated India’s migration.
2.Plate Margins and Crustal Fragments:
•Asia’s margin experienced continued subduction, forming an
Andean-type plate margin.
•India’s northern margin was a passive continental margin with
sedimentary rocks.
•Geologists identified crustal fragments between India and Asia.
1.Formation of the Himalayas:
•Around 50 to 30 million years ago, India collided with Asia.
•Prior to Pangaea’s breakup, India was between Africa and Antarctica.
•India rapidly moved northward over thousands of kilometers.
•Subduction near Asia’s southern margin facilitated India’s migration.
2.Plate Margins and Crustal Fragments:
•Asia’s margin experienced continued subduction, forming an
Andean-type plate margin.
•India’s northern margin was a passive continental margin with
sedimentary rocks.
•Geologists identified crustal fragments between India and Asia.
3.Accretion and Uplift:
•During ocean basin closure, a crustal fragment
(now southern Tibet) accreted to Asia.
•Himalayan uplift raised the Tibetan Plateau.
4.Seismic Evidence and Escape Tectonics:
•Evidence suggests Indian subcontinent thrust
beneath Tibet (400 km or 250 miles).
•Escape tectonics caused lateral displacement of
Asian crust blocks.
•During ocean basin closure, a crustal fragment
(now southern Tibet) accreted to Asia.
•Himalayan uplift raised the Tibetan Plateau.
4.Seismic Evidence and Escape Tectonics:
•Evidence suggests Indian subcontinent thrust
beneath Tibet (400 km or 250 miles).
•Escape tectonics caused lateral displacement of
Asian crust blocks.
THE APPALACHIAN MOUNTAINS AND THEIR
GEOLOGICAL HISTORY
1.Formation of the Appalachian Mountains:
•Around 300 million years ago, North America collided with Gondwana.
•These mountains stretch from Alabama to Newfoundland.
•Comparable ranges exist in the British Isles, Scandinavia, Africa, and
Greenland.
2.Collision and Rock Uplift:
•The collision lifted tons of rock, forming the southern end of the
Appalachians.
•Similar to how the Himalayas are currently forming.
•Resulted from the collision between North America and Gondwana.
3.Orogeniesand Pangaea:
•Orogeniesshaped the extensive mountain system over hundreds of
millions of years.
•Contributed to the assembly of supercontinent Pangaea.
GEOLOGICAL HISTORY
1.Formation of the Appalachian Mountains:
•Around 300 million years ago, North America collided with Gondwana.
•These mountains stretch from Alabama to Newfoundland.
•Comparable ranges exist in the British Isles, Scandinavia, Africa, and
Greenland.
2.Collision and Rock Uplift:
•The collision lifted tons of rock, forming the southern end of the
Appalachians.
•Similar to how the Himalayas are currently forming.
•Resulted from the collision between North America and Gondwana.
3.Orogeniesand Pangaea:
•Orogeniesshaped the extensive mountain system over hundreds of
millions of years.
•Contributed to the assembly of supercontinent Pangaea.
THREE DISTINCTIVE EPISODES OF APPALACHIAN
MOUNTAIN -BUILDING PROCESSES
1.Taconic Orogeny (Around 450 Million Years Ago):
•Marginal sea closure between a volcanic island arc and ancestral North America.
•Volcanic arc and ocean sediments accreted to the continental block edge.
•Remnants recognized as metamorphic rocks in the Appalachian Mountain belt.
2.Acadian Orogeny (About 350 Million Years Ago):
•Continued ocean basin closure led to microcontinent collision with North
America.
•Thrust faulting, metamorphism, and large granite intrusions.
•Significantly widened North America, especially in eastern New England.
3.AlleghanianOrogeny (Between 250 and 300 Million Years Ago):
•Africa collided with North America.
•Displaced accreted material up to 250 kilometers inland.
•Deformation of continental shelf sediments and rocks along the eastern margin.
MOUNTAIN -BUILDING PROCESSES
1.Taconic Orogeny (Around 450 Million Years Ago):
•Marginal sea closure between a volcanic island arc and ancestral North America.
•Volcanic arc and ocean sediments accreted to the continental block edge.
•Remnants recognized as metamorphic rocks in the Appalachian Mountain belt.
2.Acadian Orogeny (About 350 Million Years Ago):
•Continued ocean basin closure led to microcontinent collision with North
America.
•Thrust faulting, metamorphism, and large granite intrusions.
•Significantly widened North America, especially in eastern New England.
3.AlleghanianOrogeny (Between 250 and 300 Million Years Ago):
•Africa collided with North America.
•Displaced accreted material up to 250 kilometers inland.
•Deformation of continental shelf sediments and rocks along the eastern margin.
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