2. PLATE: LITHOSPHERE
1. Internally rigid
2. Variable thickness
3.Interact mostly at their edges
7 Large Plates
and
a dozon or more
small plates
Plate Tectonics
7. Continental
amalgamation and
fragmentation are
repeated in geologic
records and
geologists
reconstructing the
movements of the
continents through
time with
the formation of
sedimentary basin
showing details of
their structure,
stratigraphic
evolution with time.
collision zones
Assembly of Pangea - 0.3 Ga
West Gondwana
microplates and
juvenile crust
in Europe
Laurasia
North China, Kazakhstan, other
plates, and juvenile crust in Asia
INDIA
INDIA IN THE SUPERCONTINENT PANGEA
10. What is a sedimentary basin?
• A low area on the Earth’s surface relative to surroundings
– e.g. deep ocean basin (5-10 km deep), intramontane basin (2-3 km a.s.l.)
• May be of tectonic (or erosional origin)
• A receptacle for sedimentation; erosion may also be important
• Sedimentation may be interrupted - unconformities
• Basins may be small (kms2) or large (106+ km2)
• Basins may be simple or composite (sub-basins)
• Basins may change in size & shape due to:
– Erosion, - sedimentation, - tectonic activity
– eustatic sea-level changes
• Basins may overlap each other in time
11. Sedimentary basin
With the development of plate tectonics, much has become clear. Most
sedimentary basins can now be explained in terms of plate-margin processes.
}Normal continental
lithosphere
Crustal
Tension
Crustal
Compression
Thermal bulge
Erosion
Infilling
Zone of
subduction
Rift/drift
sequence
Mantle phase
change
Sediments Lithosphere Asthenosphere
1. Convergent
plate margin
2.Crustal doming 3. Rift basin 4. Crustal loading
Due to sedimentation
12. Convergent plate margin basins
• Origin
– oceanic plate being subducted under continental margin
– trench, accretionary prism, continental margin volcanic arc
• Basin types: environments & facies
• Trench basin
– deep marine
– turbidites, pelagic seds.
• Forearc basin
– perched on "scraped off", imbricate thrust faulted, accretionary prism
– alluvial fan, fluvial, shoreline shelf, deep turbidite fans
• Back arc-foreland basin
– lies behind arc
– at foot of craton directed fold & thrust belt if present
– alluvial fan, fluvial, lakes
• Intra-arc
– arc volcanoes often lie in major graben
– alluvial fan, fluvial, lake
14. • Origin
– large scale mantle convection
– regional updoming ± regional basaltic
(flood) volcanism
• extensional failure of crust
– listric normal fault system
– subsided/rotated half grabens
• widening to form central rift graben
– may:
• rupturing of crust
• spreading ridge, oceanic basin
15. Continental Rift Zones
• Origin
– regionally extensive mantle convection
– driven by subduction oceanic spreading ridge under continent
–
• Extensional failure of crust
– complex lystric fault system
– uprise of mantle + metamorphic core complexes - regional uplift, up to 2-3 km
– widespread volcanism in complex multiple graben rift basins
• Environments and facies
– alluvial fan, fluvial, lacustrine
• Volcanism
– flood basalts, bimodal basalt-rhyolite-andesite: lavas & pyroclastics
– tholeiitic, alkaline, calc-alkaline: lavas & pyroclastics.
• Provenance
– mixed crustal sources
– contemporaneous volcanic sources
16.
17. Aulacogene Basins
• Narrow continental rifts which do not evolve into spreading ridge oceanic basins.
• Dominated by initial alluvial fan, fluvial, lake facies; up to 4 km thick.
• May extend through
– crustal subsidence & extension
– marine transgression; no oceanic crust
– coastal plain rivers, coal swamp shoreline, shelf & slope environment
• Provenance
– continental, mixed
– plutonic, metasedimentary, metavolcanic, contemporaneous volcanic
– ± marine carbonates
18. • Depositional environment –
where sediment is deposited.
It can be determined by looking
at sedimentary structures
(including fossils), the bed
shape and vertical sequences
within the sedimentary layers,
and grain composition
SEDIMENTARY ENVIRONMENTS
20. Continental
amalgamation and
fragmentation are
repeated in geologic
records and
geologists
reconstructing the
movements of the
continents through
time with
the formation of
sedimentary basin
showing details of
their structure,
stratigraphic
evolution with time.
collision zones
Assembly of Pangea - 0.3 Ga
West Gondwana
microplates and
juvenile crust
in Europe
Laurasia
North China, Kazakhstan, other
plates, and juvenile crust in Asia
INDIA
INDIA IN THE SUPERCONTINENT PANGEA
