FORELAND

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• FORELAND
• BASINS

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FORELAND BASIN

• Occurs at the subduction zones and it is formed
  due to the collision between two continental
  plates.
• Two basins are to be formed
• Primary basin develops on the subduction plate
  due to thrust loading.
• Secondary Basin is formed on the overriding plate
  due to back thrusting.

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FORELAND MECHANISM

• Thinning of the subducting plates
• Deposition of the condensed section (May be
  repeated due to stops and jumps in thinning and
  subduction rates)
• Downgoing plate of the continental sediments is
  thrusted and sheared which leads to an inverted
  sequence
• Due to crust shortening, Isostatic pushes down on
  the basin as adjustments

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Sequences

• Continental basement
• Margin Sediments (In Situ as well as thrusted)
• Oceanic Crust
• Accreted Sediments
• Uplifted oceanic crust
• Island arc rocks
• Condensed Section
• Flysch
• Molasse

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Flysch Molasse

• Flysch Thick, thinly bedded, graded, poorly
  fossilferous marine sediments with large
  percentage of turbidities (typically marls, muds,
  and sandy shale). They are mainly deep water
  sed deposited at the early stage of the basin
  development.
• Molasse Shallow water sediments (partially
  marine and partially none marine (deltaic). They
  are thick ungraded cross-bedded sand stone,
  shale, and mud sediments.

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Foreland Examples

• Most of giant oil fields in the world are
  located in the foreland basins such as
• Arabian Gulf
• Central Appalachian Basin
• Alps Foreland Basin
• North Slope of Alaska
• South Flanks of Himalayas
• East Flanks of Andes