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Appalachian structure and tectonics

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Taconic Orogeny Arc continent collision ~460 Ma ... Alleghenian Orogeny Continent continent collision, formed global supercontinent ~320 290 Ma ... – PowerPoint PPT presentation

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Title: Appalachian structure and tectonics


1
Appalachian structure and tectonics
2
Classic orogenic events
  • Greenville OrogenyContinentcontinent collision,
    formed global supercontinent 1.1 Ga
  • Rifting 600 Ma
  • Taconic OrogenyArccontinent collision 460 Ma
  • Acadian OrogenyComposite Avaloncontinent
    collision 400370 Ma
  • Alleghenian OrogenyContinentcontinent
    collision, formed global supercontinent 320290
    Ma
  • Rifting 200 Ma

3
Paleogeographic elements
  • LaurentiaNorth American crust, includes
    Greenvillian crust and inboard Archean and
    Paleoproterozoic rocks
  • Oceanic- and arc-affinity accreted terranesOften
    divided into Peri-Laurentian and Peri-Gondwanan
  • Peri-Gondwanan continental fragmentsPieces of
    continental crust and volcanic arcs accreted
    during Acadian orogeny
  • GondwanaEurope and Africa, other side of super
    continent

4
Acadian Orogeny
  • Dominant event in northern Appalachians
  • Transpressional
  • Variety of exotic peri-Gondwanan terranes
    collided with N. America

5
Alleghenian Orogeny
  • Dominant event in southern Appalachians
  • Transpressional in south, strike-slip in north
  • Formation of AppalachianCalledonide system

6
Structure of the Appalachians
  • Promontories and embayments (reentrants)
  • Northern and southern divided at NY promontory

7
Southern Appalachians
  • Master décollement zone beneath thin thrust
    sheets
  • Type locality of a thin-skinned orogenic belt

8
Northern Appalachians
  • Large-scale structural geology less well
    understood
  • Oceanic and arc-affinity terranes overlain by
    cover sequence all metamorphosed and deformed
    during Acadian
  • Most terranes bounded by high-angle faults

9
Maine regional geology
10
Maine regional geology
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