EES 106-02

  • transform boundary
  • divergent/convergent
  • slab pull stronger than ridge push
    • 237 mya, Pangaea, early Triassic
    • 195 mya, Gondwana, early Jurassic
    • 152 mya, still Gondwana, late Jurassic
    • 66mya, modern continents begin to form early tertiary, late Cretaceous

Minerals and Rocks

  • mineral
    • naturally occurring
    • solid crystalline substance
    • inorganic
    • specific chemical composition
  • rock
    • combination of 2 or more minerals
    • igneous
    • sedimentary
    • metamorphic

rock formation

  • igneous: formed from cooling & crystallization of magma/lava
    • composition
      • felsic: granite, rhyolite
      • mafic: basalt, gabbro
    • cooling rate
      • rapid: fine grained (aphanitic)
      • slow: large grained (phaneritic)
  • sedimentary: formed from sediment created from the weathering and erosion of pre-existing rocks that have been lithified
  • metamorphic: formed when  pre-existing rock changes under the influence of hear, pressure and/or chemically active fluids

lithification

  • process by which sediments become rock
    • primary process is compaction
  • cementation
    • chemical process in which minerals crystallize from solution that percolates thru the grains of sediment
      • iron oxide
        • red beds

sedimentary structures

  • distinctive arrangements of grains in sedimentary rocks
    • reflect modes of depotision
    • useful tools for interpreting ancient environment of deposition
  • graded bed
    • grain size increases from top to bottom
  • ripples
    • structures formed by wind or water
    • sediments accumulate downslope (lee)
    • symmetrical -> bidirectional current
    • asymmetrical -> unidirectional current
  • cross bedding or cross stratification
  • mudcracks

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