FORAM COILING DIRECTIONS

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FORAM COILING DIRECTIONS

• GEOL 3213

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Globorotalia truncatulinoides

• Bolli (1950, 1951) discovered that the evolution
  of coiling directions of certain species of
  planktic forams varied and tended to be
  dominantly dextral or sinistral at some times.
• He suggested that this might have stratigraphic
  value.
• Ericson, Wollin, Wollin (1954) successfully
  tested this hypothesis. Their figures are
  reproduced herein.

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Coiling Distribution Map Recent North Atlantic

• From Ericson et al. (1954)
• Note the dominantly right- left-coiled regions.
• What is the percentage direction near Bermuda?

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Coiling Direction Distributions in Cores

• Two piston cores 28 km apart 360 km SW of the
  Canary Islands
• Note the extremely similar curves.
• Can they be correlated?
• Which cored area had the faster rate of
  deposition?

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Coiling Direction Distributions in Cores

• 4 piston cores along the Atlantic equator along a
  traverse 475 km long.
• How would you correlate these sections?
• Which cored region had the fastest rate of
  deposition?
• Which cored region had the slowest rate of
  deposition?

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