Some Concerns and Clarifications

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Some Concerns and Clarifications
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Black Shales

• Poor circulation
• Anoxic conditions prevail
• Breakdown of organic matter is slow or
  non-existent
• Commonly deposited in deep oceans (not abyssal
  plain) OR shallow seas with restricted
  circulation
• Black organic matter

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Calcium Carbonate and Compaction

• Inorganic precipitation
• CO2 H2O H2CO3
• H2CO3 H HCO-3
• Ca2 2HCO-3 CaCO3 H2CO3
• Lithification of carbonates can occur
  contemporaneously with deposition
• Sediment does not become compacted by the weight
  of water
• Accumulation at a point results in earlier
  deposits being overlain by younger (overburden
  pressure)
• Most common cement in sandstone/conglomerate
  deposited in marine environment CaCO3

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Carbonate Classification
Dunham Carbonate Classification
Folk Carbonate Classification
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Sequence Stratigraphy

• Conquest of terminology over common sense
• Proceed with caution

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References

• Immenhauser, A., Holmden, C., Patterson, W.P., In
  Press, Interpreting the Carbon-Isotope Record of
  Ancient Epeiric Seas Lessons from the Recent,
  6-8 pp.
• Nichols, G., 2002, Sedimentology and
  Stratigraphy, 144 pp. Blackwell Science Ltd,
  Oxford
• Walker, R.G., James, N.P., 1992, Facies Models
  Response to Sea Level Change, 119-300 pp.
  Metrolitho, Sherbrooke