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Effects of Past Global Change on Life (1995) / Chapter Skim
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Pages 22-23

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From page 22...
... Acceptance of what might fairly be called the Cloud model requires that three criteria be satisfied: 1. geochemical documentation of environmental change; FIGURE 1.1 A summary of geochem~cal and paleobiological data relevant to considerations of Paleoproterozoic evolution and environmental change (PAL = present atmospheric level)
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From page 23...
... Other arguments against the Cloud model posit that the geochemical indicators of low PO2 during the Archean and earliest Proterozoic could be the result of burial digenesis, which generally acts to reduce minerals. Equally, it has been argued that oxide facies iron formations are themselves diagenetic replacements of carbonates.
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Key Terms

  • paleobiological data
  • macroscopic animals
  • aerobic metabolism
  • cloud model


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