Priscoan (4.00–4.03 Ga) orthogneisses from northwestern Canada

  title={Priscoan (4.00–4.03 Ga) orthogneisses from northwestern Canada},
  author={S. Bowring and I. S. Williams},
  journal={Contributions to Mineralogy and Petrology},
  • S. Bowring, I. S. Williams
  • Published 1999
  • Geology
  • Contributions to Mineralogy and Petrology
  • Abstract Ancient crustal rocks provide the only direct evidence for the processes and products of early Earth differentiation. SHRIMP zircon U-Th-Pb dating has identified, amongst the Acasta gneisses of the western Slave Province, Canada, two metatonalites and a metagranodiorite that have igneous ages of 4002 ± 4, 4012 ± 6 and 4031 ± 3 Ga respectively. These are the first identified Priscoan terrestrial rocks. A record of metamorphic events at ∼3.75, ∼3.6 and ∼1.7 Ga also is preserved. These… CONTINUE READING
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