Large 18O and 13C depletions in greenschist facies carbonate rocks, western Arizona

Antonio Guerrera, Simon M. Peacock, L. Paul Knauth

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Strongly deformed greenschist facies carbonate rocks in western Arizona exhibit large 18O and 13C depletions relative to unmetamorphosed correlative rocks in northeastern Arizona. Unmetamorphosed Permian Kaibab Formation carbonates on the Colorado Plateau yield δ13 values of +1‰ to +5‰ and δ18O values of+28‰ to +37‰. In contrast, greenschist facies Kaibab Formation in the Little Harquahala and Granite Wash Mountains yields δ13C values of-6‰ to +4‰ and δ18O values of +9‰ to +24‰ The magnitude of the observed 13C and 18O depletions cannot he explained by decarbonation reactions and requires extensive exchange with low δ13C and δ18O fluids. The 13C depletions may reflect isotopic exchange with lower δ13C carbonate in the underlying Paleozoic section and exchange with CO2 derived from oxidation of methane via reaction with hematite or sulfate in interbedded rocks. These data demonstrate that large 13C and 18O depletions can occur in strongly deformed terranes during very low-grade metamorphism. Depletions in 13C and 18O observed in some high-grade metamorphic terranes may be inherited from much lower metamorphic grades.

Original languageEnglish (US)
Pages (from-to)943-946
Number of pages4
JournalGeology
Volume25
Issue number10
DOIs
StatePublished - Oct 1997

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greenschist facies
carbonate rock
terrane
carbonate
low grade metamorphism
rock
hematite
Permian
granite
Paleozoic
methane
plateau
sulfate
oxidation
mountain
fluid

ASJC Scopus subject areas

  • Geology

Cite this

Large 18O and 13C depletions in greenschist facies carbonate rocks, western Arizona. / Guerrera, Antonio; Peacock, Simon M.; Knauth, L. Paul.

In: Geology, Vol. 25, No. 10, 10.1997, p. 943-946.

Research output: Contribution to journalArticle

Guerrera, Antonio ; Peacock, Simon M. ; Knauth, L. Paul. / Large 18O and 13C depletions in greenschist facies carbonate rocks, western Arizona. In: Geology. 1997 ; Vol. 25, No. 10. pp. 943-946.
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