Synorogenic crustal fluid infiltration in the Idaho-Montana thrust belt

Gray Edward Bebout, D. J. Anastasio, J. E. Holl

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Mississippian carbonates in the Sevier thrust belt in Idaho-Montana show shifts in δ18OV-SMOW, from marine carbonate values to as low as +11‰, which are best explained by exchange with externally-derived, low-δ18O fluids. Late-stage, synkinematic calcite veins are depleted in 18O relative to the host-rocks and earlier-formed veins, many having δ18O of +5 to +10‰. These veins could have equilibrated with H2O with δ18O of -7.5 to +2.5‰, perhaps reflecting infiltration of the Sevier thrust wedge by nearshore meteoric waters to depths of ∼10 km. Calcite veins in the hangingwall and footwall of the Pioneer Metamorphic Core Complex, produced during later Paleogene extension, have δ18O of -8.7 to +1.4‰ consistent with equilibration with meteoric waters with δ18O as low as -14‰. Transition from a Cretaceous crustal fluid regime influenced by the nearby Western Interior Seaway to one influenced by lower-δ18O, more inland meteoric waters is consistent with seaway retreat during thrust wedge emergence and Paleogene uplift and subaerial volcanism.

Original languageEnglish
Pages (from-to)4295-4298
Number of pages4
JournalGeophysical Research Letters
Volume28
Issue number22
DOIs
Publication statusPublished - Nov 15 2001
Externally publishedYes

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infiltration
meteoric water
veins
thrust
Paleogene
fluid
fluids
calcite
wedges
carbonate
carbonates
nearshore water
inland waters
footwall
host rock
volcanism
uplift
Cretaceous
rocks
shift

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

Cite this

Synorogenic crustal fluid infiltration in the Idaho-Montana thrust belt. / Edward Bebout, Gray; Anastasio, D. J.; Holl, J. E.

In: Geophysical Research Letters, Vol. 28, No. 22, 15.11.2001, p. 4295-4298.

Research output: Contribution to journalArticle

Edward Bebout, Gray ; Anastasio, D. J. ; Holl, J. E. / Synorogenic crustal fluid infiltration in the Idaho-Montana thrust belt. In: Geophysical Research Letters. 2001 ; Vol. 28, No. 22. pp. 4295-4298.
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