Age and composition of Archean crystalline rocks from the southern Madison Range, Montana: implications for crustal evolution in the Wyoming craton

P. A. Mueller, R. D. Shuster, J. L. Wooden, E. A. Erslev, D. R. Bowes

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

The southern Madison Range of southwestern Montana contains two distinct Precambrian lithologic assemblages: 1) a complex of tonalitic to granitic gneisess that has been thrust over (2) a medium-grade metasupracrustal sequence dominated by pelitic schist. Crystallization ages for the protolith of a granodioritic gneiss that intruded the metasupracrustal sequence (~2.6 Ga) along with an intercalated meta-andesite (~2.7 Ga) confirm the sequence as Archean. Chemical and geochronologic data for selected components of the gneiss complex indicate two groups of gneisses: an older, tonalitic to trondhjemitic group (~3.3 Ga) and a younger, mostly granitic group (~2.7 Ga). Both groups of gneisses exhibit the radiogenic Pb and nonradiogenic Nd isotopic signature characteristic of Middle and Late Archean rocks from throughout the Wyoming province. -from Authors

Original languageEnglish (US)
Pages (from-to)437-446
Number of pages10
JournalGeological Society of America Bulletin
Volume105
Issue number4
DOIs
StatePublished - 1993
Externally publishedYes

ASJC Scopus subject areas

  • Geology

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