Late Cretaceous extension in the hinterland of the Sevier thrust belt, northwestern Utah and southern Idaho

Journal Article · Mon Oct 01 00:00:00 EDT 1990 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1990)018<0929:LCEITH>2.3.CO;2· OSTI ID:6140142

Wells, M L; Allmendinger, R W ^[1]; Dallmeyer, R D ^[2]

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1. Cornell Univ., Ithaca, NY (USA)
2. Univ. of Georgia, Athens (USA)

Cover rocks of the Raft River metamorphic core complex, located in the Sevier belt hinterland, preserve a structural and metamorphic history that predates the middle Tertiary extension of the region. In the eastern Raft River Mountains, Cambrian( )-Permian rocks form two allochthons that occur in the hanging wall of the mid-Miocene Raft River detachment fault. Dramatically attenuated, metamorphosed Cambrian( )-Pennsylvanian strata of the lower allochthon yield Late Cretaceous muscovite {sup 40}Ar/{sup 39}Ar plateau ages (ca. 82-90 Ma) that are interpreted to date cooling during final stages of layer parallel extension. Devonian-Permian rocks exposed in the Black Pine Mountains underwent east-west extension ({approximately} 160%) associated with syntectonic growth of white mica along cleavage. {sup 40}Ar/{sup 39}Ar whole-rock spectra of associated slates also indicate a Late Cretaceous metamorphism. Together, field and {sup 40}Ar/{sup 39}Ar results suggest that Late Cretaceous extension occurred in the Sevier belt hinterland at the same time as shortening in the eastern foreland and at depth in the hinterland. Sufficient topography must have been present to drive upper-crustal extension in the eastern hinterland.

• OSTI ID: 6140142
• Journal Information: Geology; (USA), Vol. 18:10; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GEOLOGIC DEPOSITS
METAMORPHISM
IDAHO
UTAH
AGE ESTIMATION
ARGON 39
ARGON 40
CAMBRIAN PERIOD
CARBONIFEROUS PERIOD
CRETACEOUS PERIOD
DEVONIAN PERIOD
GEOLOGIC FAULTS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
ISOTOPE DATING
ISOTOPE RATIO
METAMORPHIC ROCKS
MICA
MOUNTAINS
PERMIAN PERIOD
RIVERS
TECTONICS
WESTERN US OVERTHRUST BELT
ARGON ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FEDERAL REGION VIII
FEDERAL REGION X
GEOLOGIC AGES
GEOLOGIC FRACTURES
ISOTOPES
LIGHT NUCLEI
MESOZOIC ERA
NORTH AMERICA
NUCLEI
PALEOZOIC ERA
RADIOISOTOPES
ROCKS
STABLE ISOTOPES
STREAMS
SURFACE WATERS
USA
YEARS LIVING RADIOISOTOPES
580000* - Geosciences