Geophysical study of the Precambrian basement in central Montana
A high-sensitivity magnetic anomaly map produced from total-intensity aeromagnetic data collected as part of the National Uranium Resource Evaluation program was used as the main data base in a study of the Precambrian basement in central Montana (lat 46/sup 0/-49/sup 0/N, long 106/sup 0/-112/sup 0/W). Computer modeling of a well-defined, representative magnetic anomaly pattern over a small portion of the study area yielded a physical model of the crystalline basement in the is particular area. Comparisons of the physical characteristics with those of the exposed basement terranes in the Superior Providence of the Canadian Shield suggest that the granitoid batholith-felsic orthogneiss terrane is the best geologic model for the crystalline basement in this particular portion of the study area. A deformational event akin to mechanical indentation may have affected the crystalline basement in central Montana, possibly during the Hudsonian orogeny in late-Early Proterozoic time. This event may have come about during the consolidation of individual microcontinents to form a composite craton in North America, as evidenced by the possible crustal roots of an ancient volcanic arc and marginal depositional basin in north-central Montana, which may mark a continental suture zone. Several major Phanerozoic surface structures and igneous center, such as the Little Rocky Mountains, the Bowdoin Dome, the Bearpaw Mountains, and the Central Montana Platform overlie integral parts of the pattern of interpreted basement deformation in central Montana and thus may have been controlled by the subjacent interpreted basement structures.
- Research Organization:
- Purdue Univ., Lafayette, IN (USA)
- OSTI ID:
- 6883745
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
GEOLOGIC DEPOSITS
GEOLOGIC MODELS
GEOPHYSICAL SURVEYS
MONTANA
URANIUM DEPOSITS
BASEMENT ROCK
COMPUTER CALCULATIONS
DEFORMATION
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
MOUNTAINS
PRECAMBRIAN ERA
FEDERAL REGION VIII
GEOLOGIC AGES
MINERAL RESOURCES
NORTH AMERICA
RESOURCES
SURVEYS
USA
050100* - Nuclear Fuels- Reserves
Exploration
& Mining
580200 - Geophysics- (-1989)