Geometry and kinematics of thrust system within central Snowcrest Range: a major Rocky Mountain foreland uplift and exploration target in southwest Montana

Conference · Mon Feb 01 04:00:00 EST 1988 · AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)

OSTI ID:6145978

McBride, B C

The Snowcrest Range forms the southeastern limb of the Late Cretaceous, northeast-trending, southeast-verging Blacktail-Snowcrest uplift. Field mapping and regional balanced cross sections indicate the Snowcrest thrust system consists of two master thrust faults (Snowcrest and sub-Snowcrest thrusts), each involving a system of subsidiary thrust imbricates, splays, and shear zones. East of the Snowcrest Range, the Gravelly Range thrusts are attributed to this system as regional splays. The Snowcrest thrust dips approximately 39/degrees/NW and forms the western boundary of large-scale, uprift, and overturned folds within Phanerozoic rocks above the sub-Snowcrest (Greenhorn) thrust. The sub-Snowcrest thrust is buried beneath or within the synorogenic deposit of the Beaverhead group and is inferred to merge with the Snowcrest thrust in Precambrian basement rocks at depth. Small-scale structures indicate a significant component of right-lateral oblique slip occurred on the sub-Snowcrest thrust system along the central and southern portions of the range. Preliminary strain data indicate that the principal shortening was directed east-southeast.

• Research Organization: Western Michigan Univ., Kalamazoo (USA)
• OSTI ID: 6145978
• Report Number(s): CONF-880301-
• Conference Information: Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Journal Volume: 72:2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
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CRETACEOUS PERIOD
EXPLORATION
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
MESOZOIC ERA
MINERAL RESOURCES
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PETROLEUM DEPOSITS
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USA