Geology topics
Research about Idaho, Montana
Source-linked reports with geographic coverage including Idaho, Montana.
Map showing locations of mines and prospects in the Dillon 1° x 2° quadrangle, Idaho and Montana
No abstract available.
Map showing geochemical favorability for mesothermal base- and precious-metal veins in the Wallace 1° by 2° Quadrangle, Montana and Idaho
This map shows the geochemical favorability for mesothermal base- and precious-metal veins in the Wallace 1° by 2° quadrangle, Montana and Idaho. The information presented here is part of the Wallace CUSMAP (Conterminous United States Mineral Assessment Program) project conducted by the U.S. Geological Survey.
Deformation along the northeast side of Blacktail Mountains salient, southwestern Montana
The Blacktail Mountains salient is a convex-eastward area of stacked Laramide-age thrust faults that trend north and dip west at moderate angles. The thrusts occur in Mississippian to Cretaceous strata above a basement of Archean metamorphic rocks. The northern margin of the salient is delimited by the Jake Canyon fault, a northwest-trending, northeast-dipping Laramide reverse fault. During the Laramide orogeny, the fault formed a common boundary of the present-day Blacktail Mountains and a structural high that existed in the area of the present-day valley of Blacktail Deer Creek. The fault juxtaposed Archean metamorphic rocks upon Phanerozoic strata in the northwest-era half of its extent, and against other Archean metamorphic rocks in the southeastern half. General structural relationships and study of small-scale structures in local areas show that movement along the Jake Canyon fault caused deformation of the north-trending thrust faults and associated folds. During Cenozoic extensional faulting, the Blacktail fault developed northeast of the Jake Canyon fault, and generally delimits the southwestern side of the basin of sedimentary rocks that lies beneath the valley of Blacktail Deer Creek.
Aeromagnetic and gravity anomaly maps and a hydrothermal veins favorability map of the Wallace 1 degree by 2 degrees Quadrangle, Montana and Idaho
This map is part of a folio of maps of the Wallace 1° x 2° quadrangle, Montana and Idaho, compiled as part of the Conterminous united States Mineral Assessment Program (CUSMAP). Background information about this folio is published in U.S. Geological Survey Circular 920. CUSMAP is designed to systematically assess the mineral resource potential of selected 1° x 2° quadrangles at a scale of 1:250,000. The objectives of CUSMAP are (1) to gather, interpret, and disseminate information about the geology and mineral resources for land-use planning and resource management, and (2) to provide framework information for planning more detailed research and exploration programs.
Geologic and structure maps of the Wallace 1 degree by 2 degrees quadrangle, Montana and Idaho: A digital database
This dataset was digitized by the U.S. Geological Survey EROS Data Center and U.S. Geological Survey Spokane Field Office for input into an Arc/Info geographic information system (GIS). The digital geologic map database can be queried in many ways to produce a variety of derivative geologic maps.
Resource appraisal map for placer gold in the Wallace 1° x 2° quadrangle, Montana and Idaho
No abstract available.
Resource appraisal map for stratabound copper-silver deposits in the Wallace 1° x 2° quadrangle, Montana and Idaho
No abstract available.
Resource appraisal map for Sullivan-type stratabound lead-zinc-silver deposits in the Wallace 1° x 2° quadrangle, Montana and Idaho
No abstract available.
Resource appraisal maps for mesothermal base- and precious-metal veins in the Wallace 1° x 2° quadrangle, Montana and Idaho
No abstract available.
Summary map of resource potential for metallic minerals in the Wallace 1° x 2° quadrangle, Montana and Idaho
No abstract available.
Character and regional significance of Great Falls tectonic zone, east-central Idaho and west-central Montana
The Great Falls tectonic zone, here named, is a belt of diverse northeast-trending geologic features that can be traced from the Idaho batholith in the Cordilleran miogeocline, across thrust-belt structures and basement rocks of west-central and southwestern Montana, through cratonic rocks of central Montana, and into southwesternmost Saskatchewan, Canada. Geologic mapping in east-central Idaho and west-central Montana has outlined a continuous zone of high-angle faults and shear zones. These structures (1) extend more than 150 km (93 mi) northeastward from near Salmon, Idaho, toward Anaconda, Montana, (2) had recurrent movement from middle Proterozoic to Holocene time, (3) controlled the intrusion and orientation of Late Cretaceous to early Tertiary dike swarms, and (4) ontrolled the uplift and orientation of the Anaconda-Pintlar Range. Recurrent fault movement in this zone and strong structural control over igneous intrusion suggest a fundamental tectonic feature that has influenced the tectonic development of the Idaho-Montana area from at least middle Proterozoic time to the present.