Field Guide to the Mountain View and West Fork Areas, Stillwater Complex, Montana
Route
Start point
End of the Mouat mine road, 6.4 miles from Stillwater Mining Company main office
End point
indeterminate
Roads (and Trails)
Mouat mine road, trail traverse along the Mountain View cliffs, U.S. Forest Service Road 846, West Fork Road
Total distance
unknown
Geology
Summary
The Mountain View area of the Stillwater Complex, which is exposed on the west side of the Stillwater River valley, contains a well exposed, easily accessible section through the Ultramafic series. In this area the ultramafic cumulates have, for the most part, escaped the serpentinization common in other parts of the complex. The Basal series rocks and the lowermost ultramafic cumulates, however, have suffereed extensive alteration. The hornfels and the sill/dike complex are reasonably fresh and well exposed in the Verdigris Creek area, the site of intensive exploration for Cu/Ni sulfides. The Banded series rocks are well exposed along the mine road leading to the abandoned Mouat chromite mine, although only Lower Banded series cumulates are present in this area.
Key Lithologic Features
- cyclic units in the Peridotite Zone, Ultramafic Series (olivine cumulates with chromite, olivine-bronzite cumulate, and bronzite cumulate)
- Ultramafic series-Banded series contact
- hornfels and sill/dike complex in the Verdigris Creek area
- layered rocks of the Banded series
- mafic dikes in the Stillwater Complex
- West Fork adit section (including the J-M Reef PGE seam)
- inch-scale layering in norites and gabbronorites of the Lower Banded series
Structures
Landforms
Other Features
Reference
McCallum, I.S., 1988, Field guide to the Mountain View and West Fork areas, Stillwater Complex, Montana,
in Lewis, S.E., and Berg, R.B., eds.,
Precambrian and Mesozoic plate margins: Montana, Idaho and Wyoming, with field guides for the 8th International Conference on Basement Tectonics : Montana Bureau of Mines and Geology Special Publication 96, p. 121-130.
Availability
Order from the Montana Bureau of Mines and Geology. Search for
this publication's record at the MBMG for ordering information.
