Mineral Resources On-Line Spatial Data
Mineral Resources > Online Spatial Data > Geology > by state > Montana
|Name||Diorite and gabbro|
|Geologic age||Phanerozoic | Mesozoic | Cretaceous(?)|
|Original map label||Kdg|
|Comments||Many unrelated intrusions are lumped into this map unit; most are probably Cretaceous in age, but some Tertiary rocks may be included.|
|Primary rock type||diorite|
|Secondary rock type||gabbroid|
|Other rock types|
Igneous > HypabyssalMany types of igneous forms are represented by this map unit, such as stocks, laccoliths, dikes, and sills. Likewise, a wide variety of igneous lithologies are included, not only mafic types. For example, the Lone Tree laccolith of Late Cretaceous age in the northern Madison Range consists mostly of dacite.
Ross, P.R., Andrews, D.A., and Witkind, I.J., 1955, Geologic map of Montana: U.S. Geological Survey, 2 sheets, scale 1:500,000.
Lewis, R.S., 1998, Preliminary geologic map of the Butte 1° x 2° quadrangle: Montana Bureau of Mines and Geology Open File Report 363, 16 p, scale 1:250,000.
|Geographic coverage||Broadwater - Flathead - Granite - Jefferson - Lewis and Clark - Madison - Powell - Teton|
Show this information as [XML]