No abstract

Volcanic rocks (Cenozoic) MESOPROTEROZOIC SEDIMENTARY ROCKS Belt Supergroup (Mesoproterozoic)-Area containing major bodies patterned Yellowjacket Formation and associated metasedimentary rocks (Mesoproterozoic)-Area containing major bodies patterned TRANS-HUDSON OROGEN Volcanic-plutonic arc complexes (Paleoproterozoic)-Includes Archean gneisses TRANS-MONTANA OROGEN (ACCRETED TERRANES) Wallace terrane (Paleoproterozoic)-Covered Biotite-quartz-feldspar gneiss and amphibolite of Wallace terrane (Paleoproterozoic)-Exposed in Bitterroot Range Granite, diorite, and gneiss (Paleoproterozoic)-Crops out in Little Belt Mountains. U-Pb zircon age of 1,860-1,880 Ma (Mueller and others, 2002) Medicine Hat block (Archean)-Covered CONTINENTAL-MARGIN ASSEMBLAGE (FOLD-AND-THRUST BELT) Imbricately intercalated rocks (Paleoproterozoic and Archean)-Covered Meta-sandstone, shale, iron-formation, and graphitic shale intruded by gabbro dikes (Paleoproterozoic)-Crops out in Gravelly Range. Interpreted as foreland basin deposit Marble, quartzite, and schist (Paleoproterozoic)-Inferred to have formed on a rifted, passive margin (about 2.0 Ga). Formerly regarded as Archean Massive to weakly foliated granite to granodiorite (Late Archean) Foliated and gneissic granitoid rocks (Late Archean)-About 2.74-2.79 Ga (Wooden and others, 1988) Mafic to ultramafic rocks in Spanish Peaks area and Tobacco Root Mountains (Archean) WYOMING PROVINCE (CRATON) Stillwater Complex (Late Archean)-2.7 Ga (Wooden and others, 1988). Exposed Foliated and gneissic granitoid rocks (Late Archean)-About 2.74-2.79 Ga (Wooden and others, 1988). Exposed Granitic rocks, undivided (Archean)-Magmatic domain. Covered Gneissic rocks, undivided (Archean)-Gneiss domain. Covered

No abstract

No abstract