Middle Precambrian and Keweenawan Rocks North of the Gogebic Range in Wisconsin |
Contents
Table of Illustrations | 4 |
Precambrian Rocks near Hurley Wisconsin | 15 |
10 | 34 |
7 other sections not shown
Common terms and phrases
age dates Aldrich amygdules Animikean Bad River Bessemer Formation Bessemer Quartzite biotite calcite chemical analyses chlorite clinopyroxene commonly contact metamorphic contact metamorphic zone Copper Harbor Conglomerate deposition diabase dikes Duluth Gabbro epidote exposure extrusives feet thick feldspar Felmlee felsic flows Figure fine-grained flows of Unit Freda Sandstone gabbro body geologic Gogebic Range granite gray graywacke graywacke beds Hise and Leith hornfels Huronian inches interbedded intrusion Ironwood Formation Keweenaw fault Keweenawan rocks Keweenawan volcanic rocks Lake Superior Lake Superior district lava flows locally Lower Keweenawan Quartzite Lower Keweenawan sedimentary lowermost mafic magnetite Mellen Gabbro Complex Michigan Middle Keweenawan volcanic Middle Precambrian minerals Montreal River muscovite Nonesuch Shale Oronto Group Outcrop overlying pebbles Penoke an Orogeny phenocrysts plagioclase plagioclase feldspar Precambrian primary structures quartz quartzite radiogenic rock types sedimentary rocks sediments Sibley Series siltstone structurally concordant thin sections Tyler Formation Upper Keweenawan volcanic flows volcanic sequence Wisconsin