The geology and ore deposits of the Coeur d'Alene district, Idaho

Abstract

INTRODUCTION, by Frederick Leslie Ransome ______________________________________________________________ _ Location and area of the district_ _____________________________________________________________________ _ Field work and acknowledgments __ ________ ___ ________________________________________________________ _ Outline of the geography and geology of northern Idaho and adjacent parts of Montana and Washington __ _ Introduction _____________________ ______________________________________________ ____ _______ ____ _ _ Orography _________ -•-__________ __ _______________________________________________________________ _ Geology _________________________ __ ____________________________________________________________ __ _ Industries and settlements within the Cceur d'Alene district_ ___________________________________________ _ Literature __________________ ____

Scapolite in the Belt Series in the St. Joe-Clearwater Region, Idaho

“…i), comprise a thick sequence of interbedded garnet-mica schist; quartzite; and diopside, hornblende, and biotite gneisses and their low-grade metamorphic equivalents, hornblende and biotite granofelses 1 . This sequence is divisible into formations that in their thickness, stratigraphy, and lithology-allowing for changes due to metamorphism-correspond to the five lowest formations of the Belt Series in the Coeur d'Alene district (Ransome and Calkins, 1908). A generalized section, based on previous detailed petrologic and structural studies (Hietanen, 1962b;1963a;1963b;1963c) in addition to those in this study, is presented in Table 1.…”

Structural analysis and ore controls in the Coeur D'Alene mining district, Idaho

“…The next relevant publication is that of Ransome (1905), based on work during [1903][1904]. This paragraph summarizes his contributions.…”

“…The major faults (p. 62) are established as both reverse and normal types. The Osburn fault, the one traced for the greatest distance, is established as a normal fault with a displacement in excess of 6,000 ft. Other major faults in the district, including the Placer Creek, Alhambra, Big Creek, White Ledge, O'Neill Gulch, Dobson Pass, and Carpenter Gulch, are named and described, although the Dobson Pass term was used earlier by Ransome (1905).…”

“…Underground, sitting on a muck pile and looking at a solid, homogeneous, four-ft vein of chalcopyrite exposed in the back, the mine geologist, in response to a further question about the proportion of replacement to filling, said, "Well, I guess here it looks more like 50% replacement and 50% filling." This approach seems still to be widespread, The earliest detailed work in the Coeur d" Alene district is that of Ransome and Calkins (1908), establishing the stratigraphy and a broad understanding of the structure. They showed that the contiguous formations grade into one another and that all succeed one another conformably.…”

The Conterminous United States Mineral Assessment Program; background information to accompany folio of geologic, geochemical, geophysical, remote sensing, and mineral resource maps of the Wallace 1 degree x 2 degrees Quadrangle, Montana and Idaho

“…Early interest was centered around the mining districts (MacDonald, 1906;Ransome and Calkins, 1908;Pardee, 1911;Calkins and Jones, 1914;Jones, 1919;Umpleby and Jones, 1923). Restudy of some of the same districts and new study of others occurred in the 1930's (Shenon and Taylor, 1936;Shenon, 1938) and again in the late 1940's and during the 1950's (Lyden, 1948;Cook, 1955;Hosterman, 1956;Sahinen, 1957;Weis and others, 1958;Campbell, 1960;Fryklund, 1964;Hobbs and others, 1965;Johns, 1970).…”