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Eastern and Central Montana as a Possible Source Area of Uranium

Description: From abstract: Geologic settings are recognized in central and eastern Montana and in a few places in southwestern Montana that elsewhere are similar to the settings for the occurrence of uranium deposits. Several specific areas in Montana seem favorable for the occurrence of uranium.
Date: April 1956
Creator: Armstrong, Frank C.
Partner: UNT Libraries Government Documents Department

The Bannock Thrust Zone Southeastern Idaho

Description: Abstract: The Bannock overthrust in southeastern Idaho and northcentral Utah was originally described by Richards and Mansfield (1912) as a single large thrust fault that formed at the close of the Laramide orogeny and was folded by renewed compression near the end of Pliocene time. Later Mansfield expanded and revised his interpretation of the Bannock overthrust so that at least the northern part of the overthrust was thought to be a thrust zone in which the individual faults originated in a folded sole thrust. Detailed mapping in areas critical to Richards and Mansfield's interpretations has shown that the faults thought by them to be parts of one large thrust are separate faults, and that, although some of the thrust surfaces are curved, they were not folded in Pliocene time but probably were folded during a late stage of the thrusting. Extensions of the Bannock thrust to the north, south, east, and west based upon extrapolation of a single large folded thrust surface are not warranted. The Bannock overthrust is reinterpreted as a westward-dipping imbricate thrust zone possibly several tens of miles wide extending at least from southwestern Montana to north-central Utah. It is recommended that the name "Bannock overthrust" no longer be used, and that this zone of imbricate thrusts in the southeast corner of Idaho be called the Bannock thrust zone. The thrusts range in age from Late Jurassic to post- Early Cretaceous and are progressively younger from west to east; strong regional compressive forces do not appear to have been active in the area as late as Pliocene time. The upper plates of the thrusts moved to the northeast in response to an unknown force. Steep eastward-trending tear faults formed during thrusting probably in response to differential movement among the eastward-moving thrust plates. In Tertiary and Quaternary time ...
Date: 1963
Creator: Armstrong, Frank C. & Cressman, Earle Rupert
Partner: UNT Libraries Government Documents Department

The Garm-Lamoreaux Mine, Lemhi County, Idaho

Description: From abstract: The Garm-Lamoreaux property, Lemhi County, Idaho is known to have uraninite and zippeite on two of its dumps. The property has been explored by five adits, two of which are now caved, and one of which is partly caved. The country rock is schistose micaceous quartzite and argillaceous quartzite of Belt age. An east-west fault cuts the quartzite, and the Lamoreaux vein, a gold-sulfide-quartz veins occurs in the fault. The uranium minerals are believed to have core from the vein, on the now inaccessible No. 3 level.
Date: January 1954
Creator: Armstrong, Frank C. & Weis, Paul L.
Partner: UNT Libraries Government Documents Department

Reconnaissance for Radioactive Minerals in Washington, Idaho, and Western Montana, 1952-1955

Description: From abstract: Approximately fifty radioactive deposits and nearly fifty properties not abnormally radioactive were examined during a geologic reconnaissance for radioactive minerals in Idaho, Washington, and western Montana during the period July 1952 -- June 1955. The most important uranium deposits are in or near granitic to quartz monzonitic intrusions of probable Cretaceous age in central and northern Idaho, westernmost Montana, and northeastern Washington.
Date: May 1957
Creator: Weis, Paul L.; Armstrong, Frank C. & Rosenblum, Samuel
Partner: UNT Libraries Government Documents Department