English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Weak lead-zinc mineralization was general in a narrow northwest-trending belt about 30 miles long in the southeastern part of the Lewis and Clark Range, Mont. Reconnaissance geological and geochemical studies identify the belt and indicate the stratigraphic and structural control of the mineralization; geophysical data permit inferences of the location of buried plutons that may have been the source of the metals. The mineralization appears to be spatially related to the South Fork thrust zone. This zone, containing Precambrian and Paleozoic rocks, is part of the easternmost major thrust block in this range. In this zone, anomalous quantities of lead and zinc occur in the Spokane Formation and Helena Dolomite of Precambrian age, the Flathead Sandstone of Cambrian age, and the Jefferson and Three Forks Formations of Devonian age. Most of the mineralization is in the nearest permeable and porous carbonate or calcareous sandstone bed to the westernmost thrust fault of the South Fork thrust zone. Magnetic and gravity data were used in denning the area for geological and geochemical studies of the many major magnetic anomalies that indicate buried plutons. One large positive anomaly, in particular, that lies just west of the center of the belt may have a genetic relationship to the lead and zinc mineralization. This mass is interpreted to be a quartz monzonite pluton lying just below the westwarddipping South Fork thrust at a calculated depth of about 10,500 feet beneath the surface. INTRODUCTION Detailed geological studies in the Sun River canyon area and regional gravity studies of the northern disturbed belt (Sawtooth and Lewis and Clark Ranges) indicated that buried plutons and associated mineralization might be present in the southeastern part of the Lewis and Clark Range from the West Fork of the Sun River south to the Dearborn River (fig. 1). Hence, in 1964 reconnaissance geological, geochemical, and geophysical studies were begun in this area to determine if geochemical and magnetic anomalies were present and, if so, whether they were spatially related to the known gravity El E2 CONTRIBUTIONS TO ECONOMIC GEOLOGY 113°00' 45' 30'

Reconnaissance geology, geophysics, and geochemistry of the southeastern part of the Lewis and Clark Range, Montana