Earth and Planetary Sciences ETDs

Publication Date

12-1975

Abstract

This report is a supplement to the Geologic Map of the Blackbird district which forms the southeast quadrant of the 15-minute Blackbird Mountain quadrangle, located in the Salmon River Mountains in Lemhi County, east central Idaho. Ore deposits in the district were developed during the first half of the twentieth century, but mining has been hampered by low-grade ores and the small size of the mineralized zones.

Outcrops are poor in the district because of heavy soil cover and talus slopes. Precambrian sedimentary rocks are part of the Belt Supergroup and have been divided into nine units. Precambrian units mapped are Panther Creek phyllite, Musgrove Creek phyllite, Miller Ranch quartzite, Dummy Creek quartzite, Leesburg quartzite, and the more highly metamorphosed West Fork schist, Prospect phyllite, Meadow Creek quartz schist, and Blackbird garnet schist. Granitic rocks of the Cretaceous Idaho batholith are present in the northeast corner of the district. Challis rhyolitic volcanics of Eocene and Oligocene age are found in the southwest part of the district. Volcanics overlie Tertiary pebble conglomerate which forms a veneer on an erosional surface on the Porphyry Creek quartz latite, water-laid tuffs, Porphyry Ridge latite, Porphyry Ridge rhyclitic tuff, Yankee Fork Phyolite, Forney tuff, and Yankee tuff.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

J. Paul Fitzsimmons

Second Committee Member

Lee A. Woodward

Third Committee Member

Wolfgang Eugene Elston

Language

English

Document Type

Thesis

Download

Included in

Geology Commons

Share

COinS