Unnamed (near head of Yehring Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Mo
Other commodities Ag; Au; Cu
Ore minerals chalcopyrite; molybdenite; pyrite; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale TR
Quadrangle map, 1:63,360-scale B-6
Latitude 58.4003
Longitude -133.8273
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is near the crest of the ridge between the north fork of Davidson Creek and the head of Yehring Creek. It is in SE1/4 section 15, T.40 S., R.70 E. of the Copper River Meridian. The map location is the approximate center of several reported occurrences and is accurate within 1/4 mile.

Geologic setting

Geologic description

This occurrence is in the Coast Range plutonic-metamorphic complex which consists of high-grade schist and gneiss intruded by Cretaceous and Tertiary granodiorite (Brew and Ford, 1974, 1984). The rocks at this occurrence consist of Tertiary granite to granodiorite. The occurrence consists of molybdenite, chalcopyrite, pyrite, and pyrrhotite in a granular iron-stained quartz monzonite. The molybdenite occurs as large flakes concentrated along the contact between the quartz monzonite and granodiorite. The molybdenite is erratically distributed and appears to be confined to areas marked by iron-staining (Clough, 1990). The U.S. Bureau of Mines has reported values up to 0.606% copper and more than 2.0% molybdenum in selected float samples (Clough, 1990). K/Ar dating of hydrothermal muscovite at the near by, geologically similar Boundary Creek 2 (TR003) occurrence indicates that the molybdenite formed at or after 59.7 Ma (Miller and others, 1997).
Geologic map unit (-133.82904459609, 58.3999817786331)
Mineral deposit model Porphyry Mo (Cox and Singer, 1986; model 21b)
Mineral deposit model number 21b
Age of mineralization K/Ar dating of hydrothermal muscovite at the near by, geologically similar Boundary Creek 2 (TR003) occurrence indicates that the molybdenite formed at or after 59.7 Ma (Miller and others, 1997).
Alteration of deposit Locally conspicuous iron staining.

Production and reserves

Workings or exploration This occurrence was discovered by the U.S. Bureau of Mines in 1985 (Clough, 1990) There are no surface or underground workings and exploration has been limited.
Indication of production None

References