Unnamed Occurrences (ARDF - MZ008; southwest of Hochandochtla Mountain), Hughes Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrences (ARDF - MZ008; southwest of Hochandochtla Mountain)	- not defined -
Hughes Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: The Alaska Division of Geological and Geophysical Surveys (ADGGS) reported 6 occurrences of sulfide-bearing and/or veined granodiorite in a 6-square-mile area that extends from Hochandochtla Mountain to south of Anotleneega Mountain. The site is located at the most mineralized site, ADGGS station 92DNS113 (Solie and others, 1993 [Public-Data File 93-18]). It is at an elevation of about 1,600 feet, 0.4 mile southwest of the center of section 2, T. 1 N., R. 19 E., Kateel River Meridian. The location is accurate.
Geology: The rocks in the vicinity of these occurrences consist of Lower Cretaceous andesite, pillow basalt, andesitic tuff, volcanic conglomerate, volcanic breccia, chert, cherty tuff, and coquinoidal limestone (Patton and others, 1977). Younger Cretaceous rocks include graywacke and mudstone. Intrusive rocks include Upper Cretaceous dacite and rhyolite, porphyry plugs(?), and a stock of fine-to medium-grained, biotite-hornblende granodiorite. The granodiorite has extensively hornfelsed the bedded country rocks. In the 1970s, the U.S. Geological Survey identified chalcopyrite and malachite in a fine-grained granitic dike in hornfelsed volcanic rock just south of Hochandochtla Mountain (T.P. Miller, 1978, written commun., in Chapman and Patton, 1978). The Alaska Division of Geological & Geophysical Surveys subsequently collected 8 rock samples at 3 sites on Hochandochtla Mountain (Solie and others, 1993 [Public-Data File 93-18]). The samples included quartz- or quartz-tourmaline-veined biotite granodiorite that contains variable amounts of chalcopyrite, pyrite, malachite, and azurite; andesite with trace chalcopyrite; and andesite agglomerate with chalcopyrite. The samples contained up to 1,179 parts per million (ppm) copper, 47 ppm bismuth, 18 ppm molybdenum, 38 ppm antimony, 350 ppm cerium, and 80 ppm tungsten.
Workings: In the 1970s, the U.S. Geological Survey identified chalcopyrite and malachite in a fine-grained granitic dike in hornfelsed volcanic rock just south of Hochandochtla Mountain (T.P. Miller, 1978, written commun., in Chapman and Patton, 1978). The Alaska Division of Geological & Geophysical Surveys subsequently collected 8 rock samples at 3 sites on Hochandochtla Mountain (Solie and others, 1993 [Public-data file 93-18]). The samples included quartz- or quartz-tourmaline-veined biotite granodiorite containing variable amounts of chalcopyrite, pyrite, malachite, and azurite; andesite with trace chalcopyrite; and andesite agglomerate with chalcopyrite.
Age: Cretaceous or younger based on the age of the host rocks.
Alteration: Widespread contact metamorphism (hornfelsing).

Commodities (Major) - Cu; (Minor) - Bi, Mo, W
Development Status: None
Deposit Model: Porphyry Cu (Cox and Singer, 1986; model 17)

Other Databases

Link to USGS - Alaska:	MZ008

Other Regions, Features and Areas containing this locality

References