Unnamed (south of Dulbatna Mountain)

Occurrences, Inactive

Commodities and mineralogy

Main commodities Cu; Zn
Other commodities Bi; Mn; Sn; V
Ore minerals pyrite; unspecified sulfides
Gangue minerals carbonate; quartz

Geographic location

Quadrangle map, 1:250,000-scale MZ
Quadrangle map, 1:63,360-scale B-5
Latitude 65.3193
Longitude -155.2669
Nearby scientific data Find additional scientific data near this location
Location and accuracy Four lode occurrences are in a 6-square-mile area of ridges and hills due south of Dulbatna Mountain. The site corresponds to ADGGS station 92BT268 (Solie and others, 1993 [Public-Data File 93-18]). It is at an elevation of 1,600 feet, in the northwest corner of section 18, T. 2 S., R. 18 E., Kateel River Meridian. The location is accurate.

Geologic setting

Geologic description

The rocks in the vicinity of these occurrences are part of a northeast-trending, oval-shaped outcrop of fine- to medium-grained hornblende-biotite granodiorite that is approximately 2.5 miles wide and 4.5 miles long (Patton and others, 1977). Patton and others (1977) correlate the granodiorite with the Dulbatna Mountain pluton, which is dated by K-Ar at 82.3 +/- 3 Ma (biotite) and 89.0 +/- 3 Ma (hornblende). The granodiorite intrudes and thermally alters the Lower Cretaceous volcanic and sedimentary country rocks to dark-green hornfels. These rocks consist of volcanic (tuffaceous) graywacke, and andesite and dacite tuff, breccia, and agglomerate.
The Alaska Division of Geological and Geophysical Surveys collected 7 rock samples in a 6-square-mile area along the northern contact of an 11-square-mile granodiorite body south of Dulbatna Mountain (Solie and others, 1993 [Public-Data File 93-18]). The samples included ferricrete in biotite hornfels, quartz-carbonate veins in hornfels, fine-grained sedimentary rock with sparse pyrite, graywacke with sulfide, and unmineralized biotite-hornblende granodiorite. The hornfels and graywacke samples contained up to 43 parts per million (ppm) bismuth, 188 ppm copper, 1,789 ppm manganese, 44 ppm tin, 264 ppm vanadium, and 162 ppm zinc.
Geologic map unit (-155.269460444038, 65.3187172913336)
Mineral deposit model Porphyry Cu (Cox and Singer, 1986; model 17), Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number 17, 22c
Age of mineralization Probably Late Cretaceous, assuming that the locally mineralized hornfels and graywacke reflects emplacement of the Dulbatna Mountain pluton.
Alteration of deposit Thermal metamorphism.

Production and reserves

Workings or exploration The Alaska Division of Geological and Geophysical Surveys collected 7 rock samples in a 6-square-mile area along the northern contact of an 11-square-mile granodiorite body south of Dulbatna Mountain (Solie and others, 1993 [Public-Data File 93-18]).
Indication of production None

References