Unnamed Prospect (ARDF - CR094), San Juan Bautista Island, Ketchikan Mining District, Prince of Wales-Hyder Census Area, Alaska, USAi

Regional Level Types
Unnamed Prospect (ARDF - CR094)	- not defined -
San Juan Bautista Island	Island
Ketchikan Mining District	Mining District
Prince of Wales-Hyder Census Area	Census Area
Alaska	State
USA	Country

The subsurface rights to the land in the vicinity of this prospect are held by the Sealaska Corporation.
Location: This site is at an elevation of about 950 feet where several holes were diamond drilled in the early 1970's. The location is near the middle of the west boundary of section 32, T. 74 S., R. 80 E. There are several other occurrences in the vicinity; all are probably less than 0.3 mile from the drill site.
Geology: This prospect is associated with a small Cretaceous granitic pluton at the center of San Juan Bautista Island (Eberlein and others, 1983; Brew, 1996). The pluton intrudes Devonian graywacke, mudstone, and siltstone of the Port Refugio Formation, which crops out along the entire coastline of the island. Clark and others (1970 [OF 418]) describe several types of deposits, most of which are probably at or near the contact between the pluton and the sedimentary rocks. The deposits include tactite with pyrite, pyrrhotite, and chalcopyrite; diorite with disseminated pyrite and chalcopyrite; and hornfels(?) cut by a quartz veinlet with pyrite and sphalerite. There was considerable diamond drilling at an elevation of about 950 feet near a steep gully (D.J. Grybeck, unpublished field notes,1984). There are 3 or more sites where AlVenCo Inc. drilled in the early 1970's. The rock near the drill sites consists of hornblende-biotite monzonite or granodiorite. The granitic rock contains considerable disseminated pyrite and pyrite along fractures; it is also silicified and argillized. Six grab samples of outcrop and float of the richest mineralized rock contained 300 parts per million (ppm) to 2 percent copper; one contained 100 ppm silver and 150 ppm molybdenum; and one contained 0.75 ppm gold. The deposit was probably drilled as a copper or molybdenum porphyry deposit.
Workings: There was considerable diamond drilling at an elevation of about 950 feet near a steep gully (D.J. Grybeck, unpublished field notes, 1984). There are 3 or more sites where Alvenco Exploration, Inc. drilled in the early 1970's.
Age: Probably related to the emplacement of a Cretaceous granitic stock.
Alteration: Silicification and argillization of granitic rock.

Commodities (Major) - Cu, Mo?; (Minor) - Ag, Au, Zn
Development Status: None
Deposit Model: Porphyry copper or molybdenum deposit?

Other Databases

Link to USGS - Alaska:	CR094

Other Regions, Features and Areas containing this locality

References