DDY Occurrence, Tok Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
DDY Occurrence	Occurrence
Tok Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Location: The DDY occurrence is at an elevation of about 6,300 feet, 0.6 mile east of peak 7440. It is about one-half mile southeast of the center of section 9, T. 17 N., R. 6 E., Copper River Meridian. The location is accurate.
Geology: The DDY occurrence consists of a thinly laminated discontinuous massive sulfide layer less than one-third meter thick; it is in a cherty exhalite at the contact of felsic metavolcanic rocks in the footwall and carbonaceous phyllite in the hanging wall. Samples average 0.6 percent copper, 0.04 percent lead, 0.4 percent zinc, 21 parts per million (ppm) silver, and 0.4 ppm gold (S.S. Dashevsky unpublished data, 2002). The DDY occurrence is in the same mineralized horizon as the DD North prospect (MH319), at the contact of the Drum felsic metavolcanic unit with the overlying Tok River metasedimentary sequence. The Tok River unit is a thick, mainly metasedimentary assemblage of chloritic phyllite, quartz-sericite(-chlorite) schist, variably phyllitic quartz-eye metagrits, carbonaceous phyllite, and minor marble. Some of the metagrits contain feldspathic detritus and are locally calcareous. The protolith of the Tok River unit is about three-quarters sedimentary and one-quarter volcanic. It has minor interbeds of felsic volcanic rocks similar to the rhyolite and rhyodacite of the Drum unit (Dashevsky and others, 2003).
Workings: The DDY occurrence has been explored by surface mapping, sampling, and airborne and ground geophysics as part of the broader exploration of the DD North (MH319) and DD South (MH325) prospects. One core hole drilled in 1990 by Phelps Dodge near the DDY prospect did not intersect significant mineralization (S.S. Dashevsky, oral communication, 2002).
Age: The associated Drum stratigraphic unit has been dated at the Devonian-Mississippian boundary on the basis of one SHRIMP U-Pb zircon age of 359+/- 6 Ma determined at the DD South prospect (MH325) (Dashevsky and others, 2003).

Commodities (Major) - Cu, Zn; (Minor) - Ag, Au, Pb
Development Status: None
Deposit Model: Kuroko massive sulfide (Cox and Singer, 1986; model

Other Databases

Link to USGS - Alaska:	MH320

Other Regions, Features and Areas containing this locality

References