Oxide Valley

Prospect, Active

Commodities and mineralogy

Main commodities Au; Cu
Other commodities Bi; Te
Ore minerals arsenopyrite; chalcopyrite; gold; pyrite; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale TL
Quadrangle map, 1:63,360-scale A-6
Latitude 62.0082
Longitude -152.9019
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Oxide Valley prospect is located about 2.6 miles north-northeast from Portage Pass; about 0.3 mile west of the center of section 11, T. 22 N., R. 20 W., of the Seward Meridian. The location is accurate to within 100 feet to the center of the prospect.

Geologic setting

Geologic description

Gold mineralization at Oxide Valley is associated with an elongate, northerly trending composite plutonic complex intruding a Jurassic to Early Cretaceous flysch sequence. The intrusives consist of ultramafic to felsic plutons of Late Cretaceous/Early Tertiary age (69.7 Ma) and are centrally located in a region of arc-magmatic related gold deposits. Gold mineralization is correlated with arsenic, bismuth, and tellurium anomalies (Millrock Resources Inc., 2014).
The Oxide Valley prospect was identified by Millrock Resource Inc. in 2008 when multiple vein zones containing arsenopyrite, pyrite and chalcopyrite were discovered. Since then, geologic mapping and rock chip sampling has resulted in the definition of multiple mineralized zones returning anomalous gold values including chip sample results of 0.91 gram of gold per tonne over 46 meters (151 feet) in Oxide Valley (Millrock Resources Inc., 2014).
In 2010, an induced polarization (IP) survey in Oxide Valley defined multiple chargeability anomalies, which appeared to align along a northwest trend similar to the trend of mineralized, extensional vein sets (Millrock Resources Inc., 2014).
During 2011, one core hole (SE11-001) was drilled in Oxide Valley targeting the IP anomaly. Encouraging results were obtained with an average grade of 0.375 gram of gold per tonne over the entire 461 meters (1,512 feet) length of the hole leading to further exploration and drilling in 2012, mainly northwest and southeast of drill hole SE11-001. Elevated gold values were returned from two of the four follow-up holes, both located southeast of SE11-001.  Core hole SE12-002 averaged 0.368 gram of gold per tonne over the entire 188 meters (617 feet) length and core hole SE12-004 intersected 41.45 meters (136 feet) averaging 1.14 grams of gold per tonne (Millrock Resources Inc., 2014).
A wide-spaced Reconnaissance Induced Polarization (RIP) survey was conducted in Oxide Valley during 2012 with a follow-up tighter spaced survey done in 2013. Multiple chargeability anomalies were defined by the surveys with the majority untested by drilling. Geologic mapping in 2012 and 2013 defined several mineral trends all of which remain open along trend and down dip. Of particular interest is the Oxide Valley 'corridor' which hosts several zones of close spaced gold-bearing extensional quartz veining (Millrock Resources Inc., 2014).
Geologic map unit (, )
Mineral deposit model Intrusion-related gold (Millrock Resources Inc., 2014).
Age of mineralization Relative correlation of gold with arsenic, bismuth, and tellurium at Oxide Valley is similar to other deposits in the Tintina Gold Province such as Golden Zone and Shotgun in Alaska and Casino and Mt. Nansen in the Yukon suggesting a possible large scale, age-related mineralizing event. Age dating of intrusives at Oxide Valley of 69.7 Ma indicate mineralization is no older than Late Cretaceous/Early Tertiary (Millrock Resources Inc., 2014).
Alteration of deposit Carbonate, chlorite, sericite, and quartz are commonly associated with the sulfide and gold mineralization (Millholland,1995; Crowe and others, 1991).

Production and reserves

Workings or exploration The Oxide Valley prospect was identified by Millrock Resource Inc. in 2008 when multiple vein zones containing arsenopyrite, pyrite and chalcopyrite were discovered. Since then, geologic mapping and rock chip sampling has resulted in the definition of multiple mineralized zones returning anomalous gold values including chip sample results of 0.91 gram of gold per tonne over 46 meters (151 feet) in Oxide Valley (Millrock Resources Inc., 2014). In 2010, an induced polarization (IP) survey in Oxide Valley defined multiple chargeability anomalies, which appeared to align along a northwest trend similar to the trend of mineralized, extensional vein sets (Millrock Resources Inc., 2014). Drill holes were completed in 2011 and 2012. A wide-spaced Reconnaissance Induced Polarization (RIP) survey was conducted in Oxide Valley during 2012 with a follow-up tighter spaced survey done in 2013. Geologic mapping in 2012 and 2013 defined several mineral trends all of which remain open along trend and down dip (Millrock Resources Inc., 2014).
Indication of production None
Reserve estimates None.
Production notes None.

References

References

http://www.millrockresources.com/projects/estelle (as of Sept. 20, 2014).
Millholland, M.A., 1995, Geology and discovery at Mount Estelle: Newsletter of the Alaska Geological Society, v. 24, no. 8, p. 1.
Millrock Resources, Inc. 2014, Estelle:
Reporters V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 12/10/2014