|Quadrangle map, 1:250,000-scale||TY|
|Quadrangle map, 1:63,360-scale||D-8|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The RPM prospect is located about 2.0 miles northwest of Emerald Creek; about 0.2 mile from the southwest corner of section 32, T. 29 N., R. 20 W., of the Seward Meridian. This location is accurate to within 500 feet from the center of the prospect.|
RPM is a mineralized prospect that is part of the Estelle gold property. RPM lies within a plutonic complex intruding a Jurassic to Early Cretaceous flysch sequence (Reed and Nelson, 1980). The intrusive complex 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. Though mineralization at Estelle is generally restricted to the intrusive rocks, mineralization at RPM occurs in both intrusive and hornfels (Millrock Resources Inc., 2014).
At RPM roof pendants of hornfels occur overlying multiple intrusive units. Fingers of fine grained aplite, monzonite and biotite-rich diorite cut the hornfels. All of the lithologic units are in turn cut by stockwork and/or sheeted veins. Veins range in size and character from meter wide quartz ± sulfide to millimeter scale quartz-arsenopyrite veins and centimeter scale quartz-tourmaline-sulfide veins. A granitic intrusive body, which underlies the hornfels and crops out in the southern part of the prospect area appears to be potentially related to mineralization (Millrock Resources Inc., 2014).The RPM prospect is contained in a 3,500 meter long, northwest trending gold anomaly defined by soils assaying over 0.010 part per million (ppm) gold including individual samples containing up to 13.25 ppm gold. Copper values are also elevated with the majority of samples returning assays over 200 ppm copper. The copper values outline a broader, more dispersed anomaly. In addition to soil sampling, extensive rock chip sampling has been done returning composited sample results up to 90 meters (295 feet) averaging 0.54 gram of gold per tonne (Millrock Resources Inc., 2014).
|Geologic map unit||(, )|
|Mineral deposit model||Porphyry Cu-Au or intrusion-related gold? (Cox and Singer, 1986; model 20c)|
|Mineral deposit model number||20c?|
|Age of mineralization||Late Cretaceous/early Tertiary?; mineralization in the area is thought to be related to the 66 to 67 Ma granodiorite of Mount Estelle (Reed and Lanphere,1972).|
|Alteration of deposit||Hornfelsed sedimentary rock roof pendants overlying multiplie intrusive units are cut by aplite, monzonite, and biotite-rich diorite dikes. All of these units are cut by stockwork and/or sheeted quartz +/- sulfide veins (Millrock Resources Inc., 2014).|
|Workings or exploration||
Millrock Resources Inc. conducted a 2012 exploration program consisting of prospecting, soil sampling, rock sampling, and drilling at RPM prospect. RPM is contained in a 3,500 meter long, northwest trending gold anomaly defined by soils assaying greater than 0.010 part per million (ppm) gold including individual samples containing up to 13.25 ppm copper. Copper values are also elevated with the majority of samples returning assays greater than 200 ppm copper. The copper values outline a broader, more dispersed anomaly. In addition to soil sampling, extensive rock chip sampling has been done returning composited sample results up to 90 meters (295 feet) averaging 0.54 gram of gold per tonne (Millrock Resources Inc., 2014).One drillhole completed in 2012 targeted a mineralized monzonite plug cut by sheeted and stockwork quartz veins. The hole encountered significant gold mineralization returning an intercept of 2.07 grams of gold per tonne over 21.94 meters (72 feet) within a 102.11 meters (335 feet) interval averaging 1.04 grams of gold per tonne with mineralization open in all directions (Millrock Resources Inc., 2012).
|Indication of production||None|
Cox, D.P., and Singer, D.A., eds., 1986, Mineral deposit models: U.S. Geological Survey Bulletin 1693, 379 p.
Millrock Resources Inc., 2012, Millrock Discovers New Gold Zone at Estelle Project, Alaska: (News release, September 10, 2012) http://www.millrockresources.com/news/millrock-discovers-new-gold-zone-at-estelle-project-alaska (as of January 7, 2015).
Millrock Resources Inc., 2014, Estelle: http://www.millrockresources.com/projects/estelle/ (as of April 9, 2014).
Reed, B.L., and Lanphere, M.A., 1972, Generalized geologic map of the Alaska-Aleutian range batholith showing potassium-argon ages of the plutonic rocks: U.S. Geological Survey Miscellaneous Field Studies Map MF-372, 2 sheets, scale 1:1,000,000.
|Reporters||V.C. Zinno (Alaska Earth Sciences, Inc.)|
|Last report date||1/7/2015|