Mars

Prospect, Active

Commodities and mineralogy

Main commodities Au; Mo; Cu
Other commodities Ag; W
Ore minerals azurite; chalcopyrite; galena; gold; malachite; molybdenum; pyrite; sphalerite
Gangue minerals albite; carbonate; chlorite; epidote; garnet; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-6
Latitude 63.2371
Longitude -146.8297
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Mars Prospect is located within the Stellar Project in the northeastern portion of the Clearwater Mountains; 0.15 mile from the center of section 29, T. 19 S., R. 5 E., of the Fairbanks Meridian. This location is accurate to within about 100 feet.

Geologic setting

Geologic description

The Mars Prospect is located in the northeastern portion of the Clearwater Mountains, west of the Zackly deposit and on the west side of the West Fork of the Maclaren River. The deposit geology is described as skarn hosted in andesite, basalt, gabbro, and limestone (P. St. George, Chief Exploration Officer, Millrock Resources Inc., oral communication, 2014). The geology of the area is dominated by a major, terrain-bounding, low angle thrust fault where Cretaceous argillite from the Maclaren metamorphic belt is thrust over Late Triassic greenstone, limestone and argillite of the Clearwater Terrane. In the southeastern portion of the prospect area, another thrust fault juxtaposes the Clearwater Terrane atop basalt and andesites with interlayered limestones from the Amphitheater Group (Eden, 2013).
The Mars Prospect contains several mineral occurrences including the historical Copper Knob and Joy Creek occurrences. In the northern portion of the Mars Prospect, two occurrences record porphyry-type mineralization with disseminated pyrite and chalcopyrite in argillite and felsic intrusive rocks and mineralized quartz veins. The 'Mex' scheelite skarn occurrence, previously explored by Cominco, is also located in the Mars Prospect area (Eden, 2013).
In the center of the Mars Prospect are several poly-metallic occurrences in Late Triassic andesite-basalt in footwall of the major low-angle thrust fault. These occurrences include gold-bearing quartz-carbonate veins, galena and sphalerite in brecciated greenstone and abundant pyrite in greenstone with locally abundant chalcopyrite, azurite and malachite (Eden, 2013).
Other major occurrences include the historical Joy Creek and Copper Knob occurrences of the Clearwater Mountains claim group. The Joy Creek occurrence occurs in the complexly faulted rocks of the thrust footwall that include a Late Triassic greenstone, Triassic limestone and argillite and andesite of uncertain age. Mineralization is diverse and includes disseminated pyrite and chalcopyrite in an epidote-silica altered rock with local malachite staining, a gold-bearing copper skarn that occurs parallel to a quartz porphyry dike and gold-bearing altered sedimentary rocks (Eden, 2013).
The Copper Knob occurrence also occurs in conjunction with a thrust fault that juxtaposes metabasalt of the Nikolai greenstone against argillite slate and limestone of uncertain age intruded by Cretaceous or early Tertiary dikes. The area is complex with gold, silver, copper, molybdenum and tungsten anomalies in diverse mineralization types including copper-gold skarn, mineralized dikes and shear zones and quartz veins. One significant occurrence in the area is a strongly pyritized fault zone as much as 15 feet wide that strikes west-northwest in Copper Creek and can be traced from 4700 feet to 5000 feet in elevation and for 500 feet on strike. Samples collected from this zone average 2.7 parts per million (ppm) gold (Eden, 2013).
The Mars Prospect was first visited by Millrock in 2010 following up on the large, orange color anomaly. The color anomaly is attributed to gossanous rocks, weathered carbonate rocks, and hornfelsed sediments. Copper, gold or both copper and gold were anomalous in many of the surface samples collected. The main Copper-gold geochemical anomaly is coincident with a strong circular magnetic anomaly, the center of which is composed of diorite with chalcopyrite veins. Significant geochemical results include a 1.2-kilometer soil traverse averaging 462 ppm in copper, a 950-meter soil traverse averaging 763 ppm copper and a 900-meter soil traverse averaging 891 ppm copper. In addition, a sample of altered diorite collected from the center of the magnetic anomaly returned 0.51 percent copper, 0.21 ppm gold and high grade rock samples of 7.4 percent copper and 1.79 ppm gold were collected from float and a gossanous gully, respectively (Eden, 2013).
This prospect consists of altered gabbro/diorite intruding Triassic volcanic and lesser sedimentary rocks, locally containing extensive gossan exposures. The altered zones commonly contain variable copper mineralization. Soil sampling across the prospect has defined a 420 ppm copper anomalous zone measuring approximately 950 meters by 1.7 kilometers. Rock samples of altered volcanic rock have returned assays as high as 7.4 percent copper. Anomalous gold-in-soil values are common within the area of 420 ppm copper anomaly including multiple samples assaying 0.100 ppm gold. Assays as high as 1.78 ppm gold have been returned from rock samples. The Mars prospect is bounded on the northwest by a post-mineral (?) thrust fault. Potential exists for the discovery of additional mineralization to the northwest below the fault contact (Eden, 2013).
The Mars Prospect is located in the northeastern portion of the Clearwater Mountains, west of the Zackley Prospect and on the west side of the West Fork of the Maclaren River. Mention of high grade copper lodes in the Clearwater Mountains dates back to 1918.
Kurtak et al. (1992) state that claims in the Mars area (formerly known as MEX) were first staked in 1974. In 1980, Mankomen Exploration Inc. staked several claims in the Mars area, which was followed by claim staking by Cominco American in 1981. The same year, Cominco and Mankomen formed a joint venture, which lasted until 1982. During the JV period, geochemical sampling and geological mapping conducted on the MEX claims, as well as, a ground magnetic survey, an electromagnetic (EM) survey, a very low frequency (VLF) electromagnetic survey (Kurtak et al., 1992) and limited hand trenching.
In 1983 the only work that was performed on the Mars Property was performed by Mankomen. Their work consisted of limited hand trenching, rock and stream sediment sampling, as well as, minor geologic mapping. Later in 1983, the MEX claims were leased to Anschutz Mining Corp. (Kurtak et al., 1992). Work performed by Anschutz in 1984 on the MEX claims consisted of trenching, although it is not known how much trenching was conducted. Anschutz Mining probably dropped the lease in 1985 as no Affidavit of Labor certificates could be found mentioning Anschutz Mining.
In 1988, Amax Exploration leased the MEX claims from Mankomen, but later turned them back to the owner (Kurtak et al., 1992).
In 1992, Noranda flew an aeromagnetic survey over the MEX claims and produced an interpretive total field magnetics map. The total area covered by the magnetics survey was approximately 6,000 acres. The survey revealed several large magnetic anomalies that were not followed-up on until 2012.
In 2010, Millrock staked claims covering the MEX area and gave the prospect area the name Mars. Millrock collected 27 soil and 5 rock samples within the Mars area. The results indicated a zone anomalous in copper, gold and molybdenum. In 2012, 26 rock and 54 soil samples were taken over a portion of the magnetic anomalies identified by Noranda (Hemlo Gold). The results showed a 2 mile long zone of anomalous copper-gold with an isolated zone of anomalous molybdenum. Some of the strongest geochemical anomalies are coincident with the stronger magnetic anomalies (Eden, 2013).
In 2012 and 2013, Millrock performed soil, stream sediments, and rock sampling, in addition to airborne electromagnetic geophysical survey and spectroscopy (P. St. George, Chief Exploration Officer, Millrock Resources Inc., oral communication, 2014).
Geologic map unit (, )
Mineral deposit model Porphyry Cu-Au? (Cox and Singer, 1986, model 20c)
Mineral deposit model number 20c?
Age of mineralization Probably Late Cretaceous or early Tertiary, nearly synchronous with thrust faulting (Eden, 2013).
Alteration of deposit Disseminated pyrite and chalcopyrite in an epidote-silica altered rock with local malachite staining, a gold-bearing copper skarn that occurs parallel to a quartz porphyry dike and gold-bearing altered sedimentary rocks (Eden, 2013). Generally potassic, sericite, albite, chlorite, epidote, and garnet.

Production and reserves

Workings or exploration
The Mars Prospect is located in the northeastern portion of the Clearwater Mountains, west of the Zackley Prospect and on the west side of the West Fork of the Maclaren River. Mention of high grade copper lodes in the Clearwater Mountains dates back to 1918.
Kurtak et al. (1992) state that claims in the Mars area (formerly known as MEX) were first staked in 1974. In 1980, Mankomen Exploration Inc. staked several claims in the Mars area, which was followed by claim staking by Cominco American in 1981. The same year, Cominco and Mankomen formed a joint venture, which lasted until 1982. During the JV period, geochemical sampling and geological mapping conducted on the MEX claims, as well as, a ground magnetic survey, an electromagnetic (EM) survey, a very low frequency (VLF) electromagnetic survey (Kurtak et al., 1992) and limited hand trenching.
In 1983 the only work that was performed on the Mars Property was performed by Mankomen. Their work consisted of limited hand trenching, rock and stream sediment sampling, as well as, minor geologic mapping. Later in 1983, the MEX claims were leased to Anschutz Mining Corp. (Kurtak et al., 1992). Work performed by Anschutz in 1984 on the MEX claims consisted of trenching, although it is not known how much trenching was conducted. Anschutz Mining probably dropped the lease in 1985 as no Affidavit of Labor certificates could be found mentioning Anschutz Mining.
In 1988, Amax Exploration leased the MEX claims from Mankomen, but later turned them back to the owner (Kurtak et al., 1992).
In 1992, Noranda flew an aeromagnetic survey over the MEX claims and produced an interpretive total field magnetics map. The total area covered by the magnetics survey was approximately 6,000 acres. The survey revealed several large magnetic anomalies that were not followed-up on until 2012 (Eden, 2013).
In 2010, Millrock staked claims covering the MEX area and gave the prospect area the name Mars. Millrock collected 27 soil and 5 rock samples within the Mars area. The results indicated a zone anomalous in copper, gold and molybdenum. In 2012, 26 rock and 54 soil samples were taken over a portion of the magnetic anomalies identified by Noranda (Hemlo Gold). The results showed a 2 mile long zone of anomalous copper-gold with an isolated zone of anomalous molybdenum. Some of the strongest geochemical anomalies are coincident with the stronger magnetic anomalies (Eden, 2013).
In 2012 and 2013, Millrock performed soil, stream sediments, and rock sampling, in addition to airborne electromagnetic geophysical survey and spectroscopy (P. St. George, Chief Exploration Officer, Millrock Resources Inc., oral communication, 2014).
Indication of production None
Reserve estimates None.
Production notes None.

References

References

Ellis, W.T., 1980, 1980 Alaska Range Project: Anaconda Copper Co., Anchorage, Alaska, 33 p.
Millrock Resources Inc., 2014, Stellar: http://www.millrockresources.com/projects/stellar/ (as of April 29, 2014).
www.sedar.com (posted on January 8, 2013).
Reporters V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 4/29/2014