Desert Fox Sombrero Butte Co., a wholly owned subsidiary of Copper Fox Metals Inc. owns a 100% working interest in the Sombrero Butte project (2,913 acres) located in the Bunker Hill Mining District, 44 miles northeast of Tucson, Arizona. The project is located 2 miles south of the Copper Creek porphyry copper deposit. The surface expression of the Copper Creek deposit is a cluster of mineralized breccia pipes. The breccia pipes on the Sombrero Butte property, like the Copper Creek property, were previously mined for high grade copper on a limited basis.
The Sombrero Butte project is in the Laramide age porphyry copper belt that hosts numerous large porphyry copper mines in Arizona; a mining friendly; politically secure jurisdiction with readily accessible infrastructure.
The property is underlain by the Pre-Cambrian age Pinal Schist and Laramide age Glory Hole and Galiuro Volcanics. The Glory Hole and Galiuro Volcanics were later intruded by the Laramide age Copper Creek Granodiorite and Gray Porphyry intrusive. Within the Gray Porphyry is a cluster of mineralized breccia pipes, some of which contain chalcocite, bornite, chalcopyrite, pyrite and copper oxides. The Gray Porphyry is the unit most closely related to economic copper mineralization at the Copper Creek deposit located 3 kms to the north and may be the source of the mineralizing fluids in the breccia pipes on the Sombrero Butte project.
The center of the project is underlain by Copper Creek Granodiorite. A 2 kms long area of ‘hornfels’ borders the northeast edge of the Copper Creek intrusive.
To the south end of the porperty, 12 breccia pipes containing dickite occur within the Pinal Schist. Dickite is a hydrothermal alteration mineral that occurs in multiple porphyry copper deposits throughout the Arizona copper belt including the San Manuel-Kalamazoo porphyry copper deposit located west of the property.
Between 2006 and 2008 Bell Copper completed 34 holes on the Magna-Campstool-Rattler-Audacious-Sunset-Saguaro and Victors breccia pipes. Selected mineralized intervals from the Bell Copper drilling are listed below:
|Pipe||DDH||From (m)||To (m)||Int. (m)||Cu (%)||Mo (%)||Au (ppm)||Ag (ppm)|
The mineralized intervals listed in the above table do not represent true widths.
In 2015 Copper Fox completed a Titan-24 DCIP (‘Titan’) survey that outlined positive chargeability/resistivity anomalies underlying two exploration targets.
The surface expression of the two exploration targets exhibit multiple mineralized breccia pipes, vein and veinlet-controlled porphyry style copper-molybdenum mineralization associated with pervasive potassic alteration with localized selvages of advanced argillic and phyllic alteration and and sporadic tourmaline veining over a horizontal distance of 4 kms.
The surface expression of the first target located at the north end of the property measures 1,000m by 1,200m, hosts 40 mineralized breccia pipes (see exploration activities for drill hole results) and is underlain by a deep-seated chargeability anomaly (L2IP6), the top of which is interpreted to occur approximately 500m below surface. Copper values in outcrop range from 0.076% to greater than 0.25% and from 0.007% to 0.025% molybdenum. Drilling tested the depth extent of the copper mineralization in the breccia pipes in this target and the Laramide age Copper Creek intrusive at depth. DDH SB-23 intersected mineralized breccia (coincides with chargeability anomaly L2IP5) to a depth of 580m and below that weakly mineralized Copper Creek Granodiorite to a depth of 1,231m. The lower portion of this hole intersected bornite-chalcopyrite veinlets and quartz molybdenite veinlets associated with potassic and sericite alteration over 2-3m intervals. The Titan survey shows that DDH SB-03, SB-23 and SB-11 tested the Magma and Campstool breccia pipes, the down dip extrapolation of which correlates with chargeability anomaly L2IP6, the potential porphyry source of the mineralization in the breccia pipes.
The surface expression of the second exploration target measures 1,600m by 2,800m and exhibits a cluster of dickite bearing breccia pipes and Gray Porphyry dikes located about 2km southeast of the first target area. Mineralization in outcrop where sampled returned from 0.076% to 0.24% copper and from 0.007% to 0.049% molybdenum.
To the south end of target #2, 12 dickite bearing breccia pipes occur within the Pinal Schist. The chargeability anomalies (L2IP1, L2IP2, L2IP3) and breccia pipes located within this target are located immediately east of an NNW-ESE trending Range Front Fault system, a similar structural setting to other large copper mines/deposits in Arizona. The chargeability anomaly (approximately 2,400m long, by minimum 600m wide to a depth of at least 600m below surface) occurs within a portion of the Laramide age Copper Creek intrusive which to the east is covered by older Glory Hole Volcanics. On Line 1 the top of anomaly is approximately 400m below surface and appears to be terminated by the Range Front Fault. Approximately 600m to the east (Line 2), the top of this anomaly is at surface and open to the east and northeast under the Glory Hole Volcnics. Seven histrorical dril hole collars are located within the chargeability anomaly, the analytical results for which are not available. The drill cuttings from two drill holes located in proximity to Line 2 returned up to 0.21% copper and molybdenite. Drill cuttings from drill holes further to the east contained significantly lower copper concentrations, more pyrite and stronger trace element concentrations.
2015 Titan Survey:
Two lines approximately 600m apart and 4,000m long were completed. Line 1 is located close to the Range Front Fault located on the west side of the property. Line 2 is located 600m east of Line 1. The chargeability anomaly is located with a 2,400m long portion of the Copper Creek intrusive. Other portions of the Copper Creek intrusive surrounding the anomaly exhibit no anomalous chargeability. The chargeability modelling was completed using Half Space (‘HS’) and Direct Current (‘DC’). The HS model shows a continuous body of chargeability from surface to approximately 600m below surface at which depth, the anomaly splits into two bodies of chargeability. The DC model exhibits continuous chargeability to a depth of 300m which then splits forming a ring (ranges in width from 500 to 1,000m) of chargeability around a core of background chargeability. Both models fit a potential porphyry copper system and indicate that the chargeability anomaly is open to the east-northeast and dips steeply to the northwest. The upper portion (above 300m level) of the chargeability anomaly on Line 1 appears to be truncated by the Range Front Fault on the west end portion of the property.
Mineralized Breccia Pipes:
In target #1, three distinct phases of breccia pipes were emplaced into the Copper Creek intrusive, the age of which has been dated at between 60 to 68 million years. The breccia pipes are situated above chargeability anomalies L2IP5 and L2IP6 and exhibit different styles of mineralization, associated geochemistry and accessory minerals suggesting multiple episodes of copper-molybdenum and copper mineralization introduction.
- The Magna pipe contains mineralized granodiorite boulders in the interval from 476 to 484m that averaged 1.61% Cu, 0.029% Mo, 0.056 ppm Au and 5.9 ppm Ag suggesting rafting of mineralized granodiorite from depth during breccia pipe formation.
- The Magna-Campstool-Victors pipes contain significant copper mineralization, Campstool pipe from 466 to 492m averaged 1.19% Cu, 0.013% Mo, 0.08 ppm Au and 4.83 ppm Ag and Magna pipe from 458 to 506m averaged 1.27% Cu, 0.04% Mo, 0.09 ppm Au and 3.81 ppm Ag.
- The copper mineralization in the Audacious-Rattler pipes is characterized by very high concentrations of arsenic (to 10,368 ppm), stibnite (to 260 ppm), tungsten (to 128 ppm) and manganese (to 6,270 ppm).
- The Saguaro breccia pipe is not mineralized and contains very low concentrations of all elements. Tourmaline occurs in the matrix and as thin veinlets surrounding this breccia.
The high-grade nature of the mineralized breccia pipes, the multiple phases of breccia pipe emplacement, the surface mineralization and large chargeability/resistivity anomalies hosted in the Copper Creek Granodiorite supports the presence of a buried porphyry system on the property.