West Cirque Resources Ltd. (WCQ: TSX.V) has completed its 2013 field program on the Tanzilla Copper-Gold (Cu-Au) Porphyry Project, northwestern B.C. Exploration was funded by Freeport-McMoRan of Canada Limited (“Freeport”) as part of an Earn-In Agreement announced on March 4, 2013. West Cirque was the operator of the program in 2013.
The primary goal of the 2013 field program was to delineate porphyry drill targets beneath a large advanced argillic lithocap known as Silica Ridge. Previous work by West Cirque had identified chalcopyrite bearing, altered porphyritic intrusive rocks in creek and gulley outcrops near the base of the ridge (see news release, September 28, 2011). Additionally, an induced polarization (IP) survey in 2011 outlined a 2.2 by 0.5 to 1.3 kilometer chargeability high flanking the ridge. The 2013 program included a small infill IP survey across Silica Ridge, as well as additional geological, structural and alteration mapping.
Alteration mapping at Tanzilla was guided by the analysis of 175 rock samples with a Terraspec mineral analyzer. The Terraspec is a portable reflectance spectroscopy system used to identify alteration minerals, especially clay minerals which are impossible to differentiate by normal field techniques. Mineral analysis helps identify patterns of alteration which can provide vectors to centers of porphyry mineralization. The Terraspec analyses confirmed that the central alteration at Silica Ridge and an extension about 3 kilometers to the southeast (Gopher Zone) is dominated by advanced argillic assemblages, including quartz, pyrophyllite, diaspore, alunite, kaolinite, dickite, topaz and dumortierite. Widespread phyllic alteration (quartz, sericite/muscovite, pyrite) is also present on Silica Ridge as well as the Circle Trench zone, one kilometer to the southwest, and the West Gossan zone, about three kilometers to the west.
Geological mapping in 2013 provided important new data about the alteration system at Tanzilla:
Following completion of the mapping program, an induced polarization survey was completed across Silica Ridge. The survey (two 2.2 kilometer lines) was conducted by Peter Walcott and Associates and was designed to extend the 2011 IP data to greater depths below the ridge. The 2013 survey confirmed the presence of a strong chargeability high to depths of at least 500 meters below surface. The chargeability high is open to the east and south.
Modeling of the Quest Northwest airborne magnetic data confirmed that the south side of Silica Ridge is underlain by an east trending magnetic high over 2.5 kilometers long. This feature correlates with outcrops of monzonitic to dioritic intrusive rock and hornfelsed volcanics with epidote, albite, actinolite and local biotite and K-feldspar alteration and widespread magnetite veining. Copper mineralization in outcrop generally correlates with magnetite destructive alteration around this magnetic high.
The geological and geophysical data generated by the 2013 program provide further evidence for a large porphyry system centered on the Silica Ridge lithocap. In addition to defining a number of strong coincident IP, structural and alteration anomalies, the program extended the overall size of the system, with advanced argillic alteration being mapped 800 meters north and 2.2 kilometers east of the existing IP grid. The chargeability high centered on Silica Ridge is open to the east, south, and at depth.
The Tanzilla program is being funded by Freeport, as part of an Earn-In Agreement to explore West Cirque’s Castle, Tanzilla and Pliny properties in northwestern British Columbia. Freeport can earn an initial 51% interest in the Properties by funding cumulative expenditures of $8,000,000 over a four-year period.