West Cirque Delineates Porphyry Targets at Tanzilla Project

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By peterc on December 8, 2013. No Comments

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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:

  • A previously unrecognized extension to the alteration system was located 1.8 kilometers northwest of and 545 meters elevation below the top of Silica Ridge. Outcrops in the new zone include intensely silica, clay, sericite and pyrite or hematite altered volcanics (lapilli tuff and tuff breccia) with abundant dumortierite.
  • Quartz-hematite stockworks in pervasively sericite altered rock were mapped at several sites on Silica Ridge, including a 130 meter wide zone on the northeast side.
  • A zone of hydrothermal breccia with alunite and hematite was mapped in a mainly talus covered area on the west side of the ridge.
  • Gusano textures typically found at the base of lithocaps immediately above porphyry-style alteration were noted in an outcrop southeast of Silica Ridge and east of the Circle Trench zone.  The outcrop consists mainly of intensely sericite altered hydrothermal breccia with a strongly pyritic matrix.
  • Magnetite veins and breccias with strongly magnetite altered clasts were mapped on the south side of the ridge.
  • Chalcopyrite bearing, magnetite rich feldspar porphyry dykes were mapped at the highest point of Silica Ridge (2050 meters); two grab  samples from the dykes returned anomalous levels of copper (428 and 530 parts per million).
  • Magnetite/hematite veinlets with chalcopyrite were mapped in feldspar and hornblende phyric volcanics at the north end of the Gopher Zone. A grab sample returned 1395 ppm copper. Advanced argillic assemblages with dickite and pyrophyllite were also identified in this zone.
  • Structural mapping carried out by Stephen Wetherup of Caracle Creek International Consulting Inc. identified significant east and northeast trending structures that provided the primary hydrothermal fluid pathways influencing the development of strong phyllic to advanced argillic alteration.

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.



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