Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr
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EXPLORATION MAY 2017 • E&MJ; 33 www.e-mj.com in 2015, its exploration budget for 2017 is currently $100 million, with its efforts being targeted at precious metal proper- ties in Canada, the United States, Mexico, and Central and South America. Gold- corp's stated primary focus is on brown- field exploration, its approach to greenfield exploration being to make toehold invest- ments in junior mining companies which operate in geological prospective terranes. And echoing the positive trend for gold, Australia's Newcrest Mining has an explo- ration budget of $60-80 million for the year to end-June, having spent $44 million in 2015-2016. The $23 million it spent in the first half-year, to the end of December, was 15% up on the comparable period in 2015-16, reflecting what the company re- ferred to as its "growing portfolio of stra- tegic partnerships, farm-in arrangements and investments across Asia-Pacific, West Africa and the Americas." Tools for the Job Developed as a proprietary technology by Ivanhoe Mines' associate company, GoviEx Gold, the Zeus induced polarization (IP) system was instrumental in the discovery of additional resources in the Oyu Tolgoi district of Mongolia. In 2009 GoviEx used the system on an expanded IP survey to test the full extent, on strike and at depth, of the 12 km-long chain of copper-gold porphyry deposits that Ivanhoe had dis- covered at Oyu Tolgoi since 2001. At one of the deposits surveyed, En- trée Gold's Heruga, a vertical cross-sec- tion of the data indicated that the IP sig- nature extends to depth, well below the deepest mineralized drill intercepts that had then been encountered, at 1,300 m. GoviEx president and CEO, Govind Friedland, said at the time: "Zeus has the potential to revolutionize mineral explora- tion. It has enabled our field teams to accu- rately map important geophysical anoma- lies that likely would not be detectable with other existing and competing IP systems." According to GoviEx, while tradition- al IP surveys have typically been used on a mine scale, the Zeus system could be deployed regionally, increasing the effi- ciency and effectiveness of large-scale exploration programmes. The company's chief geophysicist, Grant Hendrickson, explained that by using copper cables up to 20 km long, Zeus could transmit, receive and analyze the electrical sig- nals that dissipate from well-mineralized bodies and their weakly-mineralized host rocks due to the strong induced polariza- tion that was applied. And now, eight years on, Zeus has been replaced by a new system, Typhoon, owned and operated by High Power Ex- ploration (HPX), another private company within the Friedland group. HPX claims that "the Typhoon data acquisition sys- tem is the most accurate and powerful IP and EM geophysical survey technology available to base metal explorers today." Introduced in 2012, the first Typhoon unit is housed in a customized 20-ft con- tainer, together with a 230 kVA diesel generator. It has since undertaken sur- veys in Namibia, Chile and Australia and is designed for projects in open, flat ter- rain, HPX says. Since then, a further two units have been commissioned, in 2013 and 2014 respectively. The second, a split system with the generator and Typhoon transmitter trans- ported separately on flatbed trucks, was designed for work in remote and challeng- ing terrain, while the third unit, which HPX used on the Conico copper prospect in Chile in 2015, has a modular design for the transmitter. Each of the two transmit- ter modules is heli-portable, which means that the system can be airlifted into areas that are completely inaccessible by surface transport. All three variants use the same high-power technology while being custom- ized for use in different terrain, with the ancillary equipment required to perform ei- ther regional or focused IP and EM surveys including 25 km of high-voltage IP cable and five km of high-current EM cable. HPX states that Typhoon has an or- der of magnitude more power than other commonly used transmitters, and in like- for-like comparison tests on the same site provides at least three-times better sig- nal-to-noise ratios. Last year, HPX used the Typhoon 2 sys- tem at its joint-venture San Matias cop- per-gold project with Cordoba Minerals in Colombia. The first phase survey, covering 7.5 km 2 of the project area, involved the acquisition of 681 line-km of high-quality DC resistivity and IP data. The 3D con- ductivity and chargeability models gener- ated from the data were integrated with existing geological information, helicop- ter- and ground-based magnetometer sur- veys and 3D-magnetic models to generate new drill targets. According to Cordoba, the results showed some of the strongest chargeability anomalies ever mapped with a Typhoon IP survey, at depths ranging from 50 m to 500 m. In a second phase of the joint venture, HPX later undertook a 10,000-m drilling program to test targets identified from the initial Typhoon IP survey, as well as Collecting field data using HPX's Typhoon 2 unit at Cordoba Minerals' San Matias porphyry copper-gold prospect in northwest Colombia. The information gained was used to identify drilling targets for second-stage evaluation, with the initial Typhoon survey area later being extended as well.