Fronteer hunts for IOCG deposits

Vancouver — In addition to its foray into the Red Lake-Birch Uchi Belt, Fronteer Development Group (FRG-V) has assembled large land positions in the Bear province of the Northwest Territories and the Central Mineral Belt of Labrador, all in an effort to find iron-oxide-copper-gold (IOCG) deposits.

Iron-oxide-copper-gold deposits, which are also referred to as Olympic Dam-type deposits, are typically polymetallic. The primary metals in these iron-oxide-rich deposits are copper, gold and silver. More exotic minerals, such as uranium, bismuth, cobalt, molybdenum and rare earth elements, may also be found. Mineralization tends to be localized along structures that splay off major fault zones associated with rifting or large fold systems.

The IOCG-style of mineralization is usually found in Proterozoic-aged rocks and typically vary in size from 100 million tonnes to more than 1 billion tonnes. The original Olympic Dam deposit in Australia hosted 2 billion tonnes of reserves averaging 1.6% copper and 0.04% uranium oxide, and about 0.6 gram gold per tonne.

Fronteer believes the Bear Province is grossly under-explored for the IOCG-style of mineralization. As a result, the junior acquired 101 sq. km and is now exploring four main properties: Conjuror, Achook, McPhoo and Flex.

The junior explorer selected these properties based on an in-depth analysis of the region that included geological, aeromagnetic, gravity, LANDSAT, radiometric, lake geochemistry, and mineral occurrence interpretation.

The main features shared by all the properties are: high magnetic anomalies and coincident gravity highs that are close to granitoid intrusions; regional-scale alteration systems; long-lived north-to-northeast-striking fault zones that were active during regional magmatism; and copper and gold occurrences with associated uranium, silver, bismuth and cobalt.

Fronteer plans to spend $750,000 to follow up on results from last year’s exploration in order to advance targets to the drill-ready stage. The program will be divided into two stages: The first will consist of airborne magnetic and radiometric surveys followed by structural and geophysical interpretations to prioritize target areas. Phase 2 will consist of structural and alteration mapping, prospecting and soil sampling. This will be followed by ground geophysics, specifically gravity and induced-polarization surveys, to refine drill targets.

The Achook property is on the northeastern shore of Great Bear Lake and hosts several copper and gold showings that boast the classic IOCG-style hematite-cemented breccias and associated alteration. At the Rhy showing, on the Achook property, a grab sample from an old trench that was originally explored as a uranium prospect returned 10.3% copper and 4 grams gold per tonne. Chip sampling in the trench returned 18 metres averaging 0.3% copper and 0.048 gram gold. A grab sample from another prospect on the property, dubbed the East Bay Head showing, averaged 4.26% copper, 4.1 grams gold and 3,500 parts per million bismuth. At the Squall showing, a float sample averaged 8.27% copper and 0.17 gram gold. At the Major showing, a 5.5-metre chip sample assayed 0.78% copper with slightly elevated gold.

The Conjuror property is just north of the Terra Peninsula, which hosts the past-producing Norex, Terra and Northrim silver, copper and cobalt mines. Fronteer optioned the property from Phelps Dodge (PD-N) in October last year. According to the agreement, Fronteer can earn a 100% interest in the property by reimbursing Phelps Dodge $25,000 for its initial staking costs plus $100,000 in cash or the equivalent in Fronteer shares over four years. Fronteer must also spend $500,000 on exploration before October 2006. Phelps Dodge retains a 2% net smelter return royalty, half of which can be bought back by Fronteer for $1 million.

The 48-sq.-km Conjuror property hosts broad zones of magnetite-dominated breccias and intrusion-related albitic alteration. Fronteer has sampled structural corridors on the property and says the best assays from grab samples were 1.75% copper and 0.35 gram gold. The mineral assemblage and style of alteration throughout the property are diagnostic of IOCG deposits worldwide.

The McPhoo property exists along the eastern margin of Bear Province and covers an iron-metasomatized pendant of biotite-scapolite schist, which is hosted by an altered granite. The property is characterized by zones of wholesale magnetite replacement with copper and gold enrichment. The best assay results from the McPhoo property were from a 1.7-metre chip sample that averaged 1.22% copper and a 0.6-metre chip sample that averaged 0.45% copper and 0.3 gram gold.

The Flex property is also on the eastern edge of Bear Province. It consists of highly deformed rocks that have undergone extensive iron-metasomatism. These rocks are cut by a series of copper- and gold-bearing quartz veins. The magnetic anomaly over the property may represent widespread mineralization. The best assay results from the property came from a float sample that returned 11.24% copper, 0.47 gram gold and 632 ppm bismuth.

Meanwhile, in Labrador, Fronteer and Altius Minerals (ALS-V) have joined forces in a 50-50 joint venture to explore for IOCG-type deposits in the Central Mineral Belt.

The Middle Proterozoic-aged Central Mineral Belt exceeds 250 km in length and hosts numerous occurrences of copper, uranium and rare earth elements. The belt has never been systematically explored for IOCG-type deposits. Fronteer and Altius have acquired six properties totalling 223 sq. km.

The 84-sq.-km Michelin property hosts the past-producing Michelin uranium deposit. The deposit consists of hematite alteration and finely disseminated uranium mineralization with minor copper. On another part of the property, high-grade uranium occurrences of up to 40% U3O8 have been identified. This mineralization is associated with copper and was found in boulder trains, and in veinlets intersected by previous drilling.

The Post Hill property hosts uranium and copper mineralization in a regional-scale shear zone.

The Emben property, on the eastern part of the belt, is characterized by copper, silver, uranium and molybdenum mineralization associated with hematite, chlorite and fluorite. A regional gold-in-soil geochemical survey identified values of up to 0.55 gram gold per tonne.

On the western part of the Central Mineral Belt, Fronteer and Altius have three targets: dubbed Letitia, Storm and Croteau.

The Letitia target hosts a large zone of sericite-hematite alteration with disseminated sulphides and abundant rare earth element mineralization. The partners believe this may represent the upper part of an IOCG-mineralized system.

The Storm target hosts uranium, silver and copper showings. Grab samples were found to contain up to 3.6 grams gold.

The Croteau target boasts extensive areas of hematite and carbonate-rich brecciation. Anomalous copper and uranium values are also present (up to 18.8% U3O8).

In the summer, Fronteer and Altius plan to carry out geological mapping, prospecting, sampling and re-logging of archived core.