Gold Mountain (ASX: GMN) has jagged extensive copper-gold anomalism from stream sediment geochemical sampling of its Iguatu project tenements in Brazil, pointing to possible iron oxide-copper-gold (IOCG)-style mineralisation at the site.
The company today outlined results for a further 133 stream sediment samples out of a total of 364 samples taken across its suite of 68 granted tenements in its Iguatu project area that encloses a total of 1322 square kilometres.
The stream sediment sampling was carried out in drainages more than 500m long, with sample spacings at about 1km. Samples weighing about 1kg each were pre-processed to a -10 micron (0.01mm) sample fraction before being submitted to the laboratory.
Management says not all of its 68 tenements in the project area were sampled, with the results coming from a single block in the northern-most part of Iguatu North, Magnesite, Iguatu Central and in the four blocks comprising Quincuncá. Results are still outstanding for most of Iguatu North.
Gold Mountain found that each of its locations carry gold anomalism in at least two sample sites and more notably – at Iguatu Central and Iguatu North’s solitary tenement – occurs in significant clusters.
Substantal copper anomalism occurs in multiple sites throughout Iguatu Central to a centre peak value in the range of 71 parts per million to 121ppm copper and is surrounded by other lower-order, but anomalous responses between 31ppm and 44ppm. Four other significant clusters of results occur through the suite, but other ground within the group remains to be sampled.
At Quincuncá, about 70 per cent of the north-east block has responded with copper anomalism in the overall range of 32ppm to 68ppm copper. At Magnesite, a central solid hit is recorded in the 61ppm to 68ppm copper range, with lower responses adjacent to it and a separate cluster of the same order in the north-east.
The separate Iguatu North ground features abundant anomalous gold, accompanied by scattered moderate level hits of copper – mostly in the 27ppm to 43ppm range but reading in two areas in the 61ppm to 68ppm range.
Additionally, lithium-caesium-tantalum/tin (LCT pegmatite fertility signatures) have turned up at Iguatu Central, Magnesite and at Iguatu North.
Significant areas of anomalous copper have been detected through 38sq km of ground, with 14sq km of highly-anomalous copper. Five high-priority copper targets have been identified and justify extensive regional extension and infill sampling.
Gold anomalies occur with most of the copper anomalies and strongly-anomalous lithium results were also uncovered, indicating LCT-type pegmatites exist in the tenements.
Apart from gold and copper, multi-element analysis from the stream sediment geochemistry exhibit extensive anomalism for silver, mercury and barium, indicating an Olympic Dam-style of IOCG mineralisation.
BHP’s Olympic Dam breccia-style IOCG deposit in South Australia boasts about 2.95 billion tonnes of ore grading 1.2 per cent copper, 0.04 per cent uranium, 0.5 grams per tonne gold and 6g/t silver.
Gold Mountain says its encouraging latest results will lead it into a comprehensive follow-up program involving additional sampling and mapping to home in on targets.
The company says interpretations that have been presented in several geological survey and academic papers reveal that extensive structures typically necessary for the development of Olympic Dam-style deposits are present in the Iguatu region.
Regional-scale geochemical sampling has also confirmed the local presence of iron and base metal anomalism in the Iguatu project areas. Gold Mountain retains a 75 per cent interest in the 68 tenements and no known exploration for IOCG copper-gold deposits has been carried out within the site’s licence areas.
Gold Mountain’s low-level fine-fraction geochemistry has pulled a number of enticing targets into the limelight and it will be interesting to see how they perform when they hit centre stage.
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