Drilling on the previously untested TG-3 geophysical gravity anomaly at the Tambo Grande project in northern Peru has intersected massive sulphides.
TG-3 is a separate and distinct bull’s-eye anomaly that sits south of the TG-1 deposit. TG-1 was discovered in 1979 by French government-owned Bureau de recherches geologiques et minieres. Twenty-three drill holes defined an inferred resource, minable by open-pit methods, of 42.3 million tonnes grading 2.04% copper, 1.47% zinc and 0.36% lead, plus 37.6 grams silver, at an overall stripping ratio of 2-to-1.
The resource was defined within a 700-by-350-metre gravity anomaly and remains open to the south. The TG-1 deposit is bowl-shaped and covered by 25-40 metres of alluvium and leached cap. Its bottom extends 250 metres below surface. The deposit remains open to the south.
The TG-3 anomaly is comparable in size to TG-1. At last report, Manhattan had completed seven widely spaced holes in TG-3 and was in the process of drilling holes 7, 9 and 10. Hole 10, the northernmost hole in TG-3 to date, was collared approximately 700 metres south of the TG-1 deposit.
Hole 1 was drilled in the southern end of the TG-3 anomaly. Hole 5 stepped out more than 200 metres south of hole 1 and hit a reported 255.7 metres of sulphides beginning at a depth of 152 metres. Stepping out 70 metres northeast of hole 5, the fourth hole encountered 215.8 metres of sulphide mineralization at a depth of 178.3 metres. A further 70 metres to the northeast, the seventh hole intersected a 42.5-metre interval of sulphides, as well as a second interval of 25.5 metres of sulphides, starting at 197.2 metres of depth. Hole 7 was still in progress at last report, as was hole 9, which stepped out 70 metres southwest of hole 5.
The second hole was collared more than 200 metres northeast of hole 1. The hole was drilled to a depth of 232.9 metres but encountered only a dyke. A further 100 metres to the northeast, hole 3 intersected 100.3 metres of sulphide mineralization beginning at a depth of 155.1 metres.
Hole 6 was drilled 70 metres north of hole 3, where it intersected 51.8 metres of sulphides at a depth of 151 metres. Continuing another 70 metres to the north, hole 8 encountered 9.8 metres of sulphides before hitting a second mineralized interval of 57.8 metres, starting a depth of 154.4 metres. Hole 10 was collared a further 70 metres north of hole 8.
Assay results are pending for holes 3 through 8. All the holes have been drilled vertically and all mineralized intercepts are true width. TG-3 remains open in all directions.
Manhattan says TG-3 is similar to TG-1 in that zoned base metal mineralization occurs within a pyritic host. The massive sulphides consist of pyrite, chalcopyrite and sphalerite, and are hosted in a fault-bounded basin within andesitic and dacite flows. Holes 3 through 8 bottomed in chalcopyrite-pyrite stockwork.
Manhattan has three rigs turning on TG-3 in an attempt to define the limits of the deposit before testing the other geophysical anomalies on the property. TG-3 is one of seven geophysical gravity anomalies that are defined within a 5-km radius of the TG-1 deposit.
At last report, Manhattan had completed an additional 41 infill and stepout holes on the TG-1 deposit since beginning a 50,000-metre drilling program at Tambo Grande in late May. Results are pending.
Neither the TG-1 massive sulphide deposit nor the overlying leached oxide cap had been systematically assayed for gold, though initial test sampling of drill core by consulting firm Derry, Michener, Booth & Wahl (DMBW) confirmed a gold content in the order of 1 gram in the oxide cap and in a portion of the sulphides.
The re-assaying of the oxide portion of 21 previously drilled core holes on the TG-1 massive sulphide deposit at the Tambo Grande deposit in Peru has yielded higher-than-expected gold values.
Manhattan, which can earn a 75% interest in the project, reports that the oxide cap carries a weighted average grade of 3.06 grams gold and 62.4 grams silver per tonne over a true thickness of 18.3 metres. Out of a total of 422 samples taken, two samples yielded values greater than 30 grams gold, the highest being 80.97 grams gold over 0.4 metre.
The overlying oxide cap is composed of a stratified gossanous sequence. The base of the sequence is typically a ferruginous baritic sandstone, grading upward into oxidized and altered rhyolite, a silicified and locally barite-bearing goethite-cemented breccia and topped by a clay-rich gossan. The leached cap is overlain by about 15 metres of sandy overburden. According to DMBW, the cap contains a resource of about 5 million tonnes.
The gold concentration in the oxide cap increases with depth and appears to overlie base metal concentrations in the underlying sulphide zone.
Mineralization within the TG-1 pyrite body is zoned into three types: Type-1 mineralization is an upper 50-metre thick tabular zone containing 14.7 million tonnes grading 2.49% copper, 0.5% zinc, 0.33% lead and 40.2 grams silver.
Type-2 lies below Type 1 and is poorly defined. It contains a resource of 20.8 million tonnes grading 1.43% copper, 2.59% zinc, 0.5% lead and 43.2 grams silver.
Type-3 is a 25-50-metre-thick tabular body occurring at the base of deposit and hosts 6.8 million tonnes grading 2.91% copper, 0.11% zinc, 0.01% lead and 13.7 grams silver.
Manhattan’s re-assaying of the sulphide zone yielded 0.6 gram gold for Type-1, 0.84 gram gold for Type-2 and 0.17 gram gold for Type-3.
Sampling methods, preparation and analytical procedures at Tambo Grande are being managed by MRDI Canada, a division of H.A. Simons, and by ITS-Bondar Clegg.
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