Summary:
The Bekisopa property occurs within the Anosyen Domain and Ikalamavony sub-domain of Madagascar. More specifically Permits PRE 3757 and PR 10430 occur within the Ihosy and Amparihy Formations of the Akora Group (Anosyen Domain) and the Bekisopa and Betainamboa Formations of the Ikalamavony Group (Ikalamavony Sub-domain). To the north-east and southwest of the permits are intrusions of the Ambalavao Suite.
The local geology consists of a calc-silicate unit within schists and gneisses. The calc-silicate unit appears to be a favourable host for deposition of iron mineralisation from metasomatic fluids derived from either magmatic or metamorphic processes. Broad layers of massive magnetite–hematite are traceable over the entire 6km extent of the overall Bekisopa tenements. Mineralisation is interpreted as a series of parallel layers of predominantly massive magnetite-hematite with thicknesses of a few metres up to 20-50m, within the magnetite bearing host rocks. Disseminated mineralisation is also present and includes both coarse and disseminated types.
In most cases the Amparihy Formation is characterised by biotite- and garnet-bearing gneisses. Quartz, K-feldspar and plagioclase are also present. There is little compositional difference between the Amparihy and Ihosy Formations, even though these are notable differences in the mineral assemblages from each formation.
The Ihosy Formation rocks are also characterised by a distinctive and well-developed stromatic migmatitic layering. Cordierite and magnetite are conspicuous in these rocks and are present in abundances of between 25-50% and 3-10% respectively. These rocks are often garnet absent and contain the assemblage cordierite + sillimanite + biotite + plagioclase + K-feldspar + quartz + ilmenite and magnetite. The rocks have strikes of northwest-southeast and are characterised by tight to isoclinal folds, mostly showing sub-vertical dips (GAF-BGR, 2008).
The Bekisopa Formation is intercalated with kilometre scale layers of quartzite, impure marbles (Betainamboa Formation), and quartzo-feldspathic gneisses. These rocks of the Betainamboa Formation are medium- to coarse-grained and mainly massive, however, weak millimetre to metre scale compositional banding defined by layers of oxides is also locally present. The rocks have strikes of northwest-southeast, and are characterised by folds which mostly shows dips to the west (GAF-BGR, 2009).
The Malakialina Formation is the main host of iron mineralisation in the district, and within the project area is comprised of a sequence of mica schists, gneiss, marble, quartzite and amphibolite.
The mineralisation has the form of a tabular zone or zones and trends from steeply westerly dipping in the north to moderately westerly dipping in the centre and moderately to flat dipping in the south. Some large - scale faults have been interpreted; however, small scale faulting has not been identified with the current drill spacing.
The principal lithology seen within the drillcore is gneiss (both mineralised with Fe and barren),plus schists and calc silicates. Intervals of intense magnetite are present and, in places, become the overriding rock type.
While variable, high levels of oxidation have occurred from surface to 20m in depth, with partial oxidation occurring below this point to depths of 40m. Iron enrichment is common in the DSO mineralised zones, creating a high grade regolith profile. levels of oxidation has occurred between surface and 20 meters depth. Massive magnetite-haematite outcrops along surface. Magnetite, haematite and small levels of geothite are the principal iron bearing minerals.
Iron mineralisation at Bekisopa is believed to be of metasomatic origin and preferentially hosted by calc-silicate rocks within a high-grade metamorphic sequence. The Bekisopa deposit exhibits similarities to Algoma-style Banded Iron Formations (BIFs), Iron Oxide Apatite (IOA), Iron Oxide Copper Gold (IOCG) and iron skarn deposits. Further investigation (including drilling and petrology) is required to better understand and classify the Bekisopa deposit.
Mineralisation at Bekisopa is modelled as three separate categories, Enriched (from or near-surface), Intermediate A (immediately below the Enriched) and Main (including Intermediate B).