Summary:
Deposit Types
It is postulated that the Martison phosphate-rich residuum deposit was formed by karstic weathering of the underlying carbonatite basement rock.
Karstic weathering of the carbonatite at depth would require the water table to have been lower in the area at some time in the past and likely prior to glaciation.
The Martison carbonatite is one of 50 known locations of the Central Ontario Carbonatite Complex found on the Kapuskasing structural high (located 110 km east of the Martison Project) to the Albany Forks structural high, (located 260 km west of the Martison Project). Almost all of the carbonatite bodies occur along recognisable major tectonic features.
A number of these complexes have been examined for their mineral potential. They all contain apatite in the carbonatite phase between 5% to 25%, and some contain significant enrichments of apatite through leaching out of carbonates. Such enrichment occurs on the Cargill Limited complex, located on a branch structure off the Kapuskasing structural high and at the Martison phosphate deposit.
Property Geology
Differential weathering of the Martison Carbonatite Complex has resulted in an irregular weathered ‘karst’ type surface of the carbonatite, a topography formed from the dissolution of soluble, carbonate rich, rocks, the depth of which varies greatly over short distances. Depressions in this carbonate rich, karstic, surface are filled with the weathered breakdown product of the carbonatite, the Residuum. This apatite rich Residuum represents the bulk of the phosphatic material of economic interest. Above the Residuum lies a less consistent layer of lateritic material containing niobium mineralisation, also at levels of economic interest. More recent glacial deposits, typical of the James Bay Lowlands, form a blanket of glacial till over the Residuum and lateritic material sub-outcrop, reaching up to 80 m in depth.
Mineralization
Apatite is the principal phosphate bearing mineral of economic interest within the Residuum. The lateritic material is enriched in niobium, typically found in the form of pyrochlore, its occurrence is also of economic interest. Both the phosphate bearing apatite and the niobium have been the subject of significant drilling and metallurgical test work to establish if they may be extracted economically.
Anomaly A strikes approximately N 30° W and is without a definable dip. The current strike length is approximately 1,700 m with a width varying between 300 m and 600 m. The northwest and southwest edges of this anomaly zone are sharp due to the effects of the possible postulated faults and the resulting intensive weathering of the carbonatite in this fractured zone. However, the residuum resource in Anomaly A remains open to the northwest, northeast and east and at depth in its central and northern areas.
Anomaly B is located approximately five kilometres south of Anomaly A. An initial two holes were drilled in Anomaly B in 1981, no further work was carried out until 2001 when an additional 12 holes were drilled at approximately 200 m spacing. Although not fully explored, Anomaly B is considered to have been developed by the same geological processes as Anomaly A. Several of the drillholes have intersected phosphate mineralization of a similar level as Anomaly A. The aeromagnetic anomaly is as strong as the Anomaly A response but does not appear to have the aerial extent. Geologically Anomaly B is very similar to Anomaly A. Residuum thickness in Anomaly B varies in the holes drilled from 4.5 m to 90 m, with P2O5 grades up to 30%.
An approximate average thickness of 18 m of residuum is identified in the borehole logging, though the phosphate distribution appears to be more irregular.
Anomaly C occurs as a significantly smaller magnetic anomaly approximately two kilometres to the east southeast of Anomaly A. Only one hole appears to have been drilled in Anomaly ‘C’ in 1981 (Drillhole number 81-13), which apparently did not intersect any of the mineralised residuum. Since that time no further drilling has been carried out on this anomaly.