Hello Koan
This regional geology summary pretty much says it all and should help guide you decisions:
A. REGIONAL GEOLOGY
The Nipissing Magmatic Province encompasses a region about 450 km east-west and up to 350 km north-south in southeast Ontario (Lightfoot and Naldrett, 1996). This area is host to mafic Nipissing Diabase (dominantly gabbroic) tholeittic intrusive rocks which form undulating sills, cone sheets, dikes and/or lopolithic structures within sediments of Gowganda, Lorrain and Mississagi Formations, members of the regionally extensive Aphebian (2.39Ga-2.48Ga) Huronian Supergroup. The Nipissing Diabase represents a major Proterozoic (2.21Ga - 2.22Ga) (Card and Poulsen, 1998) intrusive event and is likely the remnants of an eroded system of Continental Flood Basalts (Lightfoot et al., 1987). An environment favorable for the formation of significant concentrations of magmatic sulphide minerals rich in Cu-Ni-PGE is suggested, as it is probable that the Nipissing Diabase is associated with rifting, intraplate volcanism and basin development (Lightfoot et al., 1987).
B. STYLES OF MINERALIZATION
The region between Sault Ste. Marie and Cobalt, Ont. has long been known to host hundreds of Cu-Ni sulfide occurrences associated with Nipissing and East Bull Lake intrusives (Easton, 1998). Mineralization occurs in both the intrusives and the enclosing Huronian metasediments. Recently, these generally uneconomic Cu-Ni occurrences have been recognized to contain significant concentrations of PGE's (Jobin-Bevans and Peck, 1999).
Research has identified three general categories of mineralization (Jobin - Bevans et.al, 1998):
Type 1: massive sulfide mineralization within the upper parts of the stratigraphic succession, with a high Ni:Cu ratio and a very low PGE component;
Type 2: disseminated and bleb sulfide mineralization (2-5%) in massive hypersthene gabbro in the lower parts of the stratigraphic succession, with a low Ni:Cu ratio and anomalous PGE contents; and
Type 3: contact-related disseminated (2-5%) to semi-massive (>25%) sulfide mineralization in hypersthene gabbro and gabbronorite within the lower parts of the stratigraphic succession, with a low Ni:Cu ratio and highly anomalous concentrations of PGE's.
Those portions of the Nipissing Diabase that host Type 2 and Type 3 mineralization are hypersthene (10-30 model %) and magnesium (>9 weight % MgO) rich with low titanium (<0.42 weight % TiO2) and zirconium (<52 ppm Zr) contents. (Lightfoot and Naldrett, 1996)
Type 2 mineralization has been observed in the lower stratigraphic portions of the Kukagami Lake Sill where both disseminated and blebby sulfide mineralization has yielded up to 4.16 g/t Pd, 1.10 g/t Pt, 0.6 g/t Au, 1.10 % Cu and 0.39 % Ni (Lightfoot, et al, 1991).
Type 3 mineralization has been recognized at the Janes Property, operated Pacific Northwest Capital Corp. (Janes Township), where both net-textured and blebby sulfide mineralization associated with the Chiniguchi River intrusion has produced significant assay results including (amongst others) (Pacific Northwest Capital, 2000):
a 2.8 m interval of 13.4g/t Pd, 6.20 g/t Pt, 2.20 g/t Au, 0.61 % Cu, 0.24% Ni within Trench #4 and
a 15.05 m interval of 3.10 g/t combined Pd, Pt, Au, 1.08 % Cu, 0.27% Ni within drill hole JR99-01.
In addition to the aforementioned styles of mineralization, Rowell and Edgar (1986) have documented a hydrothermal Cu-Ni-PGE sulfide system (referred to as the "Rathbun High-Grade Occurrence" in Figure 2) associated with the Wanapitei Intrusion, part of the Nipissing Diabase Suite, at Rathbun Lake, 40 km northeast of Sudbury. The intrusion is ring-shaped and consists of fractured and hydrothermally altered gabbronorite. Here, the Pd bismuthotelluride mineralogy (merenskyite, kotulskite, temagamite, and michenerite to name a few) appears to be characteristic of deposits where platinum group elements have been concentrated by hydrothermal fluids. Extremely high average grades were reported for a sulfide zone approximately 3 m wide by 14 m long: eleven samples collected yielded an average of: 20.8 g/t Pd, 9.7 g/t Pt, 3.1 g/t Au, 9.32 % Cu and 0.24 % Ni.
Any exploration program for PGE'a in this area would need to be designed considering the characteristics of the Type 2 and Type 3 styles of mineralization with attention directed to contact zones between the Nipissing Diabase and Huronian sediments.
Based on several geochemical and structural similarities, a few comparative deposit types have been considered for the Nipissing Diabase. These include the sills and intrusives of the Noril'sk Cu-Ni-PGE deposit in Russia (Lightfoot & Naldrett, 1996) and the basin related Insizwa Complex of Southern Africa (Lightfoot, et al,1984)
This pretty much answers all my questions except if there is a more accurate map showing the Nipissing Diabase around?
Regards |
