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Geological Settting of Ni-Cu + PGE Sulphide Deposits: Barnes and Lightfoot (2005)

Relationship between Massive, Matrix, Disseminated and Vein Sulphides Ni-Cu + PGE Sulphide Deposits; Barnes and Lightfoot (2005)

Deposit Type

The exploration model / deposit type that defines the Rottenstone deposit is a typical, deep-rooted, mantle derived, Magmatic Ni-Cu and PGE deposit; however unique in that it contained the richest concentration of PGE’s of any deposit of its type in Canada. It has been suggested up to 50% of the host ultramafic intrusion consisted of sulphides and that the intrusion is the result of a significant magma chamber at depth within the vicinity of the Rottenstone deposit. Fathom believes there is ample evidence suggesting that the Rottenstone deposit formed as a sill and the deposit was the result of a structural trap / embayment that provided the framework for the deposit to form. What is encouraging is within the geochemical data set numerous other sill-like bodies have been recognized suggesting the possibility for other Rottenstone type deposits on the property.

The two Figures depicted below portray a possible deposit scenario for the Rottenstone Deposit. The first Figure suggests the Rottenstone Deposit is one of several pods of metal enriched magma chambers occurring within the supracrustal rocks at the Rottenstone property. Glencore’s Raglan nickel-copper mine in northern Quebec is a deposit model consisting of multiple sulphide lenses consisting of disseminated, net-textured and massive pyrrhotite-pentlandite-chalcopyrite mineralization contained in individual lenses that average 0.2Mt in size; but lenses can be as small as 0.01Mt (Desharnais, Arne and Bow, 2014). Although not proven to date, the geologic setting / model, mineralization and the Rottenstone Deposit occurring at the Rottenstone property has similarities to the Raglan deposits. The second Figure depicts typical style of mineralization in a Ni-Cu + PGE sulphide type deposit; Massive Ore at the bottom of a structural trap / embayment grading up through Matrix Ore, also referred to as net-texture ore. In addition to massive, matrix ore; interstitial, and vein ore has been recognized at Rottenstone.