Hello Terry
***WARNING GEOLOGY POST***
As Teck's vice-president and Donner have both made direct comparisons of the 1,200km2 SVB deposit to that of the geology of the Sudbury basin, I thought I would attempt to do a little research on the latter. For those (Ed) who might be interested, this is what I found in the May 1997 Journal Of Geochemical Exploration published by Elsevier Science.
Firstly, there are some graphics published in the Journal indicating in broad terms the general orientation and geology of the Sudbury Basin.
Simply, it appears as an elongated (elliptical)doughnut orientated and elongated from the southwest to the northeast. The surrounding rocks are Archean volcanics (very old) and the middle or hole in the doughnut is filled with Wackes and Mudstones (old compressed sedimentary ocean floor). The doughnut itself is made up of three concentric rings, starting on the outside with Noritic rocks described as Granophyric, Transitional Noritic Phases. In addition, on the outside of the northern most and northeasterly Noritic ring, there is a narrow ring of Archean mafic intrusive rocks (similar to SVB mafic intrusive Troctolites I believe) with marginal sublayers and offsets. The ore deposits appear to be almost exclusively located within close contact between the outside ring and the host Archean volcanic rocks that surround the doughnut with the complete exception of the south ring contact. In particular, there appears to be significant concentrations of ore associated with the northern most and northeasterly narrow ring of Archean mafic intrusive rocks with marginal sublayers and offsets. This is repeated to a lessor extent at the southwest elongated ring contact where there is a smaller but similar geological structure. It is also interesting to note that there appears to be significant economic gold (Au) deposits primarily to the northeast, but also to a lessor extent to the southwest.
I will retype a few paragraphs from the article that are particularly relevant. Readers may wish to take special note of the references to where Platinum and Palladium concentrations occur as this may also apply to SVB.
"The study area occupies 1,300km2 and includes: all of the Sudbury Igneous Complex on the north and east ranges of the Sudbury Basin; and a portion of the Huronian Whitewater Group (Onaping, Onwatin and Chelmsford Formations) within the Basin.
The elliptically-shaped Sudbury structure, which is famous for its Ni-Cu sulfide ores, is situated northeast of the Grenville Front along the boundary of the Superior and Sourthern Provinces. It measures approximately 60km long and 23km wide with its long axis orientated to the northeast. Archean Granites and Granitic Gneisses and metavolcanic rocks of the Superior Province lie to the northwest of the Sudbury structure, whereas a predominantly clastic Huronian succession with some metavolcanic rocks of the Southern Province surrounds the remaining portions of the basin (Dressler 1994).
The Sudbury structure consists of: (1) the Sudbury Igneous Complex (SIC), a funnel-shaped, differentiated mafic to felsic intrusion; (2), the overlying Sudbury Basin assemblage which contains heterolithic breccias, mudstones and wackes of the Whitewater Group; and (3), brecciated footwall rocks which occur along the outer edges of the Sudbury Igneous Complex. Ni-Cu-PGE mineralization occurs primarily along the contact of the SIC and the surrounding footwall rocks, as well as in offset dikes that both radiate out from and parallel the outer edges of the SIC.
Sudbury ores can be grouped into three main types or classes (Morrison et al., 1994; Jago et al., 1994):
(1) Contact ores, mainly located near contacts of the Sublayer and Archean igneous rocks, and characterized by a relatively low Cu:Ni ratio (<1) and low precious metal content.
(2) Offset ores, which occur along offset dikes, in which the Cu:Ni ratio is >1, and have a precious metal content that is enriched as compared to the contact ores.
(3) Footwall ores which are distinguished by Cu;Ni ratio >>1, and are enriched in platinum group elements."
"Within the study region 165 mineral occurrences of Ni, Cu, and Au, including 17 mineral deposits (producers, past producers and reserves) have been located (OGS-Mineral Deposit Inventory). These occurrences can be classified by commodity into three classes: Cu-Ni, Au and Pd-Pt."
"Seventy-five percent of the Ni-Cu occurrences occur within 2km of the Sublayer or offset contact. Gold or Au-Pd-Pt occurrences are present as two groups on the basis of distance to the same contact, and a smaller group (about 35% of the occurrences) is located within 5 to 7km of the contact. This last subset is genetically unrelated to the SIC."
So if the Sudbury model applies to SVB as the companies suggest, then we could potentially anticipate multiple ore bodies, the majority of ore concentrations within 2km of the troctalite contacts with any Archean volcanic rocks. We could further expect significant grades and Pd-Pt-Au concentrations in any brecciated footwall rocks which occur along the outer edges of the Olivin Gabro intrusion (Troctalite)as well as in offset dikes that might radiate out from or parallel the outer edges of any igneous contact.
If readers scan the available geological maps on various web sites including DML's and refer to DML's lengthy NR a week ago, it may help readers decide on which JV DML partners they may want to consider for speculation.
Just a thought.
The article does not explain why there were no ore deposits to the south of the SIC so I assume that there were no igneous rocks in contact with the Noritic Phases there and there were no mafic intrusions shown onthe map.
Hope the above was an interesting read?
Regards |
