Pretivm and Seabridge Gold have used a very specific form of geophysics which has played a significant role in the discovery and development of their respective deposits. It’s called a Magnetotelluric (MT) survey.
“MT technology has proven to be an effective tool for conceptual modeling of deep targets at KSM and helped to guide the discovery of the Deep Kerr. The same method is being used to identify other potential core zones” – Rudi Fronk (CEO Seabridge Gold), 2014.
Since that statement was made, MT technology has been used to discover the “Mitchell at depth” and “Lower Iron Cap” zones and expand the “Deep Kerr” zone. This technology has proven its accuracy time and again, which is why it has been used so extensively by Pretivm and Seabridge over the years.
In 2016, Tudor Gold conducted the same MT survey on Treaty Creek using the same equipment with the same geophysicist that designed and interpreted the MT surveys on the adjoining properties. The results of that survey are remarkable as it confirms the geology in showing that the entire system is connected at depth. The leading authority on the Golden Triangle, and former regional geologist of the area, Dani Alldrick stated:
“Due to the extensive bedrock exposures (gossans and close to surface mineralization) of the Sulphurets porphyry system, we know that the diameter of the Sulphurets system is at least 25 km; this is a measured value documented across the mapped exposure of the intensely altered, pyritized paleosurface of the hydrothermal system which is well exposed through the area as an altered dacite pyroclastic unit, including extensive exposures on the Treaty Creek claimblock” - Alldrick, 1988.
Surface sampling and drilling on Treaty Creek has confirmed its relationship to other deposits within this world-scale hydrothermal system and now this same geophysical technology that has led to numerous discoveries is also showing a continuation of rock signature and structure at depth within the system.
Below is a macro in-ground side image of Treaty Creek with the signature of the mineralized rock (0.7 g/t average at Copper Belle) being shown in yellow. The image is to scale with a depth of 4km and extending 7km from the KSM border (SSW) to the right of image (NNE). The two drill holes shown (downward arrows) intersected 241m @ 0.8 g/t gold (open at depth) and 338m @ 0.7 g/t gold until it encountered the less mineralized signature of rock (red) at depth. The best (Seabridge) 2016 Iron Cap hole was the closest one to the Treaty border (800m) and measured 555m @ 0.83 g/t gold with copper. The geology and geophysics indicate that the drilling on Iron Cap is in the same signature of rock (yellow) that extends from the common border for 7km through the heart of Treaty Creek to near the Orpiment zone. This is a very deep system ranging from 1,500m up to 3 kilometers thick from top to bottom. Thickness at Copper Bell is about +/- 400m making it a potentially easy-to-access gold deposit with potential for substantial resources.
Micro MT images of the Copper Belle reveal two “close to surface” structures (1.25Km x 1.25Km together) where drilling in 2007, 2009, & 2016 took place. In June, 2017 Tudor Gold commenced a 20,000m drill program (over twice the size of the recently announced 2017 KSM – Iron Cap program) to develop a resource calculation within this structure, start working towards developing a preliminary resource estimate on the adjoining high-grade GR2 zone, and carry out deep drilling to confirm the underlying connecting mineralized system.
The GR2 zone appears to be a VMS deposit with well-defined seams and veins ranging from 5.4 g/t gold over 14.5M to 27 g/t gold or 2,280 g/t silver over half metre intervals. It also contains copper, lead, and zinc. Tudor Gold is also considering further exploration work in the Konkin Gold zone where early exploration produced grab samples, chip samples and trenching samples carrying in excess of 28 ounces of gold per tonne (over 1.2m). Both high and low-grade metallic zones have been discovered on Treaty.
The image below shows Seabridge’s Iron Cap on the bottom left which holds 10.6 M ounces gold and 3.6 billion pounds copper (all categories) within an area less than one square kilometer on surface. The yellow line is an approximation of the Treaty Creek border. The Iron Cap holds the richest grades to date in the KSM, is open at depth and to the north, and will likely be “the game changer” for Seabridge.
"We are just beginning to define the size and shape of the Lower Zone at Iron Cap. Thus far, we have traced the deposit along a strike length of about 750 meters but the limits have not been found to the north and at depth” – Fronk, 2014.
The 2016 Iron Cap hole IC-16-62 is Seabridge’s most promising hole to date and confirms that the system continues north under the Johnston Ice Field. The entire focus of Seabridge’s 2017 KSM program is on the Iron Cap “given its exceptional grades and the possibility that it may extend to the north, west, and east” – Fronk 2017. Perhaps that’s why Fronk also stated of the 12 years of successful drilling on KSM “we believe (2017) could be one of our most productive”. Some of the holes planned in their recently announced 8,750m program will be drilled within 500m of the Treaty property border and will reach over 1,200m deep. As shown earlier, the MT survey on Treaty Creek (identical to the one that helped discover the Lower Iron Cap zone) suggests that the mineralization continues north, projected to extend NNE from the Iron Cap zone across the Treaty Creek boundary for 7 kilometers, under the West Nunutak all the way to near Treaty’s Orpiment zone.
If the MT survey on Treaty is accurate (as it has thus far proven to be) in indicating deposits of this scale, this hydrothermal system could host the largest concentration of metal value in the world.