Seabridge Gold

KSM (Kerr-Sulphurets-Mitchell): GEOLOGY

The KSM Project: A Cluster of Porphyry Related, Deformed and Dismembered Au-Cu-Mo Deposits Displaying a Transition from Deep Porphyry to Shallow Vein Environments

The KSM Project in northwest British Columbia of Seabridge Gold Inc. hosts one of the world’s largest undeveloped reserves of gold, copper, silver and molybdenum. Four separate deposits, Kerr, Sulphurets, Mitchell and Iron Cap, are spread over an area of roughly two by ten kilometers, hold a total proven and probable reserve of 38.8 million ounces of gold, 10.2 billion pounds of copper, 183 million ounces of silver and 207 million pounds of molybdenum. These are contained in 2.9 billion tonnes of resources with an average grade of 0.54 g/t Au, 0.21% Cu, 2.7 g/t Ag and 44 ppm Mo.

Mineralization is disseminated and stockwork veinlet-controlled, fine-grained hypogene chalcopyrite, bornite, molybdenite, pyrite, with gold and silver closely associated with sulphide minerals. The deposits are in arc-related Triassic and Jurassic volcanic and sedimentary assemblages of the Stikine terrane, which lies between the crystalline intrusive and metamorphic rocks of the Coast Plutonic Complex and the sedimentary prism of the North American margin. The KSM ore bodies, as well as several other gold and copper deposits in the region, were formed during subduction related emplacement of Early Jurassic diorite, monzonite and quartz syenite intrusions.

The KSM and adjacent deposits exhibit clear vertical zoning from deeper, magmatic source ores upwards through transitional volcanic-hosted porphyry and skarn zones to shallow vein systems. Significant contractional deformation resulting from Cretaceous accretionary processes has severely affected the deposits at micro and macro scales. Phyllosilicate alteration assemblages and stockwork vein networks have been largely mylonitized. Thrust faulting has dismembered entire deposits and repositioned deeper ores over shallow ores.

Alteration and metal zoning confirms the adjacent Snowfield deposit is the truncated cap of the Mitchell deposit, with an offset of approximately one kilometer. All of the KSM deposits are open at depth and recent exploration drilling has indicated encouraging potential for discovery of “blind” zones beneath thrust faults.

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KSM Project Geology Summary September 2013 - Resource Download

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KSM Zone Locations and District Geology

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KSM Styles of Mineralization – Mitchell and Iron Cap Zones

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  • The KSM Au-Cu-Mo-Ag mineral deposits are magmatic derived hydrothermal systems contemporaneous with Jurassic arc volcanism and a composite intrusion complex with alkaline affinities.
  • Deep Core Zone Porphyry mineralization with potassic alteration, bornite and gold has direct genetic links to Epithermal Vein Gold mineralization.
  • Porphyry and Epithermal Alteration patterns and metal distributions have been significantly modified and obscured by deformation and metamorphism.
  • Thrust Faulting has truncated deposits and re-positioned deeper ore zones above shallow ore zones.

All disclosure of a scientific or technical nature was prepared by, or under the supervision of William E. Threlkeld (Licensed Registered Geologist #790 in the State of Washington), a Vice President of Seabridge. Mr. Threlkeld is a "Qualified Person" under National Instrument 43-101.