The GR2 zone consists of several narrow linear zones of alteration and small gossans, located near the head of the Atkins Glacier. It contains a lithologically varied sequence of sedimentary and volcanic rocks that encompasses the lower part of the Hazelton Group, proven with fossils found in outcrop and in drillcore, and according to Orellana (Assessment Report 31827), not Upper Triassic Stuhini Group rocks as described in previous maps and papers.
The upper part of GR2 zone is dominated by andesitic composition volcanic fragmental rocks. Most common are thick successions of massive, coarse, clast-supported conglomerate to breccia. Clasts consist of both plagioclase-phyric volcanic rocks and lesser mudstone, in a feldspathic, sandy matrix. These coarse clastic rocks are inter-layered with several intervals of thinly to medium-bedded feldspathic sandstone to wacke, with lesser tuffaceous siltstone. The base of the Hazelton Group at the GR2 Zone is represented by several metres of thickly-bedded, calcareous sandstone and limestone.
In 1990, the Mama Susu-A showing (now GR2 zone) covered an area of about 30 by 30 metres consisting mostly of talus with a few tiny outcrops (Assessment Report 21318). Numerous boulders with up to 20 per cent pyrite, 40 per cent limonite, 60 to 70 per cent galena, 2 to 3 per cent chalcopyrite, wad and minor azurite-malachite staining are scattered over the area. A trail of heavily mineralized boulders appears to be the surface expression of an underlying shear vein which where exposed does not exceed 40 centimetres in width. The apparent strike of the vein is northeast-southwest. The showing appears to represent a series of discrete northeast trending shear veins developed in andesite lapilli tuffs over a width of approximately 20 metres. Varying degrees of sericite, quartz, pyrite and calcite alteration are present across the zone.
By the end of 2017, the GR2 had been explored in much more detail. Pardoe (2016) describes the prospect as follows. The GR2 mineralization occurs as three main subparallel zones trending northeast and steeply dipping to the northwest. They are hosted in sericite-carbonate-pyrite altered volcanic conglomerates and breccias. The upper zone crops out in surface and has consistently high silver values. The middle zone rarely makes ore grade but is a good stratigraphic marker. Immediately below, a zone of black turbiditic mudstones showing bedded pyritic clastic beds is found in most of the drill holes. The pyrite content is usually higher in the mudstones situated in the upper hanging wall contact, whereas the mudstones of footwall contact are more deformed and crosscut by white calcite and quartz stringers, locally containing sphalerite, galena and chalcopyrite. Below the mudstones, there is a unit of sericite-carbonate-pyrite altered volcanic conglomerates and breccias similar than the one that hosts the upper mineralized zone. This unit is host of the lower mineralized zone, that is characterized by a zone of coarse-grained sulphides (sphalerite, galena, chalcopyrite and minor silver and lead sulphosalts), underlain by a bluish-grey chalcedonic/silicified zone particularly enriched in gold. This gold enriched zone locally splays and can be hosted by either sericite-carbonate-pyrite altered volcanic conglomerate (with locally black matrix cementing the clasts) or a fossiliferous graphitic-pyrite turbiditic mudstone that grades to black mudstone and well bedded fine-grained sandstones. The mineralized zone appears to be later offset by a regional fault/shear zone, producing remobilization of argentiferous galena in late-stage structures.
Pardoe (2016) reports that three styles of mineralization are observed in core: 1) stringers and veins composed chiefly of quartz and rhodochrosite, with minor galena, sphalerite and chalcopyrite, with breccia and crustiform textures 2) bedded sulphides (pyrite) in black mudstones and 3) coarse grained stratabound sulphides, locally up to 20m thick, showing intensive silicification. Elevated grades of gold and silver correlate with zinc and lead (sphalerite, galena and lead sulphosalts) in these zones, whereas gold is more commonly found in the bluish silicified zone.
Sampled in 1990, the Mama Susu-A zone yielded the 5.82 grams per tonne gold) (#34504) and 13.75 grams per tonne gold (#34505); silver assays from these samples were 181.72 grams per tonne and 168.0 grams per tonne, respectively (Assessment Report 21318). Base metals values are also anomalous with up to 1.65 per cent copper (sample 34509), 28.6 per cent lead (sample 34504), and 37.4 per cent zinc (sample 34507) (Assessment Report 21318). All of the previously mentioned results were from float samples of sulphide bearing vein material".
The HC zone (formerly Mama Susu-B zone) is characterized by numerous boulders containing up to 60 to 70 per cent galena, 10 per cent stibnite, malachite-azurite and sphalerite occurring over a talus-covered area measuring approximately 50 by 20 metres. The mineralization is related to a 20-metre-wide shear zone developed in andesitic pyroclastics, a substantial portion of which has been almost totally replaced by sericite and quartz. The HC zone is the northeast extension of the mineralization encountered at GR2 (Mama Susu-A), which is located about 400 metres to the south-southeast. Talus cover in the area between Mama Susu-A and B (GR2 and HC) conceals any potential mineralization along the structure.
The bedded sulphides in turbiditic carbonaceous mudstone, along with coarse grained sulphides in a massive sulphide lens, suggested to that mineralization intercepted to 2017 is either proximal to a VMS sulphide vent, or represents a deep low-sulphidation epithermal system.
In 1989 Tantalus Resources optioned the Treaty Creek property from Teuton Resources Corp and relinquished it in 1992. The Mama Su showings were found in 1990 on the GR2 claim by Tantalus. The area of new showings comprises seven separate exposures on the GR2 claim. A small grid totalling about 5-line kilometres, was emplaced over the showings to provide control for geological mapping, trenching and a UTEM geophysical survey, much of which was conducted over an icefield. The favourable results received from the numerous grab samples collected at the various showings prompted a more detailed trenching and chip sampling program (Assessment Report 21318). Overall in 1990, Tantalus collected 168 rocks sample samples, excavated 52 metres in 5 trenches and conducted 17.2 kilometres of VLF ground electromagnetic surveying and 14.1 kilometres of ground magnetic surveying. Work concentrated on the Treaty Gossan area and the GR2 showings.
In 1991, drilling occurred on the northern portions of the GR2 (Mama Susu) showings but is not documented. Mapping occurred in the GR2 area in 2003 by Heritage Exploration Ltd. American Creek Resources Ltd, who obtained the Treaty Creek option from Teuton, drilled the Mama SuSu-A (GR2) (104B 370) in 2007 (9 holes) and again in 2009 (11 holes) (Assessment Reports 30241,31827).
In 2017, a total of 20 drill holes comprising 5,378.27 metres were reported at the GR2 zone, with 18 of those holes returning significant values.
In 2009, exploration diamond drilling on the property totaled of 9,451.06 metres was completed. At that time drilling on the GR2 zone was confined to a relatively small area roughly 220 meters wide, 250 metres long to depths of 400 meters. Drilling on the GR-2 zone yielded intercepts including 1008.0 grams per tonne silver over 1.2 metres and 8.23 grams per tonne gold over 2.2 metres in hole GR2-09-01 and 5.44 grams per tonne gold over 14.5 metres in hole GR2-09-07 (Pardoe, J. (2016-05-21): NI43-101 Technical Report on the Treaty Creek Property).
By 2010, the GR2 zone (previously Mama Susu-B) was described as the feeder zone of a volcanogenic massive sulphide (VMS) deposit. Bedded sulphides are preserved in a mudstone-sandstone turbiditic sequence between hydrothermally altered epiclastic rocks crosscut by polymetallic vein systems. A highlight from 2007 drilling on the GR2 zone is hole TC07-24 which intersected 6.80 meters of 1.40 grams per tonne gold with 93.95 grams per tonne silver and 0.27 per cent copper, 4.41 per cent lead and 2.59 per cent zinc within a silicified breccia and stringer zone on the immediate contact with black fossiliferous mudstones and sandstones of Jurassic age (Assessment Report 31827).
Exploration on the property was halted after 2009 because of a legal dispute between American Creek and Teuton regarding the 51 per cent earn into the Treaty Creek property by American Creek.
In 2016, the property legal dispute between American Creek and Teuton Resources was settled. The Treaty Creek project soon became a 60:20:20 joint venture with Tudor Gold as operator (60 per cent owner). Teuton and American Creek Resources each own a 20 per cent carried interest, meaning neither company must contribute to exploration costs until a production notice is made.
In 2016, Tudor Gold Corp conducted a Magnetotelluric (MT) survey on a portion of the Treaty Creek property prior to a drill program. Tudor Gold drilled eight holes on the Treaty Creek claims in 2016. Three holes were drilled on the Copper Belle are including two on a new zone to the northeast. The remaining five holes were drilled on the Treaty Gossan and Eureka zone (104B 078)
In 2017, Tudor drilled 13,722 metres in 27 diamond-drill holes on their Treaty Creek property. The target was the Copper Belle zone.
In 2020, Tudor Gold Corp. completed 52 diamond drill holes, totalling 45 517 metres, on the Goldstorm (MINFILE 104B 704) and Perfect Storm zones of the Treaty Creek Gold property.
Refer to Copper Bell (04B 518) and HC (104B 371) for related geological and work history details of the Treaty Creek Property.