On April 26, 2017, McEwen Mining Inc. completed the acquisition of 100% of the issued and outstanding common shares of Lexam by the way of the Arrangement Agreement dated February 13, 2017 and related Plan of Arrangement. The Mineral property interests acquired include the 100% interest of the Buffalo Ankerite, Fuller and Davidson Tisdale deposits and 60% interest in the Paymaster deposit located in Timmins, Ontario.
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Summary:
BUFFALO ANKERITE
The mineralization is located primarily within a narrow pillowed mafic volcanic flow unit of the Central Series, Tisdale Assemblage. The volcanic rocks are complexly folded around the STA and Kayorum Syncline resulting in an S-shaped flexure in the stratigraphy. The pillowed mafic volcanic rock unit, which hosts the main mineralized domains of the Buffalo Ankerite South property, is flanked to the north and south by Hershey Lake Series magnesium-rich ultramafic flow units. In the area of the Buffalo Ankerite, the volcanic flows strike between 065° and 070°, and dip at approximately 60° to the north and thicken to the west. A discontinuous conglomerate unit is located along the contact between a flowtextured mafic volcanic rock unit and the south ultramafic rock unit. The conglomerate sedimentary rock unit is interpreted as Timiskaming in age containing mainly bleached mafic volcanic clasts with occasional porphyry and ultramafic clasts and typically follows this contact and is similarly oriented for dip. Quartz-feldspar porphyries intrude the volcanic rock units and late northwest-trending diabase dykes cut all the above rock types.
The majority of the mineralization is associated with tourmaline-quartz-carbonate breccia zones (TBX) located within a narrow pillowed mafic volcanic flow unit of the Central Series, Tisdale Assemblage. Breccia fragments are comprised of ankerite-sericite altered pillowed mafic volcanics within a tourmaline-ankerite rich matrix. The finer the size of the carbonatized mafic fragments within the vein, the higher the gold grade.
FULLER
Fuller is underlain by a generally east-west-trending assemblage of massive and pillowed mafic metavolcanic flows with minor variolitic flows. These have been traced onto the adjacent Paymaster mine and Dome mine properties to the east. To the west, the units are traceable into complex fold structures; part of the package is believed to be folded to the south around the STA, while the northerly part of the package appears to trend onto the Hollinger mine property.
Most of the mineralization found at Fuller is within the Contact Zone, which is located along the contact between massive and pillowed basalt rock units. Mineralization is characterized by numerous parallel to subparallel quartz-carbonate veinlets hosted within a suite of volcanic rocks. Pyrite is often abundant, both as very fine-grained disseminations and small pyrite trains roughly conformable to the stringers. The Contact Zone meanders along the contact between the pillowed and massive volcanic rock units, and frequently occurs entirely within one of the units. The boundaries of the zone are locally gradational.
PAYMASTER
The north part of the Paymaster property hosts the assemblage of massive and pillowed mafic metavolcanic flows with minor variolitic flows which extend east from the Fuller property which strike 075° and dip from 65° to 80° north.
In the eastern part of the property the Paymaster porphyry intrudes the basalts. The Paymaster Porphyry is characterized by the inclusion of one percent to three percent small (one to ten millimetres) clasts of the country rock, typically of ultramafic composition.
The main producing area of the Paymaster is associated with the Paymaster Porphyry stock and other small porphyry bodies to the north and northwest with quartz ankerite veins occurring to the north, west and southwest of the porphyry. In general the tenure of gold in the quartz ankerite veins appears to increase with increased silicification and quartz impregnation partially replacing the ankerite. North- and south-trending white quartz veins are barren. The #10 vein is on the north porphyry contact on the upper levels, dipping 65° away from the porphyry at depth. There is some folding and faulting along this vein. The #1 vein lies north of #10 vein with the two veins joining to the west. This vein extends west through a barren section and is again productive as No. 5 Shaft, #14 vein. The #7 vein is at the top of the Key flow (sheared variolitic flow top breccia). The #22 vein is on the strike of the #7 vein to the west, but is in a younger flow due to a drag fold. The large #20 (Kurts) vein to the northwest contains erratic gold values but has not produced any ore. In the No. 5 Shaft area, #3-24 vein, lying near the bottom of the #99 flow (chloritized, lightly to moderately foliated uniformed textured basalt) has been a substantial producer. The #8 vein lies southwest of the porphyry with the fracture entering the porphyry. The #8 vein terminates at the #18 vein which follows a strong fault. The #36 mineralized zone, lies in volcanics just north of the talc-chlorite carbonate fault zone. This zone is separated from the large ultramafic intrusive sill (or flows) by 30 ft of basalt. There is one narrow quartz carbonate vein in the mineralized zone and only a few stringers. The sulphide content is as high as ten percent combined pyrrhotite, pyrite and locally chalcopyrite. The mineralized zone extends east, and a short distance west, from a tongue of the Edward Shaft Porphyry. The #36 mineralized body is the down plunge extension of the Fuller mineralized body to the west.
DAVIDSON TISDALE
The property is located in the PGC, along the possible offset easterly projection of the Hollinger-Macintyre trend. The property is underlain by a sequence of overturned east-striking, north dipping, pillowed and massive, magnesium tholeiitic volcanic flows of the Tisdale Group. In the southernmost part of the property there are outcrops of the distinctive V8 variolitic flows, underlain by a massive flow (“99”), which forms the basal member of the iron tholeiitic group of rock. Minor graphitic sedimentary rocks containing minor pyrite and pyrrhotite have been noted locally on the property.
Two types of quartz veins were identified on the property (Brooks, 1987): The first (Type 1) are continuous tabular veins striking generally east-west and dipping 15º to 55º to the north. The other (Type 2) are discontinuous, irregular, sub-vertical and steep north-dipping to shallow south-dipping lenses of quartz stringers and veins, striking 040º to 070º azimuth.