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Detailed exploration conducted during 2006 in the western part of the Skukum Creek deposit has revealed new structural, mineralogical and geochemical features. The deposit incorporates a number of (at least six or seven) sub- parallel narrow mineralized zones, coincident with andesite-dacite-rhyolite dyke swarms extending for at least 1 km along strike and for hundreds of metres down-dip. Various mineralized zones differ in size, structural setting, intensity and composition of mineralization, and, in total, form a large mineralized package more than 200 m wide, corresponding to a property- to district-scale fault zone extending for over 10 km and traced by a dyke belt. Significant potential exists for the exploration of these structures along strike and down-dip. The diamond drilling intersected numerous high-grade intercepts of gold and silver mineralization corresponding to the low-sulphidation sub-type of epithermal gold-silver deposits. However, strong enrichment in base metals (up to 25% of combined Zn+Pb+Cu) and arsenic suggests essential differences from typical epithermal mineralized systems.

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The Kalzas W-Sn-Mo deposit is located in central Yukon, 282 km north of Whitehorse on the northern side of Big Kalzas Lake. Wolframite-molybdenite-cassiterite mineralization occurs in sets of large planar quartz veins which cross-cut Selwyn Basin clastic rocks of the Upper proterozoic Windermere Supergroup, or "Grit" unit. The deposit has a concentric alteration halo with an outer sericite dominated zone, an inner "potassic' core and intense tourmalinization throughout the potassic zone and part of the sericite fringe. Intense fracture and quartz-tourmaline veinlet stockwords are present. No plutonic rocks are exposed in the local area though an underlying pluton is suspected. Kalzas has similarities to many wolframite deposits throughout the world, including those of southeast Asia which contain the bulk of world tungsten reserves. In contrast, North American tungsten mines having wolframite as the dominant tungsten phase are not as common as scheelite skarn deposits which produce most of our domestic tungsten.

Geological map (1:50,000 scale) of the West Klondike area, central Yukon (NTS 115O/14,15 and 116B/2,3) including marginal notes on mineral occurrences.

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Geological map (1:50,000 scale) of the East Klondike area, central Yukon (NTS 115O/9,10,11,14,15,16 and 116B/2) including marginal notes on geologic history, economic geology and mineral occurrences.

Galena and pyrrhotite occur in manganese-stained quartz-carbonate breccia beneath rusty limestone. Surface geology of the area suggests that the mineralization is a replacement of brecciated limestone in the footwall of a low-angle fault. Results from previous exploration have proved disappointing but the host structure is probably regional in extent and larger deposits may exist along strike.

The RAM zinc-lead-silver property in southwest Yukon Territory (105 D/4) is on the contact between metamorphic rocks of the Yukon Crystalline Terrane and foliated granitic rocks of the Coast Plutonic Complex. Both are intruded by an Eocene granitic stock. The metamorphic rocks, predominantly biotite-quartz pelitic schists, with amphibolite, marble, graphitic phyllite and foliated metagranite, may be partly Precambrian and are modified by metamorphism. Foliated granodiorite to quartz diorite of the Coast Plutonic Complex intrudes the metamorphic rocks. Rb-Sr analyses of two of these granitic rocks give a possible whole rock date for foliated granite of 143 Ma (initial 87Sr/86 Sr ratio of 0.7068), and a maximum age of 200 Ma, while K-Ar dating of hornblende and biotite separates from a granodiorite gives 106 ±4 Ma and 53.7 ±1.9 Ma, respectively. An Eocene, porphyritic microgranite stock (Rb-Sr whole rock date:: 43 Ma with assumed initial 87Sr/86Sr ratio of 0.705) discordantly crosscuts the older rocks on the property, and has probably reset the biotite K-Ar date in the granodiorite. Mineralization on the property includes small skarns (maximum size 15m x 6 m) with disseminated sphalerite and galena, in metasedimentary rocks of the Yukon Crystalline Terrane, near the Eocene stock. Assay of grab samples from the showings average 53.8 gm/t silver, 4.35% zinc, and 2.20% lead.

for a copy of this paper please contact the Yukon Geological Survey; geology@gov.yk.ca.