Abstract: 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.

Authors: Watson, P.H., Godwin, C.I, and Armstrong, R.L.

Map Scale: 1 : 0

Citation: Watson, P.H., Godwin, C.I, and Armstrong, R.L., 1981. Geology, mineralization, and K-Ar and Rb-Sr isotopic study of the RAM zinc-lead-silver property Yukon Plateau, southwest Yukon Territory (105D/4). In: Yukon Geology and Exploration 1979-80, Indian & Northern Affairs Canada, Exploration & Geological Services Division, p. 123.