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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  06-Dec-1992 by Chris J. Rees (CRE)

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NMI
Name HOMESTAKE Mining Division Clinton
BCGS Map 092N057
Status Prospect NTS Map 092N10W
Latitude 051º 33' 32'' UTM 10 (NAD 83)
Longitude 124º 47' 09'' Northing 5713490
Easting 376205
Commodities Gold, Silver, Copper, Zinc Deposit Types
Tectonic Belt Coast Crystalline Terrane Stikine, Gambier
Capsule Geology

The Homestake occurrence consists of several minor gold and silver-bearing quartz veins in the mountainous terrain at the head of Razor Creek, 43 kilometres south of Kleena Kleene. Similar, though more significant mineralization occurs about 2 kilometres to the north at the Blackhorn Mountain occurrence (092N 019).

The area lies in the Stikinia Terrane near the northeastern margin of the Jurassic to Tertiary Coast Plutonic Complex, within a complex stack of recumbent folds and imbricated, gently southwest-dipping thrust sheets which also involve the Gambier overlap assemblage (Geological Survey of Canada Open File 1163, Map 1713A). The northeast-directed thrusting placed Upper Triassic (Carnian) and Lower Cretaceous volcanic and sedimentary rocks over Lower Cretaceous (Hauterivian) sedimentary rocks (Geological Survey of Canada Open File 1163, Papers 88-1E, 89-1E; Geology 1991). The thrusting took place in the Late Cretaceous because the thrusts are cut by a quartz diorite intrusion dated at 68 million years by the uranium-lead method on zircon (Geological Survey of Canada Paper 88-1E). The area of economic interest lies within the imbricated Upper Triassic and Lower Cretaceous rocks. The local geology probably involves more than one thrust sheet, but as thrusts were not recognized as such in the pertinent data sources, a structural interpretation of the local stratigraphy is not attempted here.

Most of the area around the occurrence is underlain by andesitic tuff and breccia, metamorphosed at greenschist grade and usually described as greenstone, or as chlorite schist where the rocks are sheared. Minor shale or argillite or sericitic schist is intercalated with the volcanics. The strata strike north to northeast and dip gently to moderately to the west. Underneath the metavolcanics are grey sericitic schist, green chloritic conglomerate, and black, platy argillite. The area is intruded by diabase dykes and numerous felsic to intermediate porphyritic dykes and sills; the dykes are generally steep, and strike east.

Quartz veins, of various thickness and length, are numerous. They are more common in the more foliated or sheared rocks, typically concordant with the foliation, suggesting that they are structurally controlled. Some silicification and rusty alteration (oxidation) is reported around some quartz veins and lenses. Locally the quartz has a honeycomb texture.

The veins that have received the most attention occur in the chloritic conglomerate or the metavolcanic greenschist; some of these are associated with shearing or faulting. Typically, the lenticular veins and quartz stringers are under 50 centimetres thick, and are discontinuous, extending for less than 10 or 20 metres. Locally they contain sulphide-rich lenses consisting of pyrite and minor chalcopyrite and sphalerite. One quartz and greenstone sample, taken over a width of 68 centimetres, assayed 26.7 grams per tonne gold and 6.8 grams per tonne silver (Minister of Mines Annual Report 1938). The greenstone host rock, containing disseminated sulphides, was analysed at 0.7 gram per tonne gold and 6.8 grams per tonne silver, measured over a width of 74 centimetres.

Apparently the only work on the Homestake occurrence was between its discovery in 1936 to 1940. This consisted of several surface cuts, the digging of a 45-metre adit, and prospecting.

Bibliography
EMPR AR 1937-F5; *1938-F37; 1940-A96
EMPR PF (Berniolles, L.M. (1991): Letter dated Nov.21, 1991)
GSC OF 1163
GSC P 68-33, p. 87; 88-1E, pp. 185-190; 89-1E, pp. 163-167
GSC MAP 5-1968; 1713A
GSA GEOLOGY 1991, pp. 941-944

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