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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  03-Nov-1994 by Chris J. Rees (CRE)

Summary Help Help

NMI
Name SAVIO Mining Division Liard
BCGS Map 094K027
Status Showing NTS Map 094K02W
Latitude 058º 14' 03'' UTM 10 (NAD 83)
Longitude 124º 47' 04'' Northing 6456169
Easting 395220
Commodities Copper Deposit Types I06 : Cu+/-Ag quartz veins
Tectonic Belt Foreland Terrane Ancestral North America
Capsule Geology

The Savio is a minor showing of copper mineralization in the headwaters of Racing River, 5 kilometres northwest of Mount Aida in the mountainous Muskwa Ranges of the Northern Rocky Mountains (Vail, J.R. (1957) - Thesis, Geological Map).

The occurrence is in a region known as the Muskwa Anticlinorium, a major structure characterized by large folded thrust sheets which expose rocks as old as Middle Proterozoic (Helikian), as well as Paleozoic rocks (Geological Survey of Canada Map 1343A; Geological Society of America, Geology of North America, Volume G-2, page 639). All belong to Ancestral North America (Geological Survey of Canada Map 1713A). The Middle Proterozoic rocks are pre-Windermere Supergroup, and are known as the Muskwa Assemblage (Geological Society of America, Geology of North America, Volume G-2, page 111). This assemblage of carbonate and clastic rocks has been divided into seven formations. The Savio showing is in the Aida Formation, a 1200 to 1800-metres thick succession of dolomitic mudstone and siltstone, dolostone, and minor mudstone, sandstone and limestone (Geological Survey of Canada Memoir 373, Paper 67-68).

Although no details are available, the Savio is typical of several minor copper showings in this anticlinorium, all of which occur in quartz-carbonate veins. The veins fill fractures, generally spaced a few metres or tens of metres apart. Individual veins are about 50 centimetres wide, and most cannot be traced very far. In many cases, the quartz-carbonate veins lie along the contacts of basic dykes (gabbroic dykes on Geological Survey of Canada Map 1343A) or near them, and here the zone of fracturing may be about 6 metres wide. Such fracture zones associated with dykes can locally be traced intermittently for about 350 metres.

Copper mineralization in the veins is sporadic and comprises chalcopyrite and, where weathered and oxidized, malachite. Only very minor, secondary chalcocite and limonite are present.

The mineralization is clearly structurally controlled given its association with the fracture-filling veins, which consistently strike north-northeast to north-northwest, and dip subvertically. Many of the copper-bearing veins in the region occur within a few kilometres west of the front of large northeast-verging thrusts (the Petersen thrust in this case), near the base of its hanging wall, and they may be related to subsidiary fracturing. This would imply that the mineralization is late Mesozoic to Tertiary, the age of the thrusting (Vail, J.R. (1957) - thesis). Alternatively and more likely, the veining and mineralization was contemporaneous with the basic dyke intrusion, which is demonstrably Precambrian (Geology, Exploration and Mining in British Columbia 1971).

Bibliography
EMPR GEM 1971-75
GSC MEM 373
GSC P 67-68
GSC MAP 1343A; 1713A
GSA (Gabrielse, H. and Yorath, C.J. (Editors) (1991): Geology of North America, Volume G-2).
*Vail, J.R. (1957): Geology of the Racing River area, British Columbia; Unpublished M.Sc. thesis, University of British Columbia.
EMPR PFD 681115

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