Stratigraphic and Paleotectonic Studies of the Middle Paleozoic Sicker Group and Contained Vms Occurrences, Vancouver Island, British Columbia 1

Vol ca nic strata of the mid-Pa leo zoic Sicker Group on Van cou ver Is land (Fig. 1) host the Myra Falls volcanogenic mas sive sul phide (VMS) de posit. With com bined pro duc tion and proven and prob a ble re serves in ex cess of 30 mil lion tonnes of Zn-Cu-(Au-Ag) ore, this is cur rently the larg est and most pro duc tive VMS mine in west ern Can ada. Other VMS de pos its and oc cur rences are known else where within the Sicker, and de pos its in the Mt. Sicker area (Mt. Sicker, Lenora and Twin J; MINFILE (2005) oc cur rences 092B 001, 002, 003; Fig. 1) have been mined on a rel a tively small scale. Ex plo ra tion for ad di tional VMS de pos its within the Sicker Group, how ever, has met with only lim ited suc cess out side the im me di ate area of the Myra Falls de posit. De spite the con sid er able po ten tial for such de pos its in the Sicker and the cur rent high base-metal prices, VMS ex plo ra tion within the group has been at a low level for the past de cade. A sig nif i cant im ped i ment to VMS ex plo ra tion within the Sicker Group is the rel a tively poor over all un der stand ing of the ge ol ogy of this as sem blage, which makes it dif fi cult to de velop a sound re gional ex plo ra tion strat egy based on typ i cal strati graphic and volcanological cri te ria. De tailed stud ies of the group in the past have been ham pered by gen er ally poor ex po sure and lim ited ac cess, ex cept in the im me di ate vi cin ity of the Myra Falls de posit (e.g., Juras, 1987; Barrett and Sherlock, 1996; Rob in son et al., 1996). New log ging-road con struc tion in the 1980s and 1990s greatly im proved ac cess to and ex po sure of the Sicker Group in cen tral Van cou ver Is land, and re gional map ping stud ies of this area were car ried out by per son nel of the BC Geo log i cal Sur vey (e.g., Massey and Fri day, 1987, 1989; Massey, 1995a, b, c; see also Yorath et al., 1999). These stud ies did not in clude all of the ex posed Sicker Group, how ever, and avail able data are still in suf fi cient to pro duce a com pre hen sive anal y sis of the stra tig ra phy and evo lu tion of the group. A new in te grated geo log i cal, geo chem i cal and geo chron ol ogi cal study of the Sicker Group on Van cou ver Is land, funded by Geoscience BC, was be gun in 2005. This study has the fol low ing main goals: • de velop a model for the phys i cal vol ca nol ogy and erup tive his tory of the Sicker Group • con strain the paleotectonic evo lu tion of this por tion of Wrangellia • eval u ate the na ture and strati graphic po si tion(s) of VMS de pos its and oc cur rences within the Sicker Group