Sur leur site, ils disent que leur projet a été identifié comme un IOGC par un chercheur(Corriveau) du GSC. Il y a définitivement des roches Protérozoïque à Terre-Neuve. J'ai retrouvé le résumé de ce papier sur le Web:
IOCG Deposit Types Definition Iron oxide copper-gold (IOCG) deposits encompass a wide spectrum of sulphide-deficient low-Ti magnetite and/or hematite ore bodies of hydrothermal origin where breccias, veins, disseminations and massive lenses with polymetallic enrichments (Cu, Au, Ag, U, REE, Bi, Co, Nb, P) are genet-ically associated with, but either proximal or distal to large-scale continental, A-to I-type magmatism, alkaline-carbon-atite stocks, and crustal-scale fault zones and splays. The deposits are characterized by more than 20% iron oxides. Their lithological hosts and ages are non-diagnostic but their alteration zones are, with calcic-sodic regional alteration superimposed by focused potassic and iron oxide alterations. The deposits form at shallow to mid crustal levels in exten-sional, anorogenic or orogenic, continental settings such as intracratonic and intra-arc rifts, continental magmatic arcs and back-arc basins. Margins of Archean craton where arcs and successor arcs were developed appear to be particularly fertile. Currently known metallogenic IOCG districts (Fig. 1) occur in Precambrian shields worldwide as well as in Circum-Pacific regions (e.g. Carlon, 2000; Fourie, 2000; Porter, 2000, 2002a and papers therein; Strickland and Martyn, 2002; Gandhi, 2004c; Goff et al., 2004). Though there is no producing mine of this deposit type in Canada, exploration is accelerating throughout the country. The most prospective settings are located in the Proterozoic granitic and felsic gneiss terranes of the Canadian Shield, and in parts of the Cordilleran and the Appalachian orogens. Many share hallmarks of the 3810 Mt Olympic Dam deposit in Australia, the deposit that guides most mineral exploration worldwide (Hitzman et al., 1992; Western Mining Corporation, 2004). Metamorphosed IOCG deposits are known and exploration should also encompass metamor-phosed volcano/sedimentary-plutonic belts and their gneis-sic derivatives. Many of the Canadian favourable "pinkstone belts" are poorly known or understood. Hence, this synthesis of IOCG deposits focuses on the regional and local geological features that can help unveil prospective zones and targets in terranes that may otherwise be ignored or underexplored. The recognition of this deposit type was triggered by the 1975 discovery of the giant Olympic Dam deposit in Australia (Roberts and Hudson, 1983) followed by the dis-covery of Starra (1980), La Candelaria (1987), Osborne (1988), Ernest-Henry (1991), and Alemao (1996). The early discoveries served to define this group of deposits as the IOCG deposit type in the 1990s (Hitzman et al., 1992). Since then, new discoveries, re-classification of existing deposits and worldwide research have led to the recognition of the oxide-mineralizing systems and the publication of a number of landmark papers and volumes (Gandhi and Bell, 1993; Kerrich et al., 2000; Porter, 2000, 2002a; Ray and Lefebure, 2000; Groves and Vielreicher, 2001; Sillitoe, 2003; Barton and Johnson, 2004). Because of the diversity of IOCG deposits there is debate whether they form a single deposit type or whether they are iron oxide-rich variants of other deposit types. In this synthesis, IOCG deposits are considered a bona fide deposit type. Polymetallic deposits lacking significant iron oxides are not considered herein as IOCG deposits while hydrothermal monometallic, low-titanium magnetite and/or hematite iron deposits (i.e., iron as sole significant metal) and polymetallic iron deposits with Nb and REE as impor-tant economic commodities are considered end-members of the IOCG deposits spectrum. This broad approach to IOCG deposits is taken even though it groups together world-class deposit types with deposit types that may not be worthy of discovery in terms of actual mineral economics. This stand is taken because the currently low value monometallic iron deposits outnumber polymetallic ones and serve as impor-tant pathfinders for grass roots exploration. |
