Rainy Lake Wrench Zone ( Rlwz )

985 WordsApr 14, 20164 Pages
Rainy Lake Wrench Zone (RLWZ) Most known mineral occurrences in the RRB are in the RLWZ, as it is the best exposed and most explored part of the block. Modest gold and silver production occurred here in the past (25,000 oz Au; 3,000 oz Ag) and magmatic sulfide deposits have been outlined in the Grassy Portage intrusion (two separate mineralized zones: 300,000 t @ 1.89% Cu and 300,000 t @ 0.8% Cu; Poulsen 2000). The RLWZ also hosts VMS-style prospects in a bi-modal volcanic pile that is underlain by a composite trondhjemite-tonalite-gabbro-anorthosite intrusion. Zn is predominant in this volcanic complex, with lesser Cu, indicating shallow water and (or) low temperature mineralization process affected the rocks. Au has been documented in the volcanic pile, but may represent orogenic style mineralization. These metal assemblages and the geometry of the volcanic pile are similar to Sturgeon lake VMS camp (e.g. Hudak 2003), indicating it has potential for hosting economic Zn-Cu deposits. However, the atypical lithologic make-up of the composite subvolcanic intrusion (i.e. anorthosite-dominated) does not match well-endowed VMS camps (Galley 2003) and the proximal high-grade metamorphism (amphibolite facies) and strong deformation (shearing) may have compromised the preservation of hypogene mineralized zones. If mineralized zones are preserved, they could be Au-rich, as the structural setting (bounded by crustal-scale faults) and inferred paleotectonic setting (rifted arc or

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