Petrology, geochemistry and economic geology of selected gold claims in rocks of the Wasekwan Lake area, Lynn Lake district, Manitoba, Canada

The purpose of this investigation was to map and study, both at regional and detailed scales, the units encountered within seven gold claims that were staked by Sherritt-Gordon Mines Limited of Lynn Lake, Manitoba. The claims are located in the wasekwan Lake area, approximately 12. 8 km southeast of Lynn Lake. Regional mapping was conducted at a scale of 1:12000 over a 6.4 km2 area and detailed mapping of potentially economic areas was conducted at a scale of 1:240. Whole-rock geochemistry, microprobe, optical and X-ray diffraction procedures were employed to describe and characterize the rocks. The Aphebian rock units of the wasekwan Lake area were divided into the following subunits: Cockeram Lake aphyric andesite (2a), aphyric basalt (2b) and amygdaloidal basalt (2c}; Mcveigh Lake porphyritic andesite (3a), porphyritic basalt (3b), porphyritic breccia (3c); Fraser Lake aphyric andesite (4a), aphyric basalt (4b), amygdaloi dal andesite (4c}, amygdaloidal basalt (4d), porphyritic basalt (4e), mafic tuff (4f), highly altered mafic tuff (4fa), and intermediate tuff (4g}; Pole Lake intermediate tuff (Sa) and dacitic tuff (5b) 1 Fraser Lake dacitic tuff (6d) 1 Eldon tuff (5b); Fraser Lake dacitic tuff (6d): Eldon Lake-Fraser Lake hornblende-bearing greywacke (9a), siltstone (9b) and garnet- and mica-bearing siltstone (9bg): subvolcanic intrusives (1): gab bro (13); tonalite (16a), quartz monzodiorite (16b), and granodiorite (16c); granodiorite (17): quartz plagioclase porphyry (22a), quartz diorite (22b); albitite (23a) and alkali-feldspar quartz syenite (23b). These rocks exhibit upper greenschist to albite-epidote amphibolite facies metamorphism. Many of the units have been metasomatically altered, particularly the areas around the gold showings. The result of this alteration has been a combination of: feldspathization, tourmalinization, silici fication, chloritization, sericitization, carbonatization, sideritization, pyritization, propylitization, hydration and beresitization. Tectonically, these rocks are part of a double island arc system of volcanoes. Chemical data supports this conclusion. The volcanic rocks progress from an initial tholeiitic submarine basal sequence to a late-stage calc-alkaline cap which coincided with the emergence of the volcano from the sea. Five episodes of structural development have occurred resulting in very complex structural relationships. During structural development, a large shear system (the Cartwright Lake shear zone) formed and became a pathway for mobile elements which ultimately resulted in gold concentrations in favorable environments. The gold occurrences are classified as gold-silver and silver-gold veins, lodes, stockworks, and silicified zones in a complex geological environment, comprising sediments, volcanics and various igneous intrusive and granitized rocks. The gold deposits are epigenetic and originated by derivation from the surrounding country rocks. Mobilization and subsequent transportation of gold in the form of various complexes was achieved by diffusion processes. Deposition occurred in favorable environments such as first-degree dilatant zones (Central showing) and second-degree dilatant zones (Brown showing)