The Gilman Formation (Roy Group) is located on the southern fl ank of the Chibougamau syncline, at the eastern end of the Archaean Abitibi Subprovince, and holds potential for volcanogenic massive-sulphide deposits. Recent geological mapping and compilation work has led to a proposed new subdivision of this formation. The David Member (lower Gilman Formation) contains tholeiitic, mas- sive to pillowed mafi c lavas, with minor fl ow breccia and hyaloclastite. The Allard Member (middle Gilman Formation) contains minor transitional to calc-alkaline mafi c lavas at its base, overlain by inter- mediate calc-alkaline volcaniclastic rocks (containing clasts of chert with varying amounts of sulphides, and mafi c to intermediate lavas), plagioclase-phyric crystal tuff, and rhyodacite. The Bruneau Member (upper Gilman Formation) is composed of tholeiitic, massive to pillowed mafi c lavas, with lenses of volcaniclastic rocks and spherulitic rhyolite.
NTS 87-G/9 (Nalluryaq) and the southernmost part of NTS 87-G/16 are mostly underlain by Neoproterozoic Shaler Supergroup sedimentary rocks, with limestone and dolostone of the Boot Inlet and Jago Bay formations, quartz arenite of the Fort Collinson Formation, and gypsum evaporite of the Minto Inlet Formation. The latter locally form quarryable alabaster deposits as a result of contact metamorphism. Sedimentary rocks are injected by basaltic sills and dykes of Franklin age (ca. 720 Ma) that can be divided into older, more olivine-rich Type 1 intrusions and younger diabasic to feldspar-porphyritic Type 2 intrusions. Fe-oxide exoskarns are developed in the hangingwall panels of some synmagmatic normal faults. Strata are either flat-lying, or dip gently to the north or south to either side of the Walker Bay Anticline. Steeper bedding orientations occur near faults as a result of structural entrainment. A regional-scale basal unconformity separates Paleozoic clastic and carbonate rocks in the north from underlying Proterozoic rocks to the south, but the contact is often faulted, and isolated domains of Paleozoic rocks are preserved within graben. North-northwest-trending syn-magmatic (Proterozoic) and east-northeast-trending (Phanerozoic) normal faults are ubiquitous, breaking up the outcrop pattern into a series of polygonal blocks.
NTS 87-G/02 is divided into fault-bounded domains by late north-trending (west-side down) and east-trending (north-side down) normal faults. Paleozoic sedimentary rocks of the Uvayualuk, Mount Phayre, Victoria Island, and Thumb Mountain formations are exposed along the coast to the west of the north-trending faults. Mostly Neoproterozoic sedimentary rocks of the upper Wynniatt and lower Kilian formations of the Shaler Supergroup (Minto Inlier) occur to the east of the north-trending faults. The northeast-trending, 4 km wide NE-trending Imaiqtaqtuq Fault Zone flanks the southeast coast of Minto Inlet, and records sinistral transtensional motions. Upper Wynniatt Formation limestones are injected by Type 1 and Type 2 Franklin sills near the coast, but only Type 2 sills are documented further south, where carbonate, shale, and evaporitic rocks of the Kilian Formation are well exposed beneath thick capping sills that form a series of south-dipping cuestas.
Most Maquereau Group lavas are tholeiitic basalts to ferro-andesites that exhibit an Fe-Ti-enrichment trend. Subordinate alkaline basalts are generally enriched in TiO2, P2O5, Nb and light rare-earth elements. Most major and trace element paleotectonic discriminants do not favour an arc-related environment. An intra-continental rift, or an incipient spreading ridge environment are most consistent with the geochemical data and field relationships. Many Maquereau lavas contain pyrite+chalcopyrite and have high Cu-contents; they thus represent a plausible source rock for the Cu-sulphide veins in the area.
NTS 87-G/08 (Iglulik) straddles Minto Inlet. On the north shore, massive to bedded carbonates of the Boot Inlet and Jago Bay formations, quartz rich sandstone of the Fort Collinson Formation, and evaporites of the Minto Inlet Formation (Neoproterozoic Shaler Supergroup) host Type 1 and feldspar-porphyritic Type 2 sills. To the east, the Iglulik Peninsula is underlain by rocks of the Minto Inlet Formation and limestones and shales of the lower Wynniatt Formation. Minto Inlet strata host Type 1 sills. The southern shore of Minto Inlet is underlain by the upper carbonate members of the Wynniatt Formation into which were intruded Type 1 and 2 sills. A thin cap of Paleozoic clastic and carbonate rocks overlies an erosional unconformity on a hilltop. Toward the south, sparse exposures of Lower Kilian Formation carbonates and evaporites host Type 2 sills. All Proterozoic strata dip shallowly to the south, marking the transition from the Walker Bay Anticline to the Holman Island Syncline. North-northwest trending synmagmatic normal faults are exposed locally. East-northeast-trending post-Proterozoic normal faults locally show north-side down motions and repeat contacts.
Foreword The Geo-mapping for Energy and Minerals (GEM) program is laying the foundation for sustainable economic development in the North. The Program provides modern public geoscience that will set the stage for long-term decision making related to investment in responsible resource development. Geoscience knowledge produced by GEM supports evidence-based exploration for new energy and mineral resources and enables northern communities to make informed decisions about their land, economy and society. Building upon the success of its first five-years, GEM has been renewed until 2020 to continue producing new, publically available, regional-scale geoscience knowledge in Canada's North. During the summer 2015, GEM program has successfully carried out 14 research activities that include geological, geochemical and geophysical surveying. These activities have been undertaken in collaboration with provincial and territorial governments, northerners and their institutions, academia and the private sector. GEM will continue to work with these key collaborators as the program advances.
NTS 87-H/6 is underlain by the middle to upper Wynniatt, Kilian, Kuujjua and Natkusiak formations of the Neoproterozoic Shaler Supergroup. The Wynniatt Formation is confined to the north-west and the Kilian Formation is intermittently exposed in the central and southern parts of the map area. The upper Kilian, Kuujjua and basal Natkusiak formations are exposed on prominent hills in the southeast. Up to 5, type 2 (diabasic), sills outcrop as stepped cuestas that strike northeast across the centre of the map area. Two, northwest-striking dykes cut across the upper Wynniatt Formation strata in the north. Several steep normal faults occur in the southern third and western side of the map area. Those cutting the Natkusiak Formation do not cut underlying strata, suggesting that faulting was syn-volcanic. West-southwest block faulting, common in map areas to the north, is evident around Tahiryuak, where it repeats strata of the upper Wynniatt Formation (unit n{W4).
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