Mapping of ice-flow indicators in the Committee Bay supracrustal belt (NTS 56 K, 56 J/9 to /16, 56-O/1 to /8, and 56 P) provides new evidence for a complicated ice-movement chronology during the Late Wisconsinan. Three main phases of ice movement have been identified at the regional scale. The oldest is northerly and is found throughout most of the area. This was followed early in the deglaciation sequence by northeastward flow in the eastern part of the area and northwesterly flow in the western part. Finally, there is a north-northwesterly flow south of the Chantrey moraines, associated with ice flow from the Keewatin Ice Divide. Results from drift-prospecting studies indicate that till geochemistry reflects a clear northerly direction of glacial transport. Most of the known gold showings are recognized in the gold-grain counts and/or the gold values in the till matrix, but at least two previously unknown, potentially gold-rich domains have been identified.

Maximum marine transgression limits are identified along the eastern and northern peripheries of the Ellice Hills map area (NTS 56 P), west-central coast of Committee Bay, Nunavut. An age estimate of 9000 to 8600 calendar (cal.) years BP is tentatively assigned to the absolute maximum marine limit (approximately 240-255 m a.s.l.) along this coastline, on the basis of marine features at comparable elevations along the northeast coast of Committee Bay. The lowest marine limit, observed 50 km inland at about 180m a.s.l., is associated with a later marine highstand. The westward-decreasing trend exhibited by the maximum marine limits is the result of relative sea-level fall during southwestward retreat of Keewatin ice. Marine fossils commonly form a shell lag atop offshore marine mud or, rarely, are in situ. Relative sea-level fall and progressive ice retreat resulted in a succession of marine communities following initial colonization by ice-proximal species such as Portlandia arctica.

The presence of lamination on sedimentary rocks is a distinct characteristic, particularly in shales. They are distinct due to the contrast between successive layers with regard to grain size, composition, color, and sedimentary structures, such as graded beds. Typically, the degree of lamination is controlled by the sedimentation rate and flow regime. Herein, we developed a mudstone classification scheme in terms of lamination because lamination-based shale facies are related to differing features in mineral composition, porosity, and Young’s modulus. This study also attempts to verify whether wireline log patterns are relevant to shale lithofacies. The relationship between the porosity and lamination of the Montney Formation can be used to estimate reservoir properties. Our results show that an increased silt lamina in mudstone leads to an increase in the quartz and calcite contents and a decrease in the clay content, which increases the porosity, permeability, and Young’s modulus. However, reservoir quality is not solely dependent on lamination because of the complex interaction between components. The degree of lamination affected the neutron, density, and sonic log responses. Furthermore, the presence of lamination tends to decrease the neutron percentage, with similar trends in density and sonic log box plots in the study area. When the percentage of clay or cement material decreases, the neutron and density log responses diminish. Meanwhile, when the rock texture variation increases with an increase in the degree of lamination, the sonic log response decreases.

No abstract

Detailed 1:50 000-scale Quaternary mapping and reconnaissance-scale till geochemistry and kimberlite indicator mineral surveys were carried out within three NTS 1:250 000-scale map areas: Laughland Lake (56 K), the northern half of Walker Lake (56 J), and the southern half of Arrowsmith River (56-O). Quaternary mapping included characterization of surficial geology units, identification of glaciogenic landforms, and the measurement of ice-movement indicators. New data related to the last active ice to occupy areas in NTS 56 K, 56 J, and 56-O suggest divergent ice movement originating from a southward-opening, arcuate ice divide or an ice-centres saddle scenario. Further investigations will elucidate the complex ice-movement history and test new hypotheses regarding the genesis of some glacial landforms and sediments.