Northern Interior Plains Research Articles

Glacial geomorphology of the northwest Laurentide Ice Sheet on the northern Interior Plains and western Canadian Shield, Canada

ABSTRACT The majority of the Northwest Territories of mainland Canada was covered by the Laurentide Ice Sheet during the Last Glacial Maximum. The increasing coverage of high resolution remotely sensed data provides new opportunities to map the glacial geomorphology and study the glacial history of this remote location. Here we present a comprehensive map of glacial landforms within the northern Interior Plains and adjacent areas of the Canadian Shield, comprising around 6% of the Laurentide Ice Sheet bed. Twelve landform types were mapped from the high resolution ArcticDEM: ice flow parallel lineations, subglacial ribs, crevasse-squeeze ridges, major and minor moraine crests, hummocky terrain complexes and ridges, shear margin moraines, major, minor and lateral and submarginal meltwater channels, esker ridges and complexes, glaciofluvial complexes, perched deltas, raised shorelines and aeolian dunes. Together, these landforms provide a record of the highly dynamic behaviour of the northwest sector of the Laurentide Ice Sheet.

Cordilleran Foreland Tectono-Sedimentary Element, Canadian Northern Interior Plains

Abstract Upper Jurassic–Paleocene siliciclastic strata comprise the Cordilleran Foreland Tectono-Sedimentary Element of Canada's northern Interior Plains. These strata record four major packages deposited on top of Paleozoic shelf strata on the NW margin of the Canadian craton. These packages are a Jurassic interval interpreted to record deposition associated with extension at the Arctic Ocean margin, a Lower Cretaceous, dominantly marine, interval deposited on the flexural margin of the foreland basin, and two Upper Cretaceous intervals of west-to-east progradational marine and non-marine strata deposited on the orogenic margin. The full succession has been affected by Cordilleran deformation within the Mackenzie Plain, Franklin Mountains and Colville Hills. Organic-rich shale is documented from Lower and Upper Cretaceous successions but these strata only reach thermal maturity in deeper parts of the basin, close to the Canadian Cordillera. Potential reservoirs exist within sandstone-dominated intervals throughout the succession, although some locally lack a top seal. One natural gas discovery has been reported from Upper Cretaceous sandstone of the Little Bear Formation at the Stewart D-57 well in the southeastern Mackenzie Plain. Oil sourced from Upper Cretaceous shale is reported from the Mackenzie Plain East Mackay B-45 well.

Mackenzie–Peel Platform and Ellesmerian Foreland Composite Tectono-Sedimentary Element, northwestern Canada

Abstract The Mackenzie–Peel Platform Tectono-Sedimentary Element (TSE), and the overlying Ellesmerian Foreland TSE, consist of Cambrian–Early Carboniferous shelf and slope sedimentary deposits in Canada's northern Interior Plains. In this chapter, these elements are combined into the Mackenzie–Ellesmerian Composite TSE. The history of the area includes early extensional faulting and subsidence in the Mackenzie Trough, passive-margin deposition across the Mackenzie–Peel Platform, local uplift and erosion along the Keele Arch, subsidence and deposition in the Ellesmerian Foreland, possible minor folding during the Ellesmerian Orogeny, and folding and faulting in Cretaceous–Eocene time associated with the development of the Canadian Cordillera. Recorded petroleum discoveries are within Cambrian sandstone (Mount Clark Formation), Devonian carbonate strata (Ramparts and Fort Norman formations) and Devonian shale (Canol Formation). Additional oil and gas shows are documented from Cambrian–Silurian carbonate units (Franklin Mountain and Mount Kindle formations), Devonian carbonate units (Arnica, Landry and Bear Rock formations) and Late Devonian–Early Carboniferous siliciclastic units (Imperial and Tuttle formations). Petroleum exploration activity within the area has occurred in several phases since 1920, most of it associated with the one producing oilfield at Norman Wells.

Subsurface analysis and correlation of Mount Clark and lower Mount Cap formations (Cambrian), Northern Interior Plains, Northwest Territories

Subsurface analysis and correlation of Mount Clark and lower Mount Cap formations (Cambrian), Northern Interior Plains, Northwest Territories

Flume tests on fluvial erosion mechanisms in till‐bed channels

AbstractSemi‐alluvial stream channels eroded into till and other glacial sediments are common in areas of extensive glacial deposition such as the Great Lakes region and northern interior plains of North America. The mechanics of erosion and erosional weakness of till results in the dominance of fluvial scour and mass erosion due to spontaneous fracture at planes of weakness under shearing flow. There have been few controlled tests looking at erosional mechanisms and resistance of till in river channels. We subjected small blocks of till to unidirectional flows in a laboratory flume to measure the threshold shear stress for erosion and observed the erosion mechanics. Critical shear stress for erosion varied from 7 to 8 Pa for samples with initial saturated moisture content in which a combination of fluvial scour and mass cracking/block erosion dominated. When dried, micro‐fissures occurred in the sample and erosional resistance of the till was extremely low at <1 Pa with erosion appearing to be by fluvial scour. When mobile gravel was added to the test conditions, the gravel reduced the erosion threshold slightly because of the enhanced scour around and below the gravel particles and the tendency for the gravel to aid in crack enlargement. Thus a partial or thin gravel cover over the till may provide no protection from erosion. The erosion processes and effects reflect the complex and contingent mechanics and properties of till, and suggest that the erosion characteristics of till bed semi‐alluvial channels differ from abrasion or plucking dominated processes in more resistant bedrock. Copyright © 2017 John Wiley & Sons, Ltd.

Magnetostratigraphy of late neogene glacial, interglacial, and preglacial sediments in the Saskatoon and Regina areas, Saskatchewan, Canada

Two new records of glacial stratigraphy obtained from borecores collected in southcentral Saskatchewan are compared to previously published records from Wellsch Valley and Swift Current Creek in southern Saskatchewan. The comparisons are based on magnetostratigraphy and tephrochronology, and describe preglacial, glacial, and interglacial deposits. The new stratigraphy is compared to the composite global marine oxygen isotope record.Although the ages and extents of late Pleistocene continental glaciations are relatively well constrained, they are less well defined for the middle and early Pleistocene. Data presented here highlight recent studies carried out from borecores and outcrops of extensive pre-Illinoian (pre-Saalian) glacial deposits. Based on this new data, at least seven Laurentide (continental) glaciations are recognized in Saskatchewan, and these records are the most extensive to date in the Northern Interior Plains of Canada.The magnetostratigraphic records from the Sutherland Overpass and Wascana Creek sites provide the first evidence of reversely magnetized glacial deposits in the Canadian Prairies. These deposits can be assigned to the latest Matuyama (MIS 20) and indicate that Laurentide (continental) glaciations did not impact southern Saskatchewan until the late Early Pleistocene.

Albian to Turonian stratigraphy and palaeoenvironmental history of the northern Western Interior Sea in the Peel Plateau Region, Northwest Territories, Canada

Cretaceous sediments in the Northern Interior Plains are widespread and their interbasinal lithostratigraphic correlations indicate several regional unconformities that require biostratigraphic confirmation. This study proposes a new zonation based on benthic foraminifera utilising the reference section for the Albian to Turonian Arctic Red and Trevor formations located along the Hume River in the Peel Plateau region (Northwest Territories). A new absolute age date of 107.0 ± 1.9 Ma from a bentonite extends the biostratigraphic range of the Early Albian Quadrimorphina albertensis Zone into the Middle Albian. Integration of the new temporal framework with detailed sedimentological observations provides an interpretation of the dynamic depositional history for this northern region of the Western Interior Seaway (WIS). Cretaceous strata in the Peel Plateau record deposition of the initial transgression of the WIS in two pulses of relative sea-level rise (Martin House Formation) and subsequent offshore marine sedimentation in a deep foreland basin (Arctic Red Formation). The global eustatic sea-level minimum at the Albian–Cenomanian boundary and renewed uplift of the Keele Arch impacted palaeogeography in this region with previously unnoticed subaerial exposure and palaeosol development. This unconformity can be correlated to the east into the Mackenzie Plain. Transgression brings anoxic bottom waters during the Early Cenomanian (Slater River Formation) that result in an interval almost barren of foraminifera. During the Turonian, a time of high eustatic sea-level, the study area marks a relatively shallow site where pulses of prograding shorelines are recorded in upward shallowing parasequences bound by pebble lags overlain by flooding surfaces (Trevor Formation). East of the Peel Plateau in the Mackenzie Plain area, an unconformity separates Albian Arctic Red from ?Upper Cenomanian–Turonian strata, there named the Slater River Formation. In order to recognise the significant unconformity associated with the loss of Albian foraminifera and the angular unconformity observed in seismic profile, we propose the use of the Slater River Formation to describe the strata bound by the pisoidal ironstone and the first metre-plus sandstone bed marking the base of the interbedded mudstones and sandstones of the overlying Trevor Formation. The Hume River section is proposed as the type section for the Slater River Formation.

Mapping Quaternary paleovalleys and drift thickness using petrophysical logs, northeast British Columbia, Fontas map sheet, NTS 94IThis article is one of a selection of papers published in this Special Issue on the theme Geology of northeastern British Columbia and northwestern Alberta: diamonds, shallow gas, gravel, and glaciers.

The relatively subdued topography of British Columbia’s northern interior plains does not reflect the irregular, buried bedrock surface. Many areas have been deeply incised by preglacial rivers that have subsequently filled with a succession of Quaternary sediments. In this study, oil and gas petrophysical logs, drill chip samples, water well logs, and surficial and bedrock outcrop maps were used to model the bedrock topography of the Fontas map sheet (NTS 94I). The modelled data produced several depressions that are interpreted to be paleovalleys incised into the soft Cretaceous shale of the Fort St. John Group. Understanding the geometry, thickness, and stratigraphy of the drift has considerable safety and resource management implications as artesian aquifers and natural gas were encountered in the drift during oil and gas well drilling. Four major paleovalleys are suggested. The most dominant paleovalley (Kotcho–Hoffard Paleovalley) is located south of the Etsho Plateau and trends west-southwest across the map area. A second depression occurs within the loop of the Hay River and may be a tributary of the Kotcho–Hoffard Paleovalley that links with the Rainbow Paleovalley in Alberta. A third paleovalley is mapped south of the Sahtaneh River (Kyklo Creek Paleovalley) and is either a tributary to, or crosscuts the Kotcho–Hoffard Paleovalley. The Niteal Creek Paleovalley is located between the Fontas and Sikanni Chief rivers. Its geometry is speculative as there are sparse data, but it may be a tributary of the Kotcho–Hoffard Paleovalley.

The Influence of Proterozoic Structures on the Development of Laramide Structures, Northern Interior Plains, Northwest Territories, Canada

ABSTRACT Regional analysis of some 5000 km of reflection seismic data in the Colville Hills and Interior Plains of the Northwest Territories reveals a thick Proterozoic sedimentary section deformed on crustal scale intra-cratonic faults that have undergone several periods of reactivation. Northeast-directed Laramide compressional stresses, imposed on the Precambrian structures, preferentially reactivated a NNW-SSE fault trend in a right-lateral sense. The result is a close correspondence between Laramide and Proterozoic structures under the Colville Hills. Under Anderson and Horton plains, where the structural grain of Proterozoic rocks is NE-SW, a close Laramide/Proterozoic structural relationship was not developed. In fact, Phanerozoic structures there may be pre-Cretaceous and Lower Cretaceous. One of these Cretaceous monoclines affected development of the easterly trending Colville Ridge. There is evidence of syn-Laramide and possible post-Laramide extension. RESUME L'analyse regionale de quelques 5000 km de donnees de reflection sismique dans les Colville Hills et Interior Plains des Territoires du Nord-Ouest revele l'existence d'une epaisse section sedimentaire Proterozoique deformee le long de failles intra-cratoniques d'echelle crustale qui ont subi plusieurs periodes de reactivation. Des contraintes compressives d'age laramide, dirigees vers le nord-est, imposees sur des structures precambriennes, reactiverent preferentiellement les failles orientees nord-nord-ouest--sud-sud-est de maniere dextrale. Ceci resultat en une proche correspondance entre les structures laramides et proterozoiques sous Colville Hills. Sous les plaines Anderson et Horton, ou le grain structural des roches proterozoiques est nord-est--sud-ouest, une forte relation structurale laramide/proterozoique ne se developpa pas. En fait, les structures phanerozoiques a cet endroit pourraient dater du pre-Cretace et du Cretace inferieur. Un de ces monoclinaux cretaces affecta le developpement de Colville Ridge qui est orientee vers l'est. Des preuves d'extension syn-Laramide et peut-etre post-Laramide existent. Traduit par Patrice de Caritat

Geology of Beaufort-Mackenzie Basin and Eastern Northern Interior Plains: ABSTRACT

The eastern part of the northern Interior Plains is underlain by rocks of Cenozoic, Mesozoic, and Paleozoic ages. The region is bounded on the east by the Coppermine arch, composed of lower Paleozoic and Precambrian rocks. The plains region is a northwest-dipping homocline, interrupted in its western part by the Kugaluk arch, a north-trending pre-Cretaceous uplift. Mesozoic rocks of the Interior Plains consist of Cretaceous sandstone, mudstone, and shale with a composite thickness of about 3,000 ft along Anderson and Horton Rivers. The Lower Cretaceous units are correlated with similar rocks on Banks Island. On the mainland, these are disconformably overlain by varicolored clastic rocks of Late Cretaceous and early Tertiary ages. Westward, in the region of the Mackenzie delta, the Tertiary Reindeer Formation consists of a northward-thickening sequence of poorly consolidated to unconsolidated cherty gravel, cross-bedded sandstone, coal, and ash beds. Its maximum outcrop thickness is about 4,000 ft. In the nearby B. A.-Shell-I.O.E. Reindeer D-27 well the Reindeer Formation is 3,970 ft thick and underlies 790 ft of Quarternary and Holocene sediments. Microfaunal studies show that the Reindeer Formation overlies 2,200 ft of Late Cretaceous clastic rocks which may be partly equivalent to the Moose Channel Formation that crops out on the west side of the delta adjacent to the Richardson Mountains. The Upper Cretaceous rocks in the Reindeer well unconformably overlie 5,690 ft of Lower Cretaceous sandstone and mudston which can be correlated with similar units in the eastern Richardson Mountains. Offshore seismic profiles obtained during the 1969 Arcticquest survey indicate the presence of a thick sequence of sedimentary rocks, the lower part of which has been deformed into broad domal structures. These lower rocks are unconformably overlain by nearly flat-lying younger rocks. This unconformity may be the same one that separates the Lower and Upper Cretaceous rocks in the Reindeer well. Analyses of the profiles indicate that these younger rocks may have been intruded by diapiric structures. If the Canadian Government's Hudson 70 program in the Beaufort Sea is successful additional information on the geology of the Beaufort Sea basin will be available. End_of_Article - Last_Page 2513------------