Hazen A.J. Russell

Sequence stratigraphy of a glaciated basin fill, with a focus on esker sedimentation

A large integrated data set of cores, outcrop data, and seismic transects from the mud-buried Vars-Winchester esker in the Champlain Sea basin, Canada, was studied to gain insight into how muddy glaciated basins fill with sediment, and how esker sedimentary systems contribute to this process. Three stratigraphic units—a till sheet over carbonate bedrock, the Vars-Winchester esker , and overlying Champlain Sea mud—are identified in the data set. The till is massive, mud rich, carbonate rich, and drumlinized. The esker is also carbonate rich, and rests erosively on till or bedrock. It consists of two elements, a narrow gravelly central ridge and a broad sandy carapace. Three units comprise the overlying mud package: gray carbonate-rich rhythmites, massive bioturbated mud, and carbonate-poor, red-and-gray rhythmites. A sequence stratigraphic model is proposed to explain these observations. Emphasis is placed on gradual ice-front translation superimposed by rapid meltwater events. The esker is interpreted to have been derived from the underlying till by water that flowed through a subglacial conduit (R-channel), within which the narrow gravelly central ridge was deposited. Most mud and finer sand bypassed the conduit and was deposited proglacially on the floor of the Champlain Sea, first as sandy outwash and, farther basinward, as muddy carbonate-rich rhythmites. Gradual ice-front retreat superposed distal facies over proximal facies, generating the upward-fining succession that starts with the esker gravel and ends with muddy rhythmites. Most esker sediment appears to have been deposited during rapid, jokulhlaup-like floods that punctuated gradual retreat. Discharges are estimated to have been high, possibly on the order of several hundred to, perhaps more commonly, several thousand cubic meters per second. The chaotic and random-looking appearance of the resultant sedimentological signatures in the esker sensu stricto is sharply contrasted with the regularity of the muddy rhythmites. If the rhythmites are indeed correlative to the esker, which seems reasonable given their geochemistry and the fact that their volume scales to the volume of mud in the till, the flood events that deposited the esker must have been seasonally mediated, and the basin water must have attenuated the flood signal, resulting in a rhythmic “on-off” signature in more distal portions of the system. The regularity of the rhythmites does not betray the chaotic nature of the esker sensu stricto, and vice versa. Studying either one in isolation would lead to a very different “end-member” impression of how eskers form and how esker sedimentary systems operate during the infilling of glaciated basins.

A 3-dimensional geological model of the Oak Ridges Moraine area, Ontario, Canada

Abstract Please click here to download the map associated with this article. The Oak Ridges Moraine area, southern Ontario, includes most of the Greater Toronto Area, which is the most populated region of Canada. The ∼ 11,000 km2 region is bounded to the south by Lake Ontario and to the north where Paleozoic bedrock abuts Precambrian Canadian Shield. The area extends 160 km eastward from the Niagara Escarpment, a prominent 100 m high regional bedrock scarp. The surficial sediment is up to 200 m thick, and reveals exposures of the oldest Quaternary sediment in southern Canada. Population growth has caused land use conflicts and increased pressure on groundwater resources. Construction of a regional 3-D geological model of the glacial stratigraphy was needed to support a better understanding of aquifer distribution, scale, and resource potential and protection. Mapping of the regional glacial geomorphology and sediment succession identified a number of distinct landforms: tunnel channels, drumlins, eskers, moraines, and till and lacustrine plains. Using sequence stratigraphic concepts, strata have been grouped into four principal units that unconformably overlie Paleozoic bedrock: Lower sediment, Newmarket Till, Oak Ridges Moraine, and Halton Till. These four Quaternary units plus bedrock have been mapped in the subsurface as a succession of interpolated surfaces using an innovative stratigraphic database-GIS approach. The model-building process involved stratigraphically coding high-quality data, then integrating an extensive and diverse array of subsurface geological and archival datasets using an expert system (geological rules). Stratigraphic data subsets were then extracted and merged with DEM-controlled surface mapping and interpolated in a GIS.

A three-dimensional hydrostratigraphic model of the Waterloo Moraine area, southern Ontario, Canada

Aquifers of the Waterloo Moraine play a key role as the main source of drinking water for the Region of Waterloo. For the effective management of this water source, a sound understanding of the aquifers contained within and below the Moraine is essential. Critical knowledge required for this understanding includes the definition of the sediment facies distribution, architectural elements and geological origin of the Quaternary-aged deposits. A basin analysis approach has been applied to geologic data collection and interpretation to unravel the paleogeographic history of the study area and to provide a predictive framework for understanding its geological variability. Coarse (sand and gravel) sediment within the Waterloo Moraine was deposited during a series of high-energy meltwater discharge events from several sediment input corridors (eskers), into a deep, large, ice-supported glacial lake. This depositional setting led to a complex three-dimensional architecture comprising sand-gravel and mud units that are increasingly interbedded away from the multi-directional influx sources around the perimeter of the Moraine. A recently completed digital, three-dimensional geologic model of the area provides details of the various geological units that help refine the understanding of the hydrostratigraphy. This information has improved the understanding of groundwater flow (including interaction between surface and groundwaters) and has provided valuable information critical for source water protection. Information on the distribution, thickness, geometry and properties of these units has resulted in a better understanding of the potential linkages between near-surface recharge areas and deep aquifers across the region. This geological information is important in developing predictive models, for example, determining the location of high transmissivity zones within the moraine. Derivative products such as aquifer vulnerability and recharge maps may help inform policy makers in developing land use and nutrient management plans in the vicinity of well fields and sensitive lands.

Geological mapping goes 3-D in response to societal needs

INTRODUCTION In the early 1800s, state and federal geological survey agencies were conceived to address increasing demands for natural resource information to fuel the Industrial Revolution. More recent urbanization, however, has spurred surveys, along with their university and industry partners, to extend their applications from mining and energy to water supply, engineering, hazards, environment, and climate change, while more directly supporting the needs of decision makers. Geological maps are at the heart of this decision support system. They are the method geologists use to synthesize and communicate an understanding of earth materials, processes, and history; however, for all geologic mapping, challenges remain in obtaining the information required to construct maps that are meaningful and helpful to users. This is particularly acute for subsurface mapping. Geologists must process data obtained through field work, geophysical surveys, and laboratory analyses and then compile that data to map the composition and distribution of materials in a format and resolution that serves map users. In turn, map users have an obligation to grasp the uncertainty of the map while providing the best possible service to their clients. Previously, technological and data limitations dictated that a two-dimensional (2-D) paper map—accompanied by at most a few cross sections and a report—was the most appropriate publication format, so users were expected to infer subsurface conditions at their site. Over the past two decades, however, in response to demands for subsurface information in extensive areas of thick sediments and sedimentary rocks, 2-D geological mapping has been superseded by three-dimensional (3-D) mapping. Geological mapping thus has been redefined in these settings—from a single-layer 2-D map to a 3-D model showing thickness and properties of multiple stacked layers (Turner, 2003; Culshaw, 2006). Having thus raised expectations among users for 3-D mapping, surveys and their partners are now seeking to rapidly improve their methods for construction, dissemination, and use of 3-D geological maps to support decision makers who must balance economic growth with environmental protection.

Estimating Snow Mass and Peak River Flows for the Mackenzie River Basin Using GRACE Satellite Observations

Flooding is projected to increase with climate change in many parts of the world. Floods in cold regions are commonly a result of snowmelt during the spring break-up. The peak river flow (Qpeak) for the Mackenzie River, located in northwest Canada, is modelled using the Gravity Recovery and Climate Experiment (GRACE) satellite observations. Compared with the observed Qpeak at a downstream hydrometric station, the model results have a correlation coefficient of 0.83 (p < 0.001) and a mean absolute error of 6.5% of the mean observed value of 28,400 m3·s−1 for the 12 study years (2003–2014). The results are compared with those for other basins to examine the difference in the major factors controlling the Qpeak. It was found that the temperature variations in the snowmelt season are the principal driver for the Qpeak in the Mackenzie River. In contrast, the variations in snow accumulation play a more important role in the Qpeak for warmer southern basins in Canada. The study provides a GRACE-based approach for basin-scale snow mass estimation, which is largely independent of in situ observations and eliminates the limitations and uncertainties with traditional snow measurements. Snow mass estimated from the GRACE data was about 20% higher than that from the Global Land Data Assimilation System (GLDAS) datasets. The model is relatively simple and only needs GRACE and temperature data for flood forecasting. It can be readily applied to other cold region basins, and could be particularly useful for regions with minimal data.

Forecasting Snowmelt-Induced Flooding Using GRACE Satellite Data: A Case Study for the Red River Watershed

Abstract. Flood forecasting of the spring freshet for cold-region watersheds where the discharge is predominately governed by snowpack accumulation and melting remains a challenge. A cold-region flood forecasting model is developed, using data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. The model forecasts flood by simulating peak surface runoff from snowmelt and the corresponding baseflow from groundwater discharge. Surface runoff is predicted from snowmelt, using a temperature index model. Baseflow is predicted, using a first order differential equation model. Streamflow measurement is used for model calibration. The model was applied to the Red River watershed, a USA–Canada transboundary basin located in central North America. The predicted flood compares well with the observed values at a downstream hydrometric station (r = 0.95). The result also reveals a 2-week hysteresis between the maximum snowmelt and the peak streamflow observed at the station. The model is relatively simple and needs only GRACE and temperature inputs for flood forecasting. It can be readily applied to other cold-region basins after simple calibration and could be particularly useful in regions with minimal data. For potential flood warning, the model also has the advantage of a much longer lead time than most traditional flood forecasting approaches.

The Waterloo Moraine: Water, science and policy

Growth is widely seen as the means to create employment and achieve economic prosperity. Growth also consumes natural resources. As a consequence, growth can create the potential for societal conflict where resources are limited. For example, urban development or aggregate extraction can conflict with ecosystem preservation and recharge zone protection. In the Canadian context, Waterloo Region (the Region) is a classical case study for this potential conflict. Economically, the Region is changing rapidly. While much of the Region’s traditional manufacturing industry has been devastated by globalization, a new high-tech industry has emerged, resulting in considerable urban growth. The provincial government has supported this trend by designating Waterloo Region as one of a number of growth centres in the province, and as a result, the population is expected to increase by 50% over the next 30 years. Growth increases the pressure on the community’s natural resources. In addition to land, the most critical natural resource for the Region is water. Although the Region is situated between two of North America’s Great Lakes, access to potable water from these lakes is complicated and expensive. Fortunately, the Region already has an excellent source of water beneath the urban landscape – the groundwater of the Waterloo Moraine. In addition to providing the Region’s drinking water, the Moraine also assures the ecological health of streams and wetlands, and it supports a healthy agricultural sector in the rural areas. The Moraine water resource is adequate for present use; however, it is also limited. Growth not only increases the demand on water but can potentially diminish the resource itself. Sprawling subdivision developments over the aquifer recharge areas can affect the quantity of water available, urban contaminants such as road salt can impact the groundwater quality and aggregate pits can weaken the protection of the aquifers from contaminants. Consequently, conflict can potentially arise when the growing demand tests the limits of the resource. Water managers at the Region of Waterloo have so far been successful in striking a balance between growth, water use and the protection of the water source, using a multi-faceted approach including demand management, delineating groundwater sensitivity zones and constraining the urbanized area by means of a “countryside line”. The sensitivity zone concept is science-based, while the countryside line has a political origin. The latter concept is being challenged by development interests, which seek to expand residential subdivisions across the countryside line into rural areas that also contain the main recharge areas of the Waterloo Moraine. Allowing urban sprawl into the main Moraine recharge areas has the associated risk of upsetting the recharge-withdrawal balance. The considerable effort to preserve and protect the Region’s water source has produced a large amount of knowledge over the past 40 years, involving different branches of groundwater science. The idea for this Special Issue arose when researchers at the Geological Survey of Canada and the University of Waterloo decided to compile an authoritative source for this body of knowledge, to be readily available to others confronted with similar land-water conflicts. The result is a set of 11 research papers by authors from government, universities and private consultants, all with different backgrounds and expertise, but all with a passion for groundwater. These papers cover both science and societal aspects of groundwater, they are all interrelated, but each stands on its own merit. Frind and Middleton (2014, this issue) examine the Region’s overall strategy for managing the complex Moraine groundwater resource and providing a reliable water source for the growing community. This successful strategy integrates the principles of sustainable water governance with a science-based understanding of the complex Moraine system. Bajc et al. (2014, this issue) lay the foundation for the science of the Waterloo Moraine by unravelling its depositional history during the Quaternary age. Understanding this history and applying a full range of exploratory tools including

Introduction to a special issue on three-dimensional geological mapping for groundwater applications

Abstract Modern societies have increasing demands for contaminant remediation and a continued supply of potable water. This is particularly the case in the densely populated and industrialized parts of North America and Europe. Coping with the demand, however, requires optimal geologic mapping and modeling methods, and for hydrogeologists to generate improved model scenarios using the best available geological information. Unfortunately, there is often a lack of collaboration between geologists and hydrogeologists. Therefore, geological complexity and understanding is often under-represented in many groundwater models. This article introduces a special issue of the Journal of Maps focusing on three-dimensional (3-D) geologic mapping for groundwater applications. Four articles in the issue are based on papers that were presented at workshops held between 2001 to 2005. The workshops provided venues for researchers to share their expertise in constructing 3-D geological models and to discuss various geological issues pertaining to groundwater and urbanization. Primary topics discussed in the workshops and in these four Journal of Maps articles are basin analysis, data integration and management, three-dimensional geologic model construction, groundwater investigations, and communication. The four papers in this issue demonstrate different philosophical and technical approaches to the development of GIS based 3-D geological models, while the modeling approaches and results reflect various issues and data support problems inherent with model development at various scales, from large regional models, to intermediate scale municipal and county scale models, to site-specific scale.

Glacial dispersal trains in North America

ABSTRACT A map depicting glacial dispersal trains in North America has been compiled from published sources. It covers the Canadian Shield, the Arctic Islands, the Cordillera and Appalachian mountains, and Phanerozoic sedimentary basins south of the Shield. In total, 140 trains are portrayed, including those emanating from major mineral-deposit types (e.g. gold, base metal, diamondiferous kimberlite, etc.). The map took 10 years of on-and-off work to generate, and it culls data from over 150 years of work by government, industry, and academia. It provides a new tool to help companies find ore deposits in Canada: the trains are generally a better predictor of dispersal distance and direction than striations and streamlined landforms, the data typically depicted on surficial-geology maps, including the Glacial Map of Canada. It also gives new insight into sedimentation patterns and processes beneath ice sheets, a sedimentary environment that, because of its inaccessibility, remains poorly understood and controversial.