Scott Dallimore

Geological Survey of Canada · Natural Resources Canada

The Mackenzie River Delta is the second largest Arctic river delta in the world. Thin and destabilizing permafrost coupled with vast natural gas reserves at depth, high organic content soils, and a high proportion of wetlands create a unique ecosystem conducive to high rates of methane production from biogenic and thermogenic sources. Hotspots are...

Significance Temperature increases in Arctic regions have focused attention on permafrost degradation on land, whereas little is known about the dynamics of extensive glacial-age permafrost bodies now submerged under the vast Arctic Continental shelves. Repeated high-resolution bathymetric surveys show that extraordinarily rapid morphologic changes...

The southern Beaufort coastline in Canada experiences significant storm surge events that are thought to play an important role in coastal erosion and influence permafrost dynamics. Unfortunately, many of these events have not been documented with tide gauge records. In this paper, we evaluate coastal driftwood accumulations as a proxy for estimati...

Mega‐scale glacial lineations formed by the raking of ice shelves across the seafloor have been reported from multiple polar regions. Here, we present the first evidence of continental slope situated buried lineations in the southern Canadian Beaufort Sea in present‐day water depths of 220 – 800 m. Three separate surfaces with lineations are define...

Seasonally ice‐covered permafrost lakes in the Arctic emit methane to the atmosphere during periods of open‐water. However, processes contributing to methane cycling under‐ice have not been thoroughly addressed despite the potential for significant methane emission to the atmosphere at ice‐out. We studied annual dissolved methane dynamics within a...

Climate change in the Arctic has recently become a major scientific issue, and detailed information on the degradation of subsea permafrost on continental shelves in the Arctic is critical for understanding the major cause and effects of global warming, especially the release of greenhouse gases. The subsea permafrost at shallow depths beneath the...

Extent and chronology of 24 buried and seabed-exposed mass transport deposits (MTDs) on the continental slope of the Canadian Beaufort Sea were compiled towards a regional geo-hazard assessment of the Beaufort region. A total of 2220 lines of 3.5 kHz sub-bottom profiler (SBP) data (~40,000-line kilometres) covering an area of 9740 km² were analyzed...

Exploration of the continental slope of the Canadian Beaufort Sea has revealed a remarkable coalescence of slide scars with headwalls between 130 and 1100 m water depth (mwd). With increased depth, the scars widen and merge into one gigantic regional slide scar that is more than 100 km wide below ~1100 mwd. To understand the development of these fe...

Permafrost sediments contain one of the largest reservoirs of organic carbon on Earth that is relatively stable when it remains frozen. As air temperatures increase, the shallow permafrost thaws which allows this organic matter to be converted into potent greenhouse gases such as methane (CH4) and carbon dioxide (CO2) through microbial processes. A...

Abstract is available at: https://epic.awi.de/id/eprint/50808/

Long-term warming of the continental shelf of the Canadian Beaufort Sea caused by the transgression associated with the last deglaciation may be causing decomposition of relict offshore subsea permafrost and gas hydrates. To evaluate this possibility, pore waters from 118 sediment cores up to 7.3-m long were taken on the shelf and slope and analyze...

The presence of a wedge of offshore permafrost on the shelf of the Canadian Beaufort Sea has been previously recognized and the consequence of a prolonged occurrence of such permafrost is the possibility of an underlying gas hydrate regime. We present the first evidence for wide-spread occurrences of gas hydrates across the shelf in water depths of...

Methane is a potent greenhouse gas, and there are concerns that its natural emissions from the Arctic could act as a substantial positive feedback to anthropogenic global warming. Determining the sources of methane emissions and the biogeochemical processes controlling them is important for understanding present and future Arctic contributions to a...

Methane is a potent greenhouse gas, and there are concerns that its natural emissions from the Arctic could act as a substantial pos. feedback to anthropogenic global warming. Detg. the sources of methane and the biogeochem. processes controlling them is important for understanding present and future Arctic emissions. Here we apply multiply substit...

Morphologic features, 600-1100 m across and elevated up to 30 m above the surrounding seafloor, interpreted to be mud volcanoes were investigated on the continental slope in the Beaufort Sea in the Canadian Arctic. Sediment cores, detailed mapping with an autonomous underwater vehicle, and exploration with a remotely operated vehicle show that thes...

This report provides a basis for understanding how gas hydrates occur and the emerging science and knowledge as to their potential environmental, economic, and social consequences of their use. The intention of this publication is to enable sound policy discourse and choices that take into account a number of important perspectives.

The Beaufort Sea–Mackenzie Basin hosts an immense petroleum resource. Fifty-two petroleum fields found by 263 wells, including four gas hydrate research wells, have discovered petroleum expected to be 172.75 x 10 6 m 3 recoverable crude oil and condensate and 254.67 x 10 9 m 3 marketable conventional natural gas. The region is estimated to have an...

The Mallik gas hydrate deposit was found to consist of 3 distinct, highly concentrated, high quality zones of structure I hydrate with partial occupancy of 5.75-6.2. Earlier simulation studies focused on history matching the 6 days production test of the lower zone, assuming 100% hydrate occupancy. The focus of the current study is on a simulation...

The delineation of the Mallik gas hydrate field has utilized extensive well logging and substantial 3D seismic testing and interpretation. This study explores the use of seismic data to quantify the areally heterogeneous gas hydrate distribution. The available Mallik 3D seismic data was compiled and compared/contrasted with available well log data...

Gas hydrates, ice-like combinations of water and methane (natural gas), are a hitherto untapped energy resource. Recent scientific drilling and evaluation programs suggest that gas hydrates occur in abundance, primarily in marine settings, with about 1% of the global gas hydrate distribution occurring in permafrost environments. (See Volume 1 Chapt...

[1] A finite element geothermal model is developed for the outer Mackenzie Delta-Beaufort Sea shelf to predict permafrost evolution since the Last Interglacial ~130–116 kaBP(cal). The purpose is to reconcile sparse observations of the depth and extent of ice-bonded permafrost with sediment properties and the paleoenvironment. Sea level curves deter...

Gas hydrate is a solid, naturally occurring substance consisting predominantly of methane gas and water. Recent scientific drilling programs in Japan, Canada, the United States, Korea and India have demonstrated that gas hydrate occurs broadly and in a variety of forms in shallow sediments of the outer continental shelves and in Arctic regions. Fie...

Generic exploration drilling structures include floating and bottom-founded drilling platforms. Both types of exploration drilling structures require knowledge of seabed stability conditions or geohazards to ensure safe exploration drilling. In addition, knowledge of geohazards is required for subsea pipelines. This report covers the state of knowl...

The sub-seafloor under the Arctic Shelf is arguably the part of the Earth that is undergoing the most dramatic warming. In the southern Beaufort Sea, the shelf area was terrestrially exposed during much of the Quaternary period when sea level was up to 120m lower than present. As a consequence, many areas are underlain by more than 600m of ice bond...

The sub-seafloor under the Arctic Shelf is arguably the part of the Earth that is undergoing the most dramatic warming. In the southern Beaufort Sea, the shelf area was terrestrially exposed during much of the Quaternary period when sea level was ~120m lower than present. As a consequence, many areas are underlain by >600m of ice-bonded permafrost...

The Kittigazuit Formation is a late Quaternary sand unit commonly observed throughout the Tuktoyaktuk Coastlands and in subbottom sediments of the southern Beaufort Shelf. Stratigraphic and sedimentology data, including sedimentary structures, grain-surface characteristics, and heavy and light mineralogy, assist in characterizing the deposit and in...

Five offshore drill holes northeast of Richards Island reveal permafrost conditions, which are interpreted in terms of the sea-level and paleoenvironmental history of the Canadian Beaufort Shelf. The top of ice-bonded permafrost lies 76–88 m below the seabed within 12 km of the shore, 11 m below the seabed 20 km offshore, and at 60 m some 50 km off...

In the Mackenzie–Beaufort region, maximum permafrost thickness is 750 m in the Pleistocene Tuktoyaktuk Coastlands, less than 100 m in the Holocene Mackenzie Delta, and 500 m and anomalously warm in the Big Lake Delta Plain between the two areas. Numerical modelling has been used to derive surface temperature histories that fit ground temperatures a...

The extensive coastal exposure of massive underground ice at Peninsula Point, southwest of Tuktoyaktuk, Northwest Territories, is believed to be intrasedimental ice. The ice grew beneath a frozen diamicton during the downward aggradation of permafrost. The water source was probably glacier meltwater, with low negative δ18O values, that flowed, unde...

Nearshore areas off northern Richards Island can be expected to show considerable variability in lithology, strengths, and geothermal setting both in a temporal and a spatial sense. Drilling and laboratory studies carried out along onshore–offshore transects at a stable coastal site and an actively eroding coastal site have identified six major str...

Attempts have been made to simulate hillslope creep observations at a site near the village of Tuktoyaktuk, Northwest Territories. Unlike other creep studies in permafrost, this site was unique in that the deformations occurred within a massive ice body, forming the core of a 30 m high concentric hill approximately 1200 m long and 700 m wide. The d...

A cruise was conducted in 2010 to provide ground truth observations of the seafloor along the outer shelf edge and slope of the Beaufort Sea where multibeam mapping in 2009 identified water column acoustic anomalies which were inferred to be gas plumes. Here we report on seafloor observations, gas sampling, pore water chemistry, and preliminary sed...

The methane hydrate (MH) production tests were conducted using the depressurization method in the JOGMEC/NRCan/Aurora Mallik production program in April 2007 and in March 2008. In addition to attaining the first and the only successful methane gas production to the surface from a MH reservoir by depressurization in the world, various data such as w...

The melting Laurentide Ice Sheet discharged thousands of cubic kilometres of fresh water each year into surrounding oceans, at times suppressing the Atlantic meridional overturning circulation and triggering abrupt climate change. Understanding the physical mechanisms leading to events such as the Younger Dryas cold interval requires identification...

International efforts and advanced techniques are being used to characterize properties and distributions of gas hydrates, which are crystalline solids that resemble ice. The Minerals Management Service (MMS) of the US Department of the Interior has used seismic data, along with wellbore, geologic, geochemical and paleontological information, to as...

We combine acoustic impedance inversion of 3D seismic data, log-to-seismic correlation, and seismic attribute analyses to delineate gas-hydrate zones at the Mallik site, Mackenzie Delta, Northwest Territories, Canada. Well-log data define three distinct hydrate zones over a depth range of 890-1100 m. Synthetic seismic modeling indicates the base of...

The magnetotelluric method is not generally utilized at extreme latitudes due primarily to difficulties in making the good electrical contact with the ground required to measure the electric field. As such, the magnetotelluric technique has not been previously investigated to direct detect gas hydrates in on-shore permafrost environments. We presen...

Arctic gas hydrates occurring within and beneath permafrost in N.W. Canada have experienced significant post glacial warming with millennial time scales sufficient to cause gas hydrate dissociation, migration and release of free gas at the surface. Forcing processes imposing changes in ground surface temperatures include warming post-glacial air te...

The U. S. Geological Survey has lead or played major roles in several efforts over the past 20 years to find geochemical evidence for gas hydrate dissociation on the Beaufort Sea shelf, a region of complex and varied geologic features that include: 1) several river deltas entering the Arctic Ocean, the largest of which is the Mackenzie River, 2) su...

During the winters of 2007 and 2008 the Japan Oil, Gas and Metals National Corporation (JOGMEC) and Natural Resources Canada (NRCan), with Aurora Research Institute as the operator, carried out an on-shore gas hydrate production test program at the Mallik site, Mackenzie Delta, Northwest Territories, Canada. The prime objective of the program was t...

A 3D seismic survey (Mallik 3D), covering 126 km(2) in the Mackenzie Delta area of Canada's north, was conducted by industry in 2002. Numerous lakes and marine inundation create a complex near-surface structure in the permafrost terrain. Much of the near subsurface remains frozen but significant melt zones exist particularly from perennially unfroz...

The responsible management and reduction of carbon dioxide (CO2) emissions requires consideration of alternative options for disposal and long-term sequestration of anthropogenic CO2. A number of conventional options for geological sequestration of CO2 are currently being evaluated worldwide, including CO2 disposal in depleted oil and gas reservoir...

The recent warming in high latitudes is affecting a broad spectrum of physical, ecological, and human/cultural systems in this region. Some of these changes may be irreversible on century time scales, and have the potential to cause rapid changes in the earth system. The response of the carbon cycle in northern high latitude regions is a major conc...

Japan Oil, Gas and Metals National Corporation (JOGMEC) and Natural Resource Canada (NRCan) have embarked on a new research program to study the production potential of gas hydrates. The program is being carried out at the Mallik gas hydrate field in the Mackenzie Delta, a location where two previous scientific investigations have been carried in 1...

Wave attenuation is an important physical property of hydrate-bearing sediments that is rarely taken into account in site characterization with seismic data. We present a field example showing improved images of hydrate-bearing sediments on seismic data after compensation of attenuation effects. Compressional quality factors estimated from zero-off...

1] The Arctic shelf is currently undergoing dramatic thermal changes caused by the continued warming associated with Holocene sea level rise. During this transgression, comparatively warm waters have flooded over cold permafrost areas of the Arctic Shelf. A thermal pulse of more than 10°C is still propagating down into the submerged sediment and ma...

Following the success of the first gas hydrate production test in JAPEC/JNOC/GSC Mallik 5L-38 Methane Hydrate Research Well in 2002, MH21 Research Consortium for Methane Hydrate Resources and Natural Resources Canada jointly conducted the second production test in the Mallik area, Northwest Territories, Canada applying depressurization method in th...

Amplitude and frequency anomalies associated with lakes and drainage systems were observed in a 3D seismic data set acquired in the Mallik area, Mackenzie Delta, Northwest Territories, Canada. The site is characterized by large gas hydrate deposits inferred from well-log analyses and coring. Regional interpretation of the gas hydrate occurrences is...

Gas hydrates are solid crystalline substances consisting of natural gas (typically methane) and water molecules, that remain stable under conditions of relatively cold formation temperatures and high pressures. Significant natural gas hydrates deposits occur in the Arctic in association with areas of thick permafrost, and in many marine environment...

As part of an interdisciplinary field program, a 1150-m deep well was drilled in the Canadian Arctic to determine, among other goals, the location, characteristics, and properties of gas hydrate. Numerous physical properties of the host sediment were measured in the laboratory and are presented in relation to the lithology and quantity of in situ g...

The JAPEX/JNOC/GSC Mallik 2L-38 research well was drilled to a depth of 1,150 m beneath the permafrost zone in the Mackenzie Delta, N.W.T., Canada, early in 1998. A large amount of natural gas hydrates were successfully retrieved from a variety of sandy and gravel sediments. Over 110 m of gas hydrate-bearing sediments were found to be distributed b...

Various estimates suggest that permafrost covers approximately 20% of the terrestrial surface of the earth. Despite its widespread occurrence, the history of permafrost formation during the Quaternary, its physical and geophysical properties, permafrost microbiology, the existence of hydrates, and the significance of permafrost as a source and sink...

Analysis of recovered core from the Mallik gas hydrate field in the Mackenzie Delta, Northwest Territories, Canada demonstrates that the magnetic properties of hydrate-bearing strata differ significantly from those strata lacking gas hydrate. The recovered core, which extends from just above (885 m) to just below (1152 m) observed gas hydrate occur...

The thickness of permafrost (i.e. depth of the 0°C isotherm) in the Mackenzie Delta area, and the associated deep geothermal regime have been strongly influenced by ground surface temperature history during the past several million years. Important considerations include periods of glacial ice cover, duration of post-glacial terrestrial exposure an...

The Arctic shelf is currently undergoing dramatic thermal changes caused by the continuing warming associated with Holocene sea level rise. During this transgression comparatively warmer waters flooded over relatively cold Arctic permafrost areas. The resulting thermal pulse is still propagating down into the ground and should be decomposing gas hy...

Gas hydrate samples recovered from a cold vent field offshore Vancouver Island were studied in detail both by macroscopic observations and instrumental methods (powder X-ray diffraction method (PXRD), nuclear magnetic resonance (NMR), and Raman spectroscopy). It was found that gas hydrates were massive from 2.64 to 2.94 m below seafloor (mbsf), elo...

The roles of diagenesis and geomechanics in the permafrost gas hydrate setting were examined by three independent studies on the Mallik 5L-38 Gas Hydrate Production Well, NE Mackenzie Delta, Canada. Gas hydrate bearing sands are locally well-cemented by dolomite-calcite cements. Previous research suggested a genetic link between gas hydrate emplace...

Glacially-deformed massive ice and icy sediments (MI–IS) in the Eskimo Lakes Fingerlands and Summer Island area of the Tuktoyaktuk Coastlands, western Arctic Canada, show, in the same stratigraphic sequences, features characteristic of both basal glacier ice and intrasedimental ice. Basal-ice features comprise (1) ice facies and facies groupings si...

Three separate techniques were employed to investigate the thermal conductivity of uncon- solidated sediments within the gas-hydrate-bearing reservoir at the Mallik gas hydrate production research site. A miniature needle probe was used to obtain thermal-conductivity measurements of quartz sand and a core specimen recovered from the Mallik reservoi...

The thermal-stimulation test conducted on the JAPEX/JNOC/GSC et al. Mallik 5L-38 gas hydrate production research well in March of 2002 was designed to increase the in situ temperature of a portion of a well defined and constrained gas hydrate reservoir a bove the gas hydrate stability point, while maintaining constant pressure. Data collected, incl...

The orientations of the principal horizontal in situ stresses, σ Hmin and σ Hmax , were analyzed in the Mallik area by investigating the local structural geology, regional borehole breakouts, drilling induced fractures, borehole ellipticity, and shear-wave-velocity anisotropy. Vertical-stress magnitudes in the Mallik area were evaluated by analyzin...