Wabush Lake Research Articles

Reprint of Evolution of an anthropic source to sink system: Wabush lake

Wabush Lake is one of the few very well-constrained source-to-sink sedimentary systems in the world that exhibits near-continuous turbidity currents. In this system, approximately 20million tons of mine tailings are delivered each year to a 40km2 lake. Multibeam bathymetric surveys of this lake were carried out between 1999 and 2011. In addition, a program of extensive sampling and seismic surveys, an airborne LiDAR survey and a photogrammetric survey were carried out during this period. The objective of this study was to determine the evolution through time of this anthropic source-to-sink system, from the point where sediments exit the slurry pipelines at the head of the system to the distal end and bottom of the Lake. The total volume of the Lake is around 1×109m3.Analysis of subaerial and subaqueous datasets allows the evaluation of disposal strategies on the delta topset and on tailings accumulation. Disposal strategies influence the dynamics of the channels on the topset, thus in turn affecting the accumulation of tailings throughout the lake, as well as the shoreline advancement rate. Subaqueous erosional channels present on the bed of the Lake influence the depositional pattern of tailings as well as their granulometric distribution. These erosional channels are created by the shoreward migration of knickpoints. In some places, this migration can be documented over multiple surveys.Finally, sequential analysis of the 1999, 2004, 2006, 2008 and 2011 surveys has allowed detailed documentation of the infilling of the Lake, including the migration of sediment depocenters, the mechanism of emplacement and the progressive infilling of a series of minibasins.

Evolution of an anthropic source-to-sink system: Wabush Lake

Wabush Lake is one of the few very well-constrained source-to-sink sedimentary systems in the world that exhibits near-continuous turbidity currents. In this system, approximately 20million tons of mine tailings are delivered each year to a 40km2 lake. Multibeam bathymetric surveys of this lake were carried out between 1999 and 2011. In addition, a program of extensive sampling and seismic surveys, an airborne LiDAR survey and a photogrammetric survey were carried out during this period. The objective of this study was to determine the evolution through time of this anthropic source-to-sink system, from the point where sediments exit the slurry pipelines at the head of the system to the distal end and bottom of the Lake. The total volume of the Lake is around 1×109m3.Analysis of subaerial and subaqueous datasets allows the evaluation of disposal strategies on the delta topset and on tailings accumulation. Disposal strategies influence the dynamics of the channels on the topset, thus in turn affecting the accumulation of tailings throughout the lake, as well as the shoreline advancement rate. Subaqueous erosional channels present on the bed of the Lake influence the depositional pattern of tailings as well as their granulometric distribution. These erosional channels are created by the shoreward migration of knickpoints. In some places, this migration can be documented over multiple surveys.Finally, sequential analysis of the 1999, 2004, 2006, 2008 and 2011 surveys has allowed detailed documentation of the infilling of the Lake, including the migration of sediment depocenters, the mechanism of emplacement and the progressive infilling of a series of minibasins.

Morphological evolution of a well‐constrained, subaerial–subaqueous source to sink system: Wabush Lake

AbstractSince 1964, the Iron Ore Company of Canada has deposited iron tailings resulting from mining operations into Wabush Lake, Western Labrador, Canada. This activity has resulted in a continuous hyperpycnal flow flowing over the lake floor. Bathymetric surveys were carried out between 1999 and 2008 as part of the overall environmental Iron Ore Company of Canada plans to maintain safe disposal strategies of tailings into the lake. Here, this dataset is used to study the evolution of different channels present in Wabush Lake and their link with knickpoints found at the head of most of these channels. The channels show notable evolution from one survey to the next. Some knickpoints and channels may be followed throughout more than one survey; the evolution of these knickpoints is the process responsible for the creation of erosional channels. The context in which they appear, as well as the evolution of some of the subaqueous channels is analysed. Cyclic steps and sediment waves are also found in the lake. These rhythmic bedforms, also created by the passage of turbidity currents, are analysed. Sediment waves found in Wabush Lake show values for both wavelength and wave height that are approximately one order of magnitude smaller than most of those found in the marine environment.

Are metal mining effluent regulations adequate: identification of a novel bleached fish syndrome in association with iron-ore mining effluents in Labrador, Newfoundland

Water quality guidelines for industrial effluents are in place in many countries but they have generally evolved within a limited ecotoxicological framework. Effluents from iron-ore mines have traditionally been viewed by regulatory bodies as posing little or no risk to the aquatic environment. However, it was recently reported that lake trout taken from a large iron-ore contaminated Lake in Labrador (Wabush Lake) had elevated levels of DNA oxidative damage and were markedly depleted in levels of vitamin A ( Payne et al., 1998) in comparison with fish from a Lake (Shabogamo Lake) receiving lesser levels of effluents. Through further observations, it has now been established that the lake trout in Wabush Lake are commonly affected with a marked skin bleaching syndrome in comparison with fish in Shabogamo Lake and a nearby Lake (Ashuanipi) which does not receive effluents. To the authors’ knowledge such a syndrome which is characterized by marked reduction in skin pigmentation and overall increase in skin whitening has not been reported before in any fish population in association with contamination. Preliminary information for liver histopathological and blood cell differences have also been obtained in fish in Wabush Lake in comparison with Ashuanipi Lake. It has also been observed through studies on phosphatidyl liposomes that iron-ore leachate contains redox-active material (iron but possibly other transition metals) that has considerable potential for causing oxidative damage to cellular constituents. Using the weight of evidence approach it is indicated that iron-ore effluents may pose more of a risk to the aquatic environment than traditionally considered by regulatory agencies.

Iron Deposits of the Labrador Trough

The Labrador Trough contains world-class iron deposits which have been mined since 1954. The direct shipping of Knob Lake ores were mined at Schefferville from 1954 to 1982. Concentrate production began in 1961 in the southwest end of the Trough, with three mines currently producing concentrate and pellets at a rate of 35 Mt per year. West and north of Schefferville, several billion tonnes of taconite have been outlined in fine-grained, cherty magnetite iron formation. Several deposits of highly metamorphosed magnetite-specularite iron formation are located west of Ungava Bay. Numerous studies have shown that this medium- to fine-grained iron formation can be beneficated to 66% to 68% iron. In the area from Wabush Lake to Mont-Wright, a medium- to coarse-grained friable specularite-quartz iron formation is repeated by folding to form several large deposits. In this area, three mining operations are located with reserves and resources in the order of 5 billion tonnes. The iron deposits occur within iron formation in sediments in the extensive Proterozoic geosyn-cline called the Labrador Trough. Several facies of iron formation within the Sokoman Formation reflect variations in chemical composition and depositional conditions. The correlation between the mineralogy and textures is discussed to illustrate the development of different types of iron ores. This band extends for about 1100 km southeast of Ungava Bay through both Quebec and Labrador. Further south, it turns southwest past the Wabush and Mont-Wright areas to within 300 km of the St. Lawrence River. The iron formation is essentially folded and faulted along most of its length. The degree of metamorphism is variable, ranging from intense in the northern and southern portions to greenschist facies in the central portion. The stratigraphy, structure and mineralogy of the producing mines are described along with the history of discoveries. Geological input is required to achieve the strict specifications of the international iron ore market.

Relationship of olivine gabbro and amphibolite schist at carol west, Labrador geosyncline

Shabogamo gabbro, an olivine gabbro, intrudes the metamorphosed sedimentary rocks in the Wabush Lake map area, southern part of the Labrador geosyncline. In close spatial relation to this intrusive is an amphibolite schist that appears conformable with these meta-sediments. Field evidence is by itself insufficient to demonstrate whether this amphibolite schist is a metamorphosed sediment or whether it is genetically related to this olivine gabbro. Since large amphibolite schist bands occur in the Smallwood Mine, determination of the origin and relation of the amphibolite schist to the olivine gabbro is of special importance because this will determine ore potential at depth in this mine.

GEOLOGY OF THE WABUSH LAKE AREA, SOUTHWESTERN LABRADOR AND EASTERN QUEBEC, CANADA

Wabush Lake, Labrador, is situated a few miles from where the unmetamorphosed younger Precambrian strata of the northwest-trending Laborador geosyncline are truncated by the southwest-trending structures of the Grenville orogenic province. Field mapping and lithologic comparisons show that the metasedimentary rocks exposed within this portion of the Grenville province can be correlated with the unmetamorphosed strata of the Labrador geosyncline. The distinctive stratigraphic units of the Wabush Lake area are quartzite, marble, muscovite and kyanite schists, and iron formation of carbonate, silicate, and oxide facies. The principal ores of the iron formation are martite-magnetite quartz rock and specular hematite quartz rock. Facies of regional metamorphism range from epidote amphibolite near the postulated “Grenville front” to granulite and migmatite farther south. Superimposed folding throughout the area can be explained as the impression of Grenville province deformation upon earlier structures of the Labrador geosyncline.