Alexander L. Peace, Gillian R. Foulger, Christian Schiffer and Ken J.W. McCaffrey
Breakup between Greenland and Canada resulted in oceanic spreading in the Labrador Sea and Baffin Bay. These ocean basins are connected through the Davis Strait, a bathymetric high comprising primarily continental lithosphere, and the focus of the West Greenland Tertiary volcanic province. It has been suggested that a mantle plume facilitated this breakup and generated the associated magmatism. Plume-driven breakup predicts that the earliest, most extensive rifting, magmatism and initial seafloor spreading starts in the same locality, where the postulated plume impinged. Observations from the Labrador Sea–Baffin Bay area do not accord with these predictions. Thus, the plume hypothesis is not confirmed at this locality unless major ad hoc variants are accepted. A model that fits the observations better involves a thick continental lithospheric keel of orogenic origin beneath the Davis Strait that blocked the northward-propagating Labrador Sea rift resulting in locally enhanced magmatism. The Davis Strait lithosphere was thicker and more resilient to rifting because the adjacent Paleoproterozoic Nagssugtoqidian and Torngat orogenic belts contain structures unfavourably orientated with respect to the extensional stress field at the time.
Geometallurgy is a cross-disciplinary science that addresses the problem of teasing out the features of the rock mass that significantly influence mining and processing. Rocks are complex composite mixtures for which the basic building blocks are grains of minerals. The properties of the minerals, how they are bound together, and many other aspects of rock texture affect the entire mining value chain from exploration, through mining and processing, waste and tailings disposal, to refining and sales. This review presents rock properties (e.g. strength, composition, mineralogy, texture) significant in geometallurgy and examples of test methods available to measure or predict these properties.Geometallurgical data need to be quantitative and spatially constrained so they can be used in 3D modelling and mine planning. They also need to be obtainable relatively cheaply in order to be abundant enough to provide a statistically valid sample distribution for spatial modelling. Strong communication between different departments along the mining value chain is imperative so that data are produced and transferred in a useable form and duplication is avoided. The ultimate aim is to have 3D models that not only show the grade of valuable elements (or minerals), but also include rock properties that may influence mining and processing, so that decisions concerning mining and processing can be made holistically, i.e. the impacts of rock properties on all the cost centres in the mining process are taken into account. There are significant costs to improving ore deposit knowledge and it is very important to consider the cost-benefit curve when planning the level of geometallurgical effort that is appropriate in individual deposits.
Three case studies in Canada are evaluated where a regulatory authority ruled that measures considered by some professionals to be without scientific basis and less protective of human health or the environment were the required courses of action. The three projects were in the field of environmental geoscience. In all three cases, the solution proposed by a Professional Geoscientist (P.Geo.) was opposed by a representative of a regulatory body that held authority for approval. The final outcomes that were approved by the Regulator were less protective of human health (increased exposure to potential contaminants) and/or the environment (more resources used, higher contaminant exposure). In two of the three cases, the solutions were also more expensive to the client and the taxpayer.
This paper explores the practice of professionalism in geoscience versus regulatory authorities that hold jurisdiction over geoscience in a broad sense. In each of the three cases, the professional opinions and analysis of the P.Geo. working for a private sector client were overridden by a professional (P.Geo. or Professional Engineer) in an approval authority. These three studies highlight the ethical decisions required by professional geoscientists in the face of regulators who hold control over areas of geoscience. Although the training of professionals is similar, regulators appear to be influenced by perceived risk as opposed to actual risk based on scientific evidence. Similarly, some policies do not have a solid scientific basis. As a result, sound scientific reasoning and resulting rational decisions may be hindered in regulatory decision-making.