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The package PbIso is a free and open R toolbox for commonly used calculations and plots of Pb–Pb isotope data and for generating Pb evolution models. In this paper, we review Pb isotope systematics and the calculations that are commonly used, such as model age, model source μ (238U/204Pb), time-integrated κ (232Th/238U), and initial Pb isotope ratios. These equations are implemented into R functions in the package PbIso. In addition, functions are provided for generating Pb evolution models, paleoisochrons, and isochrons. This allows users to apply calculations to their data in a straightforward way while providing transparency and flexibility of the calculations used. We have implemented some basic features of the PbIso package into an online shiny R application (see https://shereearmistead.github.io/software/pbiso), which makes it easy for users without any R experience to use these calculations with their own data and to generate plots. We have provided a case study from the Superior Province in Canada, showing how different Pb evolution models can be generated in PbIso and compared to Pb isotope data. [ABSTRACT FROM AUTHOR]

Canada ratified the United Nations Convention on the Law of the Sea (UNCLOS) in 2003. With that ratification is an obligation to submit data and information to the U.N. pertaining to the limits of the country's extended continental shelf (ECS); the portion of the juridical continental shelf that extends beyond 200 nautical miles. A team of Canadian scientists, managers, and legal experts that included representation from three Federal Departments (Natural Resources Canada, Fisheries and Oceans Canada, and Global Affairs Canada) with additional support from other departments, spent 13 years compiling and acquiring data to provide the scientific evidence to support delineation of Canada's seaward most maritime limit. The submission has the potential to provide Canada with 2.4 million km2 of additional submarine landmass in the Atlantic and the Arctic oceans over which Canada exercises sovereign rights for the purpose of exploring and exploiting its natural resources. Specific information such as the tectonic framework of the continental margin, the geomorphology of the margin and in particular the continental slope, the geologic nature of adjoined ridges, rises, and plateaux, and sediment thickness within adjacent basins are examples of fundamental pieces of geoscientific information needed to substantiate Canada's outermost maritime limits. This paper highlights a number of segments of Canada's continental margins to showcase this scientific evidence and how it is applied in the UNCLOS context. In doing so, the paper demonstrates the geologic complexity of Canada's margins as illustrated in scientific publications that have resulted from these new data collections, while at the same time presenting new scientific evidence and interpretations. This collection of data and information provides a wealth of new knowledge in Canada's offshore regions. The massive data compilation in the Atlantic led to conception of continental margins, in a source-to-sink scenario, as having an equilibrium base level or graded form, comparable to river systems. Departures from this shape relate to the interplay of sedimentary processes and in particular to those processes that do not fit the source-to-sink paradigm. For example, a significant part of the Atlantic margin is shown to be heavily influenced by along-slope geostrophic currents that generated massive contourite drift deposits. These deposits reflect lateral transport of sediment that had a significant impact on the morphology of the margin. The role of mass transport processes in shaping continental margins is also highlighted, and in particular the collapses of entire segments of the margin were observed. The prominent role mass failure processes play in delivering sediment to the adjacent abyssal plain is also critical in the ECS context. These observations challenge the entrenched notion of a continental margin comprising a shelf, slope, and rise and in particular the concept of the "continental rise". Prior to 2006, regions of the Arctic Ocean seaward of the Canadian landmass had fewer than 5000 km of seismic reflection data. The massive efforts of Arctic coastal States to map their margins for ECS purposes have led to a leap in technological advances to acquire data in ice-covered seas and have led to a wealth of new geoscientific knowledge. Perhaps foremost amongst this knowledge is demonstration that Canada Basin is indeed a fully developed ocean basin, albeit significantly infilled with sediment. Based on this knowledge and identification of related structures, new realistic tectonic scenarios for opening of the Amerasia Basin are proposed that include a significant component of transform or strike-slip motions. With seismic velocity and rock sample information, the continental nature of Alpha and Mendeleev ridges has been substantiated. Even bathymetric data were lacking in the Arctic and new editions of seafloor maps now support grids of 500 m spacing; although some regions remain sparse. Once thought to be relatively stagnant, sedimentary processes such as found in many ocean basins were discovered in the Arctic Ocean. Evidence of geostrophic currents, sediment mass failures, and deep-sea turbidity current channels were found to be ubiquitous, even in the deepest parts of the Arctic's basins. [ABSTRACT FROM AUTHOR]

The article announces that Tiffani A. Fraser and Matt P. Hutchison won the 2017 Best Paper Award from the Canadian Science Publishing and the Geological Association of Canada.

This paper analyzes short gravity cores sampled along transects in three adjacent deep fjord-lakes (lakes Pentecôte, Walker, and Pasteur) on the Québec North Shore, eastern Canada, to evaluate the distribution of laminated sediments and potential for varve formation. Facies analysis based on lithological description, digital photos, CT-scan images, and bathymetric data allowed for the identification of four main sediment facies, namely laminated sediments, partially laminated sediments, bioturbated sediments, and massive sediments. Direct evidence that Lake Walker undergoes thermal stratification was monitored from 2014 to 2016. Mean sedimentation rates and sedimentation fluxes of postglacial sediments in the distal basin of the three studied lakes are ≤0.12 cm a−1 and 0.03-0.16 g cm−2 a−1, respectively, based on 210Pb, 137Cs, and AMS radiocarbon dating. On the basis of thin section image analysis and 210Pb (CIC) chronology model, Lake Pentecôte contains mainly massive, partially laminated sediments, while Lake Pasteur contains partially laminated sediments and non-annual varve-like sediments. However, Lake Walker contains laminated sediments that are likely varves. The increased potential for laminae preservation observed in Lake Walker compared to lakes Pentecôte and Pasteur is associated with more favourable morphological characteristics including higher relative depth, mean depth, maximum depth, and topographic exposure. [ABSTRACT FROM AUTHOR]

Government geological survey maps and research publications have portrayed the distribution of glacial landforms associated with the advance and retreat of the Laurentide and Cordilleran ice sheets across Alberta at a local, regional, and continental scale. To date, this information has not been systematically synthesized into a single compilation at a consistent scale. Although this original work provided valuable information to constrain reconstructions of former ice sheet extent, configuration, and flow geometry, its derivation primarily from the interpretation of aerial photographs and the Shuttle Radar Topography Mission 90 m digital elevation model (DEM) may result in methodological inconsistencies and spatial biases. These biases, together with challenges associated with geomorphic mapping in densely forested areas of western and northern Alberta limit the usefulness of previous mapping when applied to inversion-based ice sheet reconstructions, which have specific input data demands. Recently, light detection and ranging (LiDAR) DEMs have become increasingly available throughout Alberta. Hill-shaded imagery of these data provides unprecedented geomorphic detail beneath the forest cover and reveals that that the glacial geomorphology of northern and western Alberta is more complex than previously recognized. In this paper, we describe the methodology and geomorphic criteria used to produce a glacial landform map of Alberta using previously published data, supplemented by comprehensive new analysis of high-resolution (2-25 m) DEMs. These include 306 624 km2 of LiDAR imagery, with which it is now possible to verify and where necessary augment previous mapping, particularly across areas with a dense forest cover. [ABSTRACT FROM AUTHOR]

This Special volume published by the Canadian Journal of Earth Sciences consists of a collection of six papers on the petrology, geochemistry, and metallogeny of igneous rocks emplaced in large igneous provinces (LIPs). The papers provide a snapshot of results presented at a Special Session of the 2017 Geological Association of Canada – Mineral Association of Canada Joint Annual Meeting held in Kingston, Ontario, by members of the vibrant geoscience community dedicated to the study of LIPs. Participants applauded the idea of a joint session on these topics and as a result, the session fostered animated discussions and new collaborations. The scope of magmatic and metallogenic studies of LIPs often precludes the type of brainstorming that took place during the meeting. This Special volume demonstrates that a robust understanding of magmatic processes represents the essential first step towards the search for mineral deposits in LIPs worldwide. [ABSTRACT FROM AUTHOR]