Carbonatites are defined as an igneous rock containing > 50% carbonate minerals, although not all rocks labelled as carbonatite fit strict mineralogical criteria. Carbonatites are rare, very unusual in terms of mineralogy and geochemistry, compositionally variable and extraordinarily diverse. These enigmatic rocks are also highly prospective, hosting large resources of Nb, REE, phosphates and other commodities now classed as 'critical minerals'. Ideas on the genesis and evolution of carbonatite are divergent and many observations or hypotheses remain controversial. This review focuses mostly on geochemical aspects, notably as applied to models for the generation of carbonatite parental magmas, and the wider implications of such data. These rare and fascinating rocks provide insights into the secular evolution of the sub-continental mantle, the role of metasomatism at both crustal and mantle levels, and the nature of deeper parts of the mantle.
The Grande Ronde Basalt (GRB) is the main volcanic phase of the Columbia River Basalt Group. It erupted in less than half a million years yet makes up more than 72% (150,000 km(3)) of this famous Cenozoic flood-basalt sequence. The Teepee Butte Member is one of the most representative components of the Grande Ronde Basalt. It includes extensive lava flows, a well-preserved similar to 100 km-long system of dykes and a vent complex. The vent complex consists of tephra, "Pele's tears" (frozen lava droplets), bombs, shelly pahoehoe flows, a lava lake and a feeder dyke. The Teepee Butte Member includes two high-MgO basalt flows with two intercalated low-MgO flows, collectively representing two cycles of high-MgO to low-MgO eruptions. The first high-MgO flow (Joseph Creek flow) was followed by a hiatus during which the magma chamber fractionated olivine, plagioclase and clinopyroxene (i.e. gabbroic fractionation) and later erupted a low-MgO flow and remnant lava lake. The first low-MgO flow, the Joseph Creek Lava Lake flow, advanced over 350 km nearly reaching the Columbia River Gorge. The magma chamber was subsequently recharged with a high-MgO magma which then erupted as the Pruitt Draw flow, which advanced nearly 500 km to the Portland Basin in Oregon. After the Pruitt Draw eruption waned, the remaining magma again fractionated and then erupted as a separate low-MgO flow termed the Dog Mountain flow. This also reached the Columbia River Gorge. The flows of the Teepee Butte Member exemplify multiple cycles of high-MgO-low-MgO lava flows that persisted throughout the eruption of the Grande Ronde Basalt. Field relationships and geochemical data suggest that the composition of the Grande Ronde Basalt magma chamber was relatively consistent over time, remaining close to the composition of the highest-MgO GRB flow, but periodically fractionated to produce low-MgO flows. We document at least ten such cycles of high-MgO to low-MgO flows within the GRB. Each cycle is characterized by recharge of high-MgO magma into the magma chamber and eruption followed by fractionation in the chamber, producing a low-MgO magma that subsequently erupted, prior to the next recharge event. Poor correlations between pairs of compatible and incompatible elements support a model of periodic recharge, tapping and fractionation. The low-MgO magma compositions that mark the end of each fractionation and recharge cycle are tightly clustered, suggesting that the low-MgO magmas represent the steady-state composition of the GRB magma system. Variations in Zr/Nb and Zr/Y through the 10 cycles are broadly consistent with gabbroic fractionation; however, they also suggest the presence of subtle heterogeneities within the mantle source region supplying the recharging magma. The end of the Grande Ronde Basalt eruptions is marked by a hiatus and compositional change of the magma source, the latter resulted in the eruption of the younger Fe-and Ti-rich flows of the Wanapum Basalt.
Geological Carbon Sequestration (GCS) is viable within the Cambrian sandstone reservoir of southwestern Ontario but GCS will likely be limited in sequestration capacity and CO2 injectivity. Capacity and injectivity limitations will arise during CO2 injection because of the fluid-pressure responses induced within the Cambrian reservoir and the subsequent geomechanical-hydrogeological responses in the Precambrian basement. Any coupling between a pressurized reservoir overlying a critically stressed Precambrian basement can be expected to cause local microseismicity. In this context, the challenge is to optimize CO2 injection while minimizing microseismic responses. The principal risks and responses to the development of the Cambrian sandstone that must be resolved beforehand are (i) the robust estimation of accessible pore space for the injected super-critical CO2; (ii) the limitation of the potential for fracturing or shear damage to the caprock that might allow leakage; (iii) the induced failure of seals in active, suspended or legacy oil and gas wells penetrating the reservoir allowing upward brine or CO2 migration; (iv) the buoyant transmission of CO2 along permeable or unclamped faults penetrating the reservoir; and, (v) any microseismicity induced by pressure increases penetrating critically-stressed basement rocks. Notwithstanding these risks, we believe the Cambrian sandstone is a viable CO2 reservoir for at least 10 megatonnes of CO2 sequestration annually.The Ontario Government’s 2018 goal of 30% CO2 emissions reduction by 2030 must partly occur though industrial sequestration of CO2 within the Cambrian reservoir. However, to provide information critical for regulatory management of GCS, research is needed immediately to pave the way for CO2 injection operations if they are to have any role in industrial decarbonization. This article summarizes our weak understanding of these critical issues and proposes the development of a research borehole to provide much of the necessary information for regulatory management of CO2 injection. It will also aid the design and operation of CO2 injection hubs along the north shore of Lake Erie. In short, a site similar to the Aquistore site is needed for development of the Cambrian GCS reservoir in southwestern Ontario.
The Grande Ronde Basalt (GRB) is the main volcanic phase of the Columbia River Basalt Group. It erupted in less than half a million years yet makes up more than 72% (150,000 km3) of this famous Cenozoic flood-basalt sequence. The Teepee Butte Member is one of the most representative components of the Grande Ronde Basalt. It includes extensive lava flows, a well-preserved ~100 km-long system of dykes and a vent complex. The vent complex consists of tephra, “Pele’s tears” (frozen lava droplets), bombs, shelly pāhoehoe flows, a lava lake and a feeder dyke. The Teepee Butte Member includes two high-MgO basalt flows with two intercalated low-MgO flows, collectively representing two cycles of high-MgO to low-MgO eruptions. The first high-MgO flow (Joseph Creek flow) was followed by a hiatus during which the magma chamber fractionated olivine, plagioclase and clinopyroxene (i.e. gabbroic fractionation) and later erupted a low-MgO flow and remnant lava lake. The first low-MgO flow, the Joseph Creek Lava Lake flow, advanced over 350 km nearly reaching the Columbia River Gorge. The magma chamber was subsequently recharged with a high-MgO magma which then erupted as the Pruitt Draw flow, which advanced nearly 500 km to the Portland Basin in Oregon. After the Pruitt Draw eruption waned, the remaining magma again fractionated and then erupted as a separate low-MgO flow termed the Dog Mountain flow. This also reached the Columbia River Gorge. The flows of the Teepee Butte Member exemplify multiple cycles of high-MgO - low-MgO lava flows that persisted throughout the eruption of the Grande Ronde Basalt. Field relationships and geochemical data suggest that the composition of the Grande Ronde Basalt magma chamber was relatively consistent over time, remaining close to the composition of the highest-MgO GRB flow, but periodically fractionated to produce low-MgO flows. We document at least ten such cycles of high-MgO to low-MgO flows within the GRB. Each cycle is characterized by recharge of high-MgO magma into the magma chamber and eruption followed by fractionation in the chamber, producing a low-MgO magma that subsequently erupted, prior to the next recharge event. Poor correlations between pairs of compatible and incompatible elements support a model of periodic recharge, tapping and fractionation. The low-MgO magma compositions that mark the end of each fractionation and recharge cycle are tightly clustered, suggesting that the low-MgO magmas represent the steady-state composition of the GRB magma system. Variations in Zr/Nb and Zr/Y through the 10 cycles are broadly consistent with gabbroic fractionation; however, they also suggest the presence of subtle heterogeneities within the mantle source region supplying the recharging magma. The end of the Grande Ronde Basalt eruptions is marked by a hiatus and compositional change of the magma source, the latter resulted in the eruption of the younger Fe- and Ti-rich flows of the Wanapum Basalt.
A review of information from Statistics Canada and the Council of Chairs of Canadian Earth Science Departments examined the geoscience workforce in Canada over the last two decades through economic cycles and environmental transitions. After a period of growth in Canada (2006 to 2011), geo scientist numbers in the labour market declined by 11% from 2011 to 2021, whereas the numbers of geological engineers grew by 56%. The combined total for both classifications remained fairly constant. By Census 2021 Canada had about 11,000 geoscientists (including oceanographers) and about 4,000 geological engineers. Professional, scientific and technical services, mining, quarrying and oil and gas extraction are the major employment sectors. Employment for geoscientists is cyclical and tied to economic and commodity-price cycles. Alberta experienced the largest decline in geoscientist numbers (-34.5%), correlated with reduced oil-and gas-development investments from 2014 to 2020. Growth in other provinces (e.g. British Columbia, Ontario) partly offset the decline in Alberta. Nearly 30% of geoscientists are immigrants, as defined by their countries of birth. The university education supply pipeline shows that enrolment in core geoscience and geological engineering undergraduate programs dropped significantly (50% decline from 2015 to 2022) with a corresponding drop in graduations. However, enrolments in Earth Science programs related to aspects beyond core geoscience and geological engineering (e.g. environmental science in its broadest sense) tripled between 2007 and 2022. If these trends continue, the majority of students will be enrolled in these associated programs rather than graduating with core geoscience knowledge and skills. There is a need for more comprehensive and up-to-date data to represent the characteristics of the geoscience workforce accurately and to inform policy decisions and individual career choices. The current situation implies that shortages of qualified geoscience professionals could develop in future years.
A French translation of the North American Stratigraphic Code was published in 1986. It concerned the Code of 1983, which was extensively revised into the Code of 2005, itself subsequently formally updated over the years and republished in 2021*. We present here a new French version of the Code. It also includes formally revised Articles 7 and 20 published in two official Reports in 2023 and 2024, respectively. At the request of the North American Commission on Stratigraphic Nomenclature (NACSN) we have provided a new translation of the North American Stratigraphic Code for the benefit of French speaking geologists around the world. We present here this work. The North American Stratigraphic Code of 1983 was translated into French by the << Minist & egrave;re de l'& Eacute;nergie et des Ressources du Qu & eacute;bec >> and published in 1986. While this translation remains available, it does not reflect the conceptual changes that guided the subsequent rewriting of the Code nor the expansion of its content, both of which led to a new publication in 2005. Several articles of the 2005 Code have since been formally amended to reflect advances in stratigraphic thinking over the years. These amendments, published in Stratigraphy, the official journal of the NACSN, were integrated in a recent, slightly revised version of the Code (2021). Nearly forty years have thus elapsed between the current Code and the 1986 French translation, well justifying the need for an updated French version of the Code. Our translation follows as closely as possible the English text, in agreement with the wish of the NACSN. However, it was not always possible to honour this request and simultaneously meet the demands of the French syntax and grammar. We were careful in conciliating the two texts and in respecting the English meaning. We have departed from the English text in two important instances. We have translated << sequence >>, used throughout the English text, into << successions >> because the term << sequence >> has acquired a specific meaning that is not easily dissociated from << sequence stratigraphy >> whereas << succession >> remains a generic term. Perhaps more importantly, we have translated << rock unit >> and << body of rock >>, idioms that describe the basic unit of stratigraphic nomenclature in the English Code, by << ensemble de terrains >> which, we think, carries more soundly and efficiently the meaning of << rock unit >> and << body of rock >> than translations such as << unit & eacute; de roche >>, << unit & eacute; rocheuse >> and << corps rocheux >> would have. In the last two years, several articles in the 2021 Code have been formally amended and their revision officially published as Reports 15 and 16 in Stratigraphy (2023 and 2024, respectively). Our translations of the amended texts of Articles 2, 61 and 62, designed to formalize chemostratigraphic units and published in Report 15, are incorporated in the present work. Report 16, which addresses in Articles 7 and 20 the empathetic matter of respect of the cultural traditions of people living in geologically significant regions, was published together with French and Spanish translations. The French version of Report 16 uses the 1986 French translation of Articles 7 and 20 while the amendments of these articles were translated by the << Bureau de la traduction, Services publics et Approvisionnement Canada >>. By the time Report 16 was submitted for publication we had already translated Articles 7 and 20, and we retain our texts here for stylistic uniformity. For the same reason, we have modified the amended texts.
Une traduction française du North American Stratigraphic Code, publiée en 1986, concerne le Code de 1983, qui, après complète révision, donna le Code de 2005, lui-même mis formellement à jour au cours des années et republié en 2021*. Nous présentons ici une nouvelle version française du Code. Elle inclut également les révisions formelles des Articles 7 et 20 publiées dans deux rapports officiels (2023 et 2024, respectivement). À la demande de la North American Commission on Stratigraphic Nomenclature (NACSN) nous présentons une nouvelle version française du North American Stratigraphic Code pour le bénéfice des géologues de langue française dans la communauté internationale.Le North American Stratigraphic Code avait été traduit en français par le Ministère de l’Energie et des Ressources du Québec et publié en 1986. Cette traduction reste disponible, mais elle ne reflète pas les changements conceptuels qui ont guidé les révisions successives du Code et l’expansion de son contenu, conduisant ainsi à la publication du Code de 2005. Plusieurs articles de ce Code ont été formellement émendés depuis afin de refléter l’évolution plus récente des concepts stratigraphiques. Ces émendations, publiées dans Stratigraphy, le journal scientifique de la NACSN, ont été intégrées dans une version récente, légèrement révisée du Code, et publiée en 2021. Près de quarante ans se sont donc écoulés entre la traduction française de 1986 et le code actuel, ce qui justifie amplement notre nouvelle version.La traduction que nous proposons est aussi fidèle que possible au texte anglais, ainsi que l’a demandé la NACSN. Toutefois, il n’a pas toujours été possible d’honorer ce souhait et en même temps de satisfaire les règles de la syntaxe et grammaire françaises. Nous espérons avoir concilié les deux langages tout en respectant la signification du texte anglais. Nous nous sommes éloignées de ce texte dans deux cas importants. Nous avons traduit le terme « sequence », utilisé dans tout le texte anglais, par « succession » parce que « sequence » a acquis un usage commun et précis en stratigraphie séquentielle, alors que « succession » reste un terme générique. Par ailleurs, nous avons traduit « rock unit » et « body of rock », mots composés qui décrivent l’unité de base de la nomenclature stratigraphique dans le Code lui-même, par « ensemble de terrains », une expression qui, nous le pensons, exprime plus clairement et efficacement le sens de « rock unit » et « body of rock » que ne le feraient des idiomes tels que « unité de roche », « unité rocheuse », ou « corps rocheux ».Plusieurs articles du Code de 2021 ont été formellement émendés au cours des deux dernières années, et leurs révisions formelles ont fait l’objet des Rapports 15 et 16. Nous avons incorporé nos versions des textes émendés des Articles 20, 61 et 62 qui formalisent les unités chimiostratigraphiques dans le Rapport 15. Le Rapport 16, qui concerne le respect des traditions culturelles des peuples vivant dans des régions d’importance géologique, comprend une traduction en français. Cette dernière fait appel à la traduction de 1986 pour les Articles 7 et 20 alors que la traduction des émendations de ces articles a été effectuée par le Bureau de la Traduction, Services publics et Approvisionnement Canada. Nous avions déjà incorporé les Articles 7 et 20 dans notre version quand le Rapport 16 a été soumise pour publication, de sorte que nous utilisons nos textes dans un souci d’homogénéité stylistique. Pour la même raison nous avons modifié les textes émendés. *North American Commission on Stratigraphic Nomenclature, 2021, North American Stratigraphic Code: Stratigraphy, v. 18, p. 153–204.
“Geosciences are important for humanity” is the central message of a model presented to promote the geosciences as essential to the development of Canada and the world. Components of the geosciences directly or indirectly address all 17 UN Sustainable Development Goals, and geoscientific knowledge is essential in efforts to address climate change. Despite this broad relevance, many Canadians remain unaware of the importance of the geosciences, partly because the discipline is not consistently offered as a standalone high school course in all provinces and territories. The number of students entering undergraduate geology major programs declined by over 40% between 2015 and 2022, and this creates challenges within Canada’s workforce. Currently, gaps in the workforce are filled through immigration, but the federal government is now starting to limit immigration. The seven components of the proposed model include: public engagement to promote the geosciences in varied settings; engagement with politicians and policy makers; engagement with resource and other industries; development and implementation of strategic plans to promote improved awareness of the geosciences; development of public education, outreach and communication programs; promotion of courses and engagement programs at post-secondary institutions; and coordination with geoscience societies and geological surveys. Hosting the International Geological Congress (IGC) 2028 could unite the Canadian geoscience community by strengthening connections between academic geoscientists and government, advocating for a Canadian Research Chair related to geoscience education and outreach, developing an inventory for geoscience education and outreach programs, and exploring creative ways to develop standalone geoscience courses in high school. If all Canadian geoscientists use the model components to emphasize the importance of the geosciences to humanity, we can collectively work towards better public understanding of the relevance of the geosciences to most aspects of life in Canada and improve the future of our vital discipline.
Under the banner of At The Heart Of The Continent, GAC-MAC-PEG 2024 offered a wide and diverse scientific program, with a strong critical minerals component, and several workshops and fieldtrips, as well as extensive outreach and Indigenous engagement programs.It also featured several social events and formal functions that contributed to bringing geoscientists together.The meeting was strongly supported by industry, academia, and government sponsors and hosted numerous exhibitors.This year's meeting was smaller than some previous GAC-MAC events, with 260 abstracts (190 oral and 70 poster presentations) and 350 attendees, perhaps due to the remoteness and perceived lack of appeal of Brandon.Nevertheless, the meeting attracted many international delegates from 25 coun-tries located on almost every continent -indeed, approximately a fifth of the delegates came from beyond Canada.Our diverse attendees were able to learn about the strong and successful Geology Department at Brandon University and about Brandon, the Wheat City, the largest equestrian centre in Canada, and home to a surprisingly successful hockey team, the Wheat Kings.Readers will be able to appreciate the breadth and diversity of the scientific program at the GAC-MAC-PEG 2024 meeting by perusing this issue of Geoscience Canada, which includes all the abstracts.Please note that some limited additional editing was applied as part of the publishing process, so for some there may be small differences from versions distributed at the meeting or available at the conference website.In most cases, these are just format-related matters, but there were a few cases where minor adjustments to grammar, spelling, and continuity of text were resolved to the best of the Geoscience Canada editors' abilities.A very small number of abstracts originally included references, funding acknowledgments or other material that is normally excluded from abstracts, and these were removed from the final layout.Readers who have specific questions about a given contribution or who are interested in clarification should contact the author(s).Registered users can access all abstracts on the conference website (event.fourwaves.com/gacmac2024/,under Presentations).
The northern Appalachian orogen played a pivotal role in early geological studies of mountain belts. Its 100-year global influence as the "type area" for the Hall-Dana geosynclinal theory aptly changed focus with Tuzo Wilson's classic 1966 paper that posed (and answered) the question "Did the Atlantic Close and Then Re-open?" and led to the modern view of global tectonics based on the "Wilson Cycle". In retrospect, these early ideas about mountain-building were much hindered by lack of factual details. The 1978 map of the Appalachian Orogen compiled and hand-drawn by Harold Williams and his students was and remains an outstanding example of geological artwork, although the actual complexity of the orogen that it depicts was barely imagined. However, the tectonic elements and along-orogen correlations that it established still form the essence of our current models, but now supported by an abun dance of geological information collected steadily during the last decades of the 20th century and then accelerated by technological advances during the past 25 years. Examples include the Global Positioning System to provide accurate locations, enhanced geochemical and geophysical methods, computers and the Internet in general, and the development of accurate and precise absolute dating techniques, especially U-Pb dating of zircon. Appalachian studies now cover a spectrum from small areas investigated in detail to orogen-wide and global- scale interpretations that track Appalachian components back to their origins. We now know orders of magnitude more about the orogen than anyone could have imagined in 1978. Not surprisingly all that new knowledge has resolved many of the questions that were being asked in the 1970s but also not surprisingly, many more questions have arisen. It seems that every new map, new interpretation, or new model challenges us with new questions. It appears unlikely that geoscientists will ever be able to sit back and say "All done. We understand everything".
Phenocrysts in porphyritic lava flows are generally considered to have grown under conditions of slow magma cooling within source reservoirs at depth. The matrix (i.e. groundmass) surrounding the phenocrysts is assumed to form under rapid cooling conditions subsequent to eruption of the residual liquids at the surface. Alternatively, it has been demonstrated experimentally that phenocrysts could grow subaerially in basaltic lavas cooled at constant, linear rates. It has been suggested this mechanism could explain the correlation of porphyritic textures with unusually thick canyon-filling flows of Columbia River Basalt. Field and petrographic data supports intratelluric nucleation and growth of plagioclase phenocrysts in three lavas of the Columbia River Basalt Group (CRBG). The distinction is important because the typical basaltic phenocryst paragenesis (plagioclase, followed by olivine, then augite), if produced under surface conditions, cannot be used to test fractional crystallization models in magma reservoirs of the Columbia River Basalt Group or any other lavas. Ideally, to test the hypotheses of subaerial vs. intratelluric (subsurface) growth of phenocrysts, both intrusive (i.e. dykes) and extrusive samples crystallized from the same liquid need to be examined to compare sizes and abundances of phenocrysts. If phenocryst growth occurs only subaerially, then a lava flow should contain more phenocrysts than its intrusive counterpart. In the case of nucleation and growth in both a dyke and its flow, the flow still would contain more phenocrysts due to grains formed in the dyke being added to those formed in the flow. Detailed modal and grain size data were collected for three dyke-flow pairs of CRBG by the author and provide an excellent opportunity to compare intrusive and extrusive textures. These findings along with XRF major and trace element data indicate that the phenocrysts in these lavas must have grown within the magma reservoir and not at the surface. A model is proposed that explains the variation of phenocryst distribution laterally within a lava as an interplay of variations of magma flow and the underlying paleo-topography.
The most abundant iron sulphide minerals in igneous, metamorphic, and some sedimentary rocks are FeS2 (pyrite/marcasite) and Fe1-xS (pyrrhotite). The oxidation of pyrite and pyrrhotite in bedrock aggregates and mine tailings is undesirable to infrastructure and the environment because such chemical reactions are linked with concrete deterioration and acid mine drainage, respectively. The oxidation rate of pyrrhotite is up to one hundred times greater than that of pyrite; thus, pyrrhotite oxidation is of particular concern to society. Pyrrhotite-bearing concrete aggregates may lead to rapid expansion cracking and failure of critical concrete infrastructure including bridges, buildings, and houses, posing a significant safety concern. Additionally, premature disintegration of concrete requires replacement of concrete, leading to excessive aggregate resource extraction and associated increases in CO2 emissions. Considering the widespread concrete infrastructure across Canada, the distribution of pyrrhotite in bedrock used for aggregate is of fundamental importance to the short- and long-term safety of Canadians at the national, regional, and local scales. This pilot study details the initial steps taken to generate national-scale geospatial models of pyrrhotite occurrences in bedrock across Canada and illustrates the associated map products. In total, 12,577 known pyrrhotite occurrences were identified from publicly available provincial and territorial mineral occurrence datasets. The overall modelling strategy involved normalizing the number of pyrrhotite occurrences with respect to the total surface area of major bedrock types and characterizing three different classes of pyrrhotite occurrence density (< 1, 1-4, and 4-10 occurrences/1000 km(2)). The maps illustrate that pyrrhotite occurrence density is highest in volcanic rocks and undifferentiated sedimentary and volcanic rocks, moderate in intrusive and unknown rocks, and lowest in sedimentary and metamorphic rocks. Sedimentary rocks with no pyrrhotite occurrences span large surface areas across central-western Canada thus resulting in an overall low pyrrhotite occurrence density (< 1 occurrence/1000 km2) for this rock type, despite the fact that numerous pyrrhotite occurrences are identified in sedimentary rocks and may be abundant locally or regionally. Volcanic, undifferentiated sedimentary and volcanic, intrusive, and unknown rocks occur throughout the Canadian Shield of central and northern Canada, the Cordillera of western Canada, and the Appalachians of eastern Canada, but bedrock type and associated occurrence density are highly variable within these geological domains. Comparison of pyrrhotite occurrence density maps for Canada with pyrrhotite permissive geology maps for the United States of America illustrates that rocks with a high pyrrhotite occurrence density in Canada (volcanic rocks and undifferentiated sedimentary and volcanic rocks), are contiguous overall with areas of pyrrhotite potential in the United States. Inconsistencies across the international border reflect the differing methodologies and assumptions consisting of a statistically based approach for Canada and a qualitative approach for the United States. In the Cordillera and Appalachians, such discontinuities across the international border may reflect the underestimation of pyrrhotite occurrences in sedimentary rocks of Canada because of the impact of high surface area on the pyrrhotite occurrence density calculations. The maps presented herein are a first step in illustrating the distribution of pyrrhotite-bearing bedrock across Canada and greater North America. These national-scale map products are useful first-order references for selecting regions for follow-up studies on bedrock pyrrhotite occurrences. Regional and local geospatial analysis combined with field work for ground truthing will be important aspects of future research, especially in the vicinity of population centres where bedrock is utilized for concrete aggregate. Detailed regional and local studies of pyrrhotite occurrences in bedrock will help guide the extraction of safe concrete aggregate and contribute to the longterm sustainability of bedrock resources, safe infrastructure, and a habitable climate.
This paper reviews the five Ws (Why, What, Who, When, and Where) of carbon capture and storage in southwestern Ontario. This area is home to nearly one quarter of Canada’s population and approximately three-quarters of one million people work in the manufacturing sector. Fifteen of the province’s top 20 CO2 emission point sources are in this area. The industries responsible for these emissions include steel mills, refineries and petrochemical plants, and cement plants. These industries are part of the hard-to-abate sector, in that CO2 is used or generated as an integral part of the industrial process. As such, eliminating or even reducing emissions from these industries is a difficult task. Carbon capture and storage (CCS) projects aim to sequester that gas in sedimentary basins over periods exceeding several thousand years. To this end, deeply buried (> 800 m) porous and permeable rocks (a repository) must be overlain by impermeable rocks that act as a seal, preventing the upward migration of CO2 into the atmosphere. The possibility that injection activities could trigger seismicity is but one of the additional considerations. When operational, CCS projects have a negative carbon footprint and the desirability of developing and using this technology has been established for over 20 years. True CCS projects differ from carbon capture, utilization, and storage (CCUS) projects in that the former are only designed with sequestration in mind. One type of CCUS project involves using CO2 for enhanced oil recovery (EOR) and this technology has been employed for several decades. Cambrian sandstones are the most suitable injection targets for CCS in southwestern Ontario because previous oil and gas drilling has shown the rocks to have the necessary characteristics. They are buried below 800 m, can be tens of metres thick, and have adequate porosity and permeability. However, the Cambrian section is lithologically and stratigraphically heterogeneous and oil, gas, and brine can all be present in the pore space. The extent to which this complexity will affect CO2 injection has not yet been evaluated.
