<p>Oceanic crustal basalt rock has been identified to be the most abundant CO2 sequestration reservoir on earth with a total capacity of up to 250,000 Gt of CO2 and the added advantage of the CO2 mineralizing into carbonate rock in the safest and most durable way. Experiments and pilot projects have established geologic carbon storage in basalt on land (e.g. Carbfix in Iceland) but have not been carried out offshore and are therefore required to demonstrate and prove this form of carbon storage offshore. We are presenting the ongoing Solid Carbon project, which is currently in the feasibility stage of demonstrating this concept in the Cascadia Basin offshore Vancouver Island where Ocean Networks Canada operates a cabled ocean observatory, which will be utilized to monitor and verify this form of geologic carbon storage. The demonstration site is at about 2700 m water depth, where the ocean crust is overlain by 200-600 m of sediment acting as a cap for the porous and permeable crustal basalt aquifer (300-500 m thick), underlain by a thick conductive basement. From previous seafloor drilling campaigns, the subsurface and hydrogeology in this area are well known, feeding both into sequestration modelling and also planning the required monitoring. In addition to planning the offshore demonstration experiment, the Solid Carbon project further includes research on social, regulatory and social acceptance as well as adding offshore energy and direct carbon capture to transform the concept into a negative emission technology. We will present the past, present and potential future of this form of geologic carbon storage.</p>

Offshore basalts, most commonly found as oceanic crust formed at mid-ocean ridges, are estimated to offer an almost unlimited reservoir for CO2 sequestration and are regarded as one of the most durable locations for carbon sequestration since injected CO2 will mineralize, forming carbonate rock. As part of the Solid Carbon project, the potential of the Cascadia Basin, about 200 km off the west coast of Vancouver Island, Canada, is investigated as a site for geological CO2 sequestration. In anticipation of a demonstration proposed to take place, it is essential to assess the tendency of geologic faults in the area to slip in the presence of CO2 injection, potentially causing seismic events. To understand the viability of the reservoir, a quantitative risk assessment of the proposed site area was conducted. This involved a detailed characterization of the proposed injection site to understand baseline stress and pressure conditions and identify individual faults or fault zones with the potential to slip and thereby generate seismicity. The results indicate that fault slip potential is minimal (less than 1%) for a constant injection of up to ~2.5 MT/yr. This is in part due to the thickness of the basalt aquifer and its permeability. The results provide a reference for assessing the potential earthquake risk from CO2 injection in similar ocean basalt basins.

The crystalline crust that underlies the Western Canada Sedimentary Basin in northern Alberta is composed of tectonic domains that accreted to the margin of the Archean Rae province of western Laurentia, ca. 2.1‐1.8 Ga. Previous tectonic models in this region invoke complex plate dynamics, including oppositely verging subduction zones, to explain the assembly of various geologic domains. In this paper, we introduce a new tectonic model that invokes back‐arc extension within the Chinchaga Domain (CD). The basement crust in the CD hosts a vast, mid‐crustal reflection sequence (Winagami Reflection Sequence), previously interpreted as a mafic sill complex that intruded into an atypically wide domain of Paleoproterozoic arc magmatism. The latter has been interpreted to have formed during Paleoproterozoic tectonic assembly through near‐synchronous closure of multiple small oceanic basins and/or magmatism in a plate interior setting. Based on a reinterpretation of regional geophysical data and post‐compressional fabrics observed by re‐examination of drill cores, we propose that observed temporal relationships and present‐day configuration of Paleoproterozoic arcs is better explained by post‐assembly extension of the Chinchaga Domain. The proposed post‐assembly modification is analogous to the recent tectonic evolution of the Basin and Range and can be explained through back‐arc extension linked to slab rollback and/or a proximal coeval transform plate boundary. Our model implies a back‐arc setting for the Winagami sill complex; it also provides a tectonic framework for explaining the origin of an enigmatic low δ18O anomaly (Kimiwan anomaly) and reactivated basement faults associated with recent induced seismicity.