The influence of orogenesis on a large igneous province: a focus on Eurekan deformation on HALIP in the Canadian High Arctic

The Cretaceous High Arctic Large Igneous Province (HALIP; 135 – 75 Ma) is a massive magmatic province preserved in the circum-Arctic region through a series of volcanic flows, sills, and dykes. The plumbing geometry of LIPs, often showcased through the dyke swarms, can inform the paleo-stress regime, rheological behaviour, and tectonic history of the region. Pre-drift plate tectonic reconstruction models have identified the presence of HALIP’s signature 1600 km diameter, quasi-circular circumferential dyke swarm which encloses a radial dyke swarm extending onshore to continental masses including the Queen Elizabeth Islands of the Canadian Archipelago. The foci of the swarms are debated to be derived via mantle plume, continental rifting, or combined mechanisms, producing three major pulse events and resulting in the intrusion of the associated dykes. The earliest dykes are thought to bare economic concentrations of Ni-Cu-PGE sulfides, specifically in Axel Heiberg Island and western Ellesmere Island, Canada. Despite HALIP’s massive extent and prospectivity for Ni-Cu-PGE deposits, it remains one of the least explored LIPs on Earth based on its remote location, limited surface exposure, extensive glacial coverage, and scarce, discontiguous geophysical data.

In particular, the presence of HALIP dykes in northeastern Ellesmere Island is suspected, yet remains unmapped. The Paleogene Eurekan deformation and orogeny (63 – 35 Ma) has been hypothesized to have reworked the dykes in the region, overprinting the extent of HALIP with orogenic deformation. Here, we test the theory that unmapped HALIP dykes extend into northeastern Ellesmere Island and are subsequently impacted by the Eurekan deformation, suggesting an increased geographical presence and prospectivity of the LIP.

To test this theory, we present a series of three-dimensional numerical models to investigate the presence, impact, and prospectivity of HALIP dykes in northeastern Ellesmere Island. Utilising the open-source geodynamic code Advanced Solver for Planetary Evolution, Convection, and Tectonics (ASPECT), we superimpose a range of dyke configurations to evaluate the structural controls of HALIP dykes on host rocks at depth during the convergent plate tectonic boundary conditions that took place during Eurekan deformation. The range of dyke configurations are collated from a comprehensive review of dyke and host rock samples from neighbouring regions to accurately parameterize and configure the models to HALIP and the High Arctic, allowing for a direct link between outsourced field data and our numerical modelling.

The suite of Eurekan deformed HALIP dyke models are then critically contrasted to available geological and geophysical data in the region. Finally, we produce an analysis of the likelihood that HALIP intrusions were overprinted by Eurkean deformation, or that the HALIP extent is not as significant as previously thought. Our work here provides new insights into an understudied area of the Canadian Arctic, which may be a future site for critical mineral prospectivity.