Beneath the Arctic today lies a vast landscape of rocks that record the deep-time history of the region - from present-day to over thousands, millions, and even billions of years into the past. The geological history of the Arctic was complex and ever-dynamic, often times turbulent and explosive. Over the past 400 Million years (since the Devonian period) the region has experienced episodes of mountain building, the opening and destruction of ocean basins, shifting coastlines, massive volcanic eruptions, and major changes in both the marine and terrestrial environments. Furthermore, the “Arctic” itself was once located closer to the equator and gradually moved northwards over time, underscoring the need for deep time and global-scale perspectives. However, unravelling this geological complexity is hampered by the region’s relative remoteness and the difficulty and expense in acquiring new data. The project “POLARIS – evolution of the Arctic in deep time” therefore focused on integrating existing datasets and developing innovative computational workflows to better understand the geological evolution the Arctic region.
The core of POLARIS was an investigation into the interplay of plate tectonics and whole mantle convection – essentially a geodynamic approach. Through this project, the role of the Earth’s deep interior came more clearly into focus. Beneath the tectonic plates (which include the crust and lithosphere) lie very slowly moving mantle rocks. This mantle is not only a graveyard for ancient oceanic seafloor that has been subducted, but also the birthplace of hot upwellings (mantle plumes) that can trigger massive volcanic events. Connecting processes at the surface with those in the deep Earth requires cross-scale thinking and diverse skill sets.
The core POLARIS team included the PI (Dr Grace Shephard) and researcher (Dr Björn Heyn), who both worked on creating state-of-the-art, 4-dimensional (3-D space plus time) computational models. POLARIS has showcased how combining multiple types of data (both legacy and new) and merging multiple methodologies, including observational and numerical modelling approaches, can yield novel insights into the Arctic and its deep time processes.
One particular research highlight was related to a major but poorly understood volcanic event: the High Arctic Large Igneous Province (HALIP). This event is particularly unusual because it occurred over an extended time period from about 120-80 Million years ago, lasting 50 million years in duration. HALIP volcanism occurred across the Arctic, with remnants preserved in Arctic Canada, Greenland, Svalbard, the Siberian shelf, and even buried beneath the central Arctic Ocean. Its timing, causes and consequences of remain active research questions. Using novel, cutting-edge numerical models built with the ASPECT finite element code, the team identified a link between a rising, buoyant mantle plume and the shape of the Arctic lithosphere, which may explain the widespread and long-lived nature of HALIP volcanism. The POLARIS project resulted in 20 publications that ranged across the breadth of the project objectives, including tectonics, paleogeography, mantle convection, volcanism as well as other complementary topics including polar education, science in prisons, and scientific visualization.
As part of the POLARIS project, the team also contributed to field research in the Barents Sea, Svalbard, Alaska, and central Australia, and participated in undergraduate and post-graduate teaching and supervision. Science outreach was also a key priority and included STEM activities to children and Norwegian-language blog articles. Working with a wider international network, POLARIS has also contributed to new interdisciplinary studies and insights into geoscience education and communication, including the importance of selecting colour schemes and the transformative role that teaching STEM in non-traditional locations, such as in prisons.
"POLARIS - evolution of the Arctic in deep time" addressed fundamental questions regarding the long-term geological evolution of the Arctic region. It investigated the cross-scale interplay of plate tectonics, paleogeography, mantle convection, and magmatism, and resulted in 20 co-authored publications and over 50 dissemination efforts. The project focused on integrating observational data and developing computational methods and routines, including using the open source software ASPECT (for mantle convection) and GPlates (for plate reconstructions). A time-dependent link of the surface and deep mantle was a particularly under-developed avenue of research for the Arctic, and this project was amongst the first to produce numerical models of the mantle plume that may have formed the enigmatic High Arctic Large Igneous Province (HALIP) e.g. Heyn et al. (2024) Shephard et al. (in prep). Another research highlight was for the North Atlantic, a region of high industry and academic interest, and included a new deformable plate reconstruction for the opening of the North Atlantic, including four phases of rifting back to the Permian (Shephard et al., 2026; Abdelmalak et al., 2022). Another common thread in the research was Svalbard, and several co-authored papers showcased the unique window that this archipelago and the surrounding oceanic region offers in understanding the broader Arctic's geological (and polar exploration) history (e.g. Senger et al., 2024, 2025; Meza-Cala et al., 2024, 2025, Shephard 2026). Understanding long-term processes of the solid portion of the Earth also have wider implications for understanding feedbacks in the wider Earth system, including in icehouse-to-greenhouse shifts, ocean circulation pattern changes, and mass extinction events. This knowledge can in turn be used to provide analogues for how the environment may respond to, and recover from, intervals of profound change. Model outputs have been made publicly available in line with the data management plan. The project also contributed to co-supervision of 10 postgraduate and undergraduate students, a dedicated "Arctic Tectonics and Volcanism" course at UNIS, STEM outreach initiatives with children and young adults, and several other professional and leadership roles, including for the International Arctic Science Committee. POLARIS activities aligned closely with a number of Norwegian and international networks, and have led to a number of continuing initiatives and collaborations, including in IODP/ICDP drilling applications, numerical modelling studies, a humanities, science visualisation and graphics courses, and sharing science with underrepresented groups such as those in prisons. POLARIS has helped raise the profile of Arctic geodynamics and highlight the contributions of women in STEM. POLARIS served as the foundation for the PI's new project "AUSTRALIS - Deep time evolution of mineral systems in the Tasmanides" funded by The Australian Research Council.
The geological evolution of the Arctic is as long-lived as it is complicated, and this complexity is a function of its time evolution. Over the last 400+ Million years, the Arctic has experienced extreme terrane mobility, massive volcanic events, and the opening and destruction of oceans. These processes have environmental impacts like mountain building, anoxic ocean events, ice-sheet formation, and mass-extinctions. To study these interactions, the Arctic must be studied as a unique part of a 4-dimensional whole-Earth domain. However, the spatial connections (including vertically, down to the core boundary, and horizontally over 1000s kms over plates), through to their time-dependent evolution are still poorly understood. This is particularly true for the deep mantle connection, e.g. subducted slabs and mantle plumes, which is particularly underexplored for the Arctic. POLARIS aims to honour these scales and processes by linking the geodynamic evolution of the deep mantle and surface Arctic.
POLARIS will investigate plate tectonics, mantle convection and magmatism through a framework of synthesising existing data and methods, and generating novel numerical models and analyses. POLARIS will deliver a self-consistent digital Arctic plate reconstruction back to the Late Paleozoic (~419 Ma), and embed it in global plate reconstructions. It will generate palaeogeographic maps, including bathymetry, topography, facies, plate boundaries and agegrids. The time-dependent mantle connection will be established by exploring Arctic-proximal subduction events and their characteristics including via seismic tomography, forward mantle convection models, and subduction volume estimates (including for True Polar Wander). A plume-origin hypothesis for explaining Arctic Cretaceous magmatism (High Arctic LIP) will be investigated, as well as a controversial link 250 Million year link between the HALIP, the Iceland Plume and the Siberian Traps, and lowermost mantle thermal structures.
