Beneath the ice, water, and tundra of the circum-Arctic today lies a vast landscape of rocks. A map showing the topography (on land) and bathymetry (under oceans) of the region reveals some key features of interest.
The rocks are different types and ages, and form part of the Earth’s outer shell (the crust) which can be divided into tectonic plates. These plates are in perpetual motion, generally moving at the rate that our fingernails grow. This a plate moving at 1 cm/yr will have moved 10 km in a million years.
In some places the plates move apart (such as at mid-oceanic ridges) and in other places they move together (such as at subduction zones). This motion is referred to as “plate tectonics” and is a fundamental reason why we have diverse landscapes, resources, climate, natural hazards, biological species, and more. Understanding past plate motion therefore requires a consideration of timescales of hundreds of millions of years.
An animation running backwards in time from today to 200 Million years ago. It shows the motion of plates (arrows) and the plate boundaries (red) and is from the global plate model of Müller et al. (2016). At 200 Ma was the supercontinent “Pangea.”
The rocks of the high Arctic record a rich tectonic history, with major changes in the configuration of oceans and land, and which at times was explosive with massive volcanic eruptions. However, understanding this history is difficult; geological complexity is confounded due of the relative remoteness and difficulty in acquiring data – the polar regions are some of the most difficult parts of the global plate tectonic puzzle!
But it is not just a story about the surface rocks – the role of the deep Earth is coming more into focus. If we peel back the plates, there are very slowly moving rocks inside the Earth (the mantle, down to around 2800 km depth). The interior of the Earth is therefore the graveyard for extinct oceans (referred to as subducted slabs) but also the birth place of upwellings (mantle plumes which may lead to volcanic eruptions) and future oceans.
A simplified schematic of the interior zones of the Earth. POLARIS will delve from the surface (the lithosphere 0-200 km) through the upper mantle, the transition zone (410-660 km), and then down the bottom of the lower mantle (at ~2891 km depth). In the lower mantle there is sluggish convection, with rocks of different properties such as temperature and composition. This is where extinct-oceans (subducted slabs) reside, and where deep mantle plumes originate.
POLARIS aims to tackle these processes by generating state-of-the-art digital Earth models. At the links below you can learn more details – you can start at the surface with Arctic tectonics, then move to the deep interior to Arctic Mantle structure, and resurface again via eruptive Arctic volcanism.
Learn more about the tectonic plates of the Arctic and how they have shifted about through time. Landmasses have shifted, oceans have disappeared, and mountains have been built.
What is deep located below the Arctic and how does it connect to the surface? There are upwellings (such as mantle plumes) and downwellings (such as subducted slabs). We cannot directly access this region so must look to other datasets.
There have been several episodes of massive volcanic eruptions in the Arctic – these include the Iceland Plume, High Arctic Large Igneous Province, Siberian Traps. These eruptions connect processes at the surface and the deep mantle.