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FRINATEK-Fri prosj.st. mat.,naturv.,tek

POLARIS - evolution of the Arctic in deep time.

Alternative title: POLARIS - geologisk utvikling i Arktis.

Awarded: NOK 8.0 mill.

Project Number:

326238

Project Period:

2021 - 2025

Location:

Partner countries:

Beneath the ice, water, and tundra of the Arctic today lies a vast landscape of rocks. These rocks are different types and ages, and form part of Earth’s outer shell (the crust) which can be divided into tectonic plates. Today, the Arctic is located on either part of the North American or Eurasian plate, with a plate boundary between running between. Motion occurs across plate boundaries; in some places they move apart and in others they move together. Importantly, the plates and boundaries change through time, and their motion is referred to as “plate tectonics.” The rocks of the high Arctic record a rich, and at times, explosive, history; the opening and closure of oceans, collision of landmasses, eruption of massive volcanoes, major shifts in climate and ocean patterns, and mass extinction events. This geological complexity is also confounded due of the relative remoteness and difficulty in acquiring data - the polar regions are some of the most difficult parts of the global tectonic puzzle. For example, two major events occurred 120 to 80 Million years ago; a major volcanic eruption (High Arctic Large Igneous Province) and a new ocean basin (Amerasia Basin). The cause and consequences of these events are still being unraveled. In particular, 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). Earth's interior is the graveyard of extinct oceans but also the birth place of upwellings (mantle plumes) and future oceans. POLARIS will investigate the geological evolution the Arctic back to 420 Million years ago (Devonian times). It will generate state-of-the-art, 4-dimensional (3-D space plus time) computational models including the surface and the interior of the Earth. These Earth models will help us zoom into the turbulent history of the Arctic, and understand the physical processes that link the deepest Earth and the surface.

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.

Activity:

FRINATEK-Fri prosj.st. mat.,naturv.,tek