4DARCTIC: Structure and Evolution of Arctic crust and mantle based on multi-scale geophysical studies

The main goal of this Norwegian-Russian collaboration under the 4D Arctic project is to develop a geodynamic model for the Arctic region that explains the present day architecture of the crust and mantle and the tectonic evolution. To accomplish this task we mainly use geophysical data and plate tectonic methods. The new model of the present day continental and oceanic crust in the High Arctic region - ArcCRUST - includes: total crustal thickness, total sediment thickness, depth to Moho discontinuity and calculated stretching factors (Lebedeva-Ivanova et al., in review). 4D Arctic studies have been published in 2016 in four papers and 13 conference presentations. The project and collaboration was presented in several international meetings and a special interdisciplinary European Geophysical Union General Assembly session was dedicated to this (session GD6.2/GMPV8.4/SM6.7: The Arctic connection - plate tectonics and crustal and mantle dynamics in the North Atlantic, North Pacific and the High Arctic, conveners: C. Gaina, N. Lebedeva-Ivanova, and S. Lebedev). The results of our project are now used for the strategic Norwegian consortium initiative "GoNorth - Kunnskapsbygging i Polhavet". The interdisciplinary Master course: A Changing Arctic developed for the University of Oslo International School (ISS) was taught for the 3rd time this summer for 5 weeks in June/July. The course attracted 18 students, several of them from Russian universities.

We aim to undertake an interdisciplinary collaborative project with Russian partners where existent and new geophysical data will be used to build multi-scale models that will unravel the structure and evolution of Arctic's crust and mantle and their inte raction through time. We will assemble, quality-check and compile a variety of geophysical data (potential field, paleomagnetic, heatflow, bathymetry, seismic data, etc) and geological evidences for volcanism and vertical movements through time in order t o be able to characterize the heterogeneities of the present-day Arctic crust and model its kinematic evolution since the Late Jurassic (ca. 150 million years ago). New, multi-scale tomographic models for the Arctic mantle will be constructed using travel time data from the global ISC catalogue. In order to cover the less seismic active areas or with low seismic station coverage, reflected PP data will be also included and to further improve the resolution and reliability of the tomographic models in some regions, we plan to add any available information from regional networks, as well as data on Russian super-long seismic profiles acquired with nuclear explosions. Besides regional models of 1000s km scale, we plan to study the crust and uppermost mantle in selected regions (10s-100s km scale) based on local seismicity data, including data from network deployments on drifting ice. Acquisition of new seismic data along the Russian Arctic coast is also part of this project. Kinematic reconstructions and reg ional tomographic models of the Circum-Arctic regions will be used to construct geodynamic models that will include 3D numerical calculations of the mantle flow using existent academic codes and new software developed by Russian and Norwegian participant s. Finally, we will compute the dynamic topography due to the mantle flow and mantle plumes and assess its implications to anomalous subsidence and volcanism in the Arctic area through time