Lithosphere thermo-chemical heterogeneity in the European-North Atlantic region, Greenland and Anatolia

We present a new model, EUNA-rho (Shulgin and Artemieva, 2019, JGR), for the density structure of the European and the North Atlantics upper mantle based on 3D tesseroid gravity modeling and a new regional model for the lithosphere thickness in Europe, Greenland, the adjacent off-shore regions (Artemieva, 2019ab, ESR), and Anatolia (Artemieva and Shulgin, 2019, Tectonics). On continent, there is no clear difference in lithosphere mantle (LM) density between the cratonic and Phanerozoic Europe, yet a ca. 300 km wide zone of a high-density LM along the Trans-European Suture Zone may image a paleosubduction. Kimberlite provinces of the Baltica and Greenland cratons have a low density mantle, while the correlation between LM density and the depth of sedimentary basins indicates an important role of eclogitization in basin subsidence, with the presence of 10-20% of eclogite in LM beneath the super-deep platform basins and the East Barents shelf. The Barents Sea has a sharp transition in lithosphere thickness from 120-150 km in the west to 175-230 km in the eastern Barents. Highly heterogeneous lithosphere structure of Anatolia is explained by the interplay of subduction systems of different ages. The block with 150 km thick lithosphere in the North Atlantics east of the Aegir paleo-spreading may represent a continental terrane. In the North Atlantics, south of the Charlie Gibbs fracture zone (CGFZ) bathymetry, heat flow and mantle density follows half-space cooling model with significant deviations at volcanic provinces. Strong low-density LM anomalies (<-3%) beneath the Azores and north of the CGFZ correlate with geochemical anomalies and indicate the presence of continental fragments and heterogeneous melting sources. Thermal anomalies in the upper mantle averaged down to the transition zone are 100-150^o C at the Azores and can be detected seismically, while a <50^o C anomaly around Iceland is at the limit of seismic resolution.

References:

• Artemieva I.M., 2019. The lithosphere structure of the European continent from thermal isostasy. Earth-Science Reviews, 188, 454-468.     
• Artemieva I.M., 2019. Lithosphere thermal thickness and geothermal heat flux in Greenland from a new thermal isostasy method. Earth-Science Reviews, 188, 469-481.
• Shulgin A. and Artemieva I.M., 2019. Thermochemical heterogeneity and density of continental and oceanic upper mantle in the European‐North Atlantic region. Journal of Geophysical Research: Solid Earth, 124, 1-33, doi: 10.1029/2018JB017025 (open access)       
• Artemieva I.M. and Shulgin A., 2019. Geodynamics of Anatolia: Lithosphere thermal structure and thickness. Tectonics, 38, 1-23, doi: 10.1029/2019TC005594