Thermochemical Heterogeneity and Density of Continental and Oceanic Upper Mantle in the European‐North Atlantic Region

Abstract

We present a new model, EUNA‐rho, for the density structure of the continental and oceanic upper mantle based on 3‐D tesseroid gravity modeling. On continent, there is no clear difference in lithospheric mantle (LM) density between the cratonic and Phanerozoic Europe, yet an ~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 (3.32 g/cm3) mantle where all non‐damondiferous kimberlites tend to a higher‐density (3.34 g/cm3) anomalies. LM density correlates with the depth of sedimentary basins implying that mantle densification plays an important role in basin subsidence. A very dense (3.40–3.45 g/cm3) mantle beneath the superdeep platform basins and the East Barents shelf requires the presence of 10–20% of eclogite, while the West Barents Basin has LM density of 3.35 g/cm3 similar to the Variscan massifs of western Europe. In the North Atlantics, south of the Charlie Gibbs fracture zone (CGFZ) mantle density follows half‐space cooling model with significant deviations at volcanic provinces. North of the CGFZ, the entire North Atlantics is anomalous. 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 °C at the Azores and can be detected seismically, while a <50 °C anomaly around Iceland is at the limit of seismic resolution.

Lithosphere Mantle Density of the North China Craton

“…Journal of Geophysical Research: Solid Earth nearly uniform average crustal velocity and density (Xia et al, 2017), so that the difference between the Bouguer plate approximation and the full 3-D solution is also small (Shulgin & Artemieva, 2019). Due to the small density contrast across the LAB and its large depth, the 3-D gravitational effects from the LAB are insignificant.…”

“…Since the calculation is made on a 1 × 1°grid, the gravitational effect of the neighboring cells for the expected density heterogeneity in the crust and LM is small (<20 mGal) and can be neglected. Furthermore, the crust in the study region has a smooth Moho without sharp changes and a nearly uniform average crustal velocity and density (Xia et al, 2017), so that the difference between the Bouguer plate approximation and the full 3‐D solution is also small (Shulgin & Artemieva, 2019). Due to the small density contrast across the LAB and its large depth, the 3‐D gravitational effects from the LAB are insignificant.…”

Geodynamics of Anatolia: Lithosphere Thermal Structure and Thickness

“…Mantle temperature anomalies, assuming no compositional density variations, may also be calculated from gravity data, if the crustal structure is known (Shulgin & Artemieva, ). However, this requires independent information on the lithosphere thickness in order to calculate the gravitational effect of temperature‐induced density variations in the lithosphere mantle.…”

Probabilistic Linear Inversion of Satellite Gravity Gradient Data Applied to the Northeast Atlantic

“…(2017), Tan et al. (2018), and Shulgin and Artemieva (2019) are among recent publications. Tan et al.…”

“…The density structure of the lithosphere and asthenosphere in the northeast Atlantic region has been previously addressed in a number of studies based on analysis of gravity data. Haase et al (2017), Tan et al (2018), and Shulgin and Artemieva (2019) are among recent publications. Tan et al (2018) focus on the lithospheric density structure of the oceanic region around Jan Mayen Island and discuss possible impact of the Iceland hotspot on the temperature and density structure of this region.…”