Abstract
Abstract A new regional compilation of seamount-like oceanic igneous features (SOIFs) in the NE Atlantic points to three distinct oceanic areas of abundant seamount clusters. Seamounts on oceanic crust dated 54–50 Ma are formed on smooth oceanic basement, which resulted from high spreading rates and magmatic productivity enhanced by higher than usual mantle plume activity. Late Eocene–Early Miocene SOIF clusters are located close to newly formed tectonic features on rough oceanic crust in the Irminger, Iceland and Norway basins, reflecting an unstable tectonic regime prone to local readjustments of mid-ocean ridge and fracture zone segments accompanied by extra igneous activity. A SOIF population observed on Mid-Miocene–Present rough oceanic basement in the Greenland and Lofoten basins, and on conjugate Kolbeinsey Ridge flanks, coincides with an increase in spreading rate and magmatic productivity. We suggest that both tectonic/kinematic and magmatic triggers produced Mid-Miocene–Present SOIFs, but the Early Miocene westwards ridge relocation may have played a role in delaying SOIF formation south of the Jan Mayen Fracture Zone. We conclude that Iceland plume episodic activity combined with regional changes in relative plate motion led to local mid-ocean ridge readjustments, which enhanced the likelihood of seamount formation. Supplementary material: Figures detailing NE Atlantic seamounts and SOIF distribution, and the location of earthquake epicentres are available at https://doi.org/10.6084/m9.figshare.c.3459729
Highlights
If the seamounts were formed at the time of, or shortly after, seafloor spreading, their emplacement coincides with an increase in spreading rates and higher magmatic productivity
Large seamounts were formed on the Rockall plateau and in the Rockall Trough around 52 Ma, and the Iceland plume activity increased at 55 and 52 Ma, which could indicate that the Early Eocene seamount-like oceanic igneous features’ (SOIFs) formation in the NE Atlantic may have resulted from higher than usual mantle plume activity
The second SOIF group is located on Late Eocene – Early Miocene oceanic crust of the Irminger, Iceland and Norway basins
Summary
The identification of SOIFs in region I (Fig. 5a) is based on bathymetry (in most cases, satellitederived altimetry and multibeam data for a few cases: see EarthRef.org/SC) only. 13 SOIFs were identified as igneous centres, four of them on the eastern JMMC, in the vicinity of the COB (Peron-Pinvidic et al 2012; Blischke et al, this volume, in press), and linked to break-up volcanism. A few igneous centres (five out of 22) were identified on seismic reflection, bathymetry, gravity and magnetic anomaly gridded data along the Greenland margin (and may be linked to the Oligocene break-up processes). One of these igneous centres is located on continental crust. The NAG-TEC study has not included this area into its SOIF database and we will not discuss them further, as there is sparse information about volcanic centres in that region
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