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• Belosa, Lea; Callegaro, Sara; Meyzen, Christine M; Gaina, Carmen; Polteau, Stephane & Bizimis, Michael [Vis alle 7 forfattere av denne artikkelen] (2024). Deep Mantle Component and Continental Crust Remobilization in the Source of Vesteris Seamount, East Greenland Margin. Geochemistry Geophysics Geosystems. 25(1). doi: 10.1029/2023GC011196. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Vesteris Seamount is a large Quaternary intraplate submarine volcano in the SW Greenland Sea, about 1,000 km NE of Iceland and 300 km NW of the Mohn's spreading ridge, whose mode of formation remains unsolved. We present geochemical data for new samples dredged from the Vesteris edifice, including major, trace elements and Sr‐Nd‐Pb‐Hf isotopes. The isotopic characteristics of the alkaline lavas, covering the basanite/tephrite to benmoreite range, indicate the involvement of depleted and enriched mantle components. The source is dominated by the depleted mantle (85%–90%) and a deep enriched component possibly supplied by the Iceland Plume (IP) (10%–15%). Additional source enrichment was due to recycled crust and sub‐continental lithospheric mantle, as suggested by Hf isotopes (0.283147 ± 0.000005) measured for the first time in Vesteris lavas and by a decoupling in Pb isotopes evidenced by relatively low‐radiogenic 207 Pb/ 204 Pb (15.510) and high‐radiogenic 208 Pb/ 204 Pb (38.554) with respect to the Northern Hemisphere Reference Line. We interpret the geochemical results using existing knowledge about the regional lithospheric and upper mantle structure. Our findings suggest that a deep (ca. 420–320 km) mantle anomaly, with seismological characteristics of the Iceland mantle plume, extends from East Greenland to the north of Jan Mayen Fracture Zone. The regional lithospheric thinning toward the Greenland Basin enabled the melting events that produced the Vesteris seamount. This lateral NNE‐directed flow lobe of the Iceland plume may have carved and transferred enriched components from the continental lithospheric margin of Greenland north of Scoresby Sund toward the Vesteris source.

• Belosa, Lea; Murphy, D. T.; Ubide, T.; Callegaro, Sara; Meyzen, C. M. & Bizimis, M. [Vis alle 7 forfattere av denne artikkelen] (2024). Magmatic evolution and architecture of an oceanic intraplate volcano: Vesteris Seamount, Atlantic Ocean. Frontiers in Earth Science. 12. doi: 10.3389/feart.2024.1501694. Fulltekst i vitenarkiv Vis sammendrag

  Vesteris is a large (33 × 27 km) and young (summit age: 0.65–0.010 Ma) intraplate seamount in the Greenland Sea, formed from ocean island basalt (OIB) magmatism. The volcano is composed of alkali basalt, basanite/tephrite, phonotephrite, mugearite, and benmoreite. Its phenocryst assemblage includes clinopyroxene, plagioclase, olivine, amphibole, rare haüyne, and oxides (Ti–magnetite and Cr–spinel), with phenocrysts hosting inclusions of apatite, sulfides (pyrrhotite), and melt. Despite its geological significance, the processes governing magma storage, ascent, and eruption dynamics remain poorly understood. To address this, we conducted detailed micro–chemical analyses of phenocrysts, groundmass microcrysts, melt inclusions, and groundmass glass. Using mineral–melt thermobarometry, we characterized the pre– to syn–eruptive crystallization conditions and reconstructed the architecture of the volcanic plumbing system. Our findings indicate that basanite liquids were primarily stored in the upper mantle (∼6.4 kbar; ∼22 km depth) with evidence of multi-level storage extending to ∼9 kbar (∼30 km depth). Textural and compositional zoning in clinopyroxenes suggests rapid magma ascent, while mafic recharge emerged as a key mechanism for remobilizing evolved clinopyroxene mush. Mafic recharge magmas also introduced early olivine crystals, which were later overgrown by high-Mg clinopyroxene upon mixing with more evolved melts. These results demonstrate that major crystal fractionation occurs in the upper mantle beneath Vesteris, resembling processes observed in low-flux ocean island basalt volcanoes. The evidence for rapid magma ascent highlights the dynamic nature of magma movement within the plumbing system, driven by mafic recharge and crystal-melt interactions.

• Durn, Goran; Perković, Ivor; Razum, Ivan; Ottner, Franz; Škapin, Srečo D. & Faivre, Sanja [Vis alle 9 forfattere av denne artikkelen] (2023). A tropical soil (Lixisol) identified in the northernmost part of the Mediterranean (Istria, Croatia). CATENA. ISSN 0341-8162. 228. doi: 10.1016/j.catena.2023.107144. Fulltekst i vitenarkiv
• Durn, Goran; Perković, Ivor; Razum, Ivan; Ottner, Franz; Škapin, Srečo D. & Faivre, Sanja [Vis alle 9 forfattere av denne artikkelen] (2023). RETRACTED -A tropical soil (Ferralsol) identified in the northernmost part of the Mediterranean (Istria, Croatia). CATENA. ISSN 0341-8162. 224. doi: 10.1016/j.catena.2023.106955. Fulltekst i vitenarkiv

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• Durn, Goran; Perković, Ivor; Razum, Ivan; Ottner, Franz; Škapin, Srečo D. & Faivre, Sanja [Vis alle 9 forfattere av denne artikkelen] (2023). Retraction notice to “A tropical soil (Ferralsol) identified in the northernmost part of the Mediterranean (Istria, Croatia)” [CATENA 224 (2023) 106955] (Catena (2023) 224, (S0341816223000462), (10.1016/j.catena.2023.106955)). CATENA. ISSN 0341-8162. 228. doi: 10.1016/j.catena.2023.107161. Fulltekst i vitenarkiv
• Belosa, Lea; Gaina, Carmen; Callegaro, Sara; Mazzini, Adriano; Meyzen, Christine M & Polteau, Stephane [Vis alle 7 forfattere av denne artikkelen] (2022). Plume-Fracture Zone interactions in the NE Atlantic. Fulltekst i vitenarkiv
• Belosa, Lea; Gaina, Carmen; Callegaro, Sara; Trønnes, Reidar G; Mazzini, Adriano & Meyzen, Christine M [Vis alle 7 forfattere av denne artikkelen] (2021). Constraining the enigmatic source of Vesteris Seamount volcanism. Fulltekst i vitenarkiv
• Belosa, Lea (2025). Intraplate Volcanism in the Northeast Atlantic and the role of fracture zone-plume interactions. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Intraplate volcanism in oceanic settings provides constraints on mantle composition, melt generation, and magmatic evolution away from active plate boundaries. This thesis investigates intraplate volcanic processes in the Northeast Atlantic by examining the structure and evolution of the Jan Mayen Fracture Zone and the origin and internal dynamics of Vesteris Seamount. The approach integrates geophysical interpretation, whole-rock geochemistry, isotope systematics, and mineral-scale petrography to investigate how tectonic structures, mantle source variability, and magmatic plumbing systems interact across regional and local scales. The Jan Mayen Fracture Zone, one of the most prominent transform systems in the northeast Atlantic, offsets spreading centers and juxtaposes lithospheres of different ages and internal structures. High-resolution geophysical datasets, including bathymetry, gravity and magnetic anomalies, crustal-thickness models, and seismic tomography, reveal that crustal thickness variations and positive gravity anomalies coincide with intraplate volcanic features such as Logi Ridge, Eggvin Bank, Traill Ø Igneous Complex, Vøring Spur, and ridges between the East Jan Mayen Fracture Zone segments. A recent melt-production model, combined with sedimentary and lithospheric-thickness data, allows us to quantify excess melt pathways beneath these features. These spatial patterns suggest that inherited lithospheric segmentation and transform structures influence where and how melt is generated and emplaced, particularly during and after ridge reorganization and under the distal influence of the Iceland Plume. Plate-tectonic reconstructions further reveal a spatial link between the Traill Ø Igneous Complex and Vøring Spur, With crustal-thickness anomalies and excess magmatism focused at 48–50 Ma, the inferred onset of their development, and indicate the Vøring Spur anomaly originated at ∼47.3 Ma. However, Miocene reactivation cannot be ruled out. Three EJMFZ transverse ridges formed under Early–Mid Eocene transtension and were later uplifted during a switch to transpression. At Vesteris Seamount, integrated geochemical and isotopic data (Sr–Nd–Pb–Hf) reveal a mantle source predominantly dominated by depleted mantle (∼85–90%), with an additional enriched component (∼10–15%) likely introduced through lateral mantle flow from the Iceland Plume. Further enrichment is attributed to recycled subcontinental lithospheric mantle and possible crustal inputs, as indicated by relatively low-radiogenic 207Pb/204Pb (15.510) and high-radiogenic 208Pb/204Pb (38.554) concerning the Northern Hemisphere Reference Line, and positive εHf values (+12.51 to +13.12). Major and trace element data define a sodic alkaline suite from basanite to benmoreite, generated through low-degree partial melting. Elemental ratios such as La/Yb and Nb/Zr point to significant source enrichment, while Hf isotopes provide evidence for a previously unrecognized contribution from ancient mantle domains. These signatures collectively suggest that the mantle source beneath Vesteris has been modified by the influx of enriched components transported laterally in the upper mantle. The isotopic and elemental constraints highlight a complex melting regime beneath the East Greenland margin involving depleted and enriched reservoirs. An upper mantle anomaly, interpreted as a NNE-directed flow lobe from the Iceland plume, is proposed to deliver enriched lithospheric materials into the Vesteris source region, shaping the observed geochemical heterogeneity. Mineral-scale analyses of clinopyroxene reveal complex zoning patterns that reflect open-system crystallization and repeated mafic recharge. Reverse and sector zoning and resorption surfaces indicate disequilibrium crystallization triggered by replenishment events. Thermobarometry constrains magma storage to multiple levels ranging from ∼8 to 30 km, consistent with a vertically connected plumbing system. Narrow crystal rims and disequilibrium textures indicate rapid magma ascent with limited residence times in shallow crustal reservoirs. Clinopyroxene–melt equilibrium calculations yield average pressures of ∼6.3 and ∼5.2 kbar for deep and shallow crystallization, corresponding to storage depths in the lower crust and upper mantle. These results demonstrate that even small-volume, oceanic intraplate volcanoes can preserve a detailed record of mantle source variability, magma mixing, and multi-level storage. The combined geophysical and geochemical evidence contributes to a refined understanding of melt generation and transport in plume-influenced, structurally segmented oceanic lithosphere. By linking mantle heterogeneity, crustal architecture, and crystal-scale records, this thesis highlights the importance of fracture zone-plume interaction and episodic magma recharge in shaping intraplate volcanic systems.

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