Formation of the Igneous Logi Ridge, NE Atlantic. Issue 3 (12th March 2022)

• Record Type: Journal Article
• Authors: Tan, Pingchuan; Breivik, Asbjørn Johan
• Is Part Of: Journal of geophysical research. Volume 127:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-12
• Subjects: gravity modeling -- intraplate volcanism -- magmatic production rate -- Logi Ridge -- seamount crustal structure; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2021JB023891
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: The igneous Logi Ridge is located in the NE Atlantic north of the West Jan Mayen Fracture Zone on oceanic crust. The origin of the ridge may relate to the increased influence of the Iceland plume in the Oligocene though the exact mechanism is uncertain. We estimate the igneous volume and magma production rate of the ridge from 10 transects, comprising a refraction profile, six reflection profiles, and three bathymetric profiles. The refraction profile shows up to 12 km crustal thickness of the ridge, and the forward gravity modeling and/or isostatic balancing shows that this is characteristic for most of the ridges. A 3D volume model was created by interpolating between profiles and subtracted the similarly made regional crustal thickness (5–7 km), which gives an excess magma volume of (1.7 ± 0.6) × 10 13 m 3 . The admittance function between bathymetry and gravity indicates an elastic plate thickness of 3–5 km during the main ridge formation. This is consistent with the ridge being built on oceanic crust from Oligocene to earliest Miocene, indicating a main magmatic phase of ∼5 Ma duration, which gives a magma production rate of 0.07–0.15 m 3 /s, comparable to the Louisville Seamount Chain (LSC). However, the lower crustal velocities of the refraction profile differ from that of the Louisville Guyot in the LSC, suggesting that the melting event was not mainly caused by high mantle temperature, instead it may have been caused in part by the enriched mantle presently seen at the northern end of the Kolbeinsey Ridge to the south. Plain Language Summary: The igneous Logi Ridge is located in the North Atlantic Ocean, near the Norwegian Jan Mayen Island. The origin of the Logi Ridge may relate to the increased influence of the Iceland plume in the NE Atlantic in the Oligocene though the exact mechanism is uncertain. We use density modeling calibrated to one refraction profile to develop the methodology, which was applied to six reflection profiles and three bathymetric profiles to estimate the igneous volume of the ridge. Estimates of the elastic plate thickness at the time of ridge loading constrain the time of formation well and indicate a short main igneous phase, mainly Oligocene. The magma production rate is estimated to be 0.07–0.15 m 3 /s, which is comparable to the plume‐induced Louisville Seamount Chain (LSC) in the Pacific, similarly formed on young oceanic lithosphere. The lower crustal velocity of the Louisville Guyot in the LSC, which is a seamount of similar dimensions, is consistent with a hot plume origin. However, velocity is significantly lower for the Logi Ridge, suggesting that the formation was not driven by the significantly elevated temperature. The enriched mantle component currently sourcing magmatism at the northern segment of the Kolbeinsey spreading ridge to the south could have contributed. Key Points: We represent a high‐resolution 3D volume model of the Logi Ridge from refraction/reflection seismic data, bathymetry, and gravity Estimates of the elastic plate thickness under the Logi Ridge show a short main igneous phase with a magma production rate of 0.07–0.15 m 3 /s The Logi Ridge is not caused by high mantle temperature but in part by the enriched mantle presently seen at the Eggvin Bank to the south