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  • 1
    Publication Date: 2021-02-08
    Description: The decarbonisation of our energy supply is reliant on new technologies that are raw material intensive and will require a significant increase in the production of metals to sustain them. Ferromanganese (FeMn) crusts are seafloor precipitates, enriched in metals such as cobalt and tellurium, both of which have a predicted future demand above current production rates. In this study, we investigate the texture and composition of FeMn crusts on Tropic Seamount, a typical Atlantic guyot off the coast of western Africa, as a basis for assessing the future mineral resource potential of Atlantic Seamounts. The majority of the summit is flat and covered by FeMn crusts with average thicknesses of 3–4 cm. The crusts are characterized by two dominant textures consisting of either massive pillared growth or more chaotic, cuspate sections of FeMn oxides, with an increased proportion of detrital and organic material. The Fe, Mn, and Co contents in the FeMn oxide layers are not affected by texture. However, detrital material and bioclasts can form about 50% of cuspate areas, and the dilution effect of this entrained material considerably reduces the Fe, Mn, and Co concentrations if the bulk samples are analyzed. Whilst Tropic Seamount meets many of the prerequisites for a crust mining area, the thickness of the crusts and their average metal composition means extraction is unlikely to be viable in the near future. The ability to exploit more difficult terrains or multiple, closely spaced edifices would make economic feasibility more likely.
    Type: Article , PeerReviewed
    Format: text
    Format: archive
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  • 2
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    AGU (American Geophysical Union) | Wiley
    In:  Geochemistry, Geophysics, Geosystems, 14 (6). pp. 1693-1702.
    Publication Date: 2017-01-09
    Description: Axial volcanic ridges (AVRs) are found on most slow-spreading mid-ocean ridges and are thought to be the main locus of volcanism there. In this study we present high-resolution mapping of a typical, well-defined AVR on the Mid-Atlantic Ridge at 45°N. The AVR is characterized by “hummocky terrain,” composed typically of hummocks with pillowed or elongate pillowed flanks with pillowed or lobate lava flow summits, often with small haystacks sitting on their highest points. The AVR is surrounded by several areas of “flat seafloor,” composed of lobate and sheet lava flows. The spatial and morphological differences between these areas indicate different eruption processes operating on and off the AVR. Volcanic fissures are found all around and on the AVR, although those with the greatest horizontal displacement are found on the ridge crest and flat seafloor. Clusters of fissures may represent volcanic vents. Extremely detailed comparisons of sediment coverage and examination of contact relations around the AVR suggest that many of the areas of flat seafloor are of a similar age or younger than the hummocky terrain of the AVR. Additionally, all the lavas surveyed have similar degrees of sediment cover, suggesting that the AVR was either built or resurfaced in the same 50 ka time frame as the flat seafloor.
    Type: Article , PeerReviewed
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  • 3
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    AGU (American Geophysical Union) | Wiley
    In:  Geochemistry, Geophysics, Geosystems, 14 (9). pp. 3586-3599.
    Publication Date: 2018-02-28
    Description: Linear, hummocky pillow mound volcanism dominates at slow and intermediate spreading rate mid-ocean ridges. Volcanic hummocks are thought to be formed by low effusion rates or as a result of flow focussing during effusive fissure style eruptions in which the initial dike intercepts the seafloor and erupts along its entire length. In this study, high-resolution autonomous underwater vehicle (AUV) bathymetry is used to accurately map the extents of four historical fissure eruptions of the Juan de Fuca and Gorda ridges: on the North Gorda, North Cleft, and CoAxial ridge segments. The four mapped eruptions take the form of pillow mounds, which are similar in both lithology and dimension to hummocks on the Mid-Atlantic Ridge. Pillow mounds may be isolated, or coalesce to form composite mounds, aligned as ridges or as clustered groups. In three of the four mapped sites, the eruptions were discontinuous along their lengths, with pillow mounds and composite mounds commonly separated by areas of older seafloor. This style of discontinuous eruption is inconsistent with typical en echelon fissure eruptions and is probably due to a mildly overpressured, fingering dike intersecting the seafloor along parts of its length.
    Type: Article , PeerReviewed
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  • 4
    Publication Date: 2023-02-08
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 5
    Publication Date: 2024-02-07
    Description: Seafloor massive sulfide deposits form in remote environments, and the assessment of deposit size and composition through drilling is technically challenging and expensive. To aid the evaluation of the resource potential of seafloor massive sulfide deposits, three-dimensional inverse modelling of geophysical potential field data (magnetic and gravity) collected near the seafloor can be carried out to further enhance geologic models interpolated from sparse drilling. Here, we present inverse modelling results of magnetic and gravity data collected from the active mound at the Trans-Atlantic Geotraverse hydrothermal vent field, located at 26o08'N on the Mid-Atlantic Ridge, using autonomous underwater vehicle (AUV) and submersible surveying. Both minimum-structure and surface geometry inverse modelling methods were utilized. Through deposit-scale magnetic modelling, the outer extent of a chloritized alteration zone within the basalt host rock below the mound was resolved, providing an indication of the angle of the rising hydrothermal fluid and the depth and volume of seawater/hydrothermal mixing zone. The thickness of the massive sulfide mound was determined by modelling the gravity data, enabling the tonnage of the mound to be estimated at 2.17 +/- 0.44 Mt through this geophysics-based, non-invasive approach.
    Type: Article , PeerReviewed
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  • 6
    Publication Date: 2024-02-07
    Description: Marine geohazards pose a significant threat to the European coastal population and to the development of the Blue Economy. This Position Paper discusses the type, distribution and impact of marine geohazards on the European coastal regions and the Blue Economy, as well as what and how novel scientific approaches may broaden our understanding of their trigger mechanisms and drive a risk-mitigating European policy.
    Type: Book , NonPeerReviewed
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