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  • 1
    Buch
    Buch
    Chichester : Wiley [u.a.]
    Schlagwort(e): Ocean bottom Remote sensing ; Sonar ; Lehrbuch ; ocean bottom ; Aufsatzsammlung ; Meeresboden ; Sonar ; Meeresboden ; Sonar ; Meeresboden ; Sonar
    Materialart: Buch
    Seiten: XI, 314 S. , Ill.
    ISBN: 0471962171
    Serie: Wiley-Praxis series in remote-sensing
    DDC: 551.46/084
    Sprache: Englisch
    Anmerkung: Literaturangaben
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  • 2
    Schlagwort(e): Bed (Oceans) Geology ; Ophiolites ; Bed (Oceans) Geology ; Aufsatzsammlung ; Ozeanische Erdkruste ; Ophiolith ; Gesteinsbildung ; Gesteinskunde ; Geochemie ; Lithosphäre ; Ozeanischer Rücken ; Ophiolith
    Materialart: Online-Ressource
    Seiten: 1 Online-Ressource (V, 330 Seiten)
    ISBN: 0903317699
    Serie: Geological Society special publication 60
    DDC: 551.4608
    RVK:
    Sprache: Englisch
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  • 3
    Schlagwort(e): Sea-floor spreading.. ; Hydrothermal deposits.. ; Chemical oceanography.. ; Hydrothermal vents ; Electronic books ; Electronic books
    Beschreibung / Inhaltsverzeichnis: Published by the American Geophysical Union as part of the Geophysical Monograph Series.Diversity of Hydrothermal Systems on Slow Spreading Ocean Ridgespresents a multidisciplinary overview of the remarkable emerging diversity of hydrothermal systems on slow spreading ocean ridges in the Atlantic, Indian, and Arctic oceans. When hydrothermal systems were first found on the East Pacific Rise and other Pacific Ocean ridges beginning in the late 1970s, the community consensus held that the magma delivery rate of intermediate to fast spreading was necessary to support black smoker-type high-temperature systems and associated chemosynthetic ecosystems and polymetallic sulfide deposits. Contrary to that consensus, hydrothermal systems not only occur on slow spreading ocean ridges but, as reported in this volume, are generally larger, exhibit different chemosynthetic ecosystems, produce larger mineral deposits, and occur in a much greater diversity of geologic settings than those systems in the Pacific. The full diversity of hydrothermal systems on slow spreading ocean ridges, reflected in the contributions to this volume, is only now emerging and opens an exciting new frontier for ocean ridge exploration, includingProcesses of heat and chemical transfer from the Earth's mantle and crust via slow spreading ocean ridges to the oceansThe major role of detachment faulting linking crust and mantle in hydrothermal circulationChemical reaction products of mantle involvement including serpentinization, natural hydrogen, abiotic methane, and hydrocarbon synthesisGeneration of large polymetallic sulfide deposits hosted in ocean crust and mantleChemosynthetic vent communities hosted in the diverse settingsThe readership for this volume will include schools, universities, government laboratories, and scientific societies in developed and developing nations, including over 150 nations that have ratified the United Nations Convention on the Law of the Sea.
    Materialart: Online-Ressource
    Seiten: Online Ressource (PDF, 54493 KB, 440 S.)
    Ausgabe: 1. Aufl.
    ISBN: 0875904785
    Serie: Geophysical Monograph Series v.188
    DDC: 551.2309162
    Sprache: Englisch
    Anmerkung: Description based upon print version of record , Title Page; Contents; Preface; Diversity of Hydrothermal Systems on Slow Spreading Ocean Ridges: Introduction; Emerging Diversity of Hydrothermal Systems on Slow Spreading Ocean Ridges; Hydrothermal Circulation at Slow Spreading Ridges: Analysis of Heat Sources and Heat Transfer Processes; Chemical Signatures From Hydrothermal Venting on Slow Spreading Ridges; The Magnetic Signature of Hydrothermal Systems in Slow Spreading Environments; Hydrothermal Activity at the Arctic Mid-Ocean Ridges , Implications of the Iceland Deep Drilling Project for Improving Understanding of Hydrothermal Processes at Slow Spreading Mid-OcCrustal Structure, Magma Chamber, and Faulting Beneath the Lucky Strike Hydrothermal Vent Field; The Relationships Between Volcanism, Tectonism, and Hydrothermal Activity on the Southern Equatorial Mid-Atlantic Ridge; The Ultraslow Spreading Southwest Indian Ridge; Deformation and Alteration Associated With Oceanic and Continental Detachment Fault Systems: Are They Similar? , Detachment Fault Control on Hydrothermal Circulation Systems:Interpreting the Subsurface Beneath the TAG HydrothermalField Using the Isotopic and Geological Evolutionof Oceanic Core Complexes in the AtlanticSerpentinization and Associated Hydrogen and Methane Fluxes at Slow Spreading Ridges; High Production and Fluxes of H2 and CH4 and Evidence of Abiotic Hydrocarbon Synthesis by Serpentinization in Ultramafic-Hosted Hydrothermal Systems on the Mid-Atlantic Ridge , Phase Equilibria Controls on the Chemistry of Vent Fluids From Hydrothermal Systems on Slow Spreading Ridges: Reactivity of Plagioclase and Olivine Solid Solutions and the pH-Silica ConnectionGeodiversity of Hydrothermal Processes Along the Mid-Atlantic Ridge and Ultramafic-HostedMineralization: A New Type of Oceanic Cu-Zn-Co-Au Volcanogenic Massive Sulfide Deposit; Hydrothermal Systems: A Decade of Discovery in Slow Spreading Environments; Chemosynthetic Communities and Biogeochemical Energy PathwaysAlong the Mid-Atlantic Ridge: The Case of Bathymodiolus Azoricus; Index
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  • 4
    ISSN: 1573-0581
    Schlagwort(e): tectonic faulting ; volcanic constructions ; oceanic crust ; side-scan sonar images
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract We analyse TOBI side-scan sonar images collected during Charles Darwin cruise CD76 in the axial valley of the Mid-Atlantic Ridge (MAR) between 27° N and 30° N (Atlantis Transform Fault). Mosaics of the two side-scan sonar swaths provide a continuous image of the axial valley and the inner valley walls along more than six second-order segments of the MAR. Tectonic and volcanic analyses reveal a high-degree intra-segment and inter-segment variability. We distinguish three types of volcanic morphologies: hummocky volcanoes or volcanic ridges, smooth, flat-topped volcanoes, and lava flows. We observe that the variations in the tectonics from one segment to another are associated with variations in the distribution of the volcanic morphologies. Some segments have more smooth volcanoes near their ends and in the discontinuities than near their mid-point, and large, hummocky axial volcanic ridges. Their tectonic deformation is usually limited to the edges of the axial valley near the inner valley walls. Other segments have smooth volcanoes distributed along their length, small axial volcanic ridges, and their axial valley floor is affected by numerous faults and fissures. We propose a model of volcano-tectonic cycles in which smooth volcanoes and lava flows are built during phases of high magmatic flux. Hummocky volcanic ridges are constructed more progressively, by extraction of magma from pockets located preferentially beneath the centre of the segments, during phases of low magma input. These cycles might result from pulses in melt migration from the mantle. Melt arrival would lead to the rapid emplacement of smooth-textured volcanic terrains, and would leave magma pockets, mostly beneath the centre of the segments where most melt is produced. During the end of the volcanic cycle magma would be extracted from these reservoirs through dikes with a low magma pressure, building hummocky volcanic ridges at low effusion rates. In extreme cases, this volcanic phase would be followed by amagmatic extension until a new magma pulse arrives from the mantle.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1573-0581
    Schlagwort(e): Mid-Atlantic Ridge ; ridge segmentation ; spreading structure ; deep-tow side-scan sonar
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The combination of multi-beam echo-sounder swath bathymetry and high-resolution deep-towed sidescan sonar provides a powerful database from which to examine mid-ocean ridge processes. We have used such a database, gathered from the Mid-Atlantic Ridge north of the Kane Fracture Zone (the MARNOK area), to examine the relationship between tectonic, volcanic, and bathymetric segmentation. We have identified structural domains, with different fault distributions, and neovolcanic segments that are distinct from the 2nd or 3rd order bathymetric segmentation. From their mutual relationships, a model is proposed for the magmatic accretion of oceanic crust at slow spreading ridges that relates the local melt supply to the tectonic style. We suggest that these are mutually interactive, and determine whether volcanic extrusion along the ridge is continuous and slow, or episodic and rapid.
    Materialart: Digitale Medien
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  • 6
    Publikationsdatum: 2021-02-08
    Beschreibung: Seafloor massive sulphides (SMSs) are regarded as a potential future resource to satisfy the growing global demand of metals including copper, zinc and gold. Aside from mining and retrieving profitable amounts of massive sulphides from the seafloor, the present challenge is to detect and delineate significant SMS accumulations, which are generally located near mid-ocean ridges and along submarine volcanic arc and backarc spreading centres. Currently, several geophysical technologies are being developed to detect and quantify SMS occurrences that often exhibit measurable contrasts in their physical parameters compared to the surrounding host rock. Here, we use a short, fixed-offset controlled source electromagnetic (CSEM) system and a coincident-loop transient electromagnetic (TEM) system, which in theory allow the detection of SMS in the shallow seafloor due to a significant electrical conductivity contrast to their surroundings. In 2016, CSEM and TEM experiments were carried out at several locations near the Trans- Atlantic Geotraverse hydrothermal field to investigate shallow occurrences of massive sulphides below the seafloor. Measurements were conducted in an area that contains distinct SMS sites located several kilometres off-axis from the Mid-Atlantic ridge, some of which are still connected to hydrothermal activity and others where hydrothermal activity has ceased. Based on the quality of the acquired data, both experiments were operationally successful. However, the data analysis indicates bias caused by three-dimensional (3D) effects of the rough bathymetry in the study area and, thus, data interpretation remains challenging. Therefore, we study the influence of 3D bathymetry for marine CSEM and TEM experiments, focusing on shallow 3D conductors located beneath mound-like structures.We analyse synthetic inversion models for attributes associated with 3D distortions of CSEM and TEM data that are not sufficiently accounted for in conventional 1D (TEM) and 2D (CSEM) interpretation schemes. Before an adequate quantification of SMS in the region is feasible, these 3D effects need to be studied to avoid over/underestimation of SMS using the acquired EM data. The sensitivity of CSEM and TEM to bathymetry is investigated by means of 3D forward modelling, followed by 1D (TEM) and 2D (CSEM) inversion of the synthetic data using realistic error conditions. Subsequently, inversion models of the synthetic 3D data are analysed and compared to models derived from the measured data to illustrate that 3D distortions are evident in the recorded data sets.
    Materialart: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
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  • 7
    Publikationsdatum: 2021-02-08
    Beschreibung: 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.
    Materialart: Article , PeerReviewed
    Format: text
    Format: archive
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  • 8
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    Mineralogical Society of America (MSA)
    In:  Elements, 14 (5). pp. 307-312.
    Publikationsdatum: 2021-02-08
    Beschreibung: Seafloor massive sulfides are deposits of metal-bearing minerals that form on and below the seabed as a result of heated seawater interacting with oceanic crust. These occurrences are more variable than previously thought, and this variability is not necessarily reflected in the analogous volcanogenic massive sulfide deposits that are preserved in the ancient rock record. The geological differences affect both the geochemistry and the size of seafloor massive sulfide deposits. Current knowledge of the distribution, tonnage, and grade of seafloor massive sulfides is inadequate to rigorously assess their global resource potential due to the limitations in exploration and assessment technologies and to our current understanding of their 3-D characteristics.
    Materialart: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 9
    Publikationsdatum: 2022-01-31
    Beschreibung: The diversity of life in the sea is critical to the health of ocean ecosystems that support living resources and therefore essential to the economic, nutritional, recreational, and health needs of billions of people. Yet there is evidence that the biodiversity of many marine habitats is being altered in response to a changing climate and human activity. Understanding this change, and forecasting where changes are likely to occur, requires monitoring of organism diversity, distribution, abundance, and health. It requires a minimum of measurements including productivity and ecosystem function, species composition, allelic diversity, and genetic expression. These observations need to be complemented with metrics of environmental change and socio-economic drivers. However, existing global ocean observing infrastructure and programs often do not explicitly consider observations of marine biodiversity and associated processes. Much effort has focused on physical, chemical and some biogeochemical measurements. Broad partnerships, shared approaches, and best practices are now being organized to implement an integrated observing system that serves information to resource managers and decision-makers, scientists and educators, from local to global scales. This integrated observing system of ocean life is now possible due to recent developments among satellite, airborne, and in situ sensors in conjunction with increases in information system capability and capacity, along with an improved understanding of marine processes represented in new physical, biogeochemical, and biological models.
    Materialart: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 10
    Publikationsdatum: 2022-01-31
    Beschreibung: Highlights • Generic geological model of hydrothermally extinct seafloor massive sulphide. • Sub-surface characterisation by combined drilling and geophysics. • New resource estimate for slow-spreading mid-ocean ridges. • Holistic approach to seafloor mineral deposits assessment. Abstract Deep-sea mineral deposits potentially represent vast metal resources that could make a major contribution to future global raw material supply. Increasing demand for these metals, many of which are required to enable a low-carbon and high-technology society and to relieve pressure on land-based resources, may result in deep sea mining within the next decade. Seafloor massive sulphide (SMS) deposits, containing abundant copper, zinc, gold and silver, have been the subject of recent and ongoing commercial interest. Although many seafloor hydrothermally systems have been studied, inactive SMS deposits are likely to more accessible to future mining and far more abundant, but are often obscured by pelagic sediment and hence difficult to locate. Furthermore, SMS deposits are three dimensional. Yet, to date, very few have been explored or sampled below the seafloor. Here, we describe the most comprehensive study to date of hydrothermally extinct seafloor massive sulphide deposits formed at a slow spreading ridge. Our approach involved two research cruises in the summer of 2016 to the TAG hydrothermal field at 26°N on the Mid-Atlantic Ridge. These expeditions mapped a number of hydrothermally extinct SMS deposits using an autonomous underwater vehicle and remotely operated vehicle, acquired a combination of geophysical data including sub-seafloor seismic reflection and refraction data from 25 ocean bottom instruments, and recovered core using a sub-seafloor drilling rig. Together, these results that have allowed us to construct a new generic model for extinct seafloor massive sulphide deposits that indicate the presence of up to five times more massive sulphide at and below the seafloor than was previously thought.
    Materialart: Article , PeerReviewed , info:eu-repo/semantics/article
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    Format: other
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