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Showing 1 to 19 of 19 for “"serpentinization"”.
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Carbon and mineral transformations in seafloor serpentinization systems
… even at high H2(aq) concentrations generated by serpentinization reactions. Although CO2(aq) attains rapid metastable equilibrium with formate, formation of thermodynamically stable CH4(aq) is kinetically limited on timescales relevant for active fluid circulation in the subseafloor. It has been …
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Carbon and mineral transformations in seafloor serpentinization systems
… even at high H2(aq) concentrations generated by serpentinization reactions. Although CO2(aq) attains rapid metastable equilibrium with formate, formation of thermodynamically stable CH4(aq) is kinetically limited on timescales relevant for active fluid circulation in the subseafloor. It has been …
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An experimental study on characterization of physical properties of ultramafic rocks and controls on evolution of fracture permeability during serpentinization at hydrothermal conditions
Serpentinization is a complex set of hydration reactions, where olivine and pyroxene are replaced by serpentine, magnetite, brucite, talc and carbonate minerals. Serpentinization reactions alter chemical, mechanical, magnetic, seismic, and hydraulic properties of the crust. To understand the …
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Novel Insights into the Palaeomagnetism of Serpentinized Peridotites from the Troodos and Oman Ophiolites
… the concurrent chemical alteration processes of serpentinization and carbonation. Serpentinization frequently results in the production of secondary magnetite that can record the direction of the Earth’s magnetic field at the time of its formation, allowing palaeomagnetism to be used as a tool to …
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An investigation of hydrogen gas in olivine
… are regarded to be product of the process of serpentinization. However other sources or explanation may exist for the natural hydrogen gas seeps. For example Zhang et al. (2005) concluded that hydrogen gas occurs within fluid inclusions contained by olivine crystals. In the present study the …
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Physiological and Phylogenetic Studies of the Biogeography of Alkaliphilic Heterotrophic Bacteria from Serpentinizing Habitats
Serpentinization occurs when ultramafic rocks containing the mineral olivine react with water to produce highly reducing conditions, which are commonly coincident with high concentrations of hydrogen. Hydrogen provides an energy source for microbial metabolism and in combination with mineral …
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Geochemistry of fluid-rock processes
… differences in the published data. Chapter IV "Serpentinization reaction rates measured in olivine micro-batch reactors" describes new insights into the serpentinization process by using olivine micro-reactors. The micro-reactor technique is a new experimental development that allows researchers …
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Geophysical and geochemical constraints on the evolution of oceanic lithosphere from formation to subduction
… indicating ultramafic host rock suggests that serpentinization may play a role in microearthquake generation but the seismic network was not capable of providing robust focal mechanism solutions to constrain the source characteristics. In Chapter 3 I find that the Juan de Fuca plate, which …
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Cooling and crystallization of komatiite flows.
… loss of Ca in these altered rocks is due to a serpentinization reaction buffered by the desilication of glass or fine-grained plagioclase in the groundmass. Serpentinization occurred under conditions of low confining pressure, caused up to 30% expansion of the basal portions of flows, and …
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Geophysical and geochemical constraints on the evolution of oceanic lithosphere from formation to subduction
… indicating ultramafic host rock suggests that serpentinization may play a role in microearthquake generation but the seismic network was not capable of providing robust focal mechanism solutions to constrain the source characteristics. In Chapter 3 I find that the Juan de Fuca plate, which …
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Geology, mineralogy and geochemistry of the Cerro Matoso nickeliferous laterite, Córdoba, Colombia
… orthopyroxene and secondary serpentine. Intense serpentinization is primarily confined to areas of faulting and brecciation particularly along the western and eastern boundaries of the peridotite body. Development of the nickel laterite profile was greater in weakly serpentinized peridotite both …
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Livadi Mafic-Ultramafic Complex and its metamorphic basement, N.E. Greece
… metamorphics. An early period of isochemical serpentinization that was associated with an initial emplacement phase, occurred at the expense of most primary minerals. Continued tectonic movement of the Complex led to the development of a major overturned structure and was followed by a period …
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The dynamics of oceanic transform faults : constraints from geophysical, geochemical, and geodynamical modeling
… may result from porosity variations, mantle serpentinization, and/or crustal thickness variations. Two-dimensional forward modeling and the correlation of the negative gravity anomalies to bathymetric highs indicate crustal thickness excesses in these locations. Finally, in Chapter 3, mantle …
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The dynamics of oceanic transform faults : constraints from geophysical, geochemical, and geodynamical modeling
… may result from porosity variations, mantle serpentinization, and/or crustal thickness variations. Two-dimensional forward modeling and the correlation of the negative gravity anomalies to bathymetric highs indicate crustal thickness excesses in these locations. Finally, in Chapter 3, mantle …
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Tectonics of the West Iberia continental margin from seismic reflection data
… seafloor spreading and caused a concentration of serpentinization at its base. This water-driven process of formation accounts for the variability of the ridge along strike. Prestack depth migration of a 340 km long seismic reflection profile across the margin served as the basis for stratigraphic …
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Structure and evolution of an oceanic megamullion on the Mid-Atlantic ridge at 27°N
… different detachment-fault angles and degrees of serpentinization of exhumed mantle that may be present in the megamullion were compared to Residual Mantle Bouguer Anomaly (RMBA) profiles. All models show gravity peaks slightly skewed towards the termination because higher-density rock is exposed …
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The kimeerlite occurrences from the vicinity of Rayton, South of premier mine, and from East Lynne, East of Pretoria
… phases (pyrophanite) and magnetite and hematite. Serpentinization of the kimberlite occurs in stage IV but depending on localized compositional differences, phlogopite II and biotite form the last sequel to the crystallization of the serpentine matrix. Silica activity results in the alteration of …
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Petrological and geochemical studies of an abyssal periodotite from the Atlantis II fracture zone
… water alteration occurs mainly as a result of serpentinization at temperatures higher than 200°C. Since the sample is less than l Ma old, and the low temperature weathering occurred only after the sample was exposed at the sea floor, it is possible that the weathering process was restricted to …
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Iron in oxides, silicates and alloys under extreme pressure-temperature conditions
… during subduction of oceanic crust, or during serpentinization (metamorphic reaction). In order to shed light on the complex physical properties of magnetite under compression we conducted a combined single crystal x-ray diffraction and Mössbauer spectroscopy at pressures below 25 GPa. We find …