scholarly journals Saline aqueous fluid circulation in mantle wedge inferred from olivine wetting properties

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yongsheng Huang ◽  
Takayuki Nakatani ◽  
Michihiko Nakamura ◽  
Catherine McCammon
Keyword(s):  
Fluid Transport ◽  
Mantle Wedge ◽  
Aqueous Fluid ◽  
High Electrical Conductivity ◽  
Interconnected Network ◽  
Fluid Circulation ◽  
Wetting Properties ◽  
Mantle Fluid ◽  
Conductivity Anomalies ◽  
Electrical Conductors

AbstractRecently, high electrical conductors have been detected beneath some fore-arcs and are believed to store voluminous slab-derived fluids. This implies that the for-arc mantle wedge is permeable for aqueous fluids. Here, we precisely determine the dihedral (wetting) angle in an olivine–NaCl–H2O system at fore-arc mantle conditions to assess the effect of salinity of subduction-zone fluids on the fluid connectivity. We find that NaCl significantly decreases the dihedral angle to below 60° in all investigated conditions at concentrations above 5 wt% and, importantly, even at 1 wt% at 2 GPa. Our results show that slab-released fluid forms an interconnected network at relatively shallow depths of ~80 km and can partly reach the fore-arc crust without causing wet-melting and serpentinization of the mantle. Fluid transport through this permeable window of mantle wedge accounts for the location of the high electrical conductivity anomalies detected in fore-arc regions.

scholarly journals Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges

2016 ◽  
Vol 2 (5) ◽  
pp. e1501631 ◽  
Author(s):  
Geeth Manthilake ◽  
Nathalie Bolfan-Casanova ◽  
Davide Novella ◽  
Mainak Mookherjee ◽  
Denis Andrault
Keyword(s):  
Electrical Conductivity ◽  
Subduction Zone ◽  
Mantle Wedge ◽  
Aqueous Fluid ◽  
Stability Field ◽  
Initial Increase ◽  
High Electrical Conductivity ◽  
Additional Source ◽  
Slab Dehydration ◽  
Subducting Slab

Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (~1 S/m) that has often been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed anomalously high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite. In this present study, we have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting. In our experiment, we observe two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity to ~3 × 10−3S/m can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity of up to 7 × 10−1S/m. This is related to the growth of an interconnected network of a highly conductive and chemically impure magnetite mineral phase. Thus, the dehydration of chlorite and associated processes are likely to be crucial in explaining the anomalously high electrical conductivity observed in mantle wedges. Chlorite dehydration in the mantle wedge provides an additional source of aqueous fluid above the slab and could also be responsible for the fixed depth (120 ± 40 km) of melting at the top of the subducting slab beneath the subduction-related volcanic arc front.

Fluid Transport and Phase Transition Experiments in Closed Multiwall Carbon Nanotubes

2003 ◽  
Author(s):  
Almila G. Yazicioglu ◽  
Constantine M. Megaridis ◽  
Yury Gogotsi
Keyword(s):  
Carbon Nanotubes ◽  
Fluid Transport ◽  
Experimental Studies ◽  
Multiwall Carbon Nanotubes ◽  
Aqueous Fluid ◽  
Experimental Apparatus ◽  
Nanofluidic Devices ◽  
Interface Dynamic ◽  
Multiphase Fluid ◽  
Multiwall Carbon

Multiwall carbon nanotubes show potential for use in various micro- and nanofluidic devices, since they resemble cylindrical channels used in the macroscopic world. However, in situ experimental studies of fluid behavior in nanotubes or nanochannels have been rare. In this work, transmission electron microscopy experiments are performed on closed-end multiwall carbon nanotubes filled with an aqueous multiphase fluid. The nanotubes form an experimental apparatus that is a few orders of magnitude smaller than the smallest channels used in other fluidic experiments. These nanotubes are synthesized hydrothermally, using Ni as a catalyst, and they contain segregated aqueous liquid and gas inclusions with clearly defined interfaces. Using electron irradiation, the multiphase fluid inside individual nanotubes is excited thermally, by expanding and contracting the electron beam. The excellent wettability of the graphitic inner tube walls by the aqueous fluid and the mobility of this liquid in the nanotubes are observed in real time with nanometer-scale resolution. Interface dynamic phenomena are visualized, as driven by thermocapillary forces as well as by evaporation and condensation. The hydrothermal nanotubes examined herein offer a promising platform for studying the behavior of multicomponent, multiphase fluids in nanosize channels at high-pressure conditions. The phenomena documented in this study demonstrate the potential of implementing such tubes in future nanofluidic devices.

scholarly journals Mineralogical Constraints on the Potassic and Sodic-Calcic Hydrothermal Alteration and Vein-Type Mineralization of the Maronia Porphyry Cu-Mo ± Re ± Au Deposit in NE Greece

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 182 ◽  
Author(s):  
Vasilios Melfos ◽  
Panagiotis Voudouris ◽  
Margarita Melfou ◽  
Matías G. Sánchez ◽  
Lambrini Papadopoulou ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Fluid Phase ◽  
Aqueous Fluid ◽  
Gas Content ◽  
Magmatic Fluid ◽  
Brittle Deformation ◽  
Fluid Circulation ◽  
Magmatic Rocks ◽  
Vein Type ◽  
Host Rocks

The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/oligoclase/andesine) + titanite + magnetite + chlorite + quartz ± calcite ± epidote-allanite. The high-oxidation state of the magmas and the hydrothermal fluid circulation were responsible for the metal and sulfur enrichments of the aqueous fluid phase, an increase in O2 gas content, the breakdown of the magmatic silicates and the production of the extensive potassic and sodic-calcic alterations. Brittle deformation also promoted the rapid upward fluid flow and caused interactions with the surrounding host rocks along the high temperature M-, EB-, A- and B-type veins.

scholarly journals The Anomalous Seismic Behavior of Aqueous Fluids Released during Dehydration of Chlorite in Subduction Zones

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 70
Author(s):  
Geeth Manthilake ◽  
Julien Chantel ◽  
Nicolas Guignot ◽  
Andrew King
Keyword(s):  
Subduction Zones ◽  
Aqueous Fluid ◽  
Elastic Behavior ◽  
Fluid Circulation ◽  
Seismic Parameters ◽  
Hydrous Minerals ◽  
Mantle Minerals ◽  
Wave Velocities ◽  
Mineral Phases ◽  
Mantle Fluids

Dehydration and fluid circulation are integral parts of subduction tectonics that govern the dynamics of the wedge mantle. The knowledge of the elastic behavior of aqueous fluid is crucial to understand the fluid–rock interactions in the mantle through velocity profiles. In this study, we investigated the elastic wave velocities of chlorite at high pressure beyond its dehydrating temperature, simulating the progressive dehydration of hydrous minerals in subduction zones. The dehydration resulted in an 8% increase in compressional (Vp) and a 5% decrease in shear wave (Vs) velocities at 950 K. The increase in Vp can be attributed to the stiffening of the sample due to the formation of secondary mineral phases followed by the dehydration of chlorite. The fluid-bearing samples exhibited Vp/Vs of 2.45 at 950 K. These seismic parameters are notably different from the major mantle minerals or hydrous silicate melts and provide unique seismic criteria for detecting mantle fluids through seismic tomography.

scholarly journals Wetting Properties of the CO2–Water–Calcite System via Molecular Simulations: Shape and Size Effects

2019 ◽  
Author(s):  
Alessandro Silvestri ◽  
Evren Ataman ◽  
Akin Budi ◽  
Susan Stipp ◽  
Julian D Gale ◽  
...  
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Water Droplet ◽  
Aqueous Fluid ◽  
Water Model ◽  
Correct Prediction ◽  
Mineral Surfaces ◽  
Water Contact ◽  
Local Conditions ◽  
Wetting Properties

<p>Assessment of the risks and environmental impacts of carbon geosequestration requires knowledge about the wetting behavior of mineral surfaces in the presence of CO<sub>2</sub> and the pore fluids. In this context, the interfacial tension (IFT) between CO<sub>2</sub> and the aqueous fluid and the contact angle, theta, with the pore mineral surfaces are the two key parameters that control the capillary pressure in the pores of the candidate host rock. Knowledge of these two parameters and their dependence on the local conditions of pressure, temperature and salinity is essential for the correct prediction of structural and residual trapping. We have performed classical molecular dynamics simulations to predict the CO<sub>2</sub>–water IFT and the CO<sub>2</sub>–water–calcite contact angle. The IFT results are consistent with previous simulations, where simple point charge water models have been shown to underestimate the water surface tension, thus affecting the simulated IFT values. When combined with the EPM2 CO<sub>2</sub> model, the SPC/Fw water model indeed underestimates the IFT in the low pressure region at all temperatures studied. On the other hand, at high pressure and low temperature, the IFT is overestimated by ~5 mN/m. Literature data regarding the water contact angle on calcite are contradictory. Using our new set of force field parameters, we performed NVT simulations at 323 K and 20 MPa to calculate the contact angle of a water droplet on the calcite {10.4} surface in a CO<sub>2</sub> atmosphere. We performed simulations for both spherical and cylindrical droplet configurations for different initial radii, to study the size dependence of the water contact angle on calcite in the presence of CO<sub>2</sub>. Our results suggest that the contact angle of a cylindrical water droplet on calcite {10.4}, in the presence of CO<sub>2</sub>, is independent of droplet size, for droplets with a radius of 50 Å or more. On the contrary, spherical droplets make a contact angle that is strongly influenced by their size. At the largest size explored in this study, both spherical and cylindrical droplets converge to the same contact angle, 38 degrees, indicating that calcite is strongly wetted by water.</p>

Experimental determination of magnesite solubility in water and silicate saturated saline solutions under high temperature and pressure

2020 ◽  
Author(s):  
Wan-Cai Li ◽  
Qinxia Wang ◽  
Huaiwei Ni
Keyword(s):  
High Temperature ◽  
Carbon Cycle ◽  
Mantle Wedge ◽  
Pure Water ◽  
Aqueous Fluid ◽  
In Situ Observation ◽  
Metasedimentary Rocks ◽  
High Temperature And Pressure ◽  
Temperature And Pressure ◽  
Subducting Slab

&lt;p&gt;Aqueous fluid derived from the dehydration of subducting slab can dissolve and transfer carbon to mantle wedge, and thus plays an important role in the globe deep carbon cycle. Carbonates are major phases of carbon in the subducting slab, however their solubilities in the subduction zone fluid are poorly constrained. This heavily hinder our understanding of the&amp;#160; deep carbon cycle. Magnesite is one of the carbonates in the subducting slab, and can be stabilized to sub-arc depth. We determined the solubility of magnesite in pure water and saline fluids buffered by silicate by in situ observation of quantitative magnesite totally dissolved in quantitative fluid under high temperature and pressure in Hydrothermal Diamond Anvil Cell (HDAC). The results demonstrated that the solubility of magnesite in pure water is 0.010-0.026 mol/kg H&lt;sub&gt;2&lt;/sub&gt;O at 1.0-3.3 GPa and 600-900 &amp;#8451;, and that it increases as increasing temperature, but has no obvious pressure effect. This data is close to the experimental measurement of calcite solubility in literature, but slightly higher than the theoretical results calculated using DEW model. The solubility of magnesite in 5 wt % NaCl solution equilibrium with quartz is 0.22 mol/ kg, at 700 &amp;#8451; and 1.5 GPa&amp;#65292;an order of magnitudes higher than that in the pure water. Since the formation of new silicate minerals, such as olivine or talc, depends on silicon activity in the fluid, the dissolution of silicate would boost the solubility of magnesite. This mechanism has been previously reported in the Alps metasedimentary rocks. Therefore, the aqueous fluid, rich in saline and silicon in fore-arc and sub-arc depths, has the ability to dissolve and transfer almost all the carbonates in the subducting slab to the overlying mantle wedge.&lt;/p&gt;

scholarly journals Heat and Fluid Transport Induced by Convective Fluid Circulation Within a Fracture or Fault

2018 ◽  
Vol 123 (4) ◽  
pp. 2658-2673 ◽  
Author(s):  
J. W. Patterson ◽  
T. Driesner ◽  
S. Matthai ◽  
R. Tomlinson
Keyword(s):  
Fluid Transport ◽  
Fluid Circulation ◽  
Convective Fluid
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