scholarly journals Interpretation of the “Northeastern Japan Anomaly” in Electrical Conductivity of the Upper Mantle

1976 ◽  
Vol 28 (4) ◽  
pp. 329-332 ◽  
Author(s):  
Hitoshi YAMASHITA ◽  
Izumi YOKOYAMA
Keyword(s):  
Electrical Conductivity ◽  
Upper Mantle ◽  
Northeastern Japan

Electrical conductivity imaging of the Philippine Sea upper mantle using seafloor magnetotelluric data

2010 ◽  
Vol 183 (1-2) ◽  
pp. 44-62 ◽  
Author(s):  
Kiyoshi Baba ◽  
Hisashi Utada ◽  
Tada-nori Goto ◽  
Takafumi Kasaya ◽  
Hisayoshi Shimizu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Upper Mantle ◽  
Magnetotelluric Data ◽  
Philippine Sea ◽  
Conductivity Imaging

Inversion of the satellite observations of the tidally induced magnetic field in terms of 3-D upper-mantle electrical conductivity: Method and synthetic tests

2021 ◽  
Author(s):  
Libor Šachl ◽  
Jakub Velímský ◽  
Javier Fullea
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Upper Mantle ◽  
Spherical Harmonic ◽  
Model Space ◽  
Conductivity Method ◽  
Satellite Gravity ◽  
Compositional Model ◽  
Mantle Conductivity ◽  
The Impact

<p><span><span>We have developed and tested a new frequency-domain, spherical harmonic-finite element approach to the inverse problem of global electromagnetic (EM) induction. It is based on the quasi-Newton minimization of data misfit and regularization, and uses the adjoint approach for fast calculation of misfit gradients in the model space. Thus, it allows for an effective inversion of satellite-observed magnetic field induced by tidally driven flows in the Earth's oceans in terms of 3-D structure of the electrical conductivity in the upper mantle.</span></span><span><span> Before proceeding to the inversion of Swarm-derived models of tidal magnetic signatures, we have performed a series of </span></span><span><span>parametric studies</span></span><span><span>, using a 3-D conductivity model WINTERC-e as a testbed.</span></span></p><p><span>The WINTERC-e model has been derived using state-of-the-art laboratory conductivity measurements of mantle minerals, and thermal and compositional model of the lithosphere and upper mantle WINTERC-grav. The latter model is based on the inversion of global surface waveforms, satellite gravity and gradiometry measurements, surface elevation, and heat flow data </span><span><span>in a thermodynamically self-consistent framework. </span></span><span><span>Therefore, the WINTERC-e model, independent of any EM data, represents an ideal target for synthetic tests of the 3-D EM inversion.</span></span><span> </span></p><p><span><span>We tested the impact of </span></span><span><span>the </span></span><span><span>satellite </span></span><span><span>altitude</span></span><span><span>, </span></span><span><span>the truncation degree of the </span></span><span><span>spherical-harmonic </span></span><span><span>expansion of the tidal signals, the random</span></span><span><span> noise in data</span></span><span><span>,</span></span><span> </span><span><span>and </span></span><span><span>of the </span></span><span><span>sub-</span></span><span><span>continental conductivity</span></span><span> </span><span><span>on the </span></span><span><span>ability to recover the sub-oceanic upper-mantle conductivity structure.</span></span><span><span> We </span></span><span><span>demonstrate </span></span><span><span>that </span></span><span><span>with </span></span><span><span>suitable regularization </span></span><span><span>we</span></span><span> </span><span><span>can successfully reconstruct the 3D upper-mantle conductivity below world oceans.</span></span></p>

scholarly journals An Overview of the Experimental Studies on the Electrical Conductivity of Major Minerals in the Upper Mantle and Transition Zone

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 408 ◽  
Author(s):  
Lidong Dai ◽  
Haiying Hu ◽  
Jianjun Jiang ◽  
Wenqing Sun ◽  
Heping Li ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Transition Zone ◽  
Oxygen Fugacity ◽  
Upper Mantle ◽  
Activation Enthalpy ◽  
Small Polaron ◽  
Experimental Studies ◽  
Transport Processes ◽  
Structural Water ◽  
Nominally Anhydrous Minerals

In this paper, we present the recent progress in the experimental studies of the electrical conductivity of dominant nominally anhydrous minerals in the upper mantle and mantle transition zone of Earth, namely, olivine, pyroxene, garnet, wadsleyite and ringwoodite. The main influence factors, such as temperature, pressure, water content, oxygen fugacity, and anisotropy are discussed in detail. The dominant conduction mechanisms of Fe-bearing silicate minerals involve the iron-related small polaron with a relatively large activation enthalpy and the hydrogen-related defect with lower activation enthalpy. Specifically, we mainly focus on the variation of oxygen fugacity on the electrical conductivity of anhydrous and hydrous mantle minerals, which exhibit clearly different charge transport processes. In representative temperature and pressure environments, the hydrogen of nominally anhydrous minerals can tremendously enhance the electrical conductivity of the upper mantle and transition zone, and the influence of trace structural water (or hydrogen) is substantial. In combination with the geophysical data of magnetotelluric surveys, the laboratory-based electrical conductivity measurements can provide significant constraints to the water distribution in Earth’s interior.

scholarly journals The electrical conductivity of the oceanic upper mantle

1992 ◽  
Vol 110 (1) ◽  
pp. 159-179 ◽  
Author(s):  
Graham Heinson ◽  
Steven Constable
Keyword(s):  
Electrical Conductivity ◽  
Upper Mantle
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