Electrical Conductivity of Talc Dehydration at High Pressures and Temperatures: Implications for High‐Conductivity Anomalies in Subduction Zones

AbstractThe dehydration and decarbonation in the subducting slab are intricately related and the knowledge of the physical properties of the resulting C–H–O fluid is crucial to interpret the petrological, geochemical, and geophysical processes associated with subduction zones. In this study, we investigate the C–H–O fluid released during the progressive devolatilization of carbonate-bearing serpentine-polymorph chrysotile, with in situ electrical conductivity measurements at high pressures and temperatures. The C–H–O fluid produced by carbonated chrysotile exhibits high electrical conductivity compared to carbon-free aqueous fluids and can be an excellent indicator of the migration of carbon in subduction zones. The crystallization of diamond and graphite indicates that the oxidized C–H–O fluids are responsible for the recycling of carbon in the wedge mantle. The carbonate and chrysotile bearing assemblages stabilize dolomite during the devolatilization process. This unique dolomite forming mechanism in chrysotile in subduction slabs may facilitate the transport of carbon into the deep mantle.

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Dehydration of phengite inferred by electrical conductivity measurements: Implication for the high conductivity anomalies relevant to the subduction zones

Geology ◽

10.1130/g39716.1 ◽

2017 ◽

Vol 46 (1) ◽

pp. 11-14 ◽

Cited By ~ 12

Author(s):

Sibo Chen ◽

Xinzhuan Guo ◽

Takashi Yoshino ◽

Zhenmin Jin ◽

Ping Li

Keyword(s):

Electrical Conductivity ◽

Subduction Zones ◽

High Conductivity ◽

Conductivity Measurements ◽

Conductivity Anomalies

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Effect of Temperature, Pressure, and Chemical Composition on the Electrical Conductivity of Schist: Implications for Electrical Structures under the Tibetan Plateau

Materials ◽

10.3390/ma12060961 ◽

2019 ◽

Vol 12 (6) ◽

pp. 961 ◽

Cited By ~ 1

Author(s):

Wenqing Sun ◽

Lidong Dai ◽

Heping Li ◽

Haiying Hu ◽

Changcai Liu ◽

...

Keyword(s):

Tibetan Plateau ◽

High Pressures ◽

High Conductivity ◽

Effect Of Temperature ◽

The Tibetan Plateau ◽

Temperature Range ◽

Electrical Conductivities ◽

Conductivity Anomalies ◽

Lower Temperature Range ◽

Lower Temperature

The experimental study on the electrical conductivities of schists with various contents of alkali ions (CA = K2O + Na2O = 3.94, 5.17, and 5.78 wt.%) were performed at high temperatures (623–1073 K) and high pressures (0.5–2.5 GPa). Experimental results indicated that the conductivities of schist markedly increased with the rise of temperature. Pressure influence on the conductivities of schist was extremely weak at the entire range of experimental temperatures. Alkali ion content has a significant influence on the conductivities of the schist samples in a lower temperature range (623–773 K), and the influence gradually decreases with increasing temperature in a higher temperature range (823–1073 K). In addition, the activation enthalpies for the conductivities of three schist samples were fitted as being 44.16–61.44 kJ/mol. Based on the activation enthalpies and previous studies, impurity alkaline ions (K+ and Na+) were proposed as the charge carriers of schist. Furthermore, electrical conductivities of schist (10−3.5–10−1.5 S/m) were lower than those of high-conductivity layers under the Tibetan Plateau (10−1–100 S/m). It was implied that the presence of schist cannot cause the high-conductivity anomalies in the middle to lower crust beneath the Tibetan Plateau.

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