Electrical conductivity of anhydrous and hydrous gabbroic melt under high temperature and high pressure: Implications for the high conductivity anomalies in the region of mid‒ocean ridge
Abstract. The electrical conductivity of gabbroic melt with four different water contents (i.e. 0, 2.59 wt%, 5.92 wt% and 8.32 wt%) was measured at temperatures of 873–1373 K and pressures of 1.0–3.0 GPa using YJ–3000t multi‒anvil high−pressure apparatus and Solartron‒1260 impedance spectroscopy analyzer. At a fixed water content of 2.59 wt%, the electrical conductivity of the sample slightly decreased with increasing pressure at the temperature range of 873‒1373 K, and its corresponding activation energy and activation volume were determined as 0.87 ± 0.04 eV and ‒1.98 ± 0.02 cm3 mole–1, respectively. Under the certain conditions of 873‒1373 K and 1.0 GPa, the electrical conductivity of the gabbroic melts tends to gradually increase as the rise of water content from 0 to 8.32 wt%, and the activation enthalpy decreases from 0.93 eV to 0.63 eV, accordingly. Furthermore, the functional relation models for the electrical conductivity of gabbroic melts with the variations of temperature, pressure and water content were constructed at high‒temperature and high‒pressure conditions, respectively. In addition, the dependence relation of the electrical conductivity of melts with the degree of depolymerization was explored under conditions of four different water contents, 1373 K and 1.0 GPa, and three previously available reported results on those of representative calc‒alkaline igneous rock melts (i.e. dacitic melt, basaltic melt and andesitic melt) were detailedly compared. In comprehensive combination with our presently acquired electrical conductivity data of gabbroic melt with four different water contents and the available data of polycrystalline olivine, the electrical conductivity of gabbroic melt‒olivine system on the variation of volume percentage of anhydrous and hydrous melts was successfully constructed by virtue of the typical Hashin–Shtrikman upper bound model. In light of the electrical conductivity of gabbroic melt‒olivine system with the previous MT results, we find that the anhydrous and hydrous gabbroic melts can be employed to reasonably interpret the high conductivity anomalies in the Mohns ridge of the Arctic Ocean.
Mengqi Wang et al.
Status: final response (author comments only)
RC1: 'Comment on egusphere-2023-345', Anonymous Referee #1, 17 Apr 2023
- AC1: 'Reply on RC1', Lidong Dai, 09 May 2023
RC2: 'Comment on egusphere-2023-345', Anonymous Referee #2, 21 Apr 2023
- AC2: 'Reply on RC2', Lidong Dai, 09 May 2023
Mengqi Wang et al.
Mengqi Wang et al.
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In this study, the authors report electrical conductivity of anhydrous and hydrous gabbroic melt under high temperature and high pressure: Implications for the high conductivity anomalies in the region of mid‒ocean ridge, and I found that it is one interesting work. It is first time that the functional model of the electrical conductivity on gabbroic melt was constructed under conditions of 873–1373 K, 1.0–3.0 GPa and water content ranges of 0–8.32 wt%. Their results indicate that the electrical conductivity of gabbroic melts can be employed to reasonably interpret the high conductivity anomalies in the Mohns ridge of the Arctic Ocean. The paper contains the unique data of the electrical conductivities of anhydrous and hydrous gabbroic melts.
As a whole, high-pressure electrical conductivity experimental measurements seem to have been designed and executed very consciously. The manuscript is well written, extremely well organized, is easy to read and well-illustrated. The data support the conclusion of this study. The data can potentially provide a new model to deeply explore the origin of the high conductivity anomalies in the Mohns ridge of the Arctic Ocean. I have two recommendations, listed below, but none of them are severe, thus I would strongly recommend its publication in Solid Earth.