YANG Hua1,2, JIANG Jia-jun1,2, YU Tian-cheng3, ZHANG Fei-wu1,4*
(1. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
2. University of the Chinese Academy of Sciences, Beijing 100049, China; 3. School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009, China; 4. State Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China)
Abstract: The constitutional water in the deep earth affects a range of geochemical and geodynamic processes due to its unique physical and chemical properties. Based on recent advances of researches on the internal water content of the Earth, the water storage capacity of the mantle has been estimated in this paper. We have calculated that the upper mantle has an average water content of 0.03%, which means its water storage capacity is about 0.12 times of that of ocean water. The solubility of water in minerals of the mantle transition zone is relatively high (~1.53%), making the water storage capacity of the mantle transition zone about 4 to 5 times of that of ocean water. The water storage capacity in minerals of the lower mantle is highly debated at present, as it could not be well constrained by using results of high temperature and high pressure water soluble experiment, theoretical calculation, and geophysical methods. The currently existed research data show that the average water content of minerals in the lower mantle is relatively low (~ 0.13%), but the water storage capacity of which is about 2 to 3 times of that of ocean water due to the huge volume and mass of the lower mantle. The entire mantle has average water content of ~0.26%, with its water storage capacity of about 6 to 8 times of that of ocean water. In order to estimate the water storage capacity of each layers within the entire Earth, based on the conclusion by Murakami that the Earth was originated from the carbonaceous chondrite which has a water content of ~2% , we have estimated that the water storage capacity of the Earth’s core is about 76.8 times of that of ocean water. Furthermore, we have inferred that the Earth’s core could contain about 0.6% of H element.
Keywords: Constitutional water; deep earth; mantle minerals; water storage capacity; the Earth’s Core
ACTA MINERALOGICA SINICA Vol. 40, No.1, 2020, page 73-82
