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Modeling Porosity Evolution Throughout Reaction‐Induced Fracturing in Rocks With Implications for Serpentinization
Author(s) -
Zhang Lingran,
Nasika Christina,
Donzé FrédéricVictor,
Zheng Xiaojiao,
Renard François,
Scholtès Luc
Publication year - 2019
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2018jb016872
Subject(s) - brucite , periclase , peridotite , porosity , mineralogy , kinetics , thermodynamics , mineral , stress (linguistics) , geology , materials science , composite material , geochemistry , metallurgy , magnesium , mantle (geology) , linguistics , philosophy , physics , quantum mechanics
Numerical modeling based on the discrete element method was used to explore the kinetics and mechanics of fractures induced by mineral volumetric expansion during rock hydration. Two systems were considered: the hydration of periclase into brucite and the hydration of peridotite into serpentine. We modeled the coupling between mineral transformation, stress, volume increase, and deformation by simulating the volumetric growth of discrete elements based upon an Avrami‐type kinetics equation. The model was implemented to consider the effects of stress and temperature on reaction kinetics as well as the alteration of material properties during hydration reactions. We were able to reproduce experimental evidences observed during the transformation of periclase into brucite, including volume growth, fracturing of periclase, formation of a porosity pulse, as well as the slow‐down effect of effective stress on the kinetics of the transformation. The model was also applied to study the serpentinization process. We estimated a bell‐shaped relationship between temperature and reaction rate of peridotite transformation following observations made during serpentinization experiments. For both periclase and peridotite systems, we characterized a relationship between the formation of a porosity pulse and the rate of fracture development within the medium. During serpentinization, the amplitude of the porosity pulse and the duration of this pulse depend on the reaction rate and, therefore, on the temperature. Our investigations provide geomechanical explanations on how native dihydrogen formed during serpentinization can be expelled and initiates its migration process.