5:15 PM - 6:30 PM
[SSS08-P04] Generation of oxidizing fluids by comminution of fault rocks
Keywords:mechanochemical reaction, reactive oxygen species
Mechanochemical reactions exert a crucial control on the chemical environments of crustal fault zones during coseismic and postseismic periods. Comminution due to faulting causes activation of fault rock surfaces, such as the production of reactive radical species. In this study, we report on the generation of H2O2 by immersion of pulverized sedimentary, igneous, and metamorphic rocks that cover an extensive area of a plate subduction boundary across which various types of earthquake are generated.
We analyzed five natural rock samples collected from an ancient plate subduction boundary. The paleo-temperatures of the samples range from ∼150 to ∼550 °C. The H2O2 concentrations of the reacted solutions were measured with the Scopoletin–Horseradish peroxidase (HRP) Fluorometric method.
The experiments demonstrate that all of the studied samples were able to produce H2O2 by mechanical activation and subsequent immersion in water. The H2O2 productivities of the natural rock samples are generally one order of magnitude greater than those of quartz, ranging from 2.4 to 9.4 nmol/m2 (mean = 5.5 nmol/m2). Empirical relationships between earthquake magnitude, slip displacement, and energy involved in the creation of fractures (i.e., fracture energy) indicate that earthquakes of greater magnitude can result in higher concentrations of H2O2 (up to ∼10−1 mol/L) within the fault zone. The oxidizing fluid produced by fault rupture in one patch may spread and induce corrosion and degradation of surrounding fault zones. Such chemical interaction may be critical in influencing the sequential manner of earthquake activity within a subduction zone.
We analyzed five natural rock samples collected from an ancient plate subduction boundary. The paleo-temperatures of the samples range from ∼150 to ∼550 °C. The H2O2 concentrations of the reacted solutions were measured with the Scopoletin–Horseradish peroxidase (HRP) Fluorometric method.
The experiments demonstrate that all of the studied samples were able to produce H2O2 by mechanical activation and subsequent immersion in water. The H2O2 productivities of the natural rock samples are generally one order of magnitude greater than those of quartz, ranging from 2.4 to 9.4 nmol/m2 (mean = 5.5 nmol/m2). Empirical relationships between earthquake magnitude, slip displacement, and energy involved in the creation of fractures (i.e., fracture energy) indicate that earthquakes of greater magnitude can result in higher concentrations of H2O2 (up to ∼10−1 mol/L) within the fault zone. The oxidizing fluid produced by fault rupture in one patch may spread and induce corrosion and degradation of surrounding fault zones. Such chemical interaction may be critical in influencing the sequential manner of earthquake activity within a subduction zone.