1. Fabrication methods of multi-mineralic fault gouge analogues using a high-energy ball mill.
- Author
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Lee, Yu Na, Song, Insun, and Kim, Hyun Na
- Subjects
- *
FAULT gouge , *SIZE reduction of materials , *PARTICLE size distribution , *DEFORMATION of surfaces , *ENERGY minerals - Abstract
The fault gouge, a crushed fault rock resulting from seismic slip, exhibits variations in crystallinity and particle size contingent on the magnitude of deformation. Therefore, the fabrication of fault gouge analogues with carefully controlled properties such as crystallinity, grain size, and mineral composition is necessary to systematically study their role in a range of fault slips. While the single mineral fault gouge analogues have been reproduced using a milling method, the fabrication methods for multi-mineralic fault gouge analogues with varying particle size and crystallinity are rarely reported, yet. In this study, we propose two methodologies for fabricating multi-mineralic fault gouges controlling the degree of amorphization and the particle size using a high-energy ball mill: mixing-grinding (MG) and grinding-mixing (GM) types. The MG type was designed to simulate the fault gouge that the same grinding energy is applied to all the constituent minerals, while the GM type can be controlled the degree of deformation of each mineral according to the research objective. To investigate the effects of these methodologies on the reduction in crystallinity and particle size, we compared the characteristics of MG type_6h and GM type_6h samples, both ground for 6 h. Consequently, despite undergoing the same grinding duration, the GM type_6h sample exhibited more significant reduction in crystallinity and more heterogeneous particle size. Additionally, we fabricated the GM type_Xc50 sample, where the crystallinity of all constituent minerals was reduced to < 50%. For this, each mineral was ground for an optimized duration that reduced its crystallinity to < 50%, after which the samples were mixed. Consequently, the GM type_Xc50 sample demonstrated the greatest reduction in crystallinity and the most uniform particle size distribution. To fabricate the generation process of natural fault gouge, it is appropriate to use the MG type to apply the same energy to constituent mineral, resulting the deformation reflecting its hardness. The GM type is recommended for use in fabricating the characteristics of the fault gouge that has undergone intense deformation at the slip surface, which allows for controlling the uniform crystallinity and particle size reduction of each constituent mineral. Our results suggest that the diverse nature of naturally occurring fault gouges can be fabricated in laboratory settings by adjusting the grinding conditions. This study offers effective methods for fabricating fault gouge analogue for frictional experiments for fault slip and potential applications in simulating geochemical reactions in fault zones. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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