Quantitative modeling of the newly formed magnetic minerals in the fault gouge of 1999 Chi-Chi earthquake (Mw 7.6), Taiwan

Yu Min Chou, Sheng Rong Song, Charles Aubourg, Teh Quei Lee, Yen Fang Song, En Chao Yeh

研究成果: 雜誌貢獻文章

4 引文 斯高帕斯(Scopus)

摘要

When an earthquake occurs, magnetic minerals are formed in the gouge under the combined action of frictional heating and fluid. Generally, the gouge is altered, and a detailed analysis of neoformed minerals is difficult. The Taiwan Chelungpu fault Drilling Project provided continuous records of the active Chelungpu fault gouges. By analyzing the magnetic parameters along the 16 cm thick gouge which houses the principal slip zone of the 1999 Chi-Chi earthquake (Mw 7.6), we observed a 4 cm shift between the maximum of magnetic susceptibility and the maximum of remanence. The maximum magnetic susceptibility is localized along the principal slip zone. The main identified magnetic minerals are magnetite and goethite, which have very different magnetic parameters. We propose that the maximum of the concentration of magnetite and goethite corresponds to the maximum of magnetic susceptibility and remanence, respectively. By modeling the concentration of these two magnetic minerals, we explain satisfactorily the profiles of magnetic susceptibility and remanence. This quantitative modeling indicates that ~200 ppmv of magnetite formed in the principal slip zone and its main contact area. Similarly, ~1% of goethite is formed in the center of the gouge, where the fluids are more enriched in iron. We propose that the magnetite and goethite are formed and altered during seismic cycles. Key Points Investigate the magnetic mineral assemblage in the Chi-Chi fault gougeClarify the distribution of goethite and magnetite in the gougePropose a model for goethite and magnetite distributions within the gouge

原文英語
頁(從 - 到)6771-6781
頁數11
期刊Journal of Geophysical Research: Solid Earth
119
發行號9
DOIs
出版狀態已發佈 - 2014 九月 1

    指紋

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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