Low total and inorganic carbon contents within the Taiwan Chelungpu fault system

Ikehara, Masaaki; Hirono, Tetsuro; Tadai, Osamu; Sakaguchi, Masumi; Kikuta, Hiroyuki; Fukuchi, Tatsuro; Mishima, Tomokazu; Nakamura, Norihiro; Aoike, Kan; Fujimoto, Koichiro; Hashimoto, Yoshitaka; Ishikawa, Tsuyoshi; Ito, Hisao; Kinoshita, Masataka; Lin, Weiren; Masuda, Koji; Matsubara, Takuo; Matsubayashi, Osamu; Mizoguchi, Kazuo; Otsuki, Kenshiro; Sone, H.; Takahashi, Miki; Tanikawa, Wataru; Tanimizu, Masaharu; Soh, Wonn; Song, Sheng Rong

doi:10.2343/geochemj.41.391

Cited by 26 publications

(22 citation statements)

References 8 publications

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“…The following subzones were encountered in FZB1136, from top to bottom ( High magnetic susceptibilities and low inorganic carbon contents have been reported previously in the black gouge zone (Hirono et al, 2006bIkehara et al, 2007), and an intense 20-mm-thick shear zone within the black gouge zone is considered to have been the most likely slip zone during the 1999 Chi-Chi earthquake Hirono et al, 2008).…”

Section: Sample Descriptionsmentioning

confidence: 99%

“…Therefore, information about temperatures in earthquake faults is important. Ikehara et al (2007) measured carbon contents in core samples from each of the three major fault zones in TCDP Hole B and reported a remarkably low inorganic carbon content in the black gouge zones within each of them. These researchers suggested that these zones had been subjected to high temperatures, because thermal decomposition of carbonate minerals occurs at temperatures above approximately 400…”

Section: Introductionmentioning

confidence: 99%

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Changes to magnetic minerals caused by frictional heating during the 1999 Taiwan Chi-Chi earthquake

et al. 2009

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We carried out magnetic mineral analyses of samples from the shallowest major fault zone within the Chelungpu fault system, which is the zone that previous researchers believe slipped during the 1999 Taiwan Chi-Chi earthquake. Our aim was to gain an understanding of the changes to magnetic minerals during the earthquake. Magnetic hysteresis and low-temperature thermal demagnetization measurements showed that high magnetic susceptibilities in the black gouge zone within the major fault zone could be attributed not to fining of ferrimagnetic minerals but, rather, to their abundance. Thermomagnetic analyses indicated that the strata in and around the fault zone originally contained thermally unstable iron-bearing paramagnetic minerals, such as pyrite, siderite, and chlorite. We therefore concluded that frictional heating (>400• C) occurred in the black gouge zone in the major fault zone during the slip of the Chi-Chi earthquake and that the resultant high temperature induced thermal decomposition of paramagnetic minerals to form magnetite, resulting in the observed high magnetic susceptibilities.

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Section: Sample Descriptionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Changes to magnetic minerals caused by frictional heating during the 1999 Taiwan Chi-Chi earthquake

et al. 2009

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“…Comprehensive mineralogical, geochemical, and magnetic analyses of Hole B core samples have been performed, and some temperature information during the Chi-Chi earthquake has been obtained. Ikehara et al (2007) reported that the inorganic carbon content of the fault gouge was low, and attributed the low value to thermal decomposition of carbonate minerals. A chemical kinetic evaluation based on the Arrhenius equation of the thermal decomposition reaction induced by earthquake slip estimated the temperature reached in response to frictional heating during the Chi-Chi earthquake to be 868°C (Hirono et al 2007b).…”

Section: Introductionmentioning

confidence: 99%

Estimation of slip parameters associated with frictional heating during the 1999 Taiwan Chi-Chi earthquake by vitrinite reflectance geothermometry

et al. 2014

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To estimate the slip parameters and understand the fault lubrication mechanism during the 1999 Taiwan Chi-Chi earthquake, we applied vitrinite reflectance geothermometry to samples retrieved from the Chelungpu fault. We found a marked reflectance anomaly of 1.30% ± 0.21% in the primary slip zone of the earthquake, whereas the reflectances in the surrounding deformed and host rocks were 0.45% to 0.77%. By applying a kinetic model of vitrinite thermal maturation together with a one-dimensional heat and thermal diffusion equation, we determined the shear stress and peak temperature in the slip zone during the earthquake to be 1.00 ± 0.04 MPa and 626°C ± 25°C, respectively. Taking into account the probable overestimation of the temperature owing to a mechanochemically enhanced reaction or flash heating at grain contacts, this temperature should be considered an upper limit. The lower limit was previously constrained to 400°C by studies of fluid-mobile trace-element concentrations and magnetic minerals. Therefore, we inferred that the peak temperature during the Chi-Chi earthquake was 400°C to 626°C, corresponding to an apparent friction coefficient of 0.01 to 0.06. Such low friction and the previous evidence of a high-temperature fluid suggest that thermal pressurization likely contributed to dynamic weakening during the Chi-Chi earthquake.

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“…The black gouge zone, including the 2‐cm‐thick slip zone associated with the earthquake, has lower inorganic carbon (mainly calcite), smectite, and kaolinite contents than the surrounding zones, and its magnetic susceptibility is relatively high [ Ikehara et al , 2007; Hirono et al , 2006, 2008]. These values have been attributed to frictional heat‐induced chemical reactions, including thermal decomposition of carbonate minerals, dehydration of interlayer water of smectite, dehydroxylation of smectite, dehydroxylation of kaolinite, and the production of magnetite from thermally decomposed paramagnetic minerals such as siderite [ Ikehara et al , 2007; Hirono et al , 2008; Mishima et al , 2009]. Because these reactions are endothermic, the heat of reaction, E C , takes up energy released from the fault during the earthquake, reducing the values of other forms of energy.…”

Section: Reestimation Of Dynamic Shear Stress and Energetics During Tmentioning

confidence: 99%

Specific heat capacity and thermal diffusivity and their temperature dependencies in a rock sample from adjacent to the Taiwan Chelungpu fault

Hirono¹,

Hamada²

2010

J. Geophys. Res.

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[1] Determination of the specific heat capacity and thermal diffusivity of rock samples, together with their temperature dependencies, is crucial for estimation of frictional heating during an earthquake. We measure these properties of a rock sample taken adjacent to the Taiwan Chelungpu fault, which slipped during the 1999 Chi-Chi earthquake, by differential scanning calorimetry and by using a laser-flash apparatus. We also evaluate the temperature dependencies of these properties up to 1000°C and 800°C, respectively, and determine their fitting equations. The specific heat capacity of the sample peaks at around 565°C, and the thermal diffusivity decreases with increasing temperature to 600°C but is almost constant in the temperature range of 600°C-800°C. These changes at around 550°C-600°C probably result from the a-b phase transition of quartz, of which the sample is dominantly composed. We then perform a numerical analysis, adopting these values of specific heat capacity and thermal diffusivity along with their temperature dependencies, to reestimate dynamic shear stress and earthquake energetics during the Chi-Chi earthquake. In this way, we determine the residual shear stress after the stress drop to be 9.0 MPa and the energy taken up by coseismic chemical reactions to be 10.4 MJ m −2 , corresponding to 12.1% of the given work on the fault and tending to counteract the frictional heating.Citation: Hirono, T., and Y. Hamada (2010), Specific heat capacity and thermal diffusivity and their temperature dependencies in a rock sample from adjacent to the Taiwan Chelungpu fault,

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Low total and inorganic carbon contents within the Taiwan Chelungpu fault system

Cited by 26 publications

References 8 publications

Changes to magnetic minerals caused by frictional heating during the 1999 Taiwan Chi-Chi earthquake

Changes to magnetic minerals caused by frictional heating during the 1999 Taiwan Chi-Chi earthquake

Estimation of slip parameters associated with frictional heating during the 1999 Taiwan Chi-Chi earthquake by vitrinite reflectance geothermometry

Specific heat capacity and thermal diffusivity and their temperature dependencies in a rock sample from adjacent to the Taiwan Chelungpu fault

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