Strain-induced amorphization of graphite in fault zones of the Hidaka metamorphic belt, Hokkaido, Japan

Nakamura, Yu; Oohashi, Kiyokazu; Toyoshima, Tsuyoshi; Satish-Kumar, M.; Akai, Junji

doi:10.1016/j.jsg.2014.10.012

Cited by 67 publications

(64 citation statements)

References 53 publications

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“…Kouketsu et al (2019) proposed two possible explanations for this phenomenon: (1) a mixture of detrital and metamorphic graphite grains, and (2) a mixture of different reactive CM during short-lived metamorphism. Another possibility is (3) amorphization due to brittle deformation of CM (Nakamura et al, 2015), which reduces the estimated temperature. In our case, the effect of the different reactive CM is probably negligible because the duration of metamorphism is estimated to be~20 Myr (Miyazaki et al, 2017).…”

Section: Peak Metamorphic Temperaturementioning

confidence: 99%

Peak metamorphic temperature of the Nishisonogi unit of the Nagasaki Metamorphic Rocks, western Kyushu, Japan

Mori

Shigeno

Miyazaki

et al. 2019

Journal of Mineralogical and Petrological Sciences

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The Nishisonogi unit of the Nagasaki Metamorphic Rocks represents a part of a Late Cretaceous subduction complex exposed in western Kyushu, Japan. We estimate peak metamorphic temperatures using a Raman carbonaceous material (CM) geothermometer on 60 pelitic schists. No systematic regional changes were observed in the mineral assemblage of samples collected over a large area (about 30 × 15 km), which include chlorite ± garnet + white micas + albite + quartz + titanite + CM. However, the estimated peak metamorphic temperature increases structurally upward from 440 to 524°C, suggesting an inverted thermal gradient.

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Section: Peak Metamorphic Temperaturementioning

confidence: 99%

Peak metamorphic temperature of the Nishisonogi unit of the Nagasaki Metamorphic Rocks, western Kyushu, Japan

Mori

Shigeno

Miyazaki

et al. 2019

Journal of Mineralogical and Petrological Sciences

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“…The natural CM used for our high-pressure-high-temperature (HPHT) experiments is identical to that employed by Nakamura et al (2017), and it was chemically extracted from two different naturally occurring sedimentary rocks, one from the Hidaka metamorphic belt (HMB) in Hokkaido, Japan (Nakamura et al 2015), and another from the Cretaceous Shimanto accretionary complex (SM) in Kochi, SW Japan (Nakamura et al 2019). The natural CM is distributed along the grain boundaries of silicate minerals and closely associated with phyllosilicates.…”

Section: Experimental Methodsmentioning

confidence: 99%

Pressure dependence of graphitization: implications for rapid recrystallization of carbonaceous material in a subduction zone

Nakamura

Yoshino

Satish-Kumar

2020

Contrib Mineral Petrol

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We report the results of kinetic experiments of graphitization at various pressures (0.5-8.0 GPa) and durations (1 s to 24 h) at 1200 °C. The natural carbonaceous material in sedimentary rocks from the Shimanto accretionary complex and the Hidaka metamorphic belt, Japan, underwent systematic changes in crystallinity and morphology with increasing pressure. To assess the pressure dependence of graphitization, we adopted three approaches to formulating the graphitization kinetics using a power law rate model, a Johnson-Mehl-Avrami-Kolmogorov model, and a superposition method. Activation volumes of − 21.7 ± 3.0 to − 45.7 ± 4.5 cm 3 mol −1 and − 0.7 ± 0.2 to − 16.8 ± 1.8 cm 3 mol −1 were obtained for pressures from 0.5 to 2.0 GPa and 2.0 to 8.0 GPa, respectively. Such large negative activation volumes might arise from structural modification and compression in the primary carbonaceous material. We applied the experimental data to the Arrhenius-type equation of graphitization, extrapolated to geological P-T-t conditions. Our model predicts that carbonaceous material undergoing metamorphism for ~ 10 Myr at pressures of 0.5-3.0 GPa will begin to crystallize at around 350-420 °C and transform fully to ordered graphite at around 450-600 °C, depending on the peak pressure. Thus, natural graphitization might proceed much more rapidly than previously estimated, owing to the large negative activation volumes for the reaction rate. This indicates that subducted carbonaceous materials will completely convert to fully ordered graphite by rapid recrystallization and metamorphic devolatilization before reaching sub-arc depths (< 100 km).

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“…Since graphite has a very low shear strength, it is likely that the microtexture of graphite is readily modified by shearing associated with faulting. For example, Nakamura et al (2015) reported the shear-induced amorphization of graphite in a fault zone in the Hidaka metamorphic belt. This evidence indicates shearing-related damage to graphite during fault movement.…”

Section: Effect Of Shearing On Graphite In Fault Rocksmentioning

confidence: 99%

“…Several studies successfully detected the shear heating recorded in the CM of the fault rocks and discussed the properties of earthquake slips such as displacement rate and coefficient of friction (Mori et al 2015;Hirono et al 2015). On the other hand, Nakamura et al (2015) and Kouketsu et al (2017) reported the mechanical damage on CM in the fault rocks, and they pointed out that not only the evolution of CM crystallinity by shear heating but also the destruction of crystal structure by shearing should be taken into consideration in the fault rocks.…”

Section: Introductionmentioning

confidence: 99%

Drastic effect of shearing on graphite microtexture: attention and application to Earth science

Kouketsu

Miyake

Igami

et al. 2019

Prog Earth Planet Sci

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The microtexture of graphite exposed on the polished surface was studied using confocal laser scanning microscopy, laser Raman spectroscopy, and focused ion beam-transmission electron microscopy (FIB-TEM) to elucidate the effect on surface condition and crystallinity of graphite by polishing process. The polished surface of the graphite was divided into a flat part with no irregularities and a grooved band with a width of < 1 μm and a depth of < 100 nm. Raman analyses revealed that the original structure of the graphite covered by the host mineral was a well-ordered graphite, whereas the polished graphite at the surface had a reduced crystallinity, particularly in the flat part of the sample. Based on scanning TEM observations of an ultra-thin FIB section, fractures that developed during sample preparation were concentrated in the region extending from the surface to a depth of 1 μm. Furthermore, graphite sheets were peeled away by shearing, with scraped graphite sheets filling in the gap. Our results demonstrate that the original microtexture of graphite was easily deformed by shearing during polishing, and careful attention should be paid to sample preparation. In addition, we also need to pay more attention to the effects of natural shearing such as faulting on the graphite or sheet-like minerals.

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Strain-induced amorphization of graphite in fault zones of the Hidaka metamorphic belt, Hokkaido, Japan

Cited by 67 publications

References 53 publications

Peak metamorphic temperature of the Nishisonogi unit of the Nagasaki Metamorphic Rocks, western Kyushu, Japan

Peak metamorphic temperature of the Nishisonogi unit of the Nagasaki Metamorphic Rocks, western Kyushu, Japan

Pressure dependence of graphitization: implications for rapid recrystallization of carbonaceous material in a subduction zone

Drastic effect of shearing on graphite microtexture: attention and application to Earth science

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