180 research outputs found

    Investigation of the records of earthquake slip in carbonaceous materials from the Taiwan Chelungpu fault by means of infrared and Raman spectroscopies

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    To understand the mechanism of fault lubrication during the 1999 Taiwan Chi‐Chi earthquake, we developed a new temperature proxy for carbonaceous materials by using infrared and Raman spectroscopies together with heating and friction experiments. We found marked anomalies in the infrared and Raman spectra of carbonaceous materials retrieved from the primary slip zone of the earthquake: the infrared spectra exhibited very weak aliphatic CH2 and CH3 peaks and aromatic C=C absorbance peaks, and the Raman spectra exhibited very weak disordered and graphitic bands and a high ratio of disordered band area to graphitic band area. Those weak peaks and bands and the band area ratio were reproduced by heating carbonaceous materials from the nearby host rock to 700°C. These results suggest that the frictional heat in the slip zone reached approximately 700°C. We characterized the host rock's carbonaceous materials by means of elemental analysis, pyrolysis‐gas chromatography‐mass spectrometry, and simultaneous thermogravimetry‐differential scanning calorimetry and found that the H/C and O/C ratios were 1.29 and 0.30, respectively (which are close to the ratios for lignin) and that the volatile fraction was as high as 48 wt %. The pyrolysates obtained by heating from 100 to 400°C were dominated by phenols, fatty alcohols, and n‐alkanes. When the residue from pyrolysis at 100–400°C was rapidly heated to 700°C, the resulting pyrolysate was dominated by phenols, aromatic compounds, heterocyclic compounds, and n‐alkenes. This information suggests that change in the infrared and Raman spectra with increasing temperature may have been due to decomposition and aromatization reactions during pyrolysis. Rapid heating during earthquake slip may promote reactions of carbonaceous materials that are different from the reactions that occur during long‐term geological metamorphism.This research was supported by a Grant-in-Aid for Young Scientists (A) from the Japan Ministry of Education, Science, Sports, and Culture (23684039, 2013)

    Tetra- and pentacyclic alkanes in the Cretaceous/Tertiary boundary sediments at Kawaruppu, Hokkaido, Japan

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    Twenty two steranes and 17 triterpanes were detected in the Cretaceous-Tertiary (K/T) boundary sediments at Kawaruppu, Hokkaido, Japan. These steranes and triterpanes were detected at a concentration level of 0.001-0.1nmol g-1. Their concentrations were smaller within the K/T boundary claystone than in the sediments above and below the claystone, which are likely related to the large biomass extinction event at the end of the Cretaceous. The concentrations of 5α-cholestane and the relative ones of 17α,21β-hopane in the sediments above the boundary claystone were about a half of those in the sediments below the claystone, whereas those of 5α-ergostane, 5α-stigmastane, and oleanane in the sediments above were less than a half abundance level of those in the sediments below the claystone. Diastereomer ratios of steranes and triterpanes were nearly constant over the sediments. No tricyclic alkanes were detected in the sediments.This work was supported by the Grant-in-Aid for ScientificResearch (B) No.11440166 from the Ministry of Education, Science, Sports and Culture, Japan and the Research Grant for Fellowship No.00007064 to H. Y. from Japanese Society for the Promotion of Science

    Raman spectroscopic thermometer for carbonaceous material in chondrites

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    第6回極域科学シンポジウム[OA] 南極隕石11月16日(月) 国立国語研究所 2階 講

    Organic Matter in the Solar System—Implications for Future on-Site and Sample Return Missions

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    Solar system bodies like comets, asteroids, meteorites and dust particles contain organic matter with different abundances, structures and chemical composition. This chapter compares the similarities and differences of the organic composition in these planetary bodies. Furthermore, these links are explored in the context of detecting the most pristine organic material, either by on-site analysis or sample return missions. Finally, we discuss the targets of potential future sample return missions, as well as the contamination controls that should be in place in order to successfully study pristine organic matter

    Shock vaporization/devolatilization of evaporitic minerals, halite and gypsum, in an open system investigated by a two-stage light gas gun

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    Dry lakebeds might constitute large volatile reservoirs on Mars. Hypervelocity impacts onto ancient dry lakebeds would have affected the volatile distribution on Mars. We developed a new experimental method to investigate the response of evaporitic minerals (halite and gypsum) to impact shocks in an open system. This technique does not result in chemical contamination from the operation of the gas gun. The technique is termed the two-valve method and the gun system is located in the Planetary Exploration Research Center, Chiba Institute of Technology, Japan. We detected the vaporization of halite at 31 GPa and devolatilization from gypsum at 11 GPa, suggesting that impact-induced volatile release from dry lakebeds has periodically occurred throughout Martian history. The vaporization of halite deposits might have enhanced the production of perchlorates, which are found globally on Mars. The water loss from gypsum possibly explains the coexisting types of Ca-sulfates found in Gale Crater.Comment: 17 pages, 4 figures, 1 supporting information, accepted for publication in Geophysical Research Letter

    H, C, and N isotopic compositions of Hayabusa category 3 organic samples

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    Since isotopic ratios of H, C, and N are sensitive indicators for determining extraterrestrial organics, we have measured these isotopes of Hayabusa category 3 organic samples of RB-QD04-0047-02, RA-QD02-0120, and RB-QD04-0001 with ion imaging using a NanoSIMS ion microprobe. All samples have H, C, and N isotopic compositions that are terrestrial within errors (approximately ±50‰ for H, approximately ±9‰ for C, and approximately ±2‰ for N). None of these samples contain micrometer-sized hot spots with anomalous H, C, and N isotopic compositions, unlike previous isotope data for extraterrestrial organic materials, i.e., insoluble organic matters (IOMs) and nano-globules in chondrites, interplanetary dust particles (IDPs), and cometary dust particles. We, therefore, cannot conclude whether these Hayabusa category 3 samples are terrestrial contaminants or extraterrestrial materials because of the H, C, and N isotopic data. A coordinated study using microanalysis techniques including Fourier transform infrared spectrometry (FT-IR), time-of-flight secondary ion mass spectrometry (ToF-SIMS), NanoSIMS ion microprobe, Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), and transmission electron microscopy/scanning transmission electron microscopy (TEM/STEM) is required to characterize Hayabusa category 3 samples in more detail for exploring their origin and nature.This research was supported by the JSPS Strategic Fund for Strengthening Leading-edge Research and Development to the JAMSTEC

    ToF-SIMS analysis of carbonaceous particles in the sample catcher of the Hayabusa spacecraft

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    Three carbonaceous category 3 particles (RA-QD02-0180, RB-QD04-0037-01, and RB-QD04-0047-02) returned in the sample catcher from the Hayabusa spacecraft were analyzed by time of flight-secondary ion mass spectrometry (ToF-SIMS) to establish an analytical procedure for determination of their origins. By the different analytical schemes, the three particles gave distinct elemental and molecular ions, in which the organic carbons commonly appear to be associated with nitrogen, silicon, and/or fluorine. The particles could be debris of silicon rubber and fluorinated compounds and are therefore man-made artifacts rather than natural organic matter
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