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71.
Ayako?ShinozakiEmail author Hisako?Hirai Hiroyuki?Kagi Tadashi?Kondo Taku?Okada Daisuke?Nishio-Hamane Shin-ichi?Machida Tetsuo?Irifune Takumi?Kikegawa Takehiko?Yagi 《Physics and Chemistry of Minerals》2012,39(2):123-129
High pressure and temperature reactions of a mixture of forsterite and hydrogen molecules have been carried out using a laser
heated diamond anvil cell at 9.8–13.2 GPa and ~1,000 K. In situ X-ray diffraction measurements showed no sign of decomposition
or phase transitions of the forsterite under these experimental conditions, indicating that the olivine structure was maintained
throughout all runs. However, a substantial expansion of the unit cell volume of the forsterite was observed for samples down
to ~3 GPa upon quenching to ambient pressure at room temperature. The Raman spectroscopy measurements under pressure showed
significant shifts of the Raman peaks of the Si–O vibration modes for forsterite and of the intramolecular vibration mode
for H2 molecules toward a lower frequency after heating. Additionally, no OH vibration modes were observed by Raman and FT-IR spectroscopic
measurements. These lines of evidence show that the observed volume expansion in forsterite is not explained by the incorporation
of hydrogen atoms as hydroxyl, but suggest the presence of hydrogen as molecules in the forsterite structure under these high
pressure and temperature conditions. 相似文献
72.
Daisuke NAKASHIMA Takayuki USHIKUBO Rudraswami N. GOWDA Noriko T. KITA John W. VALLEY Keisuke NAGAO 《Meteoritics & planetary science》2011,46(6):857-874
Abstract– The ion microprobe is the only technique capable of determining high‐precision stable isotope ratios in individual tiny extraterrestrial particles (≤100 μm in diameter), but these small samples present special analytical challenges. We produced a new sample holder disk with multiple holes (three holes and seven holes), in which epoxy disks containing a single unknown sample and a standard grain are cast and polished. Performance tests for oxygen two‐isotope analyses using San Carlos olivine standard grains show that the new multiple‐hole disks allow accurate analysis of tiny particles if the particles are located within the 500 μm and 1 mm radius of the center of holes for seven‐hole and three‐hole disks, respectively. Using the new seven‐hole disk, oxygen three‐isotope ratios of eight magnesian cryptocrystalline chondrules (approximately 100 μm in diameter) from the Sayh al Uhaymir (SaU) 290 CH chondrite were analyzed by ion microprobe at the University of Wisconsin. Five out of eight chondrules have nearly identical oxygen isotope ratios (Δ17O = ?2.2 ± 0.6‰; 2SD), which is consistent with those of magnesian cryptocrystalline chondrules in CH/CB and CB chondrites, suggesting a genetic relationship, i.e., formation by a common (possibly impact) heating event. The other three chondrules have distinct oxygen isotope ratios (Δ17O values from ?6.4‰ to +2.2‰). Given that similar variation in Δ17O values was observed in type I porphyritic chondrules in a CH/CB chondrite, the three chondrules may have formed in the solar nebula, similar to the type I porphyritic chondrules. 相似文献
73.
Lithium and strontium isotopic systematics in playas in Nevada,USA: constraints on the origin of lithium 总被引:1,自引:0,他引:1
Daisuke Araoka Hodaka Kawahata Tetsuichi Takagi Yasushi Watanabe Koshi Nishimura Yoshiro Nishio 《Mineralium Deposita》2014,49(3):371-379
Lithium-rich brine in playas is a major raw material for lithium production. Recently, lithium isotopic ratios (δ7Li) have been identified as a tool for investigating water–rock interactions. Thus, to constrain the origin of lithium in playas by the use of its isotopes, we conducted leaching experiments on various lacustrine sediment and evaporite deposit samples collected from playas in Nevada, USA. We determined lithium and strontium isotopic ratios and contents and trace element contents of the leachate, estimated the initial δ7Li values in the water flowing into the playas, and examined the origin of lithium in playas by comparison with δ7Li values of the possible sources. In samples from the playas, δ7Li values show some variation, reflecting differences both in isotopic fractionation during mineral formation and in initial δ7Li value in water flowing into each playa. However, all δ7Li values in this study are much lower than those in river water and groundwater samples from around the world, but they are close to those of volcanic rocks. Considering the temperature dependence of lithium isotopic fractionation between solid and fluid, these results indicate that the lithium concentrated in playas in Nevada was supplied mainly through high-temperature water–rock interaction associated with local hydrothermal activity and not directly by low-temperature weathering of surface materials. This study, which is the first to report lithium isotopic compositions in playas, demonstrates that δ7Li may be a useful tracer for determining the origin of lithium and evaluating its accumulation processes in playas. 相似文献
74.
This paper presents the results of a study on the use of nanoindentation test to characterize the strain rate-dependent compressive response of asphalt concrete. Nanoindentation is now widely used for characterization and testing of composite as well as single-phase materials. Using a small piece of sample, nanoindentation tests can evaluate material behavior and structure in terms of the elasticity, time-dependent response, yield strength, damage, crack advance, debonding, and fatigues. In this study, a mixture of asphalt and calcium carbonate filler powder filling the intergranular void space of the asphalt concrete was characterized in terms of strain rate sensitivity at room temperature. The indentation hardness is observed to continuously decrease during constant indentation strain rates, but the hardness response clearly indicates positive strain rate dependency when compared at the same indentation depths. Following the constant strain rate tests, indentation creep response of the asphalt–filler mixture was tested at constant load conditions. The strain rate sensitivity values characterized from double logarithmic relationships between indentation hardness and strain rate during constant strain rate and constant load tests are comparable with that determined from uniaxial compression test of cylindrical asphalt concrete samples. The observed indentation size effect on hardness value was analyzed based on an existing size effect model. The size effect in the asphalt–filler mixture, which is stronger than that defined by the model, could be attributed to a plastically graded surface of asphalt–filler sample. 相似文献
75.
The Setouchi volcanic rocks include high-Mg andesites (HMAs) and garnet-bearing dacite–rhyolite, and are sporadically distributed along the Median Tectonic Line, Japan. New U–Pb zircon ages and geological and geochemical data are presented for those rocks in the Western Setouchi region (W-Setouchi). Previous studies referred to the altered andesite in the W-Setouchi as “pre-Setouchi volcanic rocks.” However, on the basis of the new U–Pb age (14.4 Ma ± 0.3 Ma) and geochemical characteristics, we redefine it as the Jikamuro Formation, part of the Setouchi volcanic rocks. Incompatible elements are more enriched in the Jikamuro Formation rocks than in the Setouchi HMAs. The characteristic element compositions may be explained by mixing of compositionally different magmas, including subducted sediment melts, plus a contribution from crustal contamination. A stress-inversion technique with Bingham distribution method was applied to the orientations of felsic and mafic dikes within the Setouchi volcanic rocks, and indicates paleo-stress conditions during the period of Setouchi volcanism in the W-Setouchi. The analysis reveals NNW-extensional stresses and a strike-slip stress. We infer that the former represents extensional conditions during the main period of volcanism and the latter represents a stress transition during the most recent period of volcanism (after 12 Ma). 相似文献
76.
Urumu Tsunogai Kanae Kamimura Saya Anzai Fumiko Nakagawa Daisuke D. Komatsu 《Geochimica et cosmochimica acta》2011,75(16):4531-4546
In high-temperature volcanic fumaroles (>400 °C), the isotopic composition of molecular hydrogen (H2) reaches equilibrium with that of the fumarolic H2O. In this study, we used this hydrogen isotope exchange equilibrium of fumarolic H2 as a tracer for the remote temperature at volcanic fumaroles. In this remote sensing, we deduced the hydrogen isotopic composition (δD value) of fumarolic H2 from those in the volcanic plume. To ascertain that we can estimate the δD value of fumarolic H2 from those in a volcanic plume, we estimated the values in three fumaroles with outlet temperatures of 630 °C (Tarumae), 203 °C (Kuju), and 107 °C (E-san). For this we measured the concentration and δD value of H2 in each volcanic plume, along with those determined directly at each fumarole. The average and maximum mixing ratios of fumarolic H2 within a plume’s total H2 were 97% and 99% (at Tarumae), 89% and 96% (at Kuju), and 97% and 99% (at E-san). We found a linear relationship between the depletion in the δD values of H2, with the reciprocal of H2 concentration. Furthermore, the estimated end-member δD value for each H2-enriched component (−260 ± 30‰ vs. VSMOW in Tarumae, −509 ± 23‰ in Kuju, and −437 ± 14‰ in E-san) coincided well with those observed at each fumarole (−247.0 ± 0.6‰ in Tarumae, −527.7 ± 10.1‰ in Kuju, and −432.1 ± 2.5‰ in E-san). Moreover, the calculated isotopic temperatures at the fumaroles agreed to within 20 °C with the observed outlet temperature at Tarumae and Kuju. We deduced that the δD value of the fumarolic H2 was quenched within the volcanic plume. This enabled us to remotely estimate these in the fumarole, and thus the outlet temperature of fumaroles, at least for those having the outlet temperatures more than 400 °C. By applying this methodology to the volcanic plume emitted from the Crater 1 of Mt. Naka-dake (the volcano Aso) where direct measurement on fumaroles was impractical, we estimated that the δD value of the fumarolic H2 to be −172 ± 16‰ and the outlet temperature to be 868 ± 97 °C. The remote temperature sensing using hydrogen isotopes developed in this study is widely applicable to many volcanic systems. 相似文献
77.
Shuangmeng Zhai Weihong Xue Daisuke Yamazaki Shuangming Shan Eiji Ito Naotaka Tomioka Akira Shimojuku Ken-ichi Funakoshi 《Physics and Chemistry of Minerals》2011,38(5):357-361
High pressure in situ synchrotron X-ray diffraction experiment of strontium orthophosphate Sr3(PO4)2 has been carried out to 20.0 GPa at room temperature using multianvil apparatus. Fitting a third-order Birch–Murnaghan equation of state to the P–V data yields a volume of V 0 = 498.0 ± 0.1 Å3, an isothermal bulk modulus of K T = 89.5 ± 1.7 GPa, and first pressure derivative of K T ′ = 6.57 ± 0.34. If K T ′ is fixed at 4, K T is obtained as 104.4 ± 1.2 GPa. Analysis of axial compressible modulus shows that the a-axis (K a = 79.6 ± 3.2 GPa) is more compressible than the c-axis (K c = 116.4 ± 4.3 GPa). Based on the high pressure Raman spectroscopic results, the mode Grüneisen parameters are determined and the average mode Grüneisen parameter of PO4 vibrations of Sr3(PO4)2 is calculated to be 0.30(2). 相似文献
78.
Tetsuya Tokiwa Kimikazu Tsusaka Makoto Matsubara Taiki Ishikawa Daisuke Ogawa 《地学前缘(英文版)》2013,4(1):105-111
This paper focuses on the formation mechanism of fractures induced by excavation of a gallery in soft sedimentary rocks in the Horonobe area of Japan.Detailed fracture mapping of the gallery indicates that the fractures consist of both pre-existing shear fractures and excavation damaged zone(EDZ) fractures. EDZ fractures correspond to weak planes associated with bedding planes or transgranular cracks.The EDZ fractures terminate against pre-existing shear fractures.Therefore,even for excavations in soft sedimentary rocks,formation of the EDZ fractures are controlled by pre-existing fractures and earlier weak planes. 相似文献
79.
Noriko T. Kita Kees C. Welten John W. Valley Michael J. Spicuzza Daisuke Nakashima Travis J. Tenner Takayuki Ushikubo Glenn J. MacPherson Linda Welzenbach Philipp R. Heck Andrew M. Davis Matthias M. M. Meier Rainer Wieler Marc W. Caffee Matthias Laubenstein Kunihiko Nishiizumi 《Meteoritics & planetary science》2013,48(4):641-655
The Mifflin meteorite fell on the night of April 14, 2010, in southwestern Wisconsin. A bright fireball was observed throughout a wide area of the midwestern United States. The petrography, mineral compositions, and oxygen isotope ratios indicate that the meteorite is a L5 chondrite fragmental breccia with light/dark structure. The meteorite shows a low shock stage of S2, although some shock‐melted veins are present. The U,Th‐He age is 0.7 Ga, and the K‐Ar age is 1.8 Ga, indicating that Mifflin might have been heated at the time of the 470 Ma L‐chondrite parent body breakup and that U, Th‐He, and K‐Ar ages were partially reset. The cosmogenic radionuclide data indicate that Mifflin was exposed to cosmic rays while its radius was 30–65 cm. Assuming this exposure geometry, a cosmic‐ray exposure age of 25 ± 3 Ma is calculated from cosmogenic noble gas concentrations. The low 22Ne/21Ne ratio may, however, indicate a two‐stage exposure with a longer first‐stage exposure at high shielding. Mifflin is unusual in having a low radiogenic gas content combined with a low shock stage and no evidence of late stage annealing; this inconsistency remains unexplained. 相似文献
80.
Tomoya Obase Daisuke Nakashima Tomoki Nakamura Keisuke Nagao 《Meteoritics & planetary science》2020,55(5):1031-1047
We measured concentrations and isotopic ratios of noble gases in the Rumuruti (R) chondrite Mount Prestrud (PRE) 95410, a regolith breccia exhibiting dark/light structures. The meteorite contains solar and cosmogenic noble gases. Based on the solar and cosmogenic noble gas compositions, we calculated a heliocentric distance of its parent body, a cosmic‐ray exposure age on the parent body regolith (parent body exposure age), and a cosmic‐ray exposure age in interplanetary space (space exposure age) of the meteorite. Assuming a constant solar wind flux, the estimated heliocentric distance was smaller than 1.4 ± 0.3 au, suggesting inward migration from the asteroid belt regions where the parent body formed. The largest known Mars Trojan 5261 Eureka is a potential parent body of PRE 95410. Alternatively, it is possible that the solar wind flux at the time of the parent body exposure was higher by a factor of 2–3 compared to the lunar regolith exposure. In this case, the estimated heliocentric distance is within the asteroid belt region. The parent body exposure age is longer than 19.1 Ma. This result indicates frequent impact events on the parent body like that recorded for other solar‐gas‐rich meteorites. Assuming single‐stage exposure after an ejection event from the parent body, the space exposure age is 11.0 ± 1.1 Ma, which is close to the peak of ~10 Ma in the exposure age distribution for the solar‐gas‐free R chondrites. 相似文献