A primitive dark inclusion with radiation‐damaged silicates in the Ningqiang carbonaceous chondrite     

Michael ZOLENSKY  Keiko NAKAMURA  Michael K. WEISBERG  Martin PRINZ  Tomoki NAKAMURA  Kazumasa OHSUMI  Akihiro SAITOW  Masae MUKAI  Matthieu GOUNELLE 《Meteoritics & planetary science》2003,38(2):305-322

Abstract— A petrologic and TEM study of a remarkable dark inclusion (DI) in the Ningqiang CV3 chondrite reveals that it is a mixture of highly primitive solar nebula materials. The DI contains two lithologies. The first, lithology A, contains micron‐sized olivine and pyroxene grains rimmed by amorphous materials with compositions similar to the underlying crystalline grains. The second, lithology B, appears to preserve the mineralogy of lithology A before formation of the amorphous rims. Overall, the Ningqiang DI appears to record the following processes: 1) formation (condensation and Fe‐enrichment) of olivine crystals in the nebula with compositions of Fo_42–62; 2) irradiation, resulting in amorphitization of the olivine and pyroxene to varying degrees; 3) partial annealing, resulting in formation of fairly large, euhedral olivine and pyroxene grains with remnant amorphous sharply‐bounded rims; 4) in some cases, prolonged annealing, resulting in the formation of microcrystalline olivine or pyroxene rims. The latter annealing would have been a natural consequence of irradiation near the critical temperature for olivine; and 5) mixture of the above materials (lithology A) with nebular condensate high‐Ca pyroxene and olivine, which escaped nebular processing, to become lithology B. We suggest that the amorphous rims in lithology A formed in an energetic solar event such as a bi‐polar outflow or FU‐orionis flare.  相似文献   

Sequences Characterization of Microsatellite DNA Sequences in Pacific Abalone (Haliotis discus hannat)     

LI Qi  Kijima Akihiro 《中国海洋大学学报(英文版)》2007,6(1)

The microsatellite-enriched library was constructed using magnetic bead hybridization selection method, and the microsatellite DNA sequences were analyzed in Pacific abalone Haliotis discus hannai. Three hundred and fifty white colonies were screened using PCR-based technique, and 84 clones were identified to potentially contain microsatellite repeat motif. The 84 clones were sequenced, and 42 microsatellites and 4 minisatellites with a minimum of five repeats were found (13.1% of white colonies screened). Besides the motif of CA contained in the oligoprobe, we also found other 16 types of microsatellite repeats including a dinucleotide repeat, two tetranucleotide repeats, twelve pentanucleotide repeats and a hexanucleotide repeat. According to Weber(1990), the microsatellite sequences obtained could be categorized structurally into perfect repeats (73.3%), imperfect repeats(13.3%), and compound repeats (13.4%). Among the microsatellite repeats, relatively short arrays (＜ 20 repeats) were most abundant,accounting for 75.0%. The largest length of microsatellites was 48 repeats, and the average number of repeats was 13.4. The data on the composition and length distribution of microsatellites obtained in the present study can be useful for choosing the repeat motifs for microsatetlite isolation in other abalone species.  相似文献   

Petrology and geochemistry of peridotites from IODP Site U1309 at Atlantis Massif, MAR 30°N: micro- and macro-scale melt penetrations into peridotites     

Akihiro Tamura  Shoji Arai  Satoko Ishimaru  Eric S. Andal 《Contributions to Mineralogy and Petrology》2008,155(4):491-509

Peridotite samples recovered from IODP Site U1309 at the Atlantis Massif in the Mid-Atlantic Ridge were examined to understand magmatic processes for the oceanic core complex formation. Original peridotite was fragmented, and the limited short peridotite intervals are now surrounded by a huge gabbro body probably formed by late-stage melt injections. Each peridotite interval has various petrographical and geochemical features. A spinel harzburgite in contact with gabbro shows evidence of limited melt penetrations causing gradual compositional change, in terms of trace-element compositions of pyroxenes, as well as modal change near the boundary. Geochemistry of clinopyroxenes with least melt effects indicates that the harzburgite is originally mantle residue formed by partial melting under polybaric conditions, and that such a depleted peridotite is one of the components of the oceanic core complex. Some of plagioclase-bearing peridotites, on the other hand, have more complicated origin. Although their original features were partly overprinted by the injected melt, the original peridotites, both residual and non-residual materials, were possibly derived from the upper mantle. This suggests that the melt injected around an upper mantle region or into mantle material fragments. The injected melt was possibly generated at the ridge-segment center and, then, moved and evolved toward the segment end beneath the oceanic core complex.  相似文献   

Erratum to: A spatio-temporal three-dimensional conceptualization and simulation of Dera Ismail Khan alluvial aquifer in visual MODFLOW: a case study from Pakistan     

Qadir  Anwar  Ahmad  Zulfiqar  Khan  Tahseenullah  Zafar  Mohammad  Qadir  Atwar  Murata  Mamoru 《Arabian Journal of Geosciences》2016,9(7):1-17

The Gour Oumelalen area exposes Paleoproterozoic (1.9 Ga) marbles and calc-silicate granulites. Some marbles show a specific mineralogy characterized by the presence of a highly aluminous clinopyroxene with Al₂O₃ content exceeding16 wt%. This clinopyroxene shows a marked zoning with a hedenbergitic core rimmed by fassaite. Phase relations are expressed by spectacular reaction textures in calc-silicate granulites as Opx + Cpx + Pl + H₂O  == > Grt + Qtz ± Am and Cpx + Ilm + Pl ± Mt = > Grt + Qtz + Spn. In olivine-bearing marbles, clinopyroxene and dolomite occur around olivine and calcite. According to thermodynamic modeling in the Na₂O–CaO–FeO–MgO–Al₂O₃–SiO₂–H₂O–TiO₂–Fe₂O₃ (NCFMASHTO) system, the first stage of metamorphism is located at 800 °C and 6–7 kbar, which is followed by an increase in pressure at 9–10 kbar and 800 °C and an isobaric cooling at 680 °C. The deduced anticlockwise P–T path is consistent with a granulitic metamorphism occurring in an active continental margin context.

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Pleistocene geochemical stratigraphy of the borehole 1317E (IODP Expedition 307) in Porcupine Seabight,SW of Ireland: applications to palaeoceanography and palaeoclimate of the coral mound development     

Xianghui Li  Chiduru Takashima  Akihiro Kano  Saburo Sakai  Yunhua Chen  Baoliang Xu  Iodp Expedition Scientists 《第四纪科学杂志》2011,26(2):178-189

Stable isotopes and element compositions of the fine‐grained matrix were measured for IODP Expedition 307 Hole U1317E drilled from the summit of Challenger Mound in Porcupine Seabight, northeast Atlantic, to explore the palaeoceanographic and palaeoclimatic background to development of the deep‐water coral mound. The 155 m long mound section was divided into two units by an unconformity at 23.6 mbsf: Unit M1 (2.6–1.7 Ma) and Unit M2 (1.0–0.5 Ma). Results from 519 specimens show a difference in δ¹³C value between Unit M1 (?0.6‰ to ?5.0‰) and Unit M2 (?1.0‰ to 1.0‰), but such a distinct difference was not seen in δ¹⁸O values (1.0‰–2.5‰), CaCO₃ content (40–60 wt%), Sr/Ca ratio (2.0–8.0 mmol mol^?1), and Mg/Ca ratio (10.0–20.0 mmol mol^?1) through the mound. Positive δ¹⁸O and negative δ¹³C shifts at the mound base are consistent with the oceanographic changes in the northeast Atlantic at the beginning of the Quaternary. The positive δ¹³C regression in Unit M2 suggests a linkage to the mid Pleistocene intensified glaciation in the Northern Hemisphere. Warm Mediterranean Upper Core Water of Mediterranean Outflow Water, Eastern North Atlantic Water and cold Labrador Sea Water of North Atlantic Deep Water are key oceanographic features that cause spikes and shifts in stable isotope and element composition. However, the stable isotope values of the sediment matrix could not primarily record the glacial–interglacial eustatic/temperature change, but indirectly indicate current regimes of the intermediate oceanic layer where the coral mound grew. Similarly, elemental ratios and CaCO₃ content may not represent the productivity and temperature of surface sea water, respectively, but superpose the fractions from both surface and bottom water. It is concluded that palaeoceanographic change coupled to the Pleistocene glacial/interglacial cycles is a key control on the geochemical stratigraphy of the matrix sediments of the carbonate mound developed in Porcupine Seabight. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Positive electrification on the floor of an underground mine gallery at the arrival of seismic waves and similar electrification on the surface of partially stressed rocks in laboratory     

Akihiro Takeuchi  Yukako Futada  Kan Okubo  Nobunao Takeuchi 《地学学报》2010,22(3):203-207

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Position Measurements of the Core in 3C 66B     

G. -Y. Zhao  Y. -J. Chen  Z. -Q. Shen  H. Sudou  S. Iguchi  Y. Murata  Y. Taniguchi 《Journal of Astrophysics and Astronomy》2011,32(1-2):61-63

It was argued that 3C 66B, a nearby radio galaxy, harbors a supermassive black hole binary (SMBHB). To investigate this, a 4-epoch VLBA phase referencing imaging observation was performed in 2004–2005. Here we present some preliminary results of this project. We found a large position difference compared to previous results.  相似文献   

Effects of the Anticyclonic Eddies on Water Masses, Chemical Parameters and Chlorophyll Distributions in the Oyashio Current Region     

Masashi Kusakabe  Andrey Andreev  Vyacheslav Lobanov  Igor Zhabin  Yuichiro Kumamoto  Akihiro Murata 《Journal of Oceanography》2002,58(5):691-701

Data from the R/V Mirai cruise (May–June 2000) have been examined to discover how mesoscale processes associated with eddy dynamics direct affect the water masses, the distributions and the vertical fluxes of the dissolved oxygen, nutrients and dissolved inorganic carbon in the western subarctic Pacific. Using maps of the temperature, salinity, dissolved oxygen, nutrients, chlorophyll and sea-air pCO₂ difference we show that the boundaries of the anticyclone eddies in the study region were composed of high productivity coastal Oyashio water. The coastal waters were wrapped around the anticyclone eddies (thus creating a high productivity belt) and intruded inside of them. Using SeaWifs data we demonstrate that temporal variations in the position and the strength of anticyclone eddies advected the Kuril island coastal high productivity waters to the pelagic part, resulting in temporal variations of the chlorophyll in the Oyashio region. Computed vertical fluxes of the dissolved oxygen (DO), inorganic carbon (DIC) and silicate show that the anticylonic eddies in the Kuroshio-Oyashio Zone are characterized by enhanced vertical fluxes of the DO and DIC between the upper (σ_θ = 26.7–27.0) and lower (σ_θ = 27.1–27.5) intermediate layer, probably due to the intrusions of the Oyashio waters into the eddies. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Rainfall on the Meghalaya plateau in northeastern India—one of the rainiest places in the world     

Fumie Murata  Taiichi Hayashi  Jun Matsumoto  Haruhisa Asada 《Natural Hazards》2007,42(2):391-399

Monthly and daily variations in rainfall over Cherapunjee and Mawsynram on the Meghalaya plateau of northeastern India are analysed. Cherapunjee and Mawsynram are well known as two of the places with the heaviest rainfall in the world. The daily rainfall variation is attributed to the influence of synoptic scale disturbances, with a periodicity of 10–20 days, and the orographic interaction. The annual and monthly highest rainfalls over Cherapunjee during the 31 years from 1973 to 2003 were much larger than mean values.  相似文献   

Divergence of high-degree harmonic solutions of a rotating elliptical earth     

Wenke Sun  Ichiro Murata 《Geophysical Journal International》1994,118(1):269-271

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