Development of an automatic chamber system for long-term measurements of CO₂ flux from roots     

MASAKO DANNOURA  YUJI KOMINAMI  KOJI TAMAI  MAYUKO JOMURA  TAKAFUMI MIYAMA  YOSHIAKI GOTO  YOICHI KANAZAWA 《Tellus. Series B, Chemical and physical meteorology》2006,58(5):502-512

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Automated foliage chamber method for long-term measurement of CO₂ flux in the uppermost canopy     

TAKAFUMI MIYAMA  YUJI KOMINAMI  KOJI TAMAI  TATSUHIKO NOBUHIRO  YOSHIAKI GOTO 《Tellus. Series B, Chemical and physical meteorology》2003,55(2):322-330

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灌溉后的黄土剪切特征变化          下载免费PDF全文

M. UENO  T. NISHIMURA  M. KATO  H. NAKAMURA  ZENG Si-wei 《地震工程学报》2005,27(2):128-134

在中国甘肃省的黑方台阶地上从上世纪60年代开始出现人类定居和开垦活动,并自1968年发展为灌溉农业。随着灌溉的进行地面已出现沉陷和滑坡。地表沉陷是由灌溉水的充填引起黄土结构崩塌造成的。然而崩塌和湿润化对剪切特征的影响目前还不清楚。为了研究湿化后的黄土剪切特征的变化,进行了对马兰黄土未经扰动和重塑土样的直接剪切盒测试。结果显示未扰动土样的粘合力和内摩擦角在湿润化后都下降了,而所观察到的重塑土的弹度参数只有少许变化。未扰动土的不饱合粘合力,据认为其受胶结物质的影响,在饱合后消失了。经灌溉的土的不饱合强度参数与未灌溉土相比表现出差异,它们可能受土壤水分的强烈影响。  相似文献   

Assimilation and Fractional Crystallization Controlled by Transport Process of Crustal Melt: Implications from an Alkali Basalt-Dacite Suite from Rishiri Volcano, Japan   总被引：2，自引：0，他引：2  

KURITANI  TAKESHI; KITAGAWA  HIROSHI; NAKAMURA  EIZO 《Journal of Petrology》2005,46(7):1421-1442

Mechanisms of fractional crystallization with simultaneous crustalassimilation (AFC) are examined for the Kutsugata and Tanetomilavas, an alkali basalt–dacite suite erupted sequentiallyfrom Rishiri Volcano, northern Japan. The major element variationswithin the suite can be explained by boundary layer fractionation;that is, mixing of a magma in the main part of the magma bodywith a fractionated interstitial melt transported from the mushyboundary layer at the floor. Systematic variations in SiO₂ correlatewith variations in the Pb, Sr and Nd isotopic compositions ofthe lavas. The geochemical variations of the lavas are explainedby a constant and relatively low ratio of assimilated mass tocrystallized mass (‘r value’). In the magma chamberin which the Kutsugata and Tanetomi magmas evolved, a strongthermal gradient was present and it is suggested that the marginalpart of the reservoir was completely solidified. The assimilantwas transported by crack flow from the partially fused floorcrust to the partially crystallized floor mush zone throughfractures in the solidified margin, formed mainly by thermalstresses resulting from cooling of the solidified margin andheating of the crust. The crustal melt was then mixed with thefractionated interstitial melt in the mushy zone, and the mixedmelt was further transported by compositional convection tothe main magma, causing its geochemical evolution to be characteristicof AFC. The volume flux of the assimilant from the crust tothe magma chamber is suggested to have decreased progressivelywith time (proportional to t^–1/2), and was about 3 x 10^–2m/year at t = 10 years and 1 x 10^–2 m/year at t = 100years. It has been commonly considered that the heat balancebetween magmas and the surrounding crust controls the couplingof assimilation and fractional crystallization processes (i.e.absolute value of r). However, it is inferred from this studythat the ratio of assimilated mass to crystallized mass canbe controlled by the transport process of the assimilant fromthe crust to magma chambers. KEY WORDS: assimilation and fractional crystallization; mass balance model; magma chamber; melt transport; Pb isotope  相似文献   

Prograde amphiboles in hematite-bearing basic and quartz schists in the Sanbagawa belt, central Shikoku: relationship between metamorphic field gradient and P-T paths of individual rocks   总被引：1，自引：0，他引：1  

C. NAKAMURA  M. ENAMI 《Journal of Metamorphic Geology》1994,12(6):841-852

The prograde amphibole that coexists with chlorite, epidote, muscovite, albite, quartz and hematite in Sanbagawa schists was examined to investigate the relationship between the prograde P-T paths of individual rocks and the metamorphic field gradient in the Sanbagawa metamorphic belt, central Shikoku. The amphibole changes from actinolite, through ferri-winchite and crossite, to barroisite and hornblende with increasing grade along the metamorphic field gradient. However, the sequence of prograde amphibole compositions in each sample varies in different mineral zones. The general scheme can be summarized as: magnesioriebeckite-riebeckite crossite in the upper chlorite zone of lower-grade rocks; crossite or glaucophane barroisite in the garnet zone of medium-grade rocks; and actinolite or winchite barroisite hornblende in the albite-biotite zone of higher-grade rocks. Changes of amphibole composition indicate that the prograde P-T path recorded in the higher-grade rocks was situated on the higher-temperature side of that of the lower-grade rocks and on the lower-pressure side of the metamorphic field gradient. The systematic change of P-T paths implies an increasing d P /d T during continuous subduction. These features can be interpreted as documenting prograde metamorphism within a young subduction zone that has a non-steady-state geotherm.  相似文献   

Geochemical Evolution of Akagi Volcano, NE Japan: Implications for Interaction Between Island-arc Magma and Lower Crust, and Generation of Isotopically Various Magmas   总被引：3，自引：3，他引：3  

KOBAYASHI  KATSURA; NAKAMURA  EIZO 《Journal of Petrology》2001,42(12):2303-2331

Major and trace element, and Sr, Nd and Pb isotopic compositionswere determined for whole-rock samples from the ‘isotopicallyanomalous’ Akagi volcano in the volcanic front of theNE Japan arc. Sr and Nd isotopic compositions of phenocrystswere also analyzed together with their major and trace elementcompositions. Compared with the other volcanoes from the volcanicfront, the whole-rock isotope compositions of Akagi show highlyenriched characteristics; ⁸⁷Sr/⁸⁶Sr = 0·7060–0·7088,  相似文献   

Shift and Rotation of Composition Trends by Magma Mixing: 1983 Eruption at Miyake-jima Volcano, Japan   总被引：1，自引：0，他引：1  

KURITANI  TAKESHI; YOKOYAMA  TETSUYA; KOBAYASHI  KATSURA; NAKAMURA  EIZO 《Journal of Petrology》2003,44(10):1895-1916

Pre-eruption processes are investigated for magmas erupted in1983 from Miyake-jima volcano, which is one of the most activevolcanoes in Japan. The whole-rock compositional trends of theeruptive products are principally smooth and linear. Magmaserupted from some fissures have compositions that deviate fromthe main linear trend. Phenocryst contents of samples displacedfrom the linear compositional trends are significantly lowerthan those of samples on the main trends. Anorthite-rich plagioclasephenocrysts, present throughout the 1983 products, are too calcicto have crystallized from the erupted magma composition, andwere derived from a basaltic magma through magma mixing. Althoughthe linear whole-rock composition trends favor simple two-componentmagma mixing, this cannot explain the presence of samples thatdeviate from the main trend. Instead, the observed compositiontrends were formed by mixing of a homogeneous basaltic magmawith andesitic magmas exhibiting compositional diversity. Theoriginal linear composition trends of the andesitic end-membermagma were rotated and shifted to the direction of the basalticend-member magma by magma mixing. The samples out of the maintrends represent magmas with less basaltic component than thoseon the trend. The density and viscosity of the basaltic end-membermagma were comparable with those of the andesitic end-membermagmas. The basaltic magma, discharged from one magma chamberat 2 kbar pressure, was injected into a magma chamber at lowerpressure occupied by the chemically zoned andesite magma (1kbar), and possibly as a fountain. To establish the characteristicmixing trend of the 1983 magma, the basaltic component musthave been distributed systematically in the zoned andesite magma.A requirement is that the basaltic magma spread laterally andmixed with the andesite magma at various levels of ascent ofthe fountain in the host andesite magma. Analysis of compositionalzoning in titanomagnetite crystals revealed that the eruptionof the 1983 magmas was initiated soon after the replenishmentof the basaltic magma in the 1 kbar magma chamber. KEY WORDS: compositional trend; liquid–liquid blending; magma chamber; magma mixing; Miyake-jima Volcano  相似文献   

Nanometer‐scale anatomy of entire Stardust tracks     

Keiko NAKAMURA‐MESSENGER  Lindsay P. KELLER  Simon J. CLEMETT  Scott MESSENGER  Motoo ITO 《Meteoritics & planetary science》2011,46(7):1033-1051

Abstract– We have developed new sample preparation and analytical techniques tailored for entire aerogel tracks of Wild 2 sample analyses both on “carrot” and “bulbous” tracks. We have successfully ultramicrotomed an entire track along its axis while preserving its original shape. This innovation allowed us to examine the distribution of fragments along the entire track from the entrance hole all the way to the terminal particle. The crystalline silicates we measured have Mg‐rich compositions and O isotopic compositions in the range of meteoritic materials, implying that they originated in the inner solar system. The terminal particle of the carrot track is a ¹⁶O‐rich forsteritic grain that may have formed in a similar environment as Ca‐, Al‐rich inclusions and amoeboid olivine aggregates in primitive carbonaceous chondrites. The track also contains submicron‐sized diamond grains likely formed in the solar system. Complex aromatic hydrocarbons distributed along aerogel tracks and in terminal particles. These organics are likely cometary but affected by shock heating.  相似文献   

Three‐dimensional shapes and Fe contents of Stardust impact tracks: A track formation model and estimation of comet Wild 2 coma dust particle densities     

Yosuke IIDA  Akira TSUCHIYAMA  Toshihiko KADONO  Kanako SAKAMOTO  Tomoki NAKAMURA  Kentaro UESUGI  Tsukasa NAKANO  Michael E. ZOLENSKY 《Meteoritics & planetary science》2010,45(8):1302-1319

Abstract– We investigated three‐dimensional structures of comet Wild 2 coma particle impact tracks using synchrotron radiation (SR) X‐ray microtomography at SPring‐8 to elucidate the nature of comet Wild 2 coma dust particles captured in aerogel by understanding the capture process. All tracks have a similar entrance morphology, indicating a common track formation process near the entrance by impact shock propagation irrespective of impactor materials. Distributions of elements along the tracks were simultaneously measured using SR‐XRF. Iron is distributed throughout the tracks, but it tends to concentrate in the terminal grains and at the bottoms of bulbs. Based on these results, we propose an impact track formation process. We estimate the densities of cometary dust particles based on the hypothesis that the kinetic energy of impacting dust particles is proportional to the track volume. The density of 148 cometary dust particles we investigated ranges from 0.80 to 5.96 g cm^?3 with an average of 1.01 (±0.25) g cm^?3. Moreover, we suggest that less fragile crystalline particles account for approximately 5 vol% (20 wt%) of impacting particles. This value of crystalline particles corresponds to that of chondrules and CAIs, which were transported from the inner region of the solar system to the outer comet‐forming region. Our results also suggest the presence of volatile components, such as organic material and perhaps ice, in some bulbous tracks (type‐C).  相似文献   

Components and seasonal variation of night-time total ecosystem respiration in a Japanese broad-leaved secondary forest     

TAKAFUMI MIYAMA  YUJI KOMINAMI  KOJI TAMAI  YOSHIAKI GOTO  TERUHIKO KAWAHARA  MAYUKO JOMURA  MASAKO DANNOURA 《Tellus. Series B, Chemical and physical meteorology》2006,58(5):550-559

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