Rare-earth and trace elements in the Quaternary volcanic rocks of Hokkaido,Japan     

Yasuyuki Masuda  Susumu Nishimura  Takashi Ikeda  Yoshio Katsui 《Chemical Geology》1975,15(4):251-271

Seven rare-earth elements (La, Ce, Sm, Eu, Tb, Yb, Lu) and Co, Cr, Sc, Ba, Hf and Th have been determined by non-destructive neutron activation analysis on the Quaternary volcanic rocks in Hokkaido, Japan. The trace-element abundances are discussed in terms of the petrological problems, particularly the origin of calc-alkali magma. On the basis of the La/Sm ratio and the contents of K, Ba, Th and La, lateral variations in the contents of trace elements exist across the Kurile and the northern Honshū arcs. The calc-alkali rocks can be classified into three types which correspond to Kuno's three basalt-magma types. There is no essential difference in the rare-earth patterns between the basaltic rocks and the associated calc-alkali rocks in each petrographic province. This suggests that the calcalkali rocks may be derived from the basaltic magmas by fractional crystallization under certain conditions.  相似文献   

Heavily fractionated noble gases in an acid residue from the Klein Glacier 98300 EH3 chondrite     

Daisuke Nakashima  Ulrich Ott  Tomoki Nakamura 《Geochimica et cosmochimica acta》2010,74(17):5134-5149

Noble gases were measured both in bulk samples (stepped pyrolysis and total extraction) and in a HF/HCl residue (stepped pyrolysis and combustion) from the Klein Glacier (KLE) 98300 EH3 chondrite. Like the bulk meteorite and as seen in previous studies of bulk type 3 E chondrites (“sub-Q”), the acid residue contains elementally fractionated primordial noble gases. As we show here, isotopically these are like those in phase-Q of primitive meteorites, but elementally they are heavily fractionated relative to these. The observed noble gases are different from “normal” Q noble gases also with respect to release patterns, which are similar to those of Ar-rich noble gases in anhydrous carbonaceous chondrites and unequilibrated ordinary chondrites (with also similar isotopic compositions). While we cannot completely rule out a role for parent body processes such as thermal and shock metamorphism (including a later thermal event) in creating the fractionated elemental compositions, parent body processes in general seem not be able to account for the distinct release patterns from those of normal Q noble gases. The fractionated gases may have originated from ion implantation from a nebular plasma as has been suggested for other types of primordial noble gases, including Q, Ar-rich, and ureilite noble gases. With solar starting composition, the corresponding effective electron temperature is about 5000 K. This is lower than inferred for other primordial noble gases (10,000-6000 K). Thus, if ion implantation from a solar composition reservoir was a common process for the acquisition of primordial gas, electron temperatures in the early solar system must have varied spatially or temporally between 10,000 and 5000 K.Neon and xenon isotopic ratios of the residue suggest the presence of presolar silicon carbide and diamond in abundances lower than in the Qingzhen EH3 and Indarch EH4 chondrites. Parent body processes including thermal and shock metamorphism and a late thermal event also cannot be responsible for the low abundances of presolar grains. KLE 98300 may have started out with smaller amounts of presolar grains than Qingzhen and Indarch.  相似文献   

Geochemical Characteristics,Origin, and Evolution of Ore‐Forming Fluids of the Khut Copper Skarn Deposit,West of Yazd in Central Iran     

Azam Zahedi  Mohammad Boomeri  Kazuo Nakashima  Mohammad Ali Mackizadeh  Masao Ban  David R. Lentz 《Resource Geology》2014,64(3):209-232

The Khut copper skarn deposit is located at about 50 km northwest of Taft City in Yazd province in the middle part of the Urumieh‐Dokhtar magmatic arc. Intrusion of granitoid of Oligocene–Miocene age into carbonate rocks of the Triassic Nayband Formation led to the formation of marble and a calcic skarn. The marble contains high grade Cu mineralization that occurs mainly as open space filling and replacement. Cu‐rich sulfide samples from the mineralized marble are also anomalous in Au, Zn, and Pb. In contrast, the calcic skarn is only weakly anomalous in Cu and W. The calcic skarn is divided into garnet skarn and garnet–pyroxene skarn zones. Paragenetic relationships and microthermometric data from fluid inclusions in garnet and calcite indicate that the compositional evolution of skarn minerals occurred in three main stages as follows. (i) The early prograde stage, which is characterized by Mg‐rich hedenbergite (Hd_53.7Di_42.3–Hd_86.1Di_9.5) with Al‐bearing andradite (69.8–99.5 mol% andradite). The temperature in the early prograde skarn varies from 400 to 500°C at 500 bar. (ii) The late prograde stage is manifested by almost pure andradite (96.2–98.4 mol% andradite). Based on the fluid inclusion data from garnet, fluid temperature and salinity in this stage is estimated to vary from 267 to 361°C and from 10.1 to 21.1 wt% NaCl equivalent, respectively. Pyrrhotite precipitation started during this stage. (iii) The retrograde stage occurs in an exoskarn, which consists of an assemblage of ferro‐actinolite, quartz, calcite, epidote, chlorite, sphalerite, pyrite, and chalcopyrite that partially replaces earlier mineral assemblages under hydrostatic conditions during fracturing of the early skarn. Fluids in calcite yielded lower temperatures (T < 260°C) and fluid salinity declined to ～8 wt% NaCl equivalent. The last stage mineralization in the deposit is supergene weathering/alteration represented by the formation of iron hydroxide, Cu‐carbonate, clay minerals, and calcite. Sulfur isotope data of chalcopyrite (δ³⁴S of +1.4 to +5.2‰) show an igneous sulfur source. Mineralogy and mineral compositions of the prograde assemblage of the Khut skarn are consistent with deposition under intermediately oxidized and slightly lower fS₂ conditions at shallow crustal levels compared with those of other typical Fe‐bearing Cu–Au skarn systems.  相似文献   

Baroclinic oscillations of tidal frequency at ocean weather station P     

Richard Thomson  Susumu Tabata 《大气与海洋》2013,51(3):242-257

Abstract

We analyse time series records of isopleth depths derived from two extended sequences of hourly and bi‐hourly sampled profiles taken at Ocean Weather Station P during the summers of 1961 and 1969. Vertical displacements to 240‐m depth are mainly of semidiurnal frequency with r.m.s. amplitudes of 1–4 m. Displacements at diurnal and near‐inertial frequencies are typically less than a metre and have little statistical significance. Within the semidiurnal band, motions appear to be predominantly at the principal solar (S₂) rather than the principal lunar (M₂) semidiurnal frequency. The phase of the M₂ baroclinic tide is roughly equal to that of the M₂ barotropic tide (as extrapolated from coastal and seamount observations); phases of other constituents differ appreciably from barotropic values.  相似文献   

A note on climate change adaptation for seaports: a challenge for global ports, a challenge for global society     

Austin H. Becker  Michele Acciaro  Regina Asariotis  Edgard Cabrera  Laurent Cretegny  Philippe Crist  Miguel Esteban  Andrew Mather  Steve Messner  Susumu Naruse  Adolf K. Y. Ng  Stefan Rahmstorf  Michael Savonis  Dong-Wook Song  Vladimir Stenek  Adonis F. Velegrakis 《Climatic change》2013,120(4):683-695

With 80 % of world trade carried by sea, seaports provide crucial linkages in global supply-chains and are essential for the ability of all countries to access global markets. Seaports are likely to be affected directly and indirectly by climatic changes, with broader implications for international trade and development. Due to their coastal location, seaports are particularly vulnerable to extreme weather events associated with increasing sea levels and tropical storm activity, as illustrated by hurricane “Sandy”. In view of their strategic role as part of the globalized trading system, adapting ports in different parts of the world to the impacts of climate change is of considerable importance. Reflecting the views of a diverse group of stakeholders with expertise in climate science, engineering, economics, policy, and port management, this essay highlights the climate change challenge for ports and suggests a way forward through the adoption of some initial measures. These include both “soft” and “hard” adaptations that may be spearheaded by individual port entities, but will require collaboration and support from a broad range of public and private sector stakeholders and from society at large. In particular, the essay highlights a need to shift to more holistic planning, investment and operation.  相似文献   

Observation of hydrogen peroxide concentrations in a Japanese red pine forest     

Xuan Chen  Masatoshi Aoki  Shangxun Zhang  Jinhua Zhang  Susumu Nozoe  Daisuke Komori  Akinori Takami  Shiro Hatakeyama 《Journal of Atmospheric Chemistry》2008,60(1):37-49

In order to study the concentrations of hydrogen peroxide (H₂O₂) and the factors controlling its concentrations, we monitored concentrations of H₂O₂ and other gases such as sulfur dioxide, ozone, and NO _x as well as meteorological factors such as air temperature, relative humidity, and wind direction/speed during eight measurement periods from 2000 to 2002 in a Japanese red pine forest in Japan. The H₂O₂ concentrations ranged from below 0.01 to 1.64 ppb, and analysis of the diurnal variation in H₂O₂ concentration showed high concentrations around noon, and low concentrations in the morning and late afternoon. The H₂O₂ concentrations were high in early summer, when O₃ concentration, temperature, and solar radiation were high, and were low in fall, when O₃ concentration, temperature, and solar radiation were low. We propose that O₃ concentration affects the production of H₂O₂ in the monitored region during the period under study, but that high H₂O₂ concentrations were sometimes caused by the transport of polluted air from urban regions. H₂O₂ concentrations decreased remarkably when SO₂ concentrations increased by transported volcanic emission on Miyake Island. In the absence of the effects of SO₂, H₂O₂ concentrations increased with increasing O₃ concentration and temperature.  相似文献   

The Miduk porphyry Cu deposit,Kerman, Iran: A geochemical analysis of the potassic zone including halogen element systematics related to Cu mineralization processes   总被引：1，自引：0，他引：1  

Mohammad Boomeri  Kazuo Nakashima  David Richard Lentz 《Journal of Geochemical Exploration》2009

Miduk hypogene and supergene porphyry Cu–Mo mineralization occurs within the Miocene porphyritic quartz–diorite and host Eocene plagioclase–hornblende phyric andesitic pyroclastic and flow sequence. Both the host rocks were extensively altered by hydrothermal fluids to dominantly potassic, phyllic, and argillic with interstitial to distal propylitic types.  相似文献   

Earthquake damage to earth dams in Japan—maximum epicentral distance to cause damage as a function of magnitude     

S. Tani  M. Nakashima 《Soil Dynamics and Earthquake Engineering》1999,18(8):605-602

Small scale agricultural earth dams have been damaged by several past earthquakes. Damage to earth dams occurred at distances from the epicentre that increased in proportion to the scale of the earthquakes. On studying the damage a constant relation between the magnitude of the earthquake and maximum epicentral distance where the damage occurred was obtained. This relationship is similar to that obtained between the magnitude and the maximum epicentral distance at which liquefaction occurs. This, and the fact that earth dams which have been damaged several times due to liquefaction were near the critical epicentral distance, suggests that liquefaction of the foundation ground is the main cause of damage to earth dams.  相似文献   

Dynamic Behaviour of a Caisson Quaywall Under Strong Earthquake     

LIU Hanlong  DAI Huichao  Susumu IAI Professor  Geotechnical Engineering Research Institute  Hohai University  Nanjing  China. Senior Engineer  China Yangtze Three Gorges Project Development Corporation  Yichang  China. Doctor  Port  Harbour Research Institute  Ministry of Transport  Nagase  Japan. 《中国海洋工程》1999,(1)

—Effective stress analysis is performed to evaluate the residual displacement of a caissonquaywall during 1994 Hokkaido-Toho-Oki Earthquake and 1993 Kushiro-Oki Earthquake.Theconstitutive model used in this study is a multiple shear mechanism type defined in strain space and cantake into account the effect of rotation of principal stress axis.The earthquake accelerations recorded atthe outcropping rock during the earthquake are used as input bedrock motion.The results of finite ele-ment analysis are in good agreement with the observed behaviour of the quaywall.The analysis also indi-cates that liquefaction and high excess pore water pressure have a significant effect on the deformation ofthe caisson.Soil improvement is speculated as the most reliable measures against liquefaction.The influ-ence of soil improvement and the reasonable improved area are discussed in the paper.  相似文献   

Postglacial stratigraphic evolution of a current-influenced sandy shelf: offshore Kujukuri strandplain,central Japan     

Naohisa Nishida  Taku Ajioka  Ken Ikehara  Rei Nakashima  Hajime Katayama  Tomoyuki Sato  Seishiro Furuyama  Toru Tamura 《Sedimentology》2020,67(1):559-575

Sandy shelf sediments are important elements of clastic sedimentary systems because of their wide distribution in the geological record and their significance as hydrocarbon reservoirs. Although many studies have investigated shelf sediments influenced by waves or tidal currents, little is known about shelf sediments influenced by oceanic currents, particularly their lithofacies characteristics and stratigraphic evolution. This study investigated the stratigraphic evolution of shelf sediments off the Kujukuri strandplain facing the Pacific Ocean, which is influenced by the strong Kuroshio Current. Sediment cores were obtained from six locations on the Kujukuri shelf (34 to 124 m water depth) using a vibrocorer. The dominant lithofacies is mud-free sand with low-angle cross-lamination associated with alternating beds of finer and coarser sand with cross-lamination. These display depositional processes influenced by storm waves and the Kuroshio Current, respectively. This finding is consistent with the previously presented modern and historical observations of the Kuroshio Current and estimates of the storm-wave base. Radiocarbon dates show that the sediment succession formed during the last transgressive and highstand stages after 13·1 ka. The depositional processes during the stages represent a transition from storm waves with abundant sediment supply to both storm waves and the Kuroshio Current with sediment starvation mainly due to its trapping in the strandplain. Comparison to other Holocene–Modern shelf systems suggests that the sandy shelf successions are strongly influenced by oceanic currents under conditions of limited riverine input and open coastal geometry. The resultant sand-dominated succession is characterized by reversal of the proximal to distal grain-size trend compared to the fining for most other recognized wave/storm-dominated shelf successions. This is because of seaward increase in the influence of the Kuroshio Current. Thus, shelf deposits are naturally complex, and these may be further complicated by the additional influence of oceanic currents above the usual wave-dominated and tide-dominated end members.  相似文献