Swelling–shrinkage properties and soil improvement of compacted expansive soil, Ning-Liang Highway, China     

Yanjun Du  Shenglin Li  Shigenori Hayashi 《Engineering Geology》1999,53(3-4):351-358

In this paper, the swelling–shrinkage properties of the compacted expansive soil in the Huaiyin Section of the Ning-Lian Highway are introduced, and swelling–shrinkage mechanisms are discussed based on changes in soil water content, dry density, material composition and fabric. The improvement of the compacted expansive soil by lime is also discussed briefly. It is concluded that careful attention should be paid to this type of compacted expansive soil.  相似文献   

Fundamental study on the response characteristics of drivers during an earthquake based on driving simulator experiments     

Yoshihisa Maruyama  Fumio Yamazaki 《地震工程与结构动力学》2004,33(6):775-792

After the 1995 Kobe earthquake, the expressway structures in Japan were retrofitted and they will not now be seriously damaged under a certain level of strong earthquake motion. However, the stability of a moving vehicle has not been investigated yet. It has been reported that drivers feel seismically induced vibrations, especially in the transverse direction of vehicles. Owing to this phenomenon, drivers have some difficulty in controlling the vehicles during strong shaking. For further safety promotion of the expressway networks, it is important to understand the drivers' reactions to seismic motion. The present authors have performed a series of seismic response analyses of a moving vehicle to investigate its response characteristics based on numerical simulation. However, the responses of the driver were not considered in the simulation process. In order to investigate the drivers' reactions during an earthquake, a series of virtual tests were conducted using a driving simulator. This driving simulator has six servomotor‐powered electric actuators that control its motions. Several types of tests were carried out for different examinees to investigate drivers' responses while controlling the simulator under seismic motion. The results of this study showed that a larger response time lag to strong shaking and over turning of the steering wheel may shift the vehicle into the next lane. According to this finding, trafficaccidents could possibly occur under strong ground shaking in the case of heavy traffic. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Prograde pressure–temperature records from inclusions in zircons from ultrahigh-pressure–high-pressure rocks of the Kokchetav Massif, northern Kazakhstan     

I. Katayama  A. A. Zayachkovsky and  S. Maruyama 《Island Arc》2000,9(3):417-427

Abstract In the first extensive, systematic study of inclusions in zircons from ultrahigh-pressure (UHP) and high-pressure (HP) metamorphic rocks of the Kokchetav Massif of Kazakhstan (separated from 232 rock samples from all representative lithologies and geographic regions), we identified graphite, quartz, garnet, phengite, phlogopite, rutile, albite, K-feldspar, amphibole, zoisite, kyanite, calcite, dolomite, apatite, monazite, omphacite and jadeite, as well as the diagnostic UHP metamorphic minerals (i.e. microdiamond and coesite) by laser Raman spectroscopy. In some instances, coesite + quartz and diamond + graphite occur together in a single rock sample, and inclusion aggregates also comprise polycrystalline diamond crystals overgrowing graphite. Secondary electron microscope and cathodoluminescence studies reveal that many zircons display distinct zonation textures, which comprise core and wide mantle, each with distinctive inclusion microassemblages. Pre-UHP metamorphic minerals such as graphite, quartz, phengite and apatite are common in the core, whereas diamond, coesite, garnet and jadeite occupy the mantle. The inclusions in core are irrelevant to the UHP metamorphism. The zircon core is of detrital or relatively low-grade metamorphic origin, whereas the mantle is of HP to UHP metamorphic origin. The zonal arrangement of inclusions and the presence of coesite and diamond without back-reaction imply that aqueous fluids were low to absent within the zircons during both prograde and retrograde metamorphism, and that the zircon preserves a prograde pressure–temperature record of the Kokchetav metamorphism which, elsewhere, has been more or less obliterated in the host rock.  相似文献   

Overview of the geology, petrology and tectonic framework of the high-pressure–ultrahigh-pressure metamorphic belt of the Kokchetav Massif, Kazakhstan     

S. Maruyama  C. D. Parkinson. 《Island Arc》2000,9(3):439-455

Abstract High‐ to ultrahigh‐pressure metamorphic (HP–UHPM) rocks crop out over 150 km along an east–west axis in the Kokchetav Massif of northern Kazakhstan. They are disposed within the Massif as a 2 km thick, subhorizontal pile of sheet‐like nappes, predominantly composed of interlayered pelitic and psammitic schists and gneisses, amphibolite and orthogneiss, with discontinuous boudins and lenses of eclogite, dolomitic marble, whiteschist and garnet pyroxenite. On the basis of predominating lithologies, we subdivided the nappe group into four north‐dipping, fault‐bounded orogen‐parallel units (I–IV, from base to top). Constituent metabasic rocks exhibit a systematic progression of metamorphic grades, from high‐pressure amphibolite through quartz–eclogite and coesite–eclogite to diamond–eclogite facies. Coesite, diamond and other mineral inclusions within zircon offer the best means by which to clarify the regional extent of UHPM, as they are effectively sequestered from the effects of fluids during retrogression. Inclusion distribution and conventional geothermobarometric determinations demonstrate that the highest grade metamorphic rocks (Unit II: T = 780–1000°C, P = 37–60 kbar) are restricted to a medial position within the nappe group, and metamorphic grade decreases towards both the top (Unit III: T = 730–750°C, P = 11–14 kbar; Unit IV: T = 530°C, P = 7.5–9 kbar) and bottom (Unit I: T = 570–680°C; P = 7–13.5 kbar). Metamorphic zonal boundaries and internal structural fabrics are subhorizontal, and the latter exhibit opposing senses of shear at the bottom (top‐to‐the‐north) and top (top‐to‐the‐south) of the pile. The orogen‐scale architecture of the massif is sandwich‐like, with the HP–UHPM nappe group juxtaposed across large‐scale subhorizontal faults, against underlying low P–T metapelites (Daulet Suite) at the base, and overlying feebly metamorphosed clastic and carbonate rocks (Unit V). The available structural and petrologic data strongly suggest that the HP–UHPM rocks were extruded as a sequence of thin sheets, from a root zone in the south toward the foreland in the north, and juxtaposed into the adjacent lower‐grade units at shallow crustal levels of around 10 km. The nappe pile suffered considerable differential internal displacements, as the 2 km thick sequence contains rocks exhumed from depths of up to 200 km in the core, and around 30–40 km at the margins. Consequently, wedge extrusion, perhaps triggered by slab‐breakoff, is the most likely tectonic mechanism to exhume the Kokchetav HP–UHPM rocks.  相似文献   

Abnormally large magnetospheric electric field on 9?November?2004 and its effect on equatorial ionosphere around the world     

R G Rastogi  H Chandra  Louis Condori  M A Abdu  B Reinisch  R T Tsunoda  D S V V D Prasad  T K Pant  T Maruyama 《Journal of Earth System Science》2012,121(5):1145-1161

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Age constraints on the Palaeoproterozoic Lomagundi–Jatuli Event in Zimbabwe: Zircon geochronology of the Magondi Supergroup     

Hikaru Sawada  Ernest Tafumanei Mugandani  Tomohiko Sato  Yusuke Sawaki  Shuhei Sakata  Yukio Isozaki  Shigenori Maruyama 《地学学报》2019,31(5):438-444

The ca. 2.2–2.1 Ga Magondi Supergroup on the Zimbabwe Craton in Southern Africa is mainly composed of sedimentary rocks deposited in a rift basin/passive continental margin, which record a unique episode in carbon isotope perturbation called the Lomagundi–Jatuli Event (LJE). This study reports new U–Pb ages of detrital zircons from the Deweras and Lomagundi groups of the Magondi Supergroup, and of igneous zircons from underlying granitoids, to constrain the timing of the LJE and to identify the provenance of the Magondi Supergroup. Most analysed detrital zircon grains range in ages between ca. 2.9 and 2.6 Ga. Three ca. 2.3–2.2 Ga detrital zircons from sandstone of the Deweras Group, with the youngest ²⁰⁷Pb‐²⁰⁶Pb age of 2,216 ± 22 Ma, indicate the onset of LJE in the Zimbabwe Craton was almost simultaneous to that in Fennoscandia and the Superior Craton, supporting the global synchronicity of the LJE.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987114000681     

Toshikazu Ebisuzaki  Shigenori Maruyama 《地学前缘(英文版)》2015,6(1):103-119

We present the disaster-forced biological evolution model as a general framework that includes Darwinian "phylogenic gradualism",Eldredge-Gould's "punctuated equilibrium",mass extinctions,and allopatric.parapatric,and sympatric speciation.It describes how reproductive isolation of organisms is established through global disasters due to supernova encounters and local disasters due to radioactive volcanic ash fall-outs by continental alkaline volcanism.Our new evolution model uniquely highlights three major factors of disaster-forced speciation:enhanced mutation rate by higher natural radiation level,smaller population size,and shrunken habitat size(i.e.,isolation among the individual populations).We developed a mathematical model describing speciation of a half-isolated group from a parental group,taking into account the population size(N_e),immigration rate(m),and mutation rate(μ).The model gives a quantitative estimate of the speciation,which is consistent with the observations of speciation speed.For example,the speciation takes at least 10~5 generations,if mutation rate is less than10~(-3) per generation per individual.This result is consistent with the previous studies,in which μ is assumed to be 10~(-3)-10~(-5).On the other hand,the speciation is much faster(less than 10~5 generations)for the case that μ is as large as 0.1 in parapatric conditions(m μ).Even a sympatric(m ~ 1) speciation can occur within 10~3 generations,if mutation rate is very high(μ~1 mutation per individual per generation),and if N_e 20-30.Such a high mutation rate is possible during global disasters due to supernova encounters and local disasters due to radioactive ash fall-outs.They raise natural radiation level by a factor of 100-1000.Such rapid speciation events can also contribute to macro-evolution during mass extinction events,such as observed during the Cambrian explosion of biodiversity.A similar rapid speciation(though in a much smaller scale) also has been undergoing in cichlid fishes and great African apes in the last several tens of thousand years in the current African rift valley,including the origin of humankind due to the radioactive ash fall-outs by continental alkaline volcanism.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987114000267   总被引：6，自引：6，他引：0  

James M.Dohm  Shigenori Maruyama 《地学前缘(英文版)》2015,6(1):95-101

Habitable Trinity is a newly proposed concept of a habitable environment.This concept indicates that the coexistence of an atmosphere(consisting largely of C and N),an ocean(H and O).and a landmass(supplier of nutrients) accompanying continuous material circulation between these three components driven by the Sun is one of the minimum requirements for life to emerge and evolve.The life body consists of C,0,H,N and other various nutrients,and therefore,the presence of water,only,is not a sufficient condition.Habitable Trinity environment must be maintained to supply necessary components for life body.Our Habitable Trinity concept can also be applied to other planets and moons such as Mars,Europa,Titan,and even exoplanets as a useful index in the quest for life-containing planetary bodies.  相似文献   

Evidences of increasing primary production in the ocean by Stommel's perpetual salt fountain     

Shigenao Maruyama  Takashi YabukiTetsuya Sato  Koutaro TsubakiAtsuki Komiya  Mikihito WatanabeHiroshi Kawamura  Katsumi Tsukamoto 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(5):567-574

The American physical oceanographer Henry Stommel and co-workers proposed “the perpetual salt fountain” and suggested the possibility of upwelling deep seawater without an energy source. In the open ocean, deep seawater containing rich nutrients becomes a source of primary production. Previously, we have tested Stommel's hypothesis by numerical simulations and in ocean experiments, and confirmed the upwelling of a perpetual salt fountain. In the present study, we conducted an open-ocean experiment in the Philippines Sea, and succeeded to demonstrate an increase in chlorophyll concentration. The chlorophyll concentration at the pipe outlet was much greater than that in the surrounding seawater. Satellite ocean-color image around the pipe was analyzed, and the signal of artificial upwelling is investigated. Composite analysis of satellite chlorophyll image indicates an increased surface chlorophyll distribution in the vicinity of pipe position, in which the increasing signal is much larger than the expected production based on nutrient supply. Although the problem must be further discussed, this increased signal is shown to be statistically significant. This mechanism may contribute to effective utilization of fishery resources in subtropical oligotrophic region.  相似文献   

The Ediacaran radiogenic Sr isotope excursion in the Doushantuo Formation in the Three Gorges area,South China     

Yusuke Sawaki  Takeshi Ohno  Miyuki Tahata  Tsuyoshi Komiya  Takafumi Hirata  Shigenori Maruyama  Brian F. Windley  Jian Han  Degan Shu  Yong Li 《Precambrian Research》2010,176(1-4):46-64

The Ediacaran period was one of the most important times for the evolution of life. However, the scarcity of well-preserved outcrops of Ediacaran rocks still leaves ambiguity in decoding ambient surface environmental changes and biological evolution.The Ediacaran strata in South China are almost continuously exposed, comprise mainly carbonate rocks with subordinate black shales and sandstones, and they contain many fossils, suitable for study of environmental and biological changes in the Ediacaran. We conducted drilling through the Doushantuo Fm at four sites in the Three Gorges area to obtain continuous, fresh samples without surface alteration and oxidation. We analyzed ⁸⁷Sr/⁸⁶Sr and ⁸⁸Sr/⁸⁶Sr ratios of the fresh carbonate rocks, selected on the basis of microscopic observations and the geochemical signatures of Sr contents, Mn/Sr and Rb/Sr ratios, and δ¹⁸O values, with a multiple collector-inductively coupled plasma-mass spectrometer (MC-ICP-MS).The chemostratigraphy of the ⁸⁷Sr/⁸⁶Sr ratios of the drilled samples displays a smooth curve and two large positive shifts during Ediacaran time. The combination of the detailed chemostratigraphies of δ¹³C, δ¹⁸O and ⁸⁷Sr/⁸⁶Sr values and Mn and Fe contents enables us to decode the surface environmental changes and their causes in the Ediacaran. The first large positive excursion of ⁸⁷Sr/⁸⁶Sr occurred together with negative δ¹³C and positive δ¹⁸O excursions. The higher ⁸⁷Sr/⁸⁶Sr values indicate an enhancement of continental weathering, whereas the positive δ¹⁸O excursion suggests global cooling. Global regression due to global cooling enhanced the oxidative decay of exposed marine organic sediments and continental weathering. Accelerated influx of nutrients promoted primary productivity, resulting in oxidation of dissolved organic carbon (DOC), whereas active sulfate reduction due to a higher sulfate influx from the continents caused remineralization of the large DOC, both of which caused a negative δ¹³C anomaly. The 580 Ma Gaskiers glaciation accounts for the close correlation among the positive ⁸⁷Sr/⁸⁶Sr, negative δ¹³C and positive δ¹⁸O excursions.The second large positive shift of ⁸⁷Sr/⁸⁶Sr firstly accompanied a positive δ¹³C excursion, and continued through the Shuram δ¹³C negative excursion. The positive correlation of δ¹³C and ⁸⁷Sr/⁸⁶Sr values is consistent with an enhanced continental weathering rate due to continental collisions that built Trans-Gondwana mountain chains, and with a higher primary activity due to the enhancement of continental weathering and consequent higher nutrient contents in seawater. The accompanied increase in Mn and Fe contents implies a gradual decline of the seawater oxygen content due to more active aerobic respiration and oxidation of reductive materials flowing in the oceans. In the Shuram excursion, higher ⁸⁷Sr/⁸⁶Sr values and a transition from increase to decrease in Mn and Fe contents were accompanied by the large negative δ¹³C excursion. The higher ⁸⁷Sr/⁸⁶Sr values are the first compelling evidence for enhanced continental weathering, which was responsible for the large δ¹³C anomaly through the remineralization of the DOC by more active sulfate reduction due to a higher sulfate influx. Higher Mn and Fe contents in the early and middle stages of the excursion suggest a decline in the oxygen content of seawater due to oxidative decay of the DOC, whereas in the late stages the decrease in Mn and Fe contents is consistent with oceanic oxygenation.The emergence of Ediacara biota after the Gaskiers glaciation and the prosperity of the latest Ediacaran is concomitant with the formation of more radiogenic seawater with high ⁸⁷Sr/⁸⁶Sr values, suggesting that enhanced continental weathering, and the consequent higher influx of nutrients, played an important role in biological evolution.  相似文献