Melting and Multi-stage Metasomatism in the Mantle Wedge beneath a Frontal Arc Inferred from Highly Depleted Peridotite Xenoliths from the Avacha Volcano, Southern Kamchatka   总被引：3，自引：0，他引：3  

Ishimaru  Satoko; Arai  Shoji; Ishida  Yoshito; Shirasaka  Miki; Okrugin  Victor M. 《Journal of Petrology》2007,48(2):395-433

  相似文献   

Simultaneous In Situ Analysis of Carbon and Nitrogen Isotope Ratios in Organic Matter by Secondary Ion Mass Spectrometry          下载免费PDF全文

Akizumi Ishida  Kouki Kitajima  Kenneth H. Williford  Michael L. Tuite  Takeshi Kakegawa  John W. Valley 《Geostandards and Geoanalytical Research》2018,42(2):189-203

An in situ measurement method for simultaneous determination of carbon and nitrogen isotope ratios in organic matter was developed by secondary ion mass spectrometry with a spatial resolution of ~ 12 μm. Secondary ion intensities of ¹²C^?₂, ¹²C¹³C^?, ¹²C¹⁴N^? and ¹²C¹⁵N^? were simultaneously measured by three Faraday cups and one electron multiplier. Ions of ¹²C₂H^? were measured to monitor hydride interferences and to correct for mass bias. The analytical precisions of δ¹³C and δ¹⁵N values of a reference material (UWLA‐1 anthracite) were 0.16‰ and 0.56‰, respectively (2s). A negative correlation was observed between the mass bias of carbon and ¹²C₂H^?/¹²C^?₂ ratios of examined reference materials. In contrast, there was no correlation between mass bias and hydrogen concentration for nitrogen. The δ¹³C_VPDB and δ¹⁵N_Air values of twenty‐two individual globules of organic matter, found in carbonate rock of the 1878 Ma Gunflint Formation, were determined by the new procedure, ranging from ?33.8‰ to ?33.3‰ and +4.2‰ to 5.8‰, respectively. Means of δ¹³C_VPDB and δ¹⁵N_Air values, ?33.5 ± 0.25‰ and +5.2 ± 0.81‰, are consistent with reported values from bulk sample analysis within analytical precision.  相似文献   

Effects of partial meridional barriers on the Antarctic Circumpolar Current—Buoyancy-driven three-layer model     

Akio Ishida 《Journal of Oceanography》1994,50(3):295-316

The transport and vertical structure of the Antarctic Circumpolar Current (ACC) are examined, especially the component of the current driven by buoyancy, by using a three-layer model. We investigate the effects of the South American peninsula, the island arc to the east, and the Macquarie ridge, which are modeled as partial meridional barriers overlapping meridionally each other. We found that the buoyancy-driven component is given as a function of the transport out of the Weddell Sea (S _W ) and the sum of the transports into the North Atlantic (S _A ) and the North Pacific (S _P ) out of the Southern Ocean. The buoyancy-driven current flows westward, ifS _W andS _A +S _P are positive. The transport depends on the value ofS _W more thanS _A +S _P by one order of magnitude within a realistic range of parameters. The most predominant term in the transport equation is inversely proportional to the difference between the Coriolis parameters at the tips of the partial meridional barriers. Thus, the magnitude of the transport strongly depends on the overlapping length of the meridional barriers. The eastward current of the ACC is driven by the predominant eastward wind stress in the Southern Ocean, although a part of the wind-driven component is canceled by the westward buoyancy-driven component. The vertical structure of the ACC is found to be attributed to the surface wind-driven circulation and the deep and bottom buoyancy-driven circulation.  相似文献   

Lethality of increasing CO2 levels on deep-sea copepods in the western North Pacific     

Yuji Watanabe  Atsushi Yamaguchi  Hiroshi Ishida  Takashi Harimoto  Shinya Suzuki  Yoshio Sekido  Tsutomu Ikeda  Yoshihisa Shirayama  Masayuki Mac Takahashi  Takashi Ohsumi  Joji Ishizaka 《Journal of Oceanography》2006,62(2):185-196

The first CO₂ exposure experiments on several species of pelagic copepods inhabiting surface and deep layers in the western North Pacific were conducted. Living organisms were collected from two layers between the surface and 1,500 m between latitudes of 11 and 44°N, and they were exposed aboard ship to various pCO₂ up to about 98,000 μatm. Mortality of copepods from both shallow and deep layers in subarctic to subtropical regions increased with increasing pCO₂ and exposure time. Deep-living copepods showed higher tolerance to pCO₂ than shallow-living copepods. Furthermore, deep-living copepods from subarctic and transitional regions had higher tolerances than the subtropical copepods. The higher tolerances of the deep-living copepods from subarctic and transitional regions may be due to the adaptation to the natural pCO₂ conditions in the subarctic ocean.  相似文献   

Latitudinal Differences in the Planktonic Biomass and Community Structure Down to the Greater Depths in the Western North Pacific     

Atsushi Yamaguchi  Yuji Watanabe  Hiroshi Ishida  Takashi Harimoto  Kazushi Furusawa  Shinya Suzuki  Joji Ishizaka  Tsutomu Ikeda  Masayuki Mac Takahashi 《Journal of Oceanography》2004,60(4):773-787

As part of the research program WEST-COSMIC Phase I (1997–2001), vertical profiles down to the greater depths (0–2000 m or 5800 m) of the plankton community structure composed of heterotrophic bacteria, phytoplankton, protozooplankton and metazooplankton were studied at one station in each subarctic (44°N) and in transitional region (39°N), and two stations in subtropical region (30°N and 25°N); all in 137–155°E in the western North Pacific Ocean. The biomass of all four taxonomic groups decreased rapidly with increasing depths at all stations, although the magnitude of depth-related decrease differed among the groups. As plankton community structure, metazooplankton biomass and bacterial biomass occupied >50% of the total in 0–2000 and 2000–4000 or 5000 m strata, respectively, at subarctic and transitional stations, while bacterial biomass contributed to >50% of the total consistently from 0 through 4800 or 5800 m at subtropical stations. Metazooplankton biomass integrated over the greater depths exhibited a clear latitudinal pattern (high north and low south), but this was not the case for those of the other taxonomic groups. As a component of metazooplankton, an appreciable contribution of diapausing copepods to the metazooplankton was noted at subarctic and transitional stations, but they were few or nil at subtropical stations. As protozooplankton assemblages, heterotrophic microflagellates (HMF) and dinoflagellates were two major components at subarctic and transitional stations, but were only HMF predominated at subtropical stations. From biomass ratios between heterotrophic bacteria, HMF and dinoflagellates, “sinking POC-DOC-heterotrophic bacteria-HMF-heterotrophic dinoflagellates” link was proposed as a microbial food chain operative in the deep layer of the western North Pacific. All results are discussed in the light of latitudinal differences in the structure and functioning of plankton community contributing to the ‘biological pump’ in the western North Pacific Ocean. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Distribution depth of the transforming stage larvae of myctophid fishes in the subtropical–tropical waters of the western North Pacific     

Chiyuki Sassa  Kouichi Kawaguchi  Yuichi Hirota  Minoru Ishida 《Deep Sea Research Part I: Oceanographic Research Papers》2007,54(12):2181-2193

We describe the day–night vertical distribution patterns of 18 species or types of myctophid fish larvae at the transforming stage based on discrete depth sampling from the surface down to 1000-m depth in the subtropical–tropical western North Pacific. A total of 551 transforming stage larvae were collected at the 19 sampling stations. Except for the Diaphus species and Notolychnus valdiviae, all of the transforming stage larvae (including genera Benthosema, Bolinichthys, Centrobranchus, Ceratoscopelus, Diogenichthys, Hygophum, Lampanyctus, Lobianchia, Myctophum, Symbolophorus, and Triphoturus) were collected in the lower mesopelagic zone from 600- to 900-m depth during both day and night, showing no diel vertical migration (DVM). On the contrary, the Diaphus species and N. valdiviae larvae undergo DVM during the transforming stage, occurring below 200-m layer during the daytime and migrating up to the upper 150-m layer at night, i.e., they show earlier adaptation to juvenile–adult behaviors. Most myctophid fish larvae are known to undertake substantial ontogenetic vertical migration (OVM) from the epipelagic to mesopelagic zones during their early life stage. Although considerable sampling effort was carried out in this study, transforming larvae, except for the above two migratory ones, were not collected in the epipelagic and upper mesopelagic zones, strongly suggesting that their sinking speed would be high. It would be advantageous for survival to spend their highly vulnerable transforming stage in the lower mesopelagic zone, where predation pressures are lower and physical conditions are more stable than in the upper layers.  相似文献   

Slab rollback and microcontinent subduction in the evolution of the Zambales Ophiolite Complex(Philippines):A review     

Graciano P.Yumul Jr.  Carla B.Dimalanta  Ricky C.Salapare  Karlo L.Queano  Decibel V.Faustino-Eslava  Edanjarlo J.Marquez  Noelynna T.Ramos  Betchaida D.Payot  Juan Miguel R.Guotana  Jillian Aira S.Gabo-Ratio  Leo T.Armada  Jenielyn T.Padrones  Keisuke Ishida  Shigeyuki Suzuki 《地学前缘(英文版)》2020,11(1):23-36

New radiolarian ages show that the island arc-related Acoje block of the Zambales Ophiolite Complex is possibly of Late Jurassic to Early Cretaceous age.Radiometric dating of its plutonic and volcanichypabyssal rocks yielded middle Eocene ages.On the other hand,the paleontological dating of the sedimentary carapace of the transitional mid-ocean ridge-island arc affiliated Coto block of the ophiolite complex,together with isotopic age datings of its dikes and mafic cumulate rocks,also yielded Eocene ages.This offers the possibility that the Zambales Ophiolite Complex could have:(1)evolved from a Mesozoic arc(Acoje block)that split to form a Cenozoic back-arc basin(Coto block),(2)through faulting,structurally juxtaposed a Mesozoic oceanic crust with a younger Cenozoic lithospheric fragment or(3)through the interplay of slab rollback,slab break-off and,at a later time,collision with a microcontinent fragment,caused the formation of an island arc-related ophiolite block(Acoje)that migrated trench-ward resulting into the generation of a back-arc basin(Coto block)with a limited subduction signature.This Meso-Cenozoic ophiolite complex is compared with the other oceanic lithosphere fragments along the western seaboard of the Philippines in the context of their evolution in terms of their recognized environments of generation.  相似文献   

Direct correlation of radiolarian <Emphasis Type="Italic">Kilinora spiralis</Emphasis> Zone with the Late Jurassic ammonite faunal succession in the Kurisaka Formation,Kurosegawa Terrane,SW Japan     

Keisuke Ishida  Yasuyuki Tsujino  Takeshi Kozai  Tadashi Sato  Francis Hirsch 《中国科学D辑(英文版)》2009,52(12):1910-1923

The last appearance datum of the radiolarian Kilinora spiralis is recorded above the first appearance datum of the ammonite Ataxioceras (A.) kurisakense in the Todoro Section of the Kurisaka Formation, Southern Kurosegawa Terrane, Shikoku, SW Japan. The constraint by ammonite age prolongs the range of the Kilinora spiralis Zone, a remarkable Jurassic radiolarian zone in Japan-NW Pacific region, into the lower Kimmeridgian. The direct correlation of the Kilinora spiralis zone with the Late Jurassic ammonite faunal succession in the Kurisaka Formation will provide a clue to the still pending chronological difference between European and North American radiolarian zones.  相似文献   

The Triassic conodonts of the NW Malayan Kodiang Limestone revisited: Taxonomy and paleogeographic significance     

Keisuke Ishida  Francis Hirsch 《Gondwana Research》2011,19(1):22-36

The revision of the Middle and early Late Triassic conodonts in the Nogami (1968) collection from the NW Malaya Kodiang Limestone Formation provides clues to the multi-element reconstruction of Triassic Gondolellacea. Septi- to octomembrate multi-elements characterize the families Gondolellidae and Gladigondolellidae nov. fam. The distribution of cratognathodiform and ozarkodiniform P2 elements supports the hypothesis of sexual dimorphism in Gladigondolella rather than that of two genera. Pseudofurnishius murcianus confers a Southern Tethyan low latitude character to the Kodiang Limestone, a part of the Cimmerian string of terranes that in Triassic times formed a diagonal partition between the gradually closing Paleo-Tethys and the accordingly widening Neo-Tethys. Our findings suggest that such a realm stretched from the Southern Alps (Dinarids) in the West to Malaya (Shan Thai Terrane) in the East. Only the Eastern edge collided with Eurasia in the Late Triassic, forming the platform of Sundaland. Consequently, the Paleo-Tethys closure remained limited to SE Asia, while a substantial Paleo-Tethys still existed in Western direction, ending up in the Pindos and Vardar oceans. The Jurassic Neo-Tethys ocean extended south of the consolidated SE Asia block and Cimmerian string of terranes.  相似文献   

SIMS Bias on Isotope Ratios in Ca‐Mg‐Fe Carbonates (Part III): δ18O and δ13C Matrix Effects Along the Magnesite–Siderite Solid‐Solution Series          下载免费PDF全文

Maciej G. Śliwiński  Kouki Kitajima  Michael J. Spicuzza  Ian J. Orland  Akizumi Ishida  John H. Fournelle  John W. Valley 《Geostandards and Geoanalytical Research》2018,42(1):49-76

This study explores the effects of cation composition on mass bias (i.e., the matrix effect), which is a major component of instrumental mass fractionation (IMF) in the microanalyses of δ¹³C and δ¹⁸O by SIMS in carbonates of the magnesite–siderite solid‐solution series (MgCO₃–FeCO₃). A suite of twelve calibration reference materials (RMs) was developed and documented (calibrated range: Fe# = 0.002–0.997, where Fe# = molar Fe/[Mg + Fe]), along with empirical expressions for regressing calibration data (affording residuals < 0.5‰ relative to certified reference material NIST‐19). The calibration curves of both isotope systems are non‐linear and have, over a 2‐year period, fallen into one of two distinct but largely self‐consistent shape categories (data from ten measurement sessions), despite adherence to well‐established analytical protocols for carbonate δ¹³C and δ¹⁸O analyses at WiscSIMS (CAMECA IMS 1280). Mass bias was consistently most sensitive to changes in composition near the magnesite end‐member (Fe# 0–0.2), deviating by up to 4.5‰ (δ¹³C) and 14‰ (δ¹⁸O) with increasing Fe content. The cause of variability in calibration curve shapes is not well understood at present and demonstrates the importance of having available a sufficient number of well‐characterised RMs so that potential complexities of curvature can be adequately delineated and accounted for on a session‐by‐session basis.  相似文献