Re-os isotope systematics of the Taklimakan Desert sands, moraines and river sediments around the taklimakan desert, and of Tibetan soils     

Yuji Hattori  Masatoshi Honda 《Geochimica et cosmochimica acta》2003,67(6):1203-1213

Reported here are the first ¹⁸⁷Os/¹⁸⁸Os ratios and abundances of Os and Re for Taklimakan Desert sands and glacial moraines from the Kunlun Mountains. Osmium isotopic data are also reported for river sediments around the Taklimakan Desert, river sediments from the Kunlun and Tianshan Mountains, Tibetan soils and loesses from the Loess Plateau, as well as Sr and Nd isotopic data for these samples. The Taklimakan Desert sands from various regions show surprisingly homogeneous Os isotopic ratios (¹⁸⁷Os/¹⁸⁸Os = 1.29 ± 0.08) and abundances (Os = 11 ppt), with some variations in Re abundances (Re = 130 to 260 ppt) and ¹⁸⁷Re/¹⁸⁸Os ratios (60 to 140). The ¹⁸⁷Os/¹⁸⁸Os ratios for the Taklimakan Desert sands are close to the average for Kunlun moraines, river sediments around the Taklimakan Desert sands, and the Tibetan soils, supporting the idea that the Taklimakan Desert sands are derived from moraines and river sediments around the desert or from Tibetan soils and are homogenized by aeolian activity in the desert. Furthermore, the Os isotopic data for the sediments studied here are compared with those (¹⁸⁷Os/¹⁸⁸Os = 1.04, Os = 32 ppt, Re = 206 ppt, ¹⁸⁷Re/¹⁸⁸Os = 35) of loesses from the Loess Plateau reported elsewhere, and it is concluded that the Re-Os data for the loess can be used as proxy for the upper continental crust.  相似文献   

Geochemistry of peat over kimberlites in the Attawapiskat area, James Bay Lowlands, northern Canada     

Kiko H. Hattori  Stewart Hamilton 《Applied Geochemistry》2008,23(12):3767-3782

The James Bay Lowlands, which is the SE part of the Hudson Bay Lowlands, Canada, and within the Paleozoic limestone terrane, is covered mostly by peatlands. Peat samples were examined in the Attawapiskat area, a region of discontinuous permafrost, where more than 19 kimberlite pipes have been found beneath a cover of peat (2–4 m thick) and Quaternary sediments (up to 20 m thick) of Tyrell Sea clay beds and glacial tills. Pore water at a depth of 40 cm in the peat has a consistently low pH, <4, and high Eh, 290 mV, in the areas over limestones far from kimberlites. On the other hand, peat pore water close to kimberlites has a high pH, up to 6.7, and low Eh, down to 49 mV; the values of pH and Eh are inversely correlated. The high pH and low Eh close to kimberlites suggest active serpentinization of olivine in the underlying kimberlites. The bulk compositions of peat indicate precipitation of secondary CaCO₃ and Fe–O–OH. The secondary carbonate contains high concentrations of kimberlite pathfinder elements, such as Ni, rare earth elements (REE) and Y. The ratios of metal concentrations extracted by ammonium acetate solution at pH 5 (AA5) to those in a total digestion confirm that a majority of the divalent cations are hosted by the secondary carbonate, whereas tri-, tetra- and penta-valent cations are not. As these charged cations are not leached in Enzyme Leach, they are most likely adsorbed on Fe–O–OH.The compositions of peat show spatial variation with the distribution of kimberlites, suggesting that they are influenced by the underlying rocks even through there are thick layers of tills and sediments between the bedrocks and peat. However, elevated concentrations of pathfinder elements of kimberlites in bulk peat samples and AA5 leach are not necessarily directly above kimberlites. The diffused metal anomalies around kimberlites are attributed to the dissolution–precipitation of secondary phases (carbonates and Fe–O–OH) in acidic and reduced waters in peat, and the movement of waters through peat. This pilot study suggests that peat compositions do reflect the underlying bedrock compositions. For kimberlite exploration, a geochemical survey of peat is useful to discriminate concealed kimberlites from other anomalies defined by geophysical and other techniques; however, such a geochemical survey is not suitable for delineating the shapes of the concealed kimberlites due to broad dispersed anomalies.  相似文献   

Ordered distribution of aluminum atoms in analcime     

M. Kato  T. Hattori 《Physics and Chemistry of Minerals》1998,25(8):556-565

Based on the connectivity relations among tetrahedron sites and the NMR spectra, we propose an ordered distribution of aluminum atoms in the framework of analcime with space groups of Pbcb and Pcaa. The symmetries of the ordered distributions are formally the same as Pcca. These symmetries are much lower than those reported by others such as Ia3d, I4₁/acd, Ibca, and I2/a. The lowering of symmetry results apparently from the fact that aluminum atoms in the framework of analcime were strictly discriminated from silicon atoms. Dependence of the populations of Si(nAl)s upon Al content was estimated from ²⁹Si MAS NMR, and can be successfully simulated by the ordered distributions. In the simulation, a small number of defects in the Al distribution were introduced into the ordered distribution mainly to adjust the deviation of Al content per unit cell from the typical composition. Analysis of the powder X-ray diffraction patterns of analcime was carried out, which suggests that the space groups proposed in the present work offer a better fit than the ones reported previously. Received: 5 April 1997 / Revised, accepted: 12 March 1998  相似文献   

Variation of the Kuroshio in the Tokara Strait Induced by Meso-Scale Eddies     

Kaoru Ichikawa 《Journal of Oceanography》2001,57(1):55-68

Temporal variations of the Kuroshio volume transport in the Tokara Strait and at the ASUKA line are decomposed by phase-propagating Complex EOF modes of high-resolution sea surface dynamic topography (SSDT) field during the first tandem period of TOPEX/POSEIDON and ERS-1 (from October 1992 to December 1993). Both variations are dominated by a mode with nearly semi-annual cycle, which indicates a series of interactions between the Kuroshio and meso-scale eddies. Namely, northern part of a westward-propagating meso-scale eddy at 23°N is captured into the southern side of the Kuroshio at the south of Okinawa, then it moves downstream along the Kuroshio path passing the Tokara Strait, and reaches to the ASUKA line where it merges with another eddy propagating from the east at 30°N. The variation at the ASUKA line is, however, less dominated by this mode; instead, it includes the SSDT variations in the south of Shikoku and the east of Kyushu which would be directly affected by eddies from the east without passing the Tokara Strait. On the other hand, the same analysis for movements of the Kuroshio axis in the Strait indicates that they are governed by short-term variations locally confined to the Kuroshio in the East China Sea without being induced by meso-scale eddies. This results, however, seem to depend strongly on a time scale of interest. It is suggested that the long-term movements of the Kuroshio axis in the Strait would demonstrate coincidence with SSDT variation in the south of Japan.  相似文献   

Three-year investigations into sperm whale-fall ecosystems in Japan   总被引：2，自引：0，他引：2  

Yoshihiro Fujiwara  Masaru Kawato  Tomoko Yamamoto  Toshiro Yamanaka  Waka Sato-Okoshi  Chikayo Noda  Shinji Tsuchida  Tomoyuki Komai  Sherine Sonia Cubelio  Takenori Sasaki  Karen Jacobsen  Kaoru Kubokawa  Katsunori Fujikura  Tadashi Maruyama  Yasuo Furushima  Kenji Okoshi  Hiroshi Miyake  Masayuki Miyazaki  Yuichi Nogi  Akiko Yatabe  & Takashi Okutani 《Marine Ecology》2007,28(1):219-232

We report the first study of sperm whale‐fall ecosystems, based on mass sinking of whale carcasses at shelf depths in the northwest Pacific. We conducted three observations over a 2‐year period on replicate sperm‐whale carcasses implanted at depths of 219–254 m off the southern part of Japan from July 2003 to August 2005. The study was made possible by a mass stranding of sperm whales in January 2002, and the subsequent sinking of 12 carcasses in the waters off Cape Nomamisaki. Dense aggregations of unique chemosynthesis‐based fauna had formed around the whale carcasses after 18 months (July 2003). The mytilid mussel Adipicola pacifica was the most abundant macrofaunal species and covered most of the exposed bone surfaces. The general composition of the fauna was similar to that of deep‐water reducing habitats, but none of the species appearing in this study has been found at hydrothermal vents, cold seeps or deep‐water whale falls. A new species of lancelet, which was the first record of the subphylum Cephalochordata from reducing environments, a new species of Osedax; a rarely encountered benthic ctenophore, and a rare gastropod species were discovered at this sperm whale‐fall site. Benthic communities were similar across all the carcasses studied, although the body sizes of the whales were very different. The succession of epifaunal communities was relatively rapid and the sulphophilic stage was considerably shorter than that of other known whale falls.  相似文献   

Distribution and seasonal variation of phosphorus in Tokyo Bay     

Kazuyasu Miyata  Akihiko Hattori 《Journal of Oceanography》1986,42(4):241-254

Phosphorus dynamics in Tokyo Bay waters were investigated along with other oceanographic variables. Seasonal variations of dissolved inorganic phosphorus (DIP) and particulate phosphorus (PP) are inversely correlated with each other, and reflect variation in biological activity. A high concentration of PP in summer surface waters is caused by high primary production. The PP settled in the deeper layer is decomposed, and orthophosphate is regenerated within the water column and in sediments. Even during summer stratification period, the regenerated orthophosphate is occasionally advected upward by wind-induced water mixing and contributes to phytoplankton growth in the upper layer. Some dissolved organic phosphorus is producedin situ from PP, but it may be rapidly decomposed in the water column. The ratios of Cchlorophylla and CN in particulate matter suggest that phytoplankton in the summer surface waters of Tokyo Bay are limited neither by nitrogen nor by phosphorus. The PN ratio in particulate matter varies substantially but it is positively correlated with the ambient concentration of DIP. Phytoplankton take up and store phosphorus within their cells when ambient DIP exceeds their demand. An abundance of total phosphorus in the summer water column can be attributed to increased discharge of river waters, although enhanced release of orthophosphate from anoxic sediments cannot be discounted.  相似文献   

Apparent Microfloral Response to Organic Degradation on Bathyal ­Seafloor: An Analysis Based on Sediment Fatty Acids     

Takeshi Naganuma  Mutsuo Hattori  Kazumi Akimoto    Jun Hashi­moto  Hiroyasu Momma  & C. Julius Meisel 《Marine Ecology》2001,22(3):267-282

Abstract. Abyssal microfloral succession induced by experimental organic degradation was investigated. Notable changes in amounts and compositions of short-chain (C9-20) sediment fatty acids were observed, which indicated the shift of sediment microflora. Biomarker fatty acids for methanotrophs and sulfate-reducing bacteria dominated. Resultant fatty acid compositions were most closely related to those from a nearby methane seep harboring a dense Calyptogena colony; the clams were also seen in close vicinity of the deployed organic mass. These observations suggest that the organic degradation on the bathyal seafloor stimulates the formation of methanotrophic and thio­trophic microflora, resulting in the formation of a methane-seep-type benthic community.  相似文献   

Abundance of nauplii and protein synthesis activity of adult female copepods in the Kuroshio front during the Japanese sardine spawning season     

Kaoru Nakata 《Journal of Oceanography》1990,46(5):219-229

In order to point out the potential importance of the Kuroshio front as a feeding ground for the early post larvae of the Japanese sardine, distributions of copepod nauplii—the principal food for the larvae—were investigated.Nauplii were abundant in and near the front and in a warm water mass off Ensyu-nada, where the concentration of chlorophylla was high. Adult females ofParacalanus sp. were dominant in the copepod group there, and the protein synthesis activity shown by the RNA/DNA ratio was high. It is expected that copepod egg productivity is enhanced in the area where food phytoplankton is abundant, because the RNA/DNA ratio showed a positive correlation to chlorophylla in situ.In and near the front, high chlorophylla concentration—which is probably supported by nutrient supply caused by local upwelling and/or eddies at the front—contributes to the high RNA/DNA ratio of the copepods. The relatively large biomass of copepod nauplii at the front may be supported by female's high egg productivity. It is supposed, as a result, that food availability for the early post larvae of the Japanese sardine is increased in and near the Kuroshio front.  相似文献   

The nitrogen cycle in the sea with special reference to biogeochemical processes     

Akihiko Hattori 《Journal of Oceanography》1982,38(4):245-265

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Reaction of juvenile flounder to grid separators   总被引：1，自引：0，他引：1  

Matsushita  Yoshiki; Fujita  Kaoru; Ikegami  Naoya; Ohata  Satoshi 《ICES Journal of Marine Science》2004,61(7):1174-1178

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