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1.
Kawaguchi M Song JY Irie K Murakami Y Nakayama K Kitamura S 《Marine pollution bulletin》2011,63(5-12):356-361
It has been well known that oil spills cause serious problems in the aquatic organisms. In particular, some species of teleosts, which develop on the sea surface thought to be affected by heavy oil (HO). During the embryogenesis, the nervous system is constructed. Therefore, it is important to study the toxicological effects of HO on the developing neurons. We exposed HO to eggs of Japanese flounder (Paralichthys olivaceus) and investigated the neural disorder. In larvae exposed by HO at the concentration of 8.75 mg/L, the facial and lateral line nerves partially entered into the incorrect region and the bundle was defasciculated. Furthermore, in the HO-exposed larvae, Sema3A, a kind of axon guidance molecule, was broadly expressed in second pharyngeal arch, a target region of facial nerve. Taken together, we suggested the possibility that the abnormal expression of Sema3A affected by HO exposure causes disruption of facial nerve scaffolding. 相似文献
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Phenocryst-bulk rock composition relations of abyssal tholeiites and their petrogenetic significance
Tsugio Shibata 《Geochimica et cosmochimica acta》1976,40(11):1407-1417
In order to infer equilibrium phase relations of abyssal tholeiites, olivine, plagioclase, augite, and pigeonite tholeiites from the ocean floor are plotted in terms of the CIPW norm proportions in the tetrahedron olivine-plagioclase-diopside-quartz. The phase relations of abyssal tholeiites have a general similarity in form to those of the experimentally studied relevant systems. Experimental studies on natural basalts allow the pressure of crystallization for abyssal tholeiitic magmas to be evaluated approximately. It appears that the pressure at which the phenocryst-stage crystallization of abyssal tholeiites takes place is as high as 2 or 3 kbar, provided that abyssal tholeiitic magmas are ‘dry’.Abyssal tholeiites could be derived from liquids that are in equilibrium with Ca-poor pyroxene in the pressure range of about 5–8 kbar. Major element chemistry of abyssal tholeiites is incompatible with the view that these tholeiitic basalts are derived from picritic magma by olivine fractionation. 相似文献
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Abstract The Wakino Subgroup is a lower stratigraphic unit of the Lower Cretaceous Kanmon Group. Previous studies on provenance of Wakino sediments have mainly concentrated on either petrography of major framework grains or bulk rock geochemistry of shales. This study addresses the provenance of the Wakino sandstones by integrating the petrographic, bulk rock geochemistry, and mineral chemistry approaches. The proportions of framework grains of the Wakino sandstones suggest derivation from either a single geologically heterogeneous source terrane or multiple source areas. Major source lithologies are granitic rocks and high‐grade metamorphic rocks but notable amounts of detritus were also derived from felsic, intermediate and mafic volcanic rocks, older sedimentary rocks, and ophiolitic rocks. The heavy mineral assemblage include, in order of decreasing abundance: opaque minerals (ilmenite and magnetite with minor rutile), zircon, garnet, chromian spinel, aluminum silicate mineral (probably andalusite), rutile, epidote, tourmaline and pyroxene. Zircon morphology suggests its derivation from granitic rocks. Chemistry of chromian spinel indicates that the chromian spinel grains were derived from the ultramafic cumulate member of an ophiolite suite. Garnet and ilmenite chemistry suggests their derivation from metamorphic rocks of the epidote‐amphibolite to upper amphibolite facies though other source rocks cannot be discounted entirely. Major and trace element data for the Wakino sediments suggest their derivation from igneous and/or metamorphic rocks of felsic composition. The major element compositions suggest that the type of tectonic environment was of an active continental margin. The trace element data indicate that the sediments were derived from crustal rocks with a minor contribution from mantle‐derived rocks. The trace element data further suggest that recycled sedimentary rocks are not major contributors of detritus. It appears that the granitic and metamorphic rocks of the Precambrian Ryongnam Massif in South Korea were the major contributors of detritus to the Wakino basin. A minor but significant amount of detritus was derived from the basement rocks of the Akiyoshi and Sangun Terrane. The chromian spinel appears to have been derived from a missing terrane though the ultramafic rocks in the Ogcheon Belt cannot be discounted. 相似文献
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Atsushi Kaneda Kouta Ayukawa Naoki Hirose Jun Tsuzuki Yutaka Kumaki Tomoharu Senjyu Yosuke Igeta Tatsuro Watanabe 《Journal of Oceanography》2017,73(2):181-192
A sudden strong coastal current called a “kyucho” occurred in August 2013 in the eastern coastal waters of Wakasa Bay, Japan. This study examined its characteristics based on both observational data collected by intensive field investigations and the simulation results of a numerical model. The field investigations comprised moored buoy observations near the coast and voyages by a research vessels and fishing boats. The mooring observations indicated that a current speed exceeding 50 cm s?1 occurred abruptly near the eastern coast of the bay, in association with a synchronous change in the current direction. Data collected by acoustic Doppler current profilers (ACDPs) mounted on the vessels showed that a clockwise eddy existed in the bay and that the current on the east side of the eddy generated the kyucho near the coast. Based on the results of the numerical model and the analysis of the ADCP data, it was considered that the clockwise eddy was generated by a strong current at the tip of the Tango Peninsula, in the western part of the bay. As the eddy propagated from west to east across the bay, it induced the kyucho in the coastal waters in the east of the bay. 相似文献
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Tsugio Shibata Stephen E. DeLong David Walker 《Contributions to Mineralogy and Petrology》1979,70(1):89-102
Fresh basalts from the Oceanographer Fracture Zone are petrographically and chemically similar to typical abyssal tholeiites, but are somewhat enriched in large ion lithophile elements, with consistent differences among separate dredge hauls. Olivine compositions are in equilibrium with host basalt for reasonable K
D
values, but some plagioclases are anomalously calcic (e.g., a rock highly differentiated in Mg/Mg+Fe bears some plagioclase of An86). Ti/Al in clinopyroxene is approximately constant at 1/6, but Ti+Al abundance decreases in the sequence basalt groundmass cpx, basalt phenocryst+microphenocryst cpx, gabbro cpx (samples from adjacent dredges), an effect that may be related to decrease in cooling rate. Least-squares calculations indicate that 45% of magma with the composition of the more primitive sample must be removed as plagioclase, clinopyroxene and olivine (in the ratio 4.42.71, respectively) to obtain the composition of the more differentiated sample. Both samples have excess plagioclase on the liquidus, however, which should not be the case for the differentiated composition if it is produced by fractionation of all three phases. The excess of plagioclase and the anomalous plagioclase compositions indicate that the samples cannot be related solely by fractional crystallization. Additional processes such as magma mixing or plagioclase accumulation (or both) must have effected these differences. 相似文献
7.
Tsugio Shibata Geoffrey Thompson Frederick A. Frey 《Contributions to Mineralogy and Petrology》1979,70(2):127-141
Tholeiitic basalts dredged from the Mid-Atlantic Ridge (MAR) axis at 43 ° N are enriched in incompatible trace elements compared to the ‘ normal’ incompatible element depleted tholeiites found from 49 ° N to 59 ° N and south of 33 ° N on the MAR. The most primitive 43 ° N glasses have MgO/FeO*= 1.2 and coexist with olivine (Fo90–91) and chrome-rich spinel. The tholeiitic basalts from the MAR 43 ° N are distinct from the strongly incompatible trace element depleted tholeiities found elsewhere in the Atlantic, and have trace element features typical of island tholeiities and MAR axis tholeiites from 45 ° N. Petrographic, major, and compatible trace element trends of the axial valley tholeiites at 43 ° N are consistent with shallow-level fractionation; in particular, evolution from primitive liquids with forsteritic olivine plus chrome spinel as liquidus phases to fractionated liquids with plagioclase plus clinopyroxene as major crystallizing phases. However, each dredge haul has distinctive incompatible trace element abundances. These trace element characteristics require a hetrogeneous mantle or complex processes such as open system fractional crystallization and magma mixing. Alkali basalts (～5% normative nepheline) were dredged from a prominent fracture zone at 43 ° N. Typical of alkali basalts they are strongly enriched (compared to tholeiites) in incompatible elements. Their highly fractionated rare-earth element (REE) abundances require residual garnet during partial melting. The 43 ° N tholeiites and alkali basalts could be derived from a garnet peridotite source with REE contents equal to 2 × chondrites by ～5% and 1% melting, respectively. Alternatively, they could be derived from a moderately light REE enriched source by ～25% and 9.5% melting, respectively. 相似文献
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Irie K Kawaguchi M Mizuno K Song JY Nakayama K Kitamura S Murakami Y 《Marine pollution bulletin》2011,63(5-12):297-302
Heavy oil (HO) on the sea surface penetrates into fish eggs and prevents the normal morphogenesis. To identify the toxicological effects of HO in the context of the egg types, we performed exposure experiments using floating eggs and sinking eggs. In the course of development, HO-exposed embryos of floating eggs showed abnormal morphology, whereas early larva of the sinking eggs had almost normal morphology. However, the developing peripheral nervous system of sinking eggs showed abnormal projections. These findings suggest that HO exposed fishes have problems in the developing neurons, although they have no morphological malformations. Through these observations, we conclude that HO is strongly toxic to floating eggs in the morphogenesis, and also affect the neuron development in both floating and sinking eggs. 相似文献
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Whole-rock, major and trace element analyses and microprobe mineral analyses were conducted on serpentinized peridotites recovered from the walls of a MAR (Mid-Atlantic Ridge) 43° N fracture zone. These peridotites are extensively serpentinized; serpentine usually makes up 30–100 vol. percent of the bulk rocks. The relict minerals observed consist mainly of olivine and orthopyroxene with subordinate amounts of clinopyroxene and brown spinel. The range in olivine composition is very limited (Fo91–92). Orthopyroxene forms large, anhedral crystals with clinopyroxene exsolution lamellae and shows undulose extinction with bent cleavages and lamellae. Broad beam microprobe analyses indicate that the composition range of orthopyroxene is also limited (En89.1–87.6Fs8.2-8.0Wo2.7–4.4; Al2O3=1.82–2.64 wt%; Cr2O3=0.63–0.88 wt%). Clinopyroxene tends to fringe large orthopyroxene crystals or fills the interstices between them. The Mg/Fe ratios of clinopyroxene are practically constant; however, the Ca/(Ca + Mg + Fe) ratios range from 0.48 to 0.45. The Cr/(Cr+Al) and Mg/(Mg+ Fe2+) ratios of brown spinel range from 0.57 to 0.36 and 0.69 to 0.56, respectively. The geothermometers utilizing coexisting spinel lherzolite mineral assemblages suggest that the MAR 43° N peridotites attained equilibrium at temperatures from 1100° to 1250° C.Peridotites recovered from the ocean floor are generally considered to have been subjected to partial melting processes and are regarded as residues left after primary magma was removed. Major element chemistry of the MAR 43° N peridotites are compared with those of the ocean-floor ultramafic tectonites reported previously and used together with those published data to demonstrate that the major element abundances of the oceanfloor peridotites define an average trend which is compatible with removal of primary magma from these peridotites at moderate pressures (10–15 kb). Then, the most primitive abyssal tholeiite glasses could be produced by ca. 10% olivine fractionation of such primary magma. Extensive fractionation of olivine and/or orthopyroxene from picritic liquids which are in equilibrium with the lherzolitic or harzburgitic mantle sources at higher pressures (>20 kb) could not yield the majority of the most primitive abyssal tholeiite glasses. 相似文献
10.
Abyssal tholeiites from the Oceanographer Fracture Zone 总被引：17，自引：0，他引：17
David Walker Tsugio Shibata Stephen E. DeLong 《Contributions to Mineralogy and Petrology》1979,70(2):111-125
Unusual effects have been discovered in the major element phase relations of basalts from the Oceanographer Fracture Zone
(OFZ) which suggest that magma mixing of primitive basalt with the differentiation residue of a previous batch of primitive
magma has occurred. These effects include a reversal in mineral crystallization sequence which cannot happen during normal
differentiation processes or be explained by any plausible change in physical conditions. This unusual effect is encountered
as a result of curvature in composition space of the liquid-line-of-descent equilibria involving olivine, plagioclase, and
high-calcium clinopyroxene. Mixing of magmas at different stages of their evolution produces mixtures that do not lie on the
curved liquid-line-of-descent. Observation of such anomalous compositions in the OFZ suite supplements accumulating petrographic
and trace-element geochemistry evidence that magma mixing is an important petrogenetic process.
Mixing of fractionated residual liquids can produce mixtures which are either superheated or supercooled depending on the
sense of ‘thermal curvature’ of the liquid-line-of-descent. Both senses are encountered in the tholeiitic system, and this
effect may exert a qualitative control on the crystallization texture of the mixture.
A comparison of approximately 2,000 abyssal tholeiite compositions to the experimental liquid-line-of-descent reveals that
erupted differentiates which would be expected from advanced fractionation are scarce. Just this sort of phenomenon (the ‘perched’
steady state) was proposed by O'Hara (1977) as an earmark of the operation of a continuously fractionating magma chamber into
which fresh magma is periodically remixed. 相似文献