An experimental study on the formation of composite intrusions from zoned magma chambers     

Takehiro Koyaguchi  Akira Takada 《Journal of Volcanology and Geothermal Research》1994,59(4)

We present a model which accounts for the common, but paradoxical arrangement of composite intrusions (i.e. silicic core and mafic margins) on the basis of analogue experiments using gelatin and aqueous solutions. The present model involves simultaneous flow-out of the upper and lower magmas from a longitudinal crack along the chamber wall. Experimental results suggest that the mafic magma from the lower layer leaks from the side-wall of the chamber and travels faster than the silicic magma because of its lower viscosity, so that the mafic magma reaches the tip of the crack first. Once the mafic magma reaches the crack tip, then the rate of dyke propagation becomes determined by the viscosity of the less viscous mafic magma, and so it can advance rapidly. The viscous silicic magma can flow efficiently into the center of the dyke, being lubricated by the mafic magma margins. This model accounts for the common arrangement of composite intrusions and gives an efficient mechanism of flow of viscous silicic magmas.  相似文献   

Crystallization of chondrules in ordinary chondrites     

Makoto Kimura  Kenzo Yagi 《Geochimica et cosmochimica acta》1980,44(4):589-602

The process of crystallization and the origin of chondrules are discussed, in terms of the phase relations of the minerals in chondrules in six ordinary chondrites of the Yamato-74 meteorites, especially the Yamato-74191 (L3).Chondrules are classified into six types. The bulk compositions of chondrules projected onto the MgO-FeO-SiO₂ system show that the compositions of chondrules vary widely. Investigations by means of the MgO-Al₂O₃-SiO₂ system indicate that porphyritic chondrules can be regarded as products of supercooling crystallization. The growth rates of crystals in porphyritic chondrules were fairly small. The difference between types of chondrules is interpreted in terms of the compositions of chondrules and the nucleation temperatures of the supercooled droplets.All these observations and estimations must be taken into account for discussing the origin of chondrules. The impact and dust fusion theories do not appear to be plausible. Molten droplets due to these mechanisms will be glassy spherules, or crystallize at equilibrium. Only a liquid condensation theory can well explain the characteristic features and the process of the crystallization of chondrules.  相似文献   

A high pressure experimental study on a magnesian-rich leucite-lamproite from the West Kimberley area,Australia: petrogenetic implications     

Makoto Arima  Alan D. Edgar 《Contributions to Mineralogy and Petrology》1983,84(2-3):228-234

Liquidus and subliquidus phase relations of a leucite-lamproite (wolgidite) from the West Kimberley area, Australia have been studied experimentally under the volatile conditions of 3.22 wt.% H₂O ( \(X_{CO_2 }\) =0.11) and 13.0 wt.% H₂O ( \(X_{CO_2 }\) =0.03) between 10 to 40 kbar. Under these conditions, liquids are vapour undersaturated. In experiments with 13.0 wt.% H₂O, olivine is the liquidus phase up to 24 kbar and orthopyroxene above 24 kbar. Phlogopite and rutile occur close to the liquidus above 16 kbar. Crystallization temperatures of clinopyroxenes are 50–120° C below the liquidus. Based on these results, wolgidite magma is unlikely to be a partial melt of a garnet- or spinel-lherzolite mantle but could be derived from phlogopite+rutile±olivine±or-thopyroxene assemblages occurring as metasomatized mantle.  相似文献   

Study of the effect of water-soluble fractions of heavy-oil on coastal marine organisms using enclosed ecosystems,mesocosms   总被引：1，自引：0，他引：1  

Ohwada K  Nishimura M  Wada M  Nomura H  Shibata A  Okamoto K  Toyoda K  Yoshida A  Takada H  Yamada M 《Marine pollution bulletin》2003,47(1-6):78-84

Mesocosm facilities composed of 4 experimental and 2 reservoir tanks (1.5 m in diameter, 3.0 m in depth and 5 tons in capacity) made of FRP plastics, were constructed in the concrete fish rearing pond in the Fisheries Laboratory, The University of Tokyo. The water-soluble fraction of Rank A heavy residual oil was formed by mixing 500 g of the oil with 10 l of seawater, which was introduced to the 5000 l-capacity tanks. Experimental Run 4 was conducted from May 31 to June 7, 2000. Oil concentrations in the tanks were 4.5 microg/l called LOW, and 13.5 microg/l, called HIGH tank. Bacterial growth rates very quickly accelerated in the HIGH tank just after the loading of oil which corresponded with a high increase of bacterial cells in the same tank after 2 days. Later, bacterial numbers in HIGH tank rapidly decreased, corresponding with the rapid increase of heterotrophic nano-flagellates and virus numbers on the same day. Sediment traps were deployed at the bottom of the experimental tanks, and were periodically retrieved. These samples were observed both under light microscope and epi-fluorescent microscope with UV-excitation. It was observed that the main components of the vertical flux were amorphous suspended matter, mostly originating from dead phytoplankton and living diatoms. It was further observed from the pictures that vertical transport of oil emulsions were probably conducted after adsorption to amorphous suspended matter and living diatoms, and were settling in the sediment traps at the bottom of the tanks. This means that the main force which drives the soluble fraction of oil into bottom sediment would be vertical flux of such amorphous suspended particles and phytoplankton. Further incubation of the samples revealed that the oil emulsions were degraded by the activity of autochtonous bacteria in the sediment in aerobic condition.  相似文献   

P-T Conditions of Metamorphism in the Neoproterozoic Rocks of the Negele Area, Southern Ethiopia     

Tadesse Yihunie  Mamoru Adachi  Makoto Takeuchi 《Gondwana Research》2004,7(2):489-500

Neoproterozoic rocks constitute the Kenticha, Alghe and Bulbul litho-tectonic domains in the Negele area of southern Ethiopia. Structural features and fabrics in these rocks were developed during north-south folding (D1), thrusting (D2) and shearing (D3) deformation. From micro-structural inferences and fabric relationships in semi-pelitic schists/gneisses of the Kenticha and Alghe domains, three episodes of metamorphic mineral growths (M1, M2 and M3) are inferred to have accompanied the deformational events. Pressure-Temperature estimates on equilibrium garnet-plagioclase-biotite and garnet-biotite assemblages from semi-pelitic schists/gneisses of the two domains indicate metamorphic recrystallization at temperatures of 520–580°C and 590–640°C, and pressures of 4–5 kb and 6–7 kb in the Kenticha and Alghe domains, respectively. These results correspond to regional metamorphism at a depth of 16–20 km for the Kenticha and 22–25 km for the Alghe domains. The P-T results suggest that the protoliths to the rocks of the Kenticha and Alghe domains were subjected to metamorphism at different crustal depths. This implies exhumation of the Alghe gneissic rocks from intermediate crustal level (ca. 25 km) before juxtaposition with the Kenticha sequence along a north-south trending thrust at the present crustal level during the Neoproterozoic. The combined deformation, fabric and mineral growth data suggest that rocks in the Kenticha and Alghe domains evolved under similar tectono-metamorphic conditions, which resulted from crustal thickening and uplift followed by extension and orogenic collapse, exhumation and cooling before litho-tectonic domains coalesced and cratonized in the Neoproterozoic southern Ethiopian segment of the East African Orogen.  相似文献   

Thermally controlled processes and preserved thermal signatures within the Earth     

Makoto Taniguchi  Ilmo T. Kukkonen 《Physics of the Earth and Planetary Interiors》2005,152(4):221-222

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The Behavior of Ni(II), Cr(III), and Zn(II) in Biological Wastewater Treatment Process     

Soon‐An Ong  Eiichi Toorisaka  Makoto Hirata  Tadashi Hano 《洁净——土壤、空气、水》2005,33(2):95-103

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Alkylbenzenes in mussels from South and South East Asian coasts as a molecular tool to assess sewage impact     

Tsutsumi S  Yamaguchi Y  Nishida I  Akiyama K  Zakaria MP  Takada H 《Marine pollution bulletin》2002,45(1-12):325-331

Alkylbenzenes, molecular markers of sewage, were measured in 34 green mussels collected from India, Indonesia, Malaysia, Thailand, Cambodia, Vietnam, and the Philippines together with blue mussels collected from Tokyo Bay, Japan. Linear alkylbenzene (LAB) concentrations in South and South East Asian countries ranged from 10 to 1640 ng-∑LAB/g-dry tissue. In some populous cities, LAB concentrations were similar or higher than those found in northern Tokyo Bay which is heavily impacted by sewage effluents. I/E ratios (a ratio of internal to external isomers of LABs) in the South and South East Asian countries (1–3) were much lower than those in Tokyo Bay (3–8), indicating sewage discharged in the coastal zone is poorly treated (e.g., raw sewage and/or primary effluents). Alkylbenzenes with branched alkyl chains, tetrapropylene-based alkylbenzenes, were also detected in mussels from Indonesia and Philippines. This “tell-tale” sign indicates that poorly degradable detergents are still in use in this area, although they have long been phased-out in many industrialized countries.  相似文献   

Chemical and isotopic signatures of the basement rocks from the Campi Flegrei geothermal field (Naples, southern Italy): inferences about the origin and evolution of its hydrothermal fluids     

Graziella Caprarelli  Makoto Tsutsumi  Bruno Turi 《Journal of Volcanology and Geothermal Research》1997,76(1-2)

The Campi Flegrei (Naples, Campanian Plain, southern Italy) geothermal system is hosted by Quaternary volcanic rocks erupted before, during and after the formation of the caldera that represents one of the major structural features in the Neapolitan area. The volcanic products rest on a Mesozoic carbonate basement, cropping out north, east and south of the area. Chemical (major, minor and trace elements) and stable isotope (C, H, O) analyses were conducted on drill-core samples recovered from geothermal wells MF-1, MF-5, SV-1 and SV-3, at depths of ˜ 1100 to 2900 m. The study was complemented by petrographic and SEM examination of thin sections. The water which feeds the system is both marine and meteoric in origin. Mineral zonation typical of a high-temperature geothermal system exists in all the geothermal wells; measured temperatures in wells are as high as ˜ 400 °C. The chemical composition of the waters suggests the existence of two reservoirs: a shallow reservoir (depth < 2000 m) fed by seawater that boiled at 320 °C and became progressively diluted by steam-heated local meteoric water during its ascent; and a deeper reservoir (depth > 2000 m) of hypersaline water. The drill-cores are mainly hydrothermally altered volcanics of trachy-latitic affinity, but some altered pelites and limestones are also present. Published Na, Mg and K concentrations of selected geothermal waters indicate that the hydrothermal fluids are in equilibrium with their host rocks, with respect to K-feldspar, albite, sericite and chlorite. The measured δ¹⁸O_(SMOW) values of rocks range from +4.3 to + 16.5%. The measured δD_(SMOW) values range from − 79 to − 46%. The calculated isotopic composition of the fluids at equilibrium with the samples vary from + 1 to + 8.3%. δ¹⁸O and from − 52 to + 1%. δD. The estimated isotopic composition of the waters at equilibrium with the studied samples confirmed the existence of two distinct fluid types circulating in the geothermal system. The shallower has a marine water signature, while the deeper water has a signature consistent both with magmatic and meteoric origins. In the latter case, the recharge of this aquifer likely occurs at the outcrop of the Mesozoic Limestones surrounding the Campanian Plain; after infiltration, the water percolates through evaporitic layers, becoming hypersaline and D-depleted.  相似文献   

Jurassic kimberlites from Picton and Varty Lake,Ontario: Geochemical and stable isotopic characteristics     

Makoto Arima  Robert Kerrien 《Contributions to Mineralogy and Petrology》1988,99(3):385-391

Micaceous ultramafic dikes of Jurassic age from Picton and Varty Lake, Ontario, consist mineralogically of olivine — phlogopite — serpentine — calcite-spinel. The rocks are characterized by abundant Ba-rich phlogopite (up to 6.5 wt.% BaO) and spinels with a diagnostic kimberlite trend-1. Compositionally the dikes are characterized by extreme silica-undersaturation (21–30 wt.% SiO₂), primitive Mg/(Mg + Fe^T) ratios (0.75–0.83), large enrichments of volatile components (CO₂ and H₂O), and relatively high abundances of both incompatible and compatible trace elements. The dikes exhibit pronounced enrichments of light rare earth elements (LREE) (La_N=320–1330) combined with strongly fractionated patterns (La_N/Yb_N=45–108). Calcite in the dikes is a primary magmatic phase, from textural relations and C-isotopic compositions ( ¹³C= –4.0 to –8.3). A calcite-rich aphanitic phase of the Picton dike is interpreted to be a late stage magmatic differentiate, which possibly involved olivine fractionation. Although the dikes lack most of the macrocrysts generally considered to be important diagnostic minerals of kimberlite magmatism, the geochemical, mineralogical and C- and O-isotopic characteristics collectively indicate that the dikes are evolved varieties of hypabyssal facies kimerlite.  相似文献