巻号一覧
42 巻 (2008)
- 6 号 p. 461-
- 5 号 p. 381-
- 4 号 p. 309-
- 3 号 p. 237-
- 2 号 p. 141-
- 1 号 p. 1-
42 巻, 5 号
選択された号の論文の6件中1～6を表示しています
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GUANQIANG CAI, FENG GUO, XIANTAI LIU, SHULING SUI, CHAOWEN LI, LIANG Z ...2008 年 42 巻 5 号 p. 381-402
発行日: 2008/10/20
公開日: 2010/11/03
ジャーナル フリーMajor and trace element compositions of 83 fine-grained sedimentary rocks (including 14 fine-grained sandstones, 24 siltstones and 45 mudstones) from the Zhanhua Sag of Jiyang basin in the North China Block were analyzed to investigate the effects of sedimentary processes (e.g., source provenance, mineral assemblage, grain size and chemical weathering etc.) on the bulk chemical compositions. Compared with the average upper continental crust (UCC), these rocks have higher TiO2, Al2O3, Fe2O3, Ba, Th, U, Nb, Ta, Zr, Hf, Y and REE, but lower SiO2, MnO, MgO, CaO, K2O, Na2O, P2O5, Cr, Co, Ni and Sr. From sandstones, siltstones to mudstones, there exist systematic increase in Rb, Cs, V, Cr, Co, Ni, Nb, Ta, Th, U and REE, and decrease in SiO2, K2O, Na2O and Ba. Such variation trends reflect a predominant role of grain size effect on the geochemistry of these sediments. K2O, Na2O, Ba, Zr and Hf positively correlate with SiO2 and negatively correlate with Al2O3, whereas other elements generally show negative correlations with SiO2 and positive correlations with Al2O3, suggesting that clay minerals are major hosts for most elements, while quartz and feldspar exert a dilution effect. The accessory heavy minerals exert a minor control on the bulk REE composition of the sediments, e.g., the contribution of heavy minerals (apatite, zircon, sphene, monazite etc.) to the bulk REE concentrations is less than 20%. Our results show that grain size and clay minerals are the two most important factors to control the bulk chemical compositions of the Zhanhua Sag sediments, and probably terrestrial fine-grained sediments in general.抄録全体を表示PDF形式でダウンロード (2528K) -
HAIZU ZHANG, ANSONG GENG, YONGQIANG XIONG, JINZHONG LIU, JINPING LIU2008 年 42 巻 5 号 p. 403-412
発行日: 2008/10/20
公開日: 2010/11/03
ジャーナル フリーThe aim of this work is to determine the molecular and stable carbon isotope compositions of pyrolysates from normal octadecane and, then, to study methane generation kinetic and carbon isotope fractionation of gaseous hydrocarbons generated from n-octadecane cracking. Pyrolyses were carried out in an anhydrous closed system (gold tubes) under a constant pressure of 50 MPa at heating rates of 20°C/h and 2°C/h. Results show that secondary cracking of pyrolysates from n-octadecane largely contributes to the amount of methane generation, much more than primary cracking of n-octadecane. Cracking and polymerization at relatively low temperatures and disproportionation reactions leading to light hydrocarbons and polyaromatic hydrocarbons at high temperatures are probable causes for the carbon isotope reversal of gaseous hydrocarbons that is commonly observed in pyrolysis experiments. This study of methane generation kinetics suggests that n-alkane hydrocarbon cracking begins to generate methane at 170°C but a great deal would be generated at 200°C in sedimentary basins.抄録全体を表示PDF形式でダウンロード (237K) -
KOTARO SHIRAI, NAOTO TAKAHATA, HIROYUKI YAMAMOTO, TAMANO OMATA, TAKENO ...2008 年 42 巻 5 号 p. 413-420
発行日: 2008/10/20
公開日: 2010/11/03
ジャーナル フリーTo study the mechanism of element incorporation into bivalve shells living in hydrothermal environments, the chemical composition of deep-sea mussel (Bathymodiolus platifrons) shell was analyzed using three microanalytical techniques. Mg/Ca, Sr/Ca, Mn/Ca, and Ba/Ca ratios were measured in ∼8-μm-diameter spots by secondary ion mass spectrometry (NanoSIMS). Mg, Sr, Ca, and S distributions were analyzed by electron probe microanalyzer (EPMA; spatial resolution, ∼2 μm). Micro-scale shell structures were observed by SEM and optical microscope. The inner aragonitic layer comprised three sublayer types. The thick organic sublayers and homogeneous sublayers were interlaminated sporadically among usually deposited nacreous layers. Elemental compositions were significantly associated with shell sublayer types. The thick organic sublayers contained higher Mg/Ca, Sr/Ca and Ba/Ca ratios by factors of up to 3.0, 2.6 and 3.2, respectively, compared to the adjacent nacreous layers. On the other hand, Mn/Ca ratios in homogeneous sublayers were depleted down to one third of those in adjacent nacreous layers. Our data suggest that biological effects are significant for micro scale elemental distributions.抄録全体を表示PDF形式でダウンロード (4707K) -
SHIGENORI OGIHARA2008 年 42 巻 5 号 p. 421-427
発行日: 2008/10/20
公開日: 2010/11/03
ジャーナル フリーLimestones associated with fossil chemosynthetic biological communities are found in Tappu Kanajirizawa and Teshionakagawa Abeshinaigawa, central Hokkaido, northern Japan. They were studied to ascertain their lipid distributions and δ13C values of lipid in order to investigate molecular records of archaea and bacteria associated with the anaerobic oxidation of methane (AOM). The limestones contain the tail-to-tail linked irregular isoprenoid hydrocarbons, 2,6,11,15-tetramethylhexadecane (crocetane), and its C25-homologue 2,6,10,15,19-pentamethylicosane (PMI). Furthermore, C30-homologue 2,6,10,15,19,23-hexamethyltetracosane (squalane) was detected. The abundance of these compounds indicates a pronounced role of particular archaea in the cold-seep. The δ13C values of PMI and crocetane were depleted, ranging from -129‰ to -116‰DB. New biomarkers found were C13 and C18 isoprenoid ketones, which could potentially be from anaerobic methanotrophic archaea. Small amounts of C14 and C19 isoprenoid ketones were also detected. The C13, C14 and C18 isoprenoid ketones also had extremely low δ13C values ranging from -115‰ to -104‰. δ13C values suggest that the origin of the isoprenoid ketones are lipids of anaerobic methanotrophioc archaea, but the diagenetic pathway leading to them is uncertain. This study shows that the limestones are cold seep carbonates and that isoprenoid ketones are potentially useful markers for anaerobic methanotrophic archaea.抄録全体を表示PDF形式でダウンロード (142K) -
SEUNG-GU LEE, TONG-KWON KIM, JIN-SOO LEE, TAE JONG LEE, BYONG WOOK CHO ...2008 年 42 巻 5 号 p. 429-441
発行日: 2008/10/20
公開日: 2010/11/03
ジャーナル フリーThe Dongrae thermal water area located at the southeast margin of the Korean Peninsula is one of the oldest hot springs in Korea and has been used in spas since the 9th Century. In this paper, a geochemical significance of 87Sr/86Sr ratios from deep thermal water, groundwater, surface water and rainwater in the Dongrae area is discussed. The bedrock of this thermal water-bearing aquifer is composed of Mesozoic granitoids. For temperatures up to 71°C, the thermal water is Na-Cl type, whereas shallow cold groundwater is Ca(-Na)-HCO3 type. 87Sr/86Sr ratios of the thermal water are in the 0.705651 ± 11-0.705696 ± 12 range and have remained nearly unchanged over the past 4 years (2004-2007). 87Sr/86Sr ratios of the shallow cold groundwater, surface water and rainwater range from 0.705781 ± 26 to 0.705789 ± 12, 0.706700 ± 14 and 0.707375 ± 11 respectively. 87Sr/86Sr ratios of the thermal water in the Dongrae area are lower than those of groundwater, surface water, rain water as well as aquifer bearing granite. These Sr isotopic signatures indicate that the circulation rate between thermal water and current meteoric water, including groundwater, surface water and rain water in the Dongrae area should be very slow. Therefore, the thermal water might be derived from a high temperature paleo-groundwater reservoir rather than from circulation of young meteoric water heated by current heat sources. Our data show that 87Sr/86Sr ratios may become an important time lag indicator for the groundwater cycle between deep and shallow groundwater in a fractured granite aquifer system.抄録全体を表示PDF形式でダウンロード (652K) -
MRUGANKA K. PANIGRAHI, RAJESH K. NAIK, DINESH PANDIT, KULA C. MISRA2008 年 42 巻 5 号 p. 443-460
発行日: 2008/10/20
公開日: 2010/11/03
ジャーナル フリーMineral chemistry of biotite, chlorite and epidote associated with the granitoid ore body of the Malanjkhand copper-molybdenum deposit have been studied to constrain temperature, oxidation and sulfidation states as well as fugacity ratios of HF, HCl and H2O of the hydrothermal mineralizing fluid. Calculated mineralizing temperatures from biotite, chlorite and epidote are mutually consistent and agree well with earlier estimates derived from fluid inclusion studies. Major element chemistry of biotite indicates low oxidation state (FMQ-NNO) and re-equilibrated nature (∼300°C). However, exchange of Cl-F-OH between biotite and the fluid continued to lower temperatures. Subtle differences between the Malanjkhand deposit and known porphyry copper deposits have been evidenced by the fugacity ratios of halogens and water. Chlorite registers equilibrium with fluid down to 200°C and, together with biotite composition, indicates that copper was transported as chloride complex in the fluid. Sulfide deposition occurred during a prompt rise in fugacity of H2S at 300°C, possibly resulting from a coupled oxidation of Fe2+ and reduction of SO42-. Interaction of ore fluid with epidote in the wall-rock favored the deposition of chalcopyrite, enhanced the Ca2+ activity in the fluid and inhibited a fall in pH and a subsequent acid alteration of K-feldspar in the wall-rock. These physicochemical characteristics of the mineralized fluid suggest that the Malanjkhand deposit represents an ancient granitoid-associated geothermal system rather than a classic porphyry copper ore deposit.抄録全体を表示PDF形式でダウンロード (1790K)
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