Hydrothermal Quartz Vein Formation, Revealed by Coupled SEM-CL Imaging and Fluid Inclusion Microthermometry: Shuteen Complex, South Gobi, Mongolia     

Bayaraa Batkhishig    Greg Bignall  Noriyoshi Tsuchiya 《Resource Geology》2005,55(1):1-8

Abstract. Scanning electron microscopy-cathodoluminescence (SEM-CL) imaging of vein quartz in the Cu-mineralised, Shuteen Complex (South Gobi, Mongolia) has revealed a complex history of crystal growth, dissolution and microfracture healing, associated with several hydrothermal events that could not be detected using other observational techniques (e.g. transmitted/reflected light microscopy, back-scattered electron imaging, or secondary electron imaging).
The quartz initially grew as CL-bright/grey crystals in a 345±30C liquid reservoir, as inferred by the analysis of primary liquid fluid inclusions (average Th of 343C; 6.6∼7.7 wt% NaCl_eq). Quartz precipitation occurred at the edge of the crystals as reservoir fluids cooled to 260±25C, as indicated by micron-scale CL-dark/CL-bright quartz growth bands containing abundant fluid inclusions (with an average T_h values of 261C). Pressure fluctuations were the likely cause of dissolution, as SEM-CL imaging reveals the quartz have corroded or rounded crystal edges, and precipitation of later quartz into open space. SEM-CL imaging shows the quartz contains healed microfractures that trapped low salinity fluids (3.9 wt% NaC1_eq) with Th values of 173±15C.
SEM-CL imaging provides a means of deciphering the thermal and chemical evolution of the fossil Shuteen hydrothermal system, and the nature of hydrothermal quartz vein-forming processes, by facilitating the correlation of distinct fluid inclusion populations and their relative chronology, with specific hydrothermal events.  相似文献   

An experimental study on felsic rock–artificial seawater interaction: implications for hydrothermal alteration and sulfate formation in the Kuroko mining area of Japan     

Yasumasa Ogawa  Naotatsu Shikazono  Daizo Ishiyama  Hinako Sato  Toshio Mizuta 《Mineralium Deposita》2005,39(8):813-821

Experimental studies on the interactions between artificial seawater (ASW) and fresh rhyolite, perlite and weakly altered dacitic tuff containing a small amount of smectite suggest changing cation transfer during smectite-forming processes. Initially, dissolution of K from the rocks accompanies incorporation of Mg and Ca from ASW during both earlier (devitrification stage) and later smectite formation, whereas Ca incorporated with early smectite formation redissolves with progressive reaction. Barium mobility increases toward the later smectite-forming reactions. Therefore, the large amounts of barite, anhydrite and gypsum in Kuroko ore deposits are considered to have precipitated from hydrothermal solutions derived from the interaction with previously altered felsic rocks during late smectite formation, rather than by the reaction with fresh felsic rocks.Editorial handling: D. Lentz  相似文献   

Field observations of debris-flow initiation processes on sediment deposits in a previous deep-seated landslide site     

Fumitoshi Imaizumi  Satoshi Tsuchiya  Okihiro Ohsaka 《山地科学学报》2016,13(2):213-222

Although information regarding the initiation processes of debris flows is important for the development of mitigation measures,field data regarding these processes are scarce.We conducted field observations of debris-flow initiation processes in the upper Ichinosawa catchment of the Ohya landslide,central Japan.On 19 June 2012,our videocamera monitoring systems recorded the moment of debris-flow initiation on channel deposits(nine surges) and talus slopes(eight surges).The initiation mechanisms of these surges were classified into three types by analyzing the video images: erosion by the surface flow,movement of deposits as a mass,and upward development of the fluid area.The first type was associated with the progress of surface flow from the upper stream on unsaturated channel deposits.The second type was likely caused by an increase in the pore water pressure associated with the rising in the groundwater level in channel deposits;a continuous water supply from the upper stream by the surface flow might have induced this saturation.The third type was associated with changes in the downstream topography caused by erosion.The flow velocity of most surges was less than 3 m s~(-1) and they usually stopped within 100 m from the initiation point.Surges with abundant pore fluid had a higher flow velocity(about 3- 5 m s~(-1)) and could travel for alonger duration.Our observations indicate that the surface flow plays an important role in the initiation of debris flows on channel deposits and talus slopes.  相似文献   

Spatial and temporal patterns of seagrass habitat use by fishes at the Ryukyu Islands,Japan     

Yohei Nakamura  Makoto Tsuchiya 《Estuarine, Coastal and Shelf Science》2008

To investigate whether or not regional–temporal patterns of seagrass habitat use by fishes existed at the Ryukyu Islands (southern Japan), visual surveys were conducted in seagrass beds and adjacent coral reefs in northern, central, and southern Ryukyu Islands, in November 2004, and May, August, and November 2005, the northern region having less extensive seagrass beds compared with the central and southern regions. During the study period, the seagrass beds were utilized primarily by 31 species, the densities of some of the latter differing significantly among regions. With the exception of Apogonidae and Holocentridae, all species were diurnal and could be divided into 6 groups based on seagrass habitat use patterns; (1) permanent residents A (10 species, e.g. Stethojulis strigiventer), juveniles and adults living in seagrass beds as well as other habitats; (2) permanent residents B (5 species, e.g. Calotomus spinidens), juveniles and adults living only or mainly in seagrass beds; (3) seasonal residents A (4 species, e.g. Cheilodipterus quinquelineatus), juveniles living in seagrass beds as well as other habitats; (4) seasonal residents B (6 species, e.g. Lethrinus atkinsoni), juveniles living only or mainly in seagrass beds; (5) transients (5 species, e.g. Parupeneus indicus), occurring in seagrass beds in the course of foraging over a variety of habitats; and (6) casual species (1 species, Acanthurus blochii), occurring only occasionally in seagrass beds. Regarding temporal differences, juvenile densities in each group were high in May and August compared with November in each region, whereas adult densities did not differ drastically in each month. For regional differences, juvenile and adult densities of permanent residents A and B were higher in the southern and central regions than in the northern region. Moreover, some seasonal residents showed possible ontogenetic habitat shift from seagrass beds to coral reefs in each region. These results indicated that seagrass habitat use patterns by fishes changed temporally and regionally and there may be habitat connectivity between seagrass beds and coral reefs via ontogenetic migration in the Ryukyu Islands.  相似文献   

Solution Chemistry and the 36~(th) International Conference on Solution Chemistry (36 ICSC) in Xining,China          下载免费PDF全文

Toshio YAMAGUCHI 《盐湖研究》2019,(2)

<正>Solution chemistry covers a broad and interdisciplinary area in chemistry,physics,biology,pharmaceutical,and medical sciences,as well as various application fields. With the advent of new theories,analytical methods,computers,and technology,the research area of solution chemistry has now been widely and deeply  相似文献   

Soldier crab (Dotilla myctiroides) distribution,food resources and subsequent role in organic matter fate in Ao Tang Khen,Phuket, Thailand     

Kimberly K. Takagi  Phaothep Cherdsukjai  Izumi Mimura  Yuka Yano  Kanjana Adulyanukosol  Makoto Tsuchiya 《Estuarine, Coastal and Shelf Science》2010

This study aimed to elucidate Dotilla myctiroides (H. Milne-Edwards) food resources and how the soldier crab influences the organic matter composition on the intertidal flat. A preliminary assessment of D. myctiroides size, sex, and population distribution was conducted to clarify the characteristics of the inhabiting population. Overall, D. myctiroides size and abundance was normal across the tidal flat area. Comparison of different sediment types from the soldier crab habitat (surface sediments, igloos, burrow lining, burrow pellets, feeding pellets, and feces) using the fatty acid (FA) analysis technique revealed D. myctiroides removes organic matter via the significantly lower contributions of polyunsaturated FAs, essential FAs, and dinoflagellates in the feeding pellets. Dotilla myctiroides tissue analysis of the hepatopancreas and hindgut in individuals that had been starved for 24 h confirmed not only the consumption of dinoflagellates, but diatoms and macroalgae as well. In addition, the FA metabolism within the digestive system implied the ability of the soldier crab to synthesize highly unsaturated FAs (HUFAs) such as 20:4n–6, 20:5n–3 and 22:6n–3.  相似文献   

Geochemistry of newly discovered quaternary Shiribeshi Volcano,Northeast Japan Sea     

Dr. K. Shuto  Dr. N. Tsuchiya  Dr. S. Tamura  Dr. H. Kagami 《Mineralogy and Petrology》1991,44(3-4):213-234

Summary Shiribeshi Seamount is located to the east of the Okushiri Ridge, in the northeast Japan Sea. Whole rock K-Ar age of olivine-augite andesite dredged from the Seamount was determined to be 0.9 ± 0.2 Ma (Tsuchiya et al., 1989), indicating that Shiribeshi Seamount is a Quaternary volcano in the back-arc region off the junction of the Northeast Japan and Kurile arcs. Shiribeshi volcano is composed of basalt to rhyolite, which show a typical island arc calc-alkaline nature on the basis of petrographical characteristics of 95 samples dredged from four sites. Abundances of incompatible elements including K, Rb, Sr, Nb, P, Ti, Y and Zr in 16 representative rocks are discussed, together with those in the Quaternary volcanic rocks from the NE Japan and Kurile arcs in terms of compositional variation across the arcs. The estimated composition of the primary magma of Shiribeshi volcano is characterized by higher incompatible element contents and a higher Zr/Y ratio than primary magmas in the volcanic front side. Based on HFS element concentrations the degree of partial melting for three primary magmas of Oshima-Oshima, Shiribeshi and Rishiri volcanoes in the northeast Japan Sea may decrease gradually with increasing distance from the volcanic front. However, LIL element contents, especially K and Rb are lower in the primary magma of Rishiri volcano located far from the volcanic front than in the remaining two primary magmas, which would imply that LIL/HFS ratios (or degree of contribution of LIL elements originating from the subducted oceanic crust) become minimal at Rishiri volcano. One basalt and three andesites from Shiribeshi volcano have the restricted range of low⁸⁷Sr/⁸⁶Sr ratios of 0.70297–0.70300, which indicates that the magma source for Shiribeshi volcano may be slightly more enriched in Sr isotopic compositions than theN-type MORB source.

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Geochemie des neuentdeckten quartären submarinen Vulkans Shiribeshi im Nordöstlichen Japanischen Meer

Zusammenfassung Der Shiribeshi Seamount liegt östlich des Okushiri Rückens im nordöstlichen Japanischen Meer. Gesamtgesteins K-Ar Alter von Olivin-Augit-Andesiten von diesem Seamount ergeben Werte von 0,9 ± 0,2 Ma (Tsuchiya et al., 1989), und weisen darauf hin, daß Shiribeshi ein quartärer Vulkan im back-arc Bereich nahe dem Kreuzungspunkt des nordostjapanischen und des Kurilen-Inselbogens ist. Er besteht aus Gesteinen, deren Zusammensetzung von Basalt bis Rhyolit reicht. Petrographische Daten von 25 Proben, die von vier submarinen Lokationen durch Dredging aufgesammelt wurden, weisen auf eine typische kalk-alkalische Inselbogenzusammensetzung hin. Die Verbreitung von inkompatiblen Elementen, die unter anderem K, Rb, Sr, Nb, P, Ti, Y und Zr umfassen, in 16 representativen Proben wird zusammen mit denen von quartären vulkanischen Gesteinen aus dem nordöstlichen Japanischen und den Kurilen-Inselbogen diskutiert; dabei wird Variationen der Zusammensetzung über die Bögen hinweg besondere Beachtung geschenkt. Die so ermittelte Zusammensetzung des primären Magmas des Shiribeshi Vulkans wird durch höhere inkompatible Elementgehalte und höhere Zr/Y Verhältnisse charakterisiert, wenn man sie mit primären Magmen an der vulkanischen Stirn des Inselbogens vergleicht. HFS Element-Konzentrationen lassen erkennen, daß der Grad teilweiser Aufschmelzung für drei primäre Magmen von Oshima-Oshima, Shiribeshi und Rishiri im nordöstlichen Japanischen Meer graduell mit zunehmender Entfernung von der vulkanischen Stirm abnimmt. Die Gehalte an LIL Elementen und besonders an K und Rb sind in dem primären Magma des Rishiri Vulkans, der weit von der vulkanischen Front entfernt liegt, höher als in den zwei anderen primären Magmen. Dies weist darauf hin, daß LIL/HFS Verhältnisse (oder der Beitrag von LIL Elementen, die aus subduzierter ozeanischer Kruste stammen) am Rishiri Vulkan ein Minimum erreichen. Ein Basalt und drei Andesite von Shiribeshi zeigen⁸⁷Sr/⁸⁶Sr Verhältnisse von 0,70297 bis 0,70300; dies läßt erkennen, daß die Quelle des Magmas für Shiribeshi etwas mehr an⁸⁷Sr angereichert war, als dieN-Typ Quelle.

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With 7 Figures  相似文献   

Annual ENSO simulated in a coupled ocean–atmosphere model     

Tomoki Tozuka  Jing-Jia Luo  Sebastien Masson  Swadhin K. Behera  Toshio Yamagata   《Dynamics of Atmospheres and Oceans》2005,39(1-2):41

Using an output from 200-year integration of the Scale Interaction Experiment of EU project-F1 model (SINTEX-F1), the annual ENSO reproduced in the coupled general circulation model is investigated, suggesting the importance of reproducing an annual cycle in realistically simulating ENSO events. Although many features of the annual ENSO are reproduced, the northward expansion of sea surface temperature anomaly (SSTA) in the eastern tropical Pacific stays south of the equator. It is suggested that this model bias is due to the excitation of the too strong Rossby waves in the southeastern tropical Pacific, which reflect at the western boundary and intrude into the eastern equatorial Pacific. The zonal wind stress anomaly along the equator also plays an important role in generating the equatorial Kelvin waves. The amplitude of SSTA for the annual ENSO mode is reproduced, but its variance is only 20% of the observation; this is again due to the lack of northward migration of seasonal SSTA in the equatorial region and weaker coastal Kelvin waves along South America. Remedies for the model bias are discussed.  相似文献   

Oxygen and Carbon Isotope Study of Calcite and Dolomite in the Disseminated Au-Ag Telluride Bulawan Deposit, Negros Island, Philippines     

Victor B. MAGLAMBAYAN  Daizo ISHIYAMA  Toshio MIZUTA  Osamu MATSUBAYA  Yohei ISHIKAWA 《Resource Geology》2001,51(2):107-116

Abstract: The disseminated Au‐Ag telluride Bulawan deposit, Negros island, Philippines, is hosted by dacite porphyry breccia pipes which formed in a Middle Miocene dacite porphyry stock. Electrum and Au‐Ag tellurides occur mostly as grains intergrown with or filling voids between sphalerite, pyrite, chalcopyrite, galena and tennantite. Calcite, quartz and rare dolomite are the principal gangue minerals. Four types of alteration were recognized in the deposit, namely; propylitic, K‐feldspar‐sericitic, sericitic and carbonate alteration. Carbonate alteration is correlatable to the gold deposition stage and occurs mostly along fault zones. The δ¹⁸O and δ¹³C compositions of calcite and dolomite in propylite zone and ore‐stage dacite porphyry breccia were determined. The δ¹⁸O values of calcite in propylitized andesite range from +12.2 to +14.7%, and their δ¹³C values range from ‐6.1 to ‐1.0%. The δ¹⁸O values of calcite and dolomite in sericite‐ and carbonate‐altered, mineralized dacite porphyry breccia and dacite porphyry rocks range from +15.1 to +23.1%, and the δ¹³C values of calcite and dolomite range from ‐3.9 to +0.9%. The δ¹⁸O and δ¹³C values of the hydrothermal fluids were estimated from inferred temperatures of formation on the basis of fluid inclusion microthermometry. The δ¹⁸O values of hydrothermal fluid for the propylitic alteration were calculated to be +8.5 ‐ +9.5%, assuming 375°C. On the other hand, the δ¹⁸O values of ore solutions for base metal and Au mineralization were computed to be +13.6 ‐ +14.6%, assuming 270°C. The hydrothermal fluids that formed the Bulawan deposit are dilute and ¹⁸O‐enriched fluids which reacted with ¹⁸O‐ and ¹³C‐rich wallrocks such as limestone.  相似文献   

藏北高原D110点不同季节土壤温度的日变化特征   总被引：11，自引：0，他引：11  

杨梅学  姚檀栋  丁永建  王绍令  陈贤章  小池俊雄 《地理科学》1999,19(6):570-574

利用１９９８年ＧＡＭＥ－Ｔｉｂｅｔ加强观测期间取得的一个年周期的土壤温度资料,对藏北高原Ｄ１１０点土壤温度日变化特征的月际变化进行了分析。结果表明,在夏半年（５－９）月土壤温度存在明显的日变化,且基本上按正弦曲线变化,但相位随深度的增加而滞后;冬半年土壤温度尽管也存在日变化,但变幅较小。  相似文献