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81.
Contributions of slab fluid and sediment melt components to magmatism in the Mariana Arc–Trough system: Evidence from geochemical compositions and Sr,Nd, and noble gas isotope systematics 下载免费PDF全文
Yasuo Ikeda Keisuke Nagao Teruaki Ishii Daisuke Matsumoto Robert J. Stern Hiroo Kagami Makoto Arima Sherman H. Bloomer 《Island Arc》2016,25(4):253-273
This study presents new major and trace element, mineral, and Sr, Nd, and noble gas isotope geochemical analyses of basalts, gabbro, and clinopyroxenite from the Mariana Arc (Central Islands and Southern Seamount provinces) including the forearc, and the Mariana Trough (Central Graben and Spreading Ridge). Mantle source compositions beneath the Mariana Arc and the Mariana Trough indicate a mantle source that is depleted in high field strength elements relative to MORB (mid‐oceanic ridge basalt). Samples from the Mariana Arc, characterized by high ratios of Ba/Th, U/Th, 84Kr/4He and 132Xe/4He, are explained by addition of fluid from the subducted slab to the mantle wedge. Correlations of noble gas data, as well as large ion lithophile elements, indicate that heavy noble gases (Ar, Kr, and Xe) provide evidence for fluid fluxing into the mantle wedge. On the other hand, major elements and Sr, Nd, He, and Ne isotopic data of basalts from the Mariana Trough are geochemically indistinguishable from MORB. Correlations of 3He/4He and 40Ar/36Ar in the Mariana Trough samples are explained by mixing between MORB and atmosphere. One sample from the Central Graben indicates extreme enrichment in 20Ne/22Ne and 21Ne/22Ne, suggesting incorporation of solar‐type Ne in the magma source. Excess 129Xe is also observed in this sample suggesting primordial noble gases in the mantle source. The Mariana Trough basalts indicate that both fluid and sediment components contributed to the basalts, with slab‐derived fluids dominating beneath the Spreading Ridge, and that sediment melts, characterized by high La/Sm and relatively low U/Th and Zr/Nb, dominate in the source region of basalts from the Central Graben. 相似文献
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Tuite has been suggested as a potential reservoir for trace elements in the deep mantle,but no evidence confirms this supposition.By using a natural apatite as starting material,the trace-element-bearing tuite large crystals were obtained under highpressure and high-temperature conditions(15 GPa and 1800 K).X-ray diffraction pattern and Micro-Raman spectrum of the run product confirm that tuite was synthesized.The concentrations of trace elements in tuite crystals were analyzed by laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS).The rare earth element patterns of tuite show enrichment of light rare earth elements relative to heavy rare earth elements.Tuite shows high concentrations of Th and Sr,and negative anomalies of Rb,Nb,and Hf.The results show that tuite can accommodate a large amount of trace elements.Tuite might be an important host to accommodate trace elements if there is much apatite subducted into the deep mantle. 相似文献
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Shigehisa Takakuwa Daisuke Iono Baltasar Vila-Vilaro Tomohiko Sekiguchi Ryohei Kawabe 《Astrophysics and Space Science》2008,313(1-3):169-173
We discuss the scientific role of the Atacama Compact Array (ACA), the Japanese contribution to the ALMA project, for low-mass
star-formation study. Our recent observations of several low-mass protostellar envelopes in the submillimeter CS (J=7–6) and HCN (J=4–3) lines with the SMA and ASTE have revealed that these submillimeter emissions are more extended than ∼2000 AU and show
different velocity structures from those traced by millimeter lines. These results suggest the importance of taking short-spacing
informations the ACA can offer. Our comprehensive imaging simulations of these protostellar envelopes, as well as prestellar
cores and debris disks, unprecedentedly demonstrate the scientific importance of ACA. 相似文献
84.
A new infra-red radiometer for volcanological purposes consists of a commercially available infra-red optical unit (IR camera), mounted on a balloon-tracking theodolite in place of the telescope. The device has a motor-driven horizontal scan at two speeds, and the output signal is fed to a portable recorder. Thus, it is possible to obtain the horizontal temperature profile of an objective area. With successive scanning with different vertical angles of the camera, the spatial temperature distribution can be obtained.The IR ground scanner was successfully utilized at two volcanoes — Kusatsu-shirane and Mihara-yama, O-shima. Repeated IR surveys were made after minor eruptive events. Variations of the surface temperature with time were detected for both volcanoes. The IR scanner is also suitable for monitoring the time and temperature of eruptions from active vents. 相似文献
85.
A 100 m laser strainmeter system installed in a 1 km deep tunnel at Kamioka, Gifu, Japan 总被引:1,自引:0,他引:1
Shuzo Takemoto Akito Araya Junpei Akamatsu Wataru Morii Hideo Momose Masatake Ohashi Ichiro Kawasaki Toshihiro Higashi Yoichi Fukuda Shinji Miyoki Takashi Uchiyama Daisuke Tatsumi Hideo Hanada Isao Naito Souichi Telada Nobuo Ichikawa Kensuke Onoue Yasuo Wada 《Journal of Geodynamics》2004,38(3-5):477
We have installed a laser strainmeter system in a deep tunnel about 1,000 m below the ground surface at Kamioka, Gifu, Japan. The system consists of three types of independent interferometers: (1) an EW linear strainmeter of the Michelson type with unequal arms, (2) an NS-EW differential strainmeter of the Michelson type with equal arms and (3) a NS absolute strainmeter of the Fabry–Perot type. These are configured in L-shaped vacuum pipes, each of which has a length of 100 m. (1) and (2) are highly sensitive (order of 10−13 strain) and have wide dynamical range (10−13–10−6). Observations with strainmeters (1) and (2) started on June 11, 2003. (3) is a new device for absolute-length measurements of the order of 10−9 of a long-baseline (100 m) Fabry–Perot cavity by the use of phase-modulated light. This third strainmeter will be ready for operation before the end of 2004. The laser source of strainmeters (1) and (2) is a frequency-doubled YAG laser with a wavelength of 532 nm. The laser frequency is locked onto an iodine absorption line and a stability of 2 × 10−13 is attained. The light paths of the laser strainmeter system are enclosed in SUS304 stainless steel pipes. The inside pressure is kept to be 10−4 Pa. Consequently, quantitative measurement of crustal strains of the order of 10−13 can be attained by employing the laser strainmeter system of (1) and (2) at Kamioka. This resolving power corresponds to that of a superconducting gravimeter. Using the laser strainmeter system, we expect to determine parameters related to fluid core resonance, core modes and core undertone as well as other geodynamic signals such as slow strain changes caused by silent earthquakes or slow earthquakes. 相似文献
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87.
Operational Data Assimilation System for the Kuroshio South of Japan: Reanalysis and Validation 总被引:3,自引:5,他引:3
Masafumi Kamachi Tsurane Kuragano Hiroshi Ichikawa Hirohiko Nakamura Ayako Nishina Atsuhiko Isobe Daisuke Ambe Masazumi Arai Noriaki Gohda Satoshi Sugimoto Kumi Yoshita Toshiyuki Sakurai Francesco Uboldi 《Journal of Oceanography》2004,60(2):303-312
We describe an operational ocean data assimilation system for the Kuroshio and its validation using a nine-year reanalysis
(historical run from 1993 to 2001) dataset of upper-ocean state estimation in the North Pacific. The horizontal structure
of volume transport of the Ryukyu Current System (RCS) is shown from the reanalysis: The RCS is connected to the flow of the
subtropical gyre, and its volume transport gradually increases from south-east of Okinawa (5–10 Sv) to the east of Amami-Ohshima
Island (20 Sv). Comparing the reanalysis with independent observations on the southeast slope of the Amami-Ohshima Island
indicates that the root mean square differences (RMSDs) are 0.076 (0.037) m/s in the period of December 1998 to November 1999
(November 1999 to November 2000) respectively. The reanalysis field has a bias (3.1 Sv) of the volume transport of the RCS
and the RMSD (3.5 Sv) which is larger than the observed variability (2.81 Sv). Surface velocity and the Kuroshio axis south
of Japan are also examined. Comparison of the reanalysis and ADCP data gave maximum RMSD of 0.749 (0.271) m/s in the strong
(weak) current regions, respectively. The annual mean value of the axis error is 19 km in 1998. The RMSD of the error is at
most 50 km, in 294 cases in the observation period, which is smaller than the observed root mean square variability of the
axis (64 km).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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