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K-Ar ages of .. Ma (Kamihara Tonalite), . . Ma (Mitsuhashi Granodiorite), .. Ma (Inagawa Granite, massive facies), .. Ma (Inagawa Granite, gneissose porphyritic facies) and .. Ma (Busetsu Granite) were determined from the Ryoke plutonic rocks in the Asuke area, central Japan. All of these ages are interpreted to be cooling ages related to the blocking temperature of biotite. The coincident -Ma cooling ages of the Kamihara Tonalite, Mitsuhashi Granodiorite, massive facies of Inagawa Granite and Busetsu Granite in -Ma suggests that these plutonic rocks followed a common cooling path in this area after solidification of the Busetsu Granite (ca. -Ma). On the other hand, solidification age of the gneissose porphyritic facies of Inagwa Granite is ca. -Ma, and K-Ar age of .. Ma from the gneissose porphyritic facies of Inagawa Granite was younger than other plutonic rocks in the Asuke area. thus, the K-Ar age is concordantly interpreted as cooling age of the granite.

( 2015 ) Multiple trace element analyses for silicate minerals and glasses by laser ablation-inductively coupled plasma-mass spectrometry ( LA-ICP-MS ) . Bull. Geol. Surv. Japan, vol. 66 ( 9/10 ) , 6 figures, 6 tables.Abstract: Programs were established in the shared research facilities of the Geological Survey of Japan ( GSJ-Lab ) for trace element analysis of silicate minerals and glasses in microspots using laser ablationinductively coupled plasma-mass spectrometry ( LA-ICP-MS ) . National Institute of Standards and Technology ( NIST ) synthetic glasses reference materials ( NIST 613 and NIST 611 ) were used as external calibration standards, and suitable instrumental operation settings were set as follows; 0.5 L min -1 He carrier gas flow rate, 100 μm laser spot diameter, 5 Hz repetition rate, and 40 % laser energy ( fluence ca. 2.0 J cm -2 ) . NIST 615 and NIST 613 were analyzed as unknown samples to evaluate precision and accuracy. Precision was mostly less than 30 % for 45 elements from 45 Sc to 238 U for laser spot diameters ranging from 100 to 10 μm. Accuracy was evaluated according to the difference ( DIF ) between the analytical results and reference values in the literature. Accuracy for the analysis of NIST 613 was DIF < 30 %, except for Sc, Mn, Ni, and Ge. For NIST 615, DIF was less than 30 %, except for Tl with laser spot diameters of 20 and 10 μm, and for Cd with a laser spot diameter of 20 μm. The depths of laser pits for generic conditions for the analysis of clinopyroxene, amphiboles and plagioclase were estimated as extents without penetration of the thin section samples. Two suites of analytical programs ( 34 and 27 elements ) were additionally prepared for general purpose petrological and geochemical discussion and the accuracy of both was evaluated. The DIFs for the suite of 34 elements were mostly less than 30 %, although some for Cr, Mn, Ni, and Cs with laser spot diameters < 40 μm exceeded 30 %. In the suite of 27 elements, the DIFs were < 30 %, except for Sc.

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The nanocrystalline Ni W alloy fabricated by an electrodeposition method has a high strength and high bending ductility. However, its fatigue properties are not known yet. Therefore, fatigue tests were carried out to clarify the fatigue properties. Nanocrystalline Ni W alloy specimens containing 16.9 at W with about 20 mm in thickness, 200 mm in parallel part length, and 100 mm in width were produced by both UV photolithography and electrodeposition methods. The average grain size was about 6 nm in diameter and the tensile strength was about 2.8 GPa. The fatigue test was conducted at a stress ratio of 0.1 and a frequency of 10 Hz. The fatigue limit and fatigue ratio showed 2.1 GPa and 0.74, respectively. Macroscopic fractured morphology showed no necking and perpendicular fracture for the loading axis. However, microscopic fracture surface showed flat and featureless morphology at near the crack initiation region and it showed striations from the region where the striation spacing became more than about 10 nm. The final unstable fracture surface showed dimples with a diameter of 100～200 nm.

The scientific research results of the Geological Survey of Japan (GSJ) from the five-year project of the Cross-ministerial Strategic Innovation Promotion Program (SIP), "Next-generation technology for ocean resources exploration" are summarized. GSJ has been involved in one of the four R&D themes, namely "Scientific research on formation processes of ocean resources" in collaboration with the Japan Agency for Marine-earth Science and Technology ( JAMSTEC ) and Kyushu University. GSJ's research focused mainly on (1) tectono-magmatic evolution of basement geology, petrogenesis of igneous rocks and the relationship between magmatism and ore-formation, and (2) determination of scientific indices for marine surveys, narrowing down the potential areas based on investigations of geochemical and physical properties of igneous rocks, sediments and sulfides, as part of the research on genesis of seafloor massive sulfide deposits in Okinawa Trough. For (1), it was observed that, based on petrological and geochemical investigations of igneous rocks, mantle-derived mafic magma ascended to shallower portions of the crust and extruded on the seafloor due to thinning by back-arc rifting. These magmatic products were hydrothermally altered while the periodical ascent of mafic magma induced hydrous partial melting of altered basaltic rocks and production of felsic magma. These processes reasonably explain composition of extrusive rocks and formation of ore-fluid. In (2), new geochemical survey method for detecting the ore-related features were proposed, based on studies of felsic igneous rocks (pumices) widely distributed in the hydrothermal field, and electrical properties of subsea rocks, including sulfides, which contribute to the upgrading of the electromagnetic survey method, were disclosed from recovered cores by D/V Chikyu cruises. These results would save the effort for the first stage of surveys by narrowing down the potential areas and contribute towards developing more efficient surveys by determining optimal spec and acquisition data for next-generation technology for ocean resources exploration. 戦略的イノベーション創造プログラム (SIP) 「次世代 海洋資源調査技術」 における，地質調査総合センター (GSJ) の 5 ヵ年の研究成果をまとめた． 「次世代海洋資源 調査技術」 においてGSJは，4 つの研究テーマの一つであ る， 「海洋資源の成因の科学的研究に基づく調査海域の 絞り込み手法の開発」 に国立研究開発法人海洋研究開発 機構や国立大学法人九州大学等とともに連携して取り組 んできた．GSJでは特に，海底熱水鉱床の成因に関する 科学的研究と成因モデル構築の一環として，モデル海域 と定めた中部沖縄トラフ海域において，主として(1) 海 − 266 − 地質調査研究報告 2018 年 第 69 巻 第 6 号 底熱水鉱床を胚胎する基盤岩類の地質構造発達史，熱水 循環の熱源として機能するマグマの発生メカニズムと資 源濃集過程との関連，そして火成岩類・堆積岩類・硫化 物の化学組成・物性の検討を通じた，(2) 有望海域の絞 り込みに資する科学的調査指標の特定に関する研究開発 を実施してきた．(1) では，火成岩類の岩石学的・地球 化学的検討を通じ，中部沖縄トラフのリフティングに伴 う地殻の薄化によって海底面に達するマントル由来苦鉄 質マグマの貫入・噴出が生じ，その結果形成された苦鉄 質岩が海水や熱水による変質を受けた後，新たな苦鉄質 マグマ・バッチにより含水部分溶融し珪長質マグマを発 生することによって，噴出岩類の組成や鉱液の形成が 合理的に説明可能であることを明らかにした．(2) では， 熱水活動域周辺に広範に分布する珪長質火成岩類 (パミ ス) の化学組成を用いて鉱徴域を絞り込むための地球化 学的調査法を開発するとともに， 地球深部探査船 「ちきゅ う」 の掘削コアの岩石物性の検討を通じ，電気・電磁探 査手法の高度化に資する，海底面下構成岩類の電気特性 を明らかにした．これらの成果は， 「次世代海洋資源調 査技術」 における，有望海域の絞り込みによる調査航海 日数及びコストの削減，最適な取得データ項目や調査機 器のスペックの決定による高効率調査システム開発に貢 献する． １．はじめに 戦略的イノベーション創造プログラム (Cross-...

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