Integrating field observation with petrochronology is critical for understanding the tectonometamorphic evolution of the North American Grenville Province. Despite methodological advances in geothermobarometry and geochronology, incorporating these data into larger models of the Adirondack Mountains remains particularly challenging due to the presence of multiple generations of deformation, primarily related to the ca. 1190 – 1140 Ma Shawinigan and ca. 1090 – 1020 Ma Ottawan Orogenies (McLelland et al.,2013). The Rock and Bear Ponds area is a dome of tight-to-isoclinally folded metapelites in structural contact with orthogneiss. Fold generations are orthogonal and partitioned such that the northern area is dominated by an earlier episode of D2 deformation and an E-W S2 fabric and the southern by D3 deformation and a N-S S3 fabric. Observed assemblages include Qtz + Pl + Kfs + Bt + Sil + Grt + Gr ± Py ± Mnz ± Zr in metapelite and Hbl + Pl + Grt + Qtz + CPx ± Ilm in metagabbro. Metapelitic garnet is anhedral and overgrows a strongly transposed S1 fabric. A population of small high-Y monazite cores are associated with S1 and yield a mean weighted date of 1174 ± 5 Ma. Monazite observed in S2-defining phases and matrix have very high-Y & HREE cores that yield dates of 1068 ± 7 Ma and are surrounded by low-Y & HREE mantles (1048 ± 4 Ma) with irregular high-Y rims (1023 ± 6 Ma). These data suggest garnet growth followed the transposition of a strong Shawinigan S1 fabric during D2 and D3 folding events, ca. 1090 – 1070 Ma. The timing of this shortening is interpreted to coincide with the early Ottawan Orogeny, ca. 1090 – 1050 Ma. Geothermobarometric calculations of S2-associated phases constrains peak metamorphic conditions to 700 – 750 ± 50 °C and 6.5-7.5 ± 1 kbar; these data are well in agreement with those reported in multiple studies, thereby suggesting that regional PT calculations reflect Ottawan tectonometamorphic conditions (Bohlen et al., 1985; Spear & Markussen, 1997; Storm & Spear, 2005). High-Y & HREE rims are also observed and interpreted to reflect garnet breakdown ca. 1050 – 990 Ma during decompression and orogenic collapse, which has become increasingly reported in the eastern Adirondack Mountains over the last decade (Wong et al., 2012; Chiarenzelli et al., 2017; Regan et al., 2019; Williams et al., 2019). The Mesoproterozoic metapelite of the Rock and Bear Ponds area record an intense polydeformational history and therefore provide a valuable window into episodic middle-to-lower crustal deformation and metamorphism. The integration of focused microstructural observation with geothermobarometric and timing constraints has provided much insight into the structural evolution of the Adirondack Mountains. Integrating field observation with petrochronology is critical for understanding the tectonometamorphic evolution of the North American Grenville Province. Despite methodological advances in geothermobarometry and geochronology, incorporating these data into larger models of the Adirondack Mountains remains particularly challenging due to the presence of multiple generations of deformation, primarily related to the ca. 1190 – 1140 Ma Shawinigan and ca. 1090 – 1020 Ma Ottawan Orogenies (McLelland et al.,2013). The Rock and Bear Ponds area is a dome of tight-to-isoclinally folded metapelites in structural contact with orthogneiss. Fold generations are orthogonal and partitioned such that the northern area is dominated by an earlier episode of D2 deformation and an E-W S2 fabric and the southern by D3 deformation and a N-S S3 fabric. Observed assemblages include Qtz + Pl + Kfs + Bt + Sil + Grt + Gr ± Py ± Mnz ± Zr in metapelite and Hbl + Pl + Grt + Qtz + CPx ± Ilm in metagabbro. Metapelitic garnet is anhedral and overgrows a strongly transposed S1 fabric. A population of small high-Y monazite cores are associated with S1 and yield a mean weighted date of 1174 ± 5 Ma. Monazite observed in S2-defining phases and matrix have very high-Y & HREE cores that yield dates of 1068 ± 7 Ma and are surrounded by low-Y & HREE mantles (1048 ± 4 Ma) with irregular high-Y rims (1023 ± 6 Ma). These data suggest garnet growth followed the transposition of a strong Shawinigan S1 fabric during D2 and D3 folding events, ca. 1090 – 1070 Ma. The timing of this shortening is interpreted to coincide with the early Ottawan Orogeny, ca. 1090 – 1050 Ma. Geothermobarometric calculations of S2-associated phases constrains peak metamorphic conditions to 700 – 750 ± 50 °C and 6.5-7.5 ± 1 kbar; these data are well in agreement with those reported in multiple studies, thereby suggesting that regional PT calculations reflect Ottawan tectonometamorphic conditions (Bohlen et al., 1985; Spear & Markussen, 1997; Storm & Spear, 2005). High-Y & HREE rims are also observed and interpreted to reflect garnet breakdown ca. 1050 – 990 Ma during decompression and orogenic collapse, which has become increasingly reported in the eastern Adirondack Mountains over the last decade (Wong et al., 2012; Chiarenzelli et al., 2017; Regan et al., 2019; Williams et al., 2019). The Mesoproterozoic metapelite of the Rock and Bear Ponds area record an intense polydeformational history and therefore provide a valuable window into episodic middle-to-lower crustal deformation and metamorphism. The integration of focused microstructural observation with geothermobarometric and timing constraints has provided much insight into the structural evolution of the Adirondack Mountains.

No description available.

第22回名古屋大学年代測定総合研究センターシンポジウム平成21(2009)年度報告

Inconel 718 is a high nickel content superalloy possessing high strength at elevated temperatures and resistance to oxidation and corrosion. The non-traditional manufacturing process of wire-electrical discharge machining (EDM) possesses many advantages over traditional machining during the manufacture of Inconel 718 parts. However, certain detrimental effects are also present. The top layer of the machined surface is melted and resolidified to form what is known as the recast layer. This layer demonstrates microstructural differences from the bulk workpiece, resulting in altered material properties. An experimental investigation was conducted to determine the main machining parameters which contribute to recast layer formation in wire-EDM of Inconel 718. It was found that average recast layer thickness increased with energy per spark, peak discharge current, current pulse duration, and open-voltage time and decreased with sparking frequency and table feed rate. Over the range of parameters tested, the recast layer was observed to be between 5 and 10 μm in average thickness, although highly variable in nature. Surface roughness of the cut parts showed an increase with energy per spark. Electron Probe Microanalysis (EPMA) revealed the recast layer to be alloyed with elements from the wire electrode. X-ray diffraction testing showed the residual tensile stresses evident near the cut surface to decrease with energy per spark. Additionally, nano-indentation hardness testing indicated that the recast layer is reduced in hardness and elastic modulus compared to the bulk material. Vibratory tumbling was found to be a moderately effective post-processing tool for recast layer removal when using pre-formed ceramic abrasive media or fine grained aluminum oxide.

Contents of major, minor and trace elements in clinopyroxenes and clinoamphiboles of basanites, volcanoclastics, essexites, sodalitic syenites, and monzodiorites of the České středohoří Mts. has been determined using an electrone microprobe and LA-ICP-MS techniques. Composition of clinopyroxenes corresponds to either diopside or augite and clinoamphiboles can be classified as kaersutite or pargasite. Some pyroxenes display pronounced sector zoning showing increased contents of Mg and Si in pyramidal sectors whereas prismatic sectors show Fe, Ti and Al enrichment. Chemical composition of both sectors corresponds to diopside. Growth zoning has been found in the samples from basanites and volcanoclastics. Grain cores display the chemistry of augite and towards the rim the chemical composition changes to diopside. Samples have also been analyzed by powder and single crystal X-ray diffraction techniques. Samples of pyroxenes appear to be either pure or they contain negligible admixtures of phlogopite. Samples of amphiboles are also either without any admixtures or they show contamination by low amounts of diopside or augite, or phlogopite may rarely be encountered. Mutual relationship between the size of the unit cell parameters b and and substitutions in M1,2,3 and A sites has been observed. Longer mean T-O...

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第22回名古屋大学年代測定総合研究センターシンポジウム平成21(2009)年度報告

第23回名古屋大学年代測定総合研究センターシンポジウム平成22(2010)年度報告

名古屋大学年代測定総合研究センターシンポジウム報告

Les cristaux de phases supraconductrices de formulation générale, TlmBa2Can-1CunO2n+m+2 (avec m=1, 2 et n=1, 2, 3) ont été préparés par une technique de croissance en flux. Chaque phase a été caractérisée par diffraction X (Weissenberg, Buerger, cristal tournant) et par micro-spectroscopie Raman. L'analyse par microsonde électronique a révélé des déficits cationiques par rapport a la formulation idéale. Une étude par HREM a montré dans la plupart des cristaux l'absence d'intercroissance à l'échelle atomique. La température critique a été mise en évidence par mesures électriques, mesures sous champ magnétique continu et susceptibilite alternative. Le comportement magnétique révèle une très forte anisotropie entre les propriétés supraconductrices dans la direction de l'axe c et dans le plan (a, b) (Hc1(c)/Hc1(a,b)=1000 pour la phase 2212). Les courbes d'effet Meissner et d'effet d'écran révèle que l'aimantation est réversible près de Tc et irréversible a plus basse température. La ligne d'irréversibilite (H*, T*) a été caractérisée pour la phase 2212.