研究者詳細 - 道林　克禎

Grain growth kinetics and the effect of crystallographic anisotropy on normal grain growth of quartz 査読有り

Michibayashi, K; Imoto, H

PHYSICS AND CHEMISTRY OF MINERALS 39 巻 ( 3 ) 頁： 213 - 218 2012年3月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics and Chemistry of Minerals

Annealing experiments on agate were performed to investigate grain growth kinetics and the effect of crystallographic anisotropy on normal grain growth of quartz. The experiments were conducted using a piston-cylinder apparatus at 700-800°C and 0.5 GPa for 0-66 h. The grain growth rate was expressed by D n-D 0n = kt with k = k 0exp(-H*/RT) where D 0 is the initial grain size at t = 0, with n = 4.4 ± 0.3, and H* = 191.3 ± 11.0 kJ/mol is the activation enthalpy and logk 0 = 19.8 ± 1.4. While the grain aspect ratios are nearly constant at ~0.7 (short/long) during grain growth, the longest axis in individual grains tends to be oriented parallel to their c-axis, indicating that a primary crystal-preferred orientation of c-axis of the agate could result in the development of a weak shape-preferred orientation during grain growth. © 2011 Springer-Verlag.

DOI： 10.1007/s00269-011-0476-6

Seismic properties of peridotite xenoliths as a clue to imaging the lithospheric mantle beneath NE Tasmania, Australia 査読有り

A serpentinite-hosted ecosystem in the Southern Mariana Forearc 査読有り国際共著

Ohara Yasuhiko, Reagan Mark K., Fujikura Katsunori, Watanabe Hiromi, Michibayashi Katsuyoshi, Ishii Teruaki, Stern Robert J., Pujana Ignacio, Martinez Fernando, Girard Guillaume, Ribeiro Julia, Brounce Maryjo, Komori Naoaki, Kino Masashi

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 109 巻 ( 8 ) 頁： 2831-2835 2012年2月

Michibayashi K., Kusafuka Y., Satsukawa T., Nasir S. J.

TECTONOPHYSICS 522 巻頁： 218 - 223 2012年2月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Tectonophysics

Peridotite xenoliths from Northeast Tasmania, Australia, consist of spinel lherzolites and minor dunites that originated from the uppermost mantle at depths of less than 40. km, based on the geothermal gradient beneath Tasmania, where the depth of the Moho is 29. km. The crystal preferred orientations (CPOs) of olivine and pyroxene were measured in 5 of 13 collected samples (1 dunite and 4 lherzolites) that were large enough to enable measurements. Olivine CPOs indicate the dominance of (010) [100] slip. Geothermobarometric analyses of the xenoliths yield temperatures of 950-1050. °C and pressures of 0.7-1.1. GPa. Using these data, we calculated changes in the seismic properties of a rock with ideal volume fractions of olivine and pyroxene under conditions of 1000. °C and 1. GPa, for various orientations of the structural reference frame in the case of three geodynamic models (extension, shear, and upwelling). The model of horizontal extension performs best in explaining the structure of the uppermost lithospheric mantle beneath Northeast Tasmania. © 2011 Elsevier B.V.

DOI： 10.1016/j.tecto.2011.12.002

かんらん石ファブリック：上部マントル構造を探る手がかり査読有り

道林克禎

岩石鉱物科学 41 巻 ( 6 ) 頁： 267 - 274 2012年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人　日本鉱物科学会

The understanding of olivine fabric has dramatically been progressed during the last~10 years by both natural and experimental studies along with the major technological improvement. Crystal-preferred orientations (CPO) are the expression of crystallographic fabrics of grains within the rock with respect to the structural frame (X-,Y- and Z-axes). CPO patterns can be interpreted based on the plane of plastic flow and the flow direction. Olivine fabrics, which are olivine CPO patterns, have been classified into five types: A, B, C, D and E types by a series of experimental studies. An additional AG type has also been proposed in recognition of its common occurrence in nature. New results have already required major modiications to the geodynamic interpretation of the upper mantle, although some uncertainties still remain regarding the olivine fabrics and their development. © 2012, Japan Association of Mineralogical Sciences. All rights reserved.

DOI： 10.2465/gkk.120712b

CiNii Research

上部マントル構造を探る手がかり査読有り

道林克禎

岩石鉱物科学 41 巻頁： 267 - 274 2012年

Seismic anisotropy of the uppermost mantle beneath the Rio Grande rift: Evidence from Kilbourne Hole peridotite xenoliths, New Mexico 査読有り国際共著

Satsukawa T., Michibayashi K., Anthony E.Y., Stern R.J., Gao S.S., Liu K.H.

Earth and Planetary Science Letters 311 巻 ( 1-2 ) 頁： 172 - 181 2011年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Earth and Planetary Science Letters

Peridotite xenoliths from the Kilbourne Hole maar, New Mexico, consist of spinel lherzolite, harzburgite, and dunite. Because Kilbourne Hole erupted at approximately 10. ka, these xenoliths represent essentially current conditions beneath the Rio Grande rift. In this study, we present detailed petrofabric data and seismic properties obtained from peridotite xenoliths from Kilbourne Hole to illuminate the origin and significance of shear-wave splitting in the uppermost mantle beneath this active rift. Using phase relations and the temperature of equilibration, we infer that these xenoliths were derived from the uppermost mantle, from depths of 35-60. km. Their crystallographic preferred orientations indicate the preservation of olivine b-axis fiber fabrics with a strong concentration of [010] with girdles of [100] and [001]. We consider three geodynamic models for the source region of these xenoliths: horizontal extension, lateral shear, and upwelling. After calculating seismic properties using a volume fraction of olivine, orthopyroxene and clinopyroxene appropriate to each model, we conclude that these xenoliths are derived from a lateral shear zone (vertical foliation (XY plane) and horizontal lineation within the plane of the foliation (X-axis)). However, the degree of seismic anisotropy generated by peridotite xenoliths alone is limited, so that the existence of melt in thin cracks or dikes could be required to cause a significant increase; the orientation of such melt pockets parallel to the XY plane in either model would result in an increase in anisotropy. These results indicate that the shear-wave splitting observed in the Rio Grande rift is a reflection of the lithospheric fabric and the presence of melts as thin cracks or dikes. © 2011 Elsevier B.V.

DOI： 10.1016/j.epsl.2011.09.013

夜久野オフィオライト待ちの山超マフィック岩体南部断層境界に発達したブロックインマトリックス構造査読有り

小森直昭, 道林克禎

静岡大学地球科学研究報告 38 巻 ( 0 ) 頁： 21 - 26 2011年10月

Nishii A., Wallis S., Mizukami T., Michibayashi K.

Journal of Structural Geology 33 巻 ( 10 ) 頁： 1436 - 1445 2011年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Structural Geology

Antigorite (Atg) is stable throughout large parts of the wedge mantle of most subduction zones. Atg shows strong acoustic anisotropy and crystallographic preferred orientation (CPO) patterns of this mineral may contribute significantly to seismic anisotropy in convergent margins. Atg CPO patterns from the Higashi-Akaishi (HA) forearc mantle body of southwest Japan adds to the data set suggesting the most common Atg CPO pattern has a c-axis perpendicular to the foliation and a b-axis parallel to the stretching lineation. Statistical analysis using the eigenvector method of Atg CPO from two mutually perpendicular directions in the same sample (YZ-section and XZ-section) shows no significant differences implying sample preparation has no significant affect on the resulting Atg CPO. Reuss (uniform stress) averages of anisotropy for the Higashi-Akaishi samples are approximately treble the values for Voigt (uniform strain) averages. When comparing calculated anisotropy of hydrated mantle peridotite samples-such as the Higashi-Akaishi unit-with observed S-wave delay times in convergent margins, the appropriate averaging method needs to be considered. © 2011.

DOI： 10.1016/j.jsg.2011.08.006

夜久野オフィオライト待ちの山超マフィック岩体南部断層境界に発達したブロックインマトリックス構造査読有り

小森直昭, 道林克禎

静岡大学地球科学研究報告 38 巻 ( 38 ) 頁： 21-26 - 26 2011年10月

Drilling constraints on lithospheric accretion and evolution at Atlantis Massif, Mid-Atlantic Ridge 30°N 査読有り国際共著

Blackman, DK; Ildefonse, B; John, BE; Ohara, Y; Miller, DJ; Abe, N; Abratis, M; Andal, ES; Andreani, M; Awaji, S; Beard, JS; Brunelli, D; Charney, AB; Christie, DM; Collins, J; Delacour, AG; Delius, H; Drouin, M; Einaudi, F; Escartín, J; Frost, BR; Früh-Green, G; Fryer, PB; Gee, JS; Godard, M; Grimes, CB; Halfpenny, A; Hansen, HE; Harris, AC; Tamura, A; Hayman, NW; Hellebrand, E; Hirose, T; Hirth, JG; Ishimaru, S; Johnson, KTM; Karner, GD; Linek, M; MacLeod, CJ; Maeda, J; Mason, OU; McCaig, AM; Michibayashi, K; Morris, A; Nakagawa, T; Nozaka, T; Rosner, M; Searle, RC; Suhr, G; Tominaga, M; von der Handt, A; Yamasaki, T; Zhao, X

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 116 巻 ( 7 ) 頁： 1 - 25 2011年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Geophysical Research: Solid Earth

Expeditions 304 and 305 of the Integrated Ocean Drilling Program cored and logged a 1.4 km section of the domal core of Atlantis Massif. Postdrilling research results summarized here constrain the structure and lithology of the Central Dome of this oceanic core complex. The dominantly gabbroic sequence recovered contrasts with predrilling predictions; application of the ground truth in subsequent geophysical processing has produced self-consistent models for the Central Dome. The presence of many thin interfingered petrologic units indicates that the intrusions forming the domal core were emplaced over a minimum of 100-220 kyr, and not as a single magma pulse. Isotopic and mineralogical alteration is intense in the upper 100 m but decreases in intensity with depth. Below 800 m, alteration is restricted to narrow zones surrounding faults, veins, igneous contacts, and to an interval of locally intense serpentinization in olivine-rich troctolite. Hydration of the lithosphere occurred over the complete range of temperature conditions from granulite to zeolite facies, but was predominantly in the amphibolite and greenschist range. Deformation of the sequence was remarkably localized, despite paleomagnetic indications that the dome has undergone at least 45 rotation, presumably during unroofing via detachment faulting. Both the deformation pattern and the lithology contrast with what is known from seafloor studies on the adjacent Southern Ridge of the massif. There, the detachment capping the domal core deformed a 100 m thick zone and serpentinized peridotite comprises ∼70% of recovered samples. We develop a working model of the evolution of Atlantis Massif over the past 2 Myr, outlining several stages that could explain the observed similarities and differences between the Central Dome and the Southern Ridge. Copyright 2011 by the American Geophysical Union.

DOI： 10.1029/2010JB007931

Deformation and hydrothermal metamorphism of gabbroic rocks within the Godzilla Megamullion, Parece Vela Basin, Philippine Sea 査読有り

Harigane, Y; Michibayashi, K; Ohara, Y

LITHOS 124 巻 ( 3-4 ) 頁： 185 - 199 2011年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Lithos

Microstructural and petrologic analyses of 7 gabbroic rocks sampled from the medial area of the Godzilla Megamullion (site KH07-02-D18), located along the Parece Vela Basin spreading ridge (Parece Vela Rift), Philippine Sea, reveal the development of a high-temperature ductile shear zone associated with hydrothermal metamorphism in the lower crust. The deformed gabbroic rocks are petrographically classified into mylonites and an ultramylonite, and are characterized by porphyroclastic textures consisting mainly of coarse plagioclase and clinopyroxene/amphibole porphyroclasts in a fine-grained matrix. Plagioclase crystallographic-preferred orientations vary from (010)[100] and (001)[100] patterns in the mylonites to a weak (001)[100] pattern in the some mylonites and ultramylonite, suggesting a change in the deformation mechanism from dislocation creep to grain-size-sensitive creep with increasing intensity of deformation. The chemical composition of matrix plagioclase is generally more sodic than that of porphyroclasts. Secondary amphibole is ubiquitous, consisting mainly of pargasite and magnesiohornblende (brown hornblende) and actinolite (green hornblende). The mineral assemblage is consistent with the hydrothermal metamorphic reaction: clinopyroxene + calcic plagioclase + fluid → amphibole + sodic plagioclase. Compared with deformed gabbroic rocks from the breakaway and termination areas of the Godzilla Megamullion, the samples record ductile shearing under high temperature conditions, possibly related to the development of the Godzilla Megamullion, although hydrothermal activity in the medial area appears to have been less intense than in both the breakaway and termination areas. © 2011 Elsevier B.V.

DOI： 10.1016/j.lithos.2011.02.001

Relicts of deformed lithospheric mantle within serpentinites and weathered peridotites from the Godzilla Megamullion, Parece Vela Back-arc Basin, Philippine Sea 査読有り

Harigane Y., Michibayashi K., Ohara Y.

Island Arc 20 巻 ( 2 ) 頁： 174 - 187 2011年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Island Arc

Relicts of deformed lithospheric mantle have been identified within serpentinites and weathered peridotites recovered from nine dredge sites and one submersible dive site from across the Godzilla Megamullion, which was emplaced at the now-extinct Parece Vela Rift in the Parece Vela Basin, a back-arc basin in the Philippine Sea. The serpentinites consist dominantly of lizardite±chrysotile and magnetite with minor relict primary minerals that include pyroxene, spinel, and rare olivine. The weathered peridotites consist of pyroxene, spinel, lizardite±chrysotile, and magnetite as well as weathering products of olivine. These rocks were classified in hand specimen into three types with different structures: massive, foliated, and mylonitic. In thin-section the serpentine minerals show no sign of deformation, whereas relict primary minerals show evidence of plastic deformation such as undulose extinction, kink bands, dynamic recrystallization, and weak to moderate crystallographic preferred orientations. Therefore, the serpentinites and weathered peridotites result from the static replacement and weathering of previously ductile-deformed peridotite. Given their location close to or on the detachment surface that exposed them, the relicts of peridotite provide evidence of deformation in the lithospheric mantle that could be related to the formation and emplacement of the Godzilla Megamullion in the Parece Vela Rift. © 2011 Blackwell Publishing Asia Pty Ltd.

DOI： 10.1111/j.1440-1738.2011.00759.x

Water content of the mantle xenoliths from Kimberley and implications for explaining textural variations in cratonic roots 査読有り

Katayama I., Michibayashi K., Terao R., Ando J., Komiya T.

Geological Journal 46 巻 ( 2-3 ) 頁： 173 - 182 2011年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Geological Journal

Water contents estimates based on infrared spectroscopy and deformation microstructures are used to constrain the origin of textural variations observed in mantle xenoliths from Kimberley, South Africa. Infrared spectra indicate water contents of 10-370ppm (H2O by weight) in olivine, 20-370ppm in orthopyroxene, up to 340ppm in garnet and 30-550ppm in clinopyroxene, although no systematic differences are detected among texturally distinct xenoliths (i.e. granular and sheared peridotites). In contrast, active slip systems in olivine, as inferred from tilt boundaries, are different between the granular and sheared peridotites; the former deformed via the [100](010) slip system, which is commonly active under hot, dry conditions, whereas the latter deformed via the [001](100) slip system, which is commonly activated in water-rich environments. The discrepancy in water contents estimates based on infrared spectroscopy and deformation microstructures may reflect different stages of the evolution of water content: the present water contents, as analysed by infrared spectroscopy, may have been modified by the most recent events (e.g. eruption by kimberlite magma), whereas the water contents inferred from tilt boundaries may have resulted from the various deformation processes in the deep cratonic mantle. Accordingly, we suggest that the observed heterogeneity in water content within cratonic roots facilitates local deformation, and gives rise to the range of textures seen in cratonic mantle xenoliths. © 2010 John Wiley & Sons, Ltd..

DOI： 10.1002/gj.1216

Direct evidence for upper mantle structure in the NW Pacific Plate: Microstructural analysis of a petit-spot peridotite xenolith 査読有り

Harigane, Y; Mizukami, T; Morishita, T; Michibayashi, K; Abe, N; Hirano, N

EARTH AND PLANETARY SCIENCE LETTERS 302 巻 ( 1-2 ) 頁： 194 - 202 2011年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Earth and Planetary Science Letters

Petit-spots, the late Miocene alkali basaltic volcanoes on the Early Cretaceous NW Pacific Plate, originate at the base of the lithosphere. The petit-spot volcanic rocks enclose fragments of tholeiitic basalt, dolerite, gabbro, and mantle peridotite, providing a unique window into the entire section of subducting oceanic lithosphere. We provide here the first direct observations on the deep structure of the Pacific lithosphere using microstructural analyses of a petit-spot peridotite xenolith. The xenolith is a lherzolite that consists mainly of coarse- and medium-grained olivine, orthopyroxene, and clinopyroxene, as well as fine-grained aggregates of spinel and orthopyroxene that probably represent replaced pyrope-rich garnet. A strong deformational fabric is marked by a parallel alignment of millimeter-sized elongate minerals and their crystallographic preferred orientation. The olivine displays a [010] fiber pattern with a girdle of [100] axes and a maximum of [010] perpendicular to the foliation, a pattern which is consistent with a transpressional deformation in high temperature conditions at the base of oceanic lithosphere. Our microstructural observations and seismic data indicate that the lower part of the NW Pacific lithosphere possess an early stage structure of mantle flow at the asthenosphere. This interpretation is compatible with a conventional model in which oceanic lithosphere is thickened during cooling and plate convection. A discrepancy between the weak anisotropy in the petit-spot peridotite and the strong azimuthal anisotropy from the seismic data in the NW Pacific plate implies the existence of a highly anisotropic component in the deep oceanic lithosphere. © 2010 Elsevier B.V.

DOI： 10.1016/j.epsl.2010.12.011