Analysis of stick-slip and earthquake mechanism     

Yoshiaki Ida 《Physics of the Earth and Planetary Interiors》1975,11(2):147-156

A mathematical model of a sliding system that contains a frictional surface embedded in an elastic specimen and machine is proposed to analyze the frictional behavior observed in laboratory and field. It is shown that stick-slip occurs if the slope of the velocity-stress relation on the sliding surface exceeds a critical value at a certain point between static and kinetic frictions. This condition, coupled with Amontons' law and other subsidiary relations, predicts the effects of normal stress, gouge thickness, temperature, and loading rate etc. on the stick-slip instability, consistent with known experimental evidence. The elastic-wave radiation associated with stick-slip is governed by Brune's source time function, in which rise time and effective stress are proportional to fault dimension and stress drop, respectively.  相似文献   

Slow-moving deformation pulses along tectonic faults     

Yoshiaki Ida 《Physics of the Earth and Planetary Interiors》1974,9(4):328-337

A model of slow-moving disturbances of deformation is proposed to interpret the observed propagations of earthquake foci and nonseismic creep. The analysis is based on the assumption that thin fault gouge participates in the viscous slip. Nonuniform deformation diffusses at the rate of ν = μw/2η for the gouge of viscosity η and thickness w that is enclosed by the elastic rocks of rigidity μ. A crack-like solution propagates uniformly, involving the discontinuity that bounds the faulted area by an unfractured part, or by another gouge with different viscosity. The unit of the propagation velocity of such cracks is also given by the above-defined ν. Comparing the expression of ν with the various field observations, most of which yield the propagation speeds of 10–10⁴ km/year, the effective viscosity of the gouge is estimated as 10¹¹–10¹⁴ poises. The nonseismic fault creep in central California is analysed, and a little higher value of acting stress is obtained than the result of Nason and Weertman (1973).  相似文献   

Provenance of Paleozoic–Mesozoic sedimentary rocks in the Inner Zone of Southwest Japan: An evaluation based on Nd model ages     

H. Kagami  Y. Kawano  M. Akiyama  T. Ikawa  T. Imaoka  J. Ishioka  T. Toyoshima  T. Hamamoto  Y. Hayasaka  Y. Ikeda  M. Yuhara  Y. Tainosho 《Gondwana Research》2006,9(1-2):142

Nd model ages using depleted mantle (TDM) values for the sedimentary rocks in the Inner Zone of the SW Japan and western area of Tanakura Tectonic Line in the NE Japan allow classification into five categories: 2.6–2.45, 2.3–2.05, 1.9–1.55, 1.45–1.25, and 1.2–0.85 Ga. The provenance of each terrane/belt/district is interpreted on the basis of the TDMs, ¹⁴⁷Sm / ¹⁴⁴Nd vs. ¹⁴³Nd / ¹⁴⁴Nd relation, Nd isotopic evolution of the source rocks in East China and U–Pb zircon ages. The provenance of 2.6–1.8 Ga rocks, which are reported from Hida–Oki and Renge belts and Kamiaso conglomerates, is inferred to be the Sino–Korean Craton (SKC). The 2.3–1.55 Ga rocks, mostly from Ryoke, Mino and Ashio belts, are originally related with the SKC and/or Yangtze Craton (YC). The provenances of the sedimentary rocks with 1.45–0.85 Ga, from the Suo belt, Higo and some districts in the Mino and Ashio belts, are different from the SKC and YC. Especially, the Higo with 1.2–0.85 Ga is considered as a fragment of collision zone in East China. Akiyoshi belt probably belongs to the youngest age category of 1.2–0.85 Ga.Some metasedimentary rocks from the Ryoke belt have extremely high ¹⁴⁷Sm / ¹⁴⁴Nd and ¹⁴³Nd / ¹⁴⁴Nd ratios, whose main components are probably derived from mafic igneous rocks within the Ryoke belt itself and from the adjacent Tamba belt.  相似文献   

Progressive metamorphism of the Taitao ophiolite; evidence for axial and off-axis hydrothermal alterations     

Takazo Shibuya  Tsuyoshi Komiya  Ryo Anma  Tsutomu Ota  Soichi Omori  Yoshiaki Kon  Shinji Yamamoto  Shigenori Maruyama 《Lithos》2007,98(1-4):233-260

We estimated metamorphic conditions for the  6 Ma Taitao ophiolite, associated with the Chile triple junction. The metamorphic grade of the ophiolite, estimated from secondary matrix minerals, changes stratigraphically downwards from the zeolite facies, through the prehnite–actinolite facies, greenschist facies and the greenschist–amphibolite transition, to the amphibolite facies. The metamorphic facies series corresponds to the low-pressure type. The metamorphic zone boundaries are subparallel to the internal lithological boundaries of the ophiolite, indicating that the metamorphism was due to axial hydrothermal alteration at a mid-ocean ridge.

Mineral assemblages and the compositions of veins systematically change from quartz-dominated, through epidote-dominated, to prehnite-dominated with increasing depth. Temperatures estimated from the vein assemblages range from  230 °C in the volcanic unit to  380 °C at the bottom of the gabbro unit, systematically  200 °C lower than estimates from the adjoining matrix minerals. The late development of veins and the systematically lower temperatures suggest that the vein-forming alteration was due to off-axis hydrothermal alteration.

Comparison between the Taitao ophiolite with its mid-ocean ridge (MOR) affinity, and other ophiolites and MOR crusts, suggests that the Taitao ophiolite has many hydrothermal alteration features similar to those of MOR crusts. This is consistent with the tectonic history that the Taitao ophiolite was formed at the South Chile ridge system near the South American continent (Anma, R., Armstrong, R., Danhara, T., Orihashi, Y. and Iwano, H., 2006. Zircon sensitive high mass-resolution ion microprobe U–Pb and fission-track ages for gabbros and sheeted dykes of the Taitao ophiolite, Southern Chile, and their tectonic implications. The Island Arc, 15(1): 130–142).  相似文献   

Correction to: A web-based real-time and full-resolution data visualization for Himawari-8 satellite sensed images     

Ken T. Murata  Praphan Pavarangkoon  Atsushi Higuchi  Koichi Toyoshima  Kazunori Yamamoto  Kazuya Muranaga  Yoshiaki Nagaya  Yasushi Izumikawa  Eizen Kimura  Takamichi Mizuhara 《Earth Science Informatics》2018,11(2):239-240

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A new record of Sebastes koreanus from China based on morphological characters and DNA barcoding     

方亚璐  宋娜  高天翔 《中国海洋湖沼学报》2015,33(3):590-596

A new record of Sebastes koreanus(Kim and Lee,1994) was documented based on morphological characters and DNA barcoding. Fifty-six S ebastes specimens were collected from the coastal waters of northern China. Samples were identified as S. koreanus based on morphological characters. The coloration and morphometric measurements were consistent with those described from specimens collected in South Korea. In this study,specimens had the following morphological characteristics:light brown body with dark stripes and tiny dark spots,4–5 wide indistinct vertical patterns on the side,2 radial stripes behind and below the eyes,1 large dark blotch on the opercle. Additionally,the following meristic characters were recorded:dorsal fin XIV-13,pectoral fin 16,anal fin III-6–7,pelvic fin I-5,lateral line scales 29–30,and vertebrae 26. The fragment of cytochrome oxidase subunit I(C OI) gene of mitochondrial DNA was sequenced for phylogenetic analysis. The mean genetic distance within the species was 0.3%. Net genetic distances between S. koreanus and other S ebastes species ranged from 3.1% to 7.6%,which was greater than the threshold for species delimitation. The phylogenetic analysis strongly supports the validity of S. koreanus in China at the genetic level. The origion,evolution,patterns of speciation and unique features in genome divergence among primate lineages of this species still need future directions of research.  相似文献   

Dissolved free amino acids in coastal seawater using a modified fluorometric method     

Kuninao Tada  Mitsutoshi Tada  Yoshiaki Maita 《Journal of Oceanography》1998,54(4):313-321

The method of Parsonset al. (1984) for measuring dissolved free amino acids (DFAA) in coastal seawater was modified. We found considerable interference in DFAA determination from ammonia dissolved in coastal seawater, although the interference of urea could be ignored. For DFAA analysis for coastal seawater samples, ammonia determinations for the same sample are needed to correct DFAA values. For coastal surface seawater samples from all over the Seto Inland Sea, Japan, values of DFAA ranged from undetectable to 1.87 μg-at N/l when corrected for ammonia, while uncorrected values ranged from undetectable to 2.61 μg-at N/l. DFAA, urea, nitrate+nitrite, ammonia and DON concentrations in surface seawater collected in the Seto Inland Sea were analyzed simultaneously. DFAA at four seasons constituted from 1.4 to 10.1% of DON, with a mean value of 6.5%. The concentration of urea was similar to that of DFAA and often higher than that of ammonium, although generally lower than that of nitrate.  相似文献   

Shuffled-cards structure and different P/T conditions in the Sanbagawa metamorphic belt, Sakuma-Tenryu area, central Japan     

Michio Tagiri  Yoshiaki Yago and  Atsushi Tanaka 《Island Arc》2000,9(2):188-203

The Sanbagawa metamorphic terrain of the study area is divided into two units, the Shirakura and Sejiri units. The metamorphic thermal structure is interpreted on the basis of the degree of graphitization (GD) of carbonaceous material in pelitic schists. The areal variations of the metamorphic grade are presented by the distribution of GD calculated using the Lc and d₀₀₂ of carbonaceous material. As a result, the two units are classified into four metamorphic zones, respectively: A₁, A₂, B₁ and B₂ for the Shirakura Unit; and I₁, I₂, II₁ and II₂ for the Sejiri Unit. The metamorphic grades of A₁, A₂, I₁ and I₂ are included in the chlorite zone, and that of B₁, B₂, II₁ and II₂ in the garnet zone of the Sanbagawa metamorphism. The degree of graphitization at the boundary between A₂ and B₁ zones is the same as that between I₂ and II₁ zones. Detailed study on the variation of GD suggests that the present‐day structure of the study area is best interpreted as a model of shuffled‐cards structure. An estimated minimum thickness of a stack of continuous cards is about 25 m. The compositions of garnet in pelitic schists and of amphibole in basic schists are different from those in the identical metamorphic range of the Shirakura and Sejiri units. It is suggested that rocks of the Shirakura Unit were metamorphosed under higher P/T conditions than those of the Sejiri Unit.  相似文献   

Sr–Nd isotopic systematics and geochemistry of intermediate plutonic rocks from Ikoma Mountains, Southwest Japan: evidence for a sequence of Mesozoic magmatic activity in the Ryoke Belt     

Hiroaki Fujii  Yoshiaki Tainosho  Hiroo Kagami and  Takashi Kakiuchi 《Island Arc》2000,9(1):37-45

Abstract The Ryoke Belt in the Ikoma Mountains, Nara Prefecture, Japan, is composed mainly of various granitic, intermediate and gabbroic rocks. Igneous activity in this area is divided into two periods, early–middle Jurassic and late Cretaceous, based on isotopic dating. The intermediate plutonic rocks in the Fukihata area are composed of two rock types: Kyuanji quartz diorite and Fukihata tonalite. Rb–Sr whole-rock isochron ages have been determined for both plutonic rocks. Their ages and initial ⁸⁷Sr/⁸⁶Sr ratios are as follows: the Kyuanji quartz diorite has an age of 161.0 ± 17.9 Ma with an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.70727 ± 0.00007, while the Fukihata tonalite has an age of 121.4 ± 24.6 Ma with an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.70753 ± 0.00020. Our chronological results indicate that the Kyuanji quartz diorite belongs to the Jurassic mafic rocks, such as the Ikoma gabbroic mass, while the Fukihata tonalite belongs to the early Cretaceous granitic rocks. Both these intermediate plutonic rocks have different chemical characteristics and were derived from different magmas.  相似文献   

Rb–Sr isochron ages of the Cretaceous granitoids in the Ryoke belt, Kinki district, Southwest Japan     

Kozaburo Morioka  Yoshiaki Tainosho and  Hiroo Kagami 《Island Arc》2000,9(1):46-54

Abstract Granitoids are widely distributed in the Ryoke belt and have been divided into four main igneous stages based on their field setting. In this paper, we present Rb–Sr isochron ages for the younger Ryoke granitoids (second stage to fourth stage) in the Kinki district. The Yagyu granite (second stage) gave a Rb–Sr whole‐rock isochron age of 74.6 ± 10.9 Ma with an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.70938 ± 0.00016, and a Rb–Sr mineral isochron age of 71.8 ± 0.1 Ma. The Narukawa granite (second stage) yielded a Rb–Sr mineral isochron age of 79.5 ± 0.4 Ma. A Rb–Sr whole‐rock isochron age of 78.3 ± 3.0 Ma with an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.70764 ± 0.00014 was obtained for the Takijiri adamellite (third stage). The Katsuragi quartzdiorite (fourth stage) gave a Rb–Sr whole‐rock isochron age of 85.1 ± 18.3 Ma (initial ⁸⁷Sr/⁸⁶Sr ratio of 0.70728 ± 0.00006), and mineral isochron ages of 76.9 ± 0.5 Ma and 74.8 ± 0.5 Ma. The Minamikawachi granite (fourth stage) gave a Rb–Sr whole‐rock isochron age of 72.8 ± 2.0 Ma with an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.70891 ± 0.00021. These age data indicate that the igneous activity in younger Ryoke granitoids of Kinki district occurred between 80 and 70 Ma, except for the Katsuragi quartz diorite. The isotopic data on the various igneous stages in Kinki district correspond with the relative timing from field observations. Based on the initial ⁸⁷Sr/⁸⁶Sr ratios, the granitoids of the Ryoke belt in Kinki district are spatially divided into two groups. One is granitoids with initial ⁸⁷Sr/⁸⁶Sr ratio of 0.707–0.708, distributed in the southern part of the Ryoke belt. The other is granitoids with initial ⁸⁷Sr/⁸⁶Sr ratio of 0.708–0.710 distributed in the northern part of the Ryoke belt. The initial ⁸⁷Sr/⁸⁶Sr ratios of granitoids increase with decreasing (becoming younger) Rb–Sr whole‐rock isochron ages.  相似文献