We have investigated K-feldspar recrystallisation in granitoid mylonites within a ductile shear zone from the Ryoke metamorphic belt, SW Japan. Fine-grained K-feldspar (20μm on average) occurs in the ...matrix and in pull-apart areas within fractured K-feldspar porphyroclasts. These fine grains are elongated and oriented parallel to the main foliation in the matrix, and their grain surfaces, observed with the scanning electron microscope, are not smooth, but rough due to the development of very fine (<1μm) round grains of K-feldspar on the surface of each grain. In pull-apart areas, the crystallographic orientation of fine-grained K-feldspar, as measured by electron backscatter diffraction (EBSD), is strongly controlled by that of the host porphyroclast, and shows rotations with shear components parallel to fractures. In the matrix, the crystallographic orientation of fine-grained K-feldspar is not consistent with intracrystalline plasticity, but rather with a growth rate that is slightly controlled by nearby porphyroclasts. All this, together with the growth features on grains, suggests that solution–precipitation of K-feldspar from K-rich aqueous fluid occurred during progressive deformation. Infrared (IR) mapping was performed to evaluate the distribution of water in pull-apart areas and the matrix. Water is heterogeneously distributed within K-feldspar porphyroclasts, which contain 150–2200ppm H2O. In contrast, the water content is low (150–300ppm H2O) and homogeneously distributed in fine-grained K-feldspar in the matrix and pull-apart areas, even though included in these analyses are grain boundaries that can generally contain abundant aqueous fluid. The results of EBSD analysis and IR mapping indicate that water is released during solution–precipitation of K-feldspar under mid-crustal conditions. The solution–precipitation process under a water-rich environment in the middle crust results in the formation of fine grains, possibly deforming dominantly by grain-size-sensitive creep, and with the release of aqueous fluid involved in the process.
► We focus on fine-grained K-feldspar in granitoid mylonites. ► Growth features of grains indicate a solution–precipitation process. ► Host-controlled crystallographic orientation may be related to grain growth. ► Water contents of fine-grained K-feldspar are low and homogeneous (250ppm H2O). ► Aqueous fluid may be released during the solution–precipitation process.
Into the Field is a collective biography of the generation of Japanese human scientists who created "objective" field knowledge of human diversity to support imperial expansionism and control before ...1945, and modernization under U.S. auspices thereafter.
Japan's diplomatic codes were broken by the Soviet Union in the late 1930s. This was due to Kōzō Izumi (1890-1956), a Japanese diplomat and Soviet specialist stationed in Eastern Europe, who provided ...Japan's code books and keys to the Soviet secret police. Married to a Muscovite of noble origin working for the Soviet Foreign Intelligence, Izumi was entrapped and ultimately chose love over country. He thus led an unwitting Japan to conduct 'open diplomacy' towards the Soviet Union.
Many landslides were induced by the heavy rainfall of Typhoons 0415 and 0421 in Niihama city, east Ehime prefecture. Detailed geomorphic analysis by using airborne laser scanner and geologic ...investigation revealed the geomorphic and geologic features of landslide sites. The affected area is underlain by the Cretaceous Izumi Group consisting of alternating beds of sandstone, mudstone, and granule conglomerate; the Izumi Group had been supposed to be not susceptible to shallow landslides by rainstorms. Landslide sites were not controlled by lithology but were controlled by the intensity of weathering: the most common landslides were shallow slides of a soil layer derived from heavily weathered rocks. Airborne laser scanner detected landslides of 2004 and of previous years and convex slope breaks. Landslide crowns are aligned laterally to form convex slope breaks, which are "denudation front": Slopes just above these denudation fronts and on heavily weathered rocks are the most susceptible slopes to rainstorms.
The heteromorph ammonite Pravitoceras sigmoidale from the Upper Cretaceous Seidan Formation (Izumi Group) in south‐west Japan is frequently encrusted by sessile anomiid bivalves. Fossils of ...P. sigmoidale with anomiids are often concentrated at the top of or just above turbidite sandstones. Projecting retroversal hooks and apertures of P. sigmoidale are usually intact, and some individuals are associated with jaw apparatuses near apertures. Anomiids are found on both sides and ventral peripheries of P. sigmoidale conchs, attached predominantly to body chambers. These modes of occurrence suggest that the encrustation by anomiids occurred not on post‐mortem floating or sunken carcasses but on live conchs and that these organisms were rapidly buried by turbidity current deposits shortly after death. Attachment to both flanks and ventral peripheries of the retroversal hooks may indicate that at least adult individuals of P. sigmoidale did not lie on the sea floor and did not drag their body chambers. It is suggested that fully mature individuals of this ammonite species lived for a long period of time after having formed the retroversal hook because a few generations of anomiids have colonized a single body chamber. Such colonization by anomiids is also observed on Didymoceras awajiense, which is considered to be the closely related ancestral species of P. sigmoidale. This anomiid–heteromorph ammonite commensal relationship might continue to persist in descendants during the course of evolution of these heteromorph ammonites.
Six oyster-shell beds of exclusively Crassostrea sp. are exposed in a thick estuarine unit in the Campanian (Late Cretaceous) upper part of the Shiroyama Formation, Izumi Group, along the Doki River, ...Mannou area, Kagawa Prefecture, SW Japan. Five modes of fossil occurrence are observed in the oyster beds: (I) Relay type, (II)single-generation cluster type, (III) mixed type in upright and lying positions, (IV) closely packed side-lying type, and (V) scattered side-lying type. Five of the shell beds consist of more than one type of fossil occurrence, indicating a heterogeneous origin (i.e., both autochthonous and allochthonous), with the beds being of variable size, thickness, and shape. The sixth bed yields only allochthonous oysters (type IV). The former five shell beds were formed on a sandy tidal flat by the intermittent accumulation of autochthonous and allochthonous shells. The combined effects of (1) clustered oyster growth, (2) subsequent destruction by tidal currents or storms and short-distance transportation, and (3) renewed clustered growth over several generations resulted in the formation of thick shell beds. These modes of fossil occurrence, formed under high-energy conditions on a sandy tidal flat, are in contrast to the oyster reefs of modern Crassostrea, which dwells in a sheltered muddy estuary environment. The thick estuarine unit in the section along the Doki River suggests that in this part of the Izumi Basin, the rates of subsidence and sediment supply were in balance during the Campanian. Moreover, the heterogeneous oyster beds may have formed in an estuarine environment during occasional stagnation phases during a transgression related to syn-depositional subsidence of the Izumi Basin.
Well-preserved upper and lower jaws of the aptychus-type found inside the body chambers of two specimens of the heteromorph ammonoid Pravitoceras sigmoidale Yabe, 1902 (Nostoceratidae, ...Ancyloceratina) are described from the Upper Cretaceous Izumi Group in Southwest Japan. They are similar in overall morphology to those of other nostoceratid and diplomoceratid ammonoids currently known, suggesting the morphological stability of the jaw features among these taxa. The equal size of the upper and lower jaws with beak-like rostral projection suggests that the jaw apparatus of this species might function to bite and cut up prey.
In my paper I intend to focus on Izumi Kyõka's "A Map of Shirogane", analyzing the way actual places and architectural structures are described through the eyes of the main character, the old kyõgen ...actor Hagiwara Yogorõ, who goes to Shirogane to look for Omachi, a girl whom he had previously met and who he thinks will help him play his roles more convincingly. A central place in the economy of the novel is taken by the University of the Sacred Heart (Seishin Joshi Gakuin), which was built in the western architectural style in 1910. As sites for acquiring advanced western learning, many colleges had been built in the western style since the beginning of the Meiji period, so in that sense there is nothing particularly new or remarkable about the structure of the University of the Sacred Heart. Rather, what is remarkable is the way in which the old man gradually comes to see it as two overlapping images: a western architectural structure, and an Inari torii (site of reverence of the fox deity since ancient times). His viewpoint might symbolize the gradually changing face of Shirogane, where the quiet residential site of a samurai family's villa is transformed by the construction of a university. Through the detailed analysis of the images of the places and buildings described in the novel, I will attempt to clarify the way Kyoka articulated the consciousness of the people living in these changing spaces and went on to create a unique world of his own. PUBLICATION ABSTRACT