Preferred orientation of antiphase boundaries in pigeonite as a cooling ratemeter

Antiphase domains (APD's) of pigeonite lamellae in natural and heated augite crystals from the Hakonetoge andesite have been examined by a transmission electron microscope (TEM). Antiphase boundaries (APB's) of the pigeonite lamellae in natural specimens have a sigmoidal shape cutting the c axis in (010) sections. APB's in specimens heated at temperatures above the high-low inversion and then quenched are nearly parallel to the c axis with almost straight boundaries. These observations indicate that the preferred orientation of APB's in (010) sections depends on cooling rate; at fast colling rates the APB's are nearly parallel to the c axis, whereas at slower cooling rates they are inclined to the c axis. The cooling rate of the natural augite specimen from Hakonetoge is estimated to be about 0.01 °C/h from the experimentally determined time-temperature-transformation (TTT) diagram for the APB orientations. APD sizes are large in specimens quenched from above the inversion temperature; they are at a minimum after cooling rates of around 1–0.1 °C/h, and then become larger with slower cooling rates.     

A design for digital signal processing in a large field radio patrol camera

An FFT processor is being developed for the present pilot system of the large field radio patrol camera. A design of the processor is discussed.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.     

GIS-based weights-of-evidence modelling of rainfall-induced landslides in small catchments for landslide susceptibility mapping

Landslide susceptibility mapping is a vital tool for disaster management and planning development activities in mountainous terrains of tropical and subtropical environments. In this paper, the weights-of-evidence modelling was applied, within a geographical information system (GIS), to derive landslide susceptibility map of two small catchments of Shikoku, Japan. The objective of this paper is to evaluate the importance of weights-of-evidence modelling in the generation of landslide susceptibility maps in relatively small catchments having an area less than 4 sq km. For the study area in Moriyuki and Monnyu catchments, northeast Shikoku Island in west Japan, a data set was generated at scale 1:5,000. Relevant thematic maps representing various factors (e.g. slope, aspect, relief, flow accumulation, soil depth, soil type, land use and distance to road) that are related to landslide activity were generated using field data and GIS techniques. Both catchments have homogeneous geology and only consist of Cretaceous granitic rock. Thus, bedrock geology was not considered in data layering during GIS analysis. Success rates were also estimated to evaluate the accuracy of landslide susceptibility maps and the weights-of-evidence modelling was found useful in landslide susceptibility mapping of small catchments.     

Estuarine, barrier-island to strand-plain sequence and related ravinement surface developed during the last interglacial in the Paleo-Tokyo Bay, Japan

Recognition of sequence boundaries and transgressive surfaces (i.e. ravinement surfaces, RS) is now known to be of great importance in stratigraphy. The sedimentary features of deposits immediately above a transgressive surface are well exposed in the Upper Pleistocene Kioroshi Formation of the Kanto Plain in central Japan. The formation comprises mainly coastal and shallow-marine deposits (estuarine, barrier-island and the strand-plain systems) which accumulated along a wavedominated coast in the Late Pleistocene, i.e., the last interglacial to last glacial period. The Kioroshi Formation is bounded above and below by sequence boundaries that formed in the lowstand periods correlative to the glacial periods of oxygen isotope stages 4 and 6, respectively. A significant transgressive surface that was formed by landward migration of barrier islands during the transgressive interval, the ravinement surface (RS), is found within the deposits of the upper shelf environment.

This ravinement surface is characterized by the exotic nature of the overlying sediment veneer (pebbles, shells and scattered mud clasts) which is poorly sorted. The RS shows a very flattened erosional surface in the shore-parallel sense, and the gradient of the surface in shore-normal sense is calculated as 0.0021, where the syndepositional tectonic movement is revised. The RS commonly cuts through the lower sequence boundary. However, in the places where the river or tidal channel valleys incised, the valley-filling sediment shows a deepening-upward sequence recognized as a transgressive systems tract and the RS can be clearly distinguished from the lower sequence boundary.     

Fresnel zone inversion for lateral heterogeneities in the earth

We propose a different kind of seismic inversion from travel-time or waveform inversion for lateral heterogeneities in the earth: Fresnel zone inversion. Amplitude and phase delay of data in several frequency ranges are inverted for model space around ray paths with a width corresponding to the considered frequency so that primary effect of finiteness of wavelength be included. For vertically heterogeneous media, Fréchet derivatives for inversion are obtained very efficiently using the paraxial ray approximation, with nearly similar amounts of computation compared to travel-time inversion. As an example, Fréchet derivatives are computed for a teleseismic observation system for a three-dimensional structure in the lithosphere beneath an array of seismic stations. Even if the used frequency is around 2 Hz, the width of Fréchet derivatives cannot be neglected, particularly near the bottom of the lithosphere. Sensitivity of model parameters to observations is, moreover, different in our approach from conventional travel-time inversion: it is zero along ray paths but large slightly away from them. Some model calculations show that travel-time inversion, particularly with models divided into very fine meshes or blocks, might give misleading results. An example of inversion for a simple Camembert model, in the event that travel-time inversion gives no reliable results, shows how this technique works with much smaller data sets and computation than waveform inversions.     

Development of a New Method of Extraction of Interstitial Water from Low‐Porosity Consolidated Sediments Recovered During Super‐Deep Drilling Projects

During the Integrated Ocean Drilling Program (IODP) Expedition 338, several methods were tested for the extraction of interstitial water in consolidated, low‐porosity deep‐sea sediments from Site C0002 in the Kumano Basin. On the basis of those tests, we propose a modified ground rock interstitial normative determination (GRIND) method of extraction of interstitial water. In separate runs of the new method, sediment samples were ground in a ball mill with either ultrapure water or a solution of HNO₃. The interstitial water was then extracted with a conventional squeezer. Sufficient solution was extracted by this method to analyse most major and a few minor components of interstitial water that were comparable to those previously reported for samples extracted by the conventional squeezing method. The new method requires much smaller amounts of sediment than that of the conventional method and will be useful for analysis of samples recovered during super‐deep drilling programmes.     

Impact of in-consistency between the climate model and its initial conditions on climate prediction

We investigated the influence of dynamical in-consistency of initial conditions on the predictive skill of decadal climate predictions. The investigation builds on the fully coupled global model “Coupled GCM for Earth Simulator” (CFES). In two separate experiments, the ocean component of the coupled model is full-field initialized with two different initial fields from either the same coupled model CFES or the GECCO2 Ocean Synthesis while the atmosphere is initialized from CFES in both cases. Differences between both experiments show that higher SST forecast skill is obtained when initializing with coupled data assimilation initial conditions (CIH) instead of those from GECCO2 (GIH), with the most significant difference in skill obtained over the tropical Pacific at lead year one. High predictive skill of SST over the tropical Pacific seen in CIH reflects the good reproduction of El Niño events at lead year one. In contrast, GIH produces additional erroneous El Niño events. The tropical Pacific skill differences between both runs can be rationalized in terms of the zonal momentum balance between the wind stress and pressure gradient force, which characterizes the upper equatorial Pacific. In GIH, the differences between the oceanic and atmospheric state at initial time leads to imbalance between the zonal wind stress and pressure gradient force over the equatorial Pacific, which leads to the additional pseudo El Niño events and explains reduced predictive skill. The balance can be reestablished if anomaly initialization strategy is applied with GECCO2 initial conditions and improved predictive skill in the tropical Pacific is observed at lead year one. However, initializing the coupled model with self-consistent initial conditions leads to the highest skill of climate prediction in the tropical Pacific by preserving the momentum balance between zonal wind stress and pressure gradient force along the equatorial Pacific.

     

Rare-earth elements in matrix,inclusions, and chondrules of the Allende meteorite

Rare-earth elements in a whole-rock sample and in major components of the Allende meteorite were investigated; for a few samples, abundances of Ba, Sr, Ca, and Al were also determined. Of the materials investigated in the present work, CaAl-rich inclusions G and O seem to be of the greatest significance. In spite of the minor difference in mineralogy between them, the apparent chondrite-normalized RE pattern is much different between these two inclusions. (Yb and Eu in inclusion G appear exceptionally irregular). This observation is inferred to reflect a rather subtle difference in condition of condensation. It is also worthwhile to note that, while two portions (pink and white) of the inclusion G show similar aspects in the abundances of lithophile trace elements investigated, they show a remarkable difference at the same time. The white portion (G_w) of inclusion G can be considered to be a mixture of chondritic material and highly fractionated material like the faintly pink portion (G_p) picked from the same inclusion. This would suggest the possibility that the G_p-like material was produced from chondritic dust.The “matrix” separated from Allende was found to be fractionated with respect to the RE abundances relative to representative chondrite. It has also a very high value for the Ba abundance.     

The roughness height and drag law over the water surface based on the hypothesis of local equilibrium

A series of measurements of winds and wind-waves were carried out in wind-wave flumes. A data analysis based on the hypothesis of local equilibrium yielded a new empirical formula on the controversial quantity of roughness heightz ₀ over the water surface: , where the nondimensional roughness height is defined bygz ₀/u _* ² and the wave-wind parameterũ byω _p u _*/g, g being the gravitational acceleration,u _* the friction velocity of air,ω _p the peak frequency of wind-wave spectra. The obtained formula is compared with Charnock's (1955) and Toba's (1979) proposals; is constant in the former and inversely proportional toũ in the latter. As in Toba's, this formula immediately leads to a practically important conclusion that the drag coefficientC _d depends not merely on the usual variableU ₁₀ (wind velocity at 10m height over the water surface), but also on the surface state represented by wind-waves. An explicit expression is provided for the drag coefficient incorporating the wave-wind parameter; it covers the range ofC _d calculated from most of the previous drag formulas, by varying the wave-wind parameter.