The low soil fertility in semi-arid land requires effective soil improvement measures. To elucidate a possible relationship between dominant minerals and organic materials that improves soil fertility in semi-arid land, several experiments is carried out using kaolinite and urea. The reaction rate of urea-kaolinite complex is determined using XPS and XRD. It is confirmed that the intercalated urea is easily released from the structure of urea-kaolinite complex after dissolution experiments. Soil-forming minerals and native organic polymer compounds which contain nitrogen distributes in semi-arid soil. We will carry out a study at semi-arid land whether complexes will be able to support more efficient agricultural productivity and to determine the applicability of the results obtained to low-fertility areas.

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The distribution of clay minerals in the universe is not well understood. However, recent observations of molecular clouds and star formation regions show evidence for the presence of silicates and water molecules, suggesting that clay minerals could be formed under certain conditions. The presence of clay minerals in such a star formation region is directly found in some meteorites. Carbonaceous chondrites, that are primitive materials formed in the solar nebula about 4.56 billion years ago, contain abundant aqueous alteration products such as saponite and serpentine. These samples are important to understand the conditions of aqueous alteration in the very early stage of the solar system history.
However, the presence of clay minerals in the present solar system seems pessimistic because liquid water is absent except for the earth. The planet Mars will be the only promising place where abundant clay minerals could be present as far as we currently know. The evidence for the presence of clay minerals on Mars is also found in meteorites. Some meteorites are widely believed to have originated from Mars due to many pieces of evidence (e.g., matching gas compositions between trapped gas in meteorites and martian atmosphere as analyzed by the Viking lander). Although all known martian meteorites are igneous rocks, some of them contain aqueous alteration products texturally and compositionally similar to terrestrial “iddingsite”. Martian iddingsites are found in a particular martian meteorite class called “nakhlite”. Nakhlite is a clinopyroxenite with minor abundance of olivine and mesostasis. The fractures and rims of olivine and mesostasis are altered into brown color similar to iddingsite. Martian iddingsite mainly consist of smectite and ferrihydrite with some minor components. Geochronological and mineralogical studies show that martian meteorites with clay minerals crystallized 1.3 billion to 180 million years ago and the crystallization of magma occurred near the surface (-30 m from the surface). Thus, the presence of aqueous alteration products in martian meteorites suggests that liquid water was present near the surface of Mars until recently although the abundance of water was small and the duration was short. Nevertheless, aqueous alteration products in martian meteorites are important samples to understand the history of volatile evolution on Mars and have recently provided interesting results.
The presence of clay minerals on Mars is also supported by recent observations of Mars by spacecrafts. 2001 Mars Odyssey found evidence for the possible wide distribution of water-bearing minerals in low latitude regions as well as abundant water ice in polar caps. Mars Exploration Rovers recently landed on two different places on Mars just started various analyses to look for evidence for past liquid water. Some early results are consistent with the presence of clay minerals. The results of thermodynamic calculation assuming martian environment also suggest that clay mineral are stable on Mars. Thus, claysphere is clearly present beyond earth and clay science is important to understand geological history of Mars.

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High-Resolution Transmission Electron Microscopy (HRTEM) is a unique and important technique to provide information on local atomic structures by direct visualization of atom columns parallel to the electron beam in clay minerals and related materials. Atom columns corresponding to each tetrahedron, octahedron and interlayer cation in phyllosilicates can be resolved if observed along the principal zone-axes parallel to the basal plane, by using an electron microscope with a point resolution of close to 0.2 nm and appropriate sample preparation. Image processing to remove noisy contrast from amorphous materials on crystals is helpful to analyze local structures. It is shown that these near-atomic resolution images are applied to determine the stacking sequences (lateral displacement and rotation between adjacent layers) or polytypes in 1: 1 phyllosilicates, chlorite and micas. Combination of two HRTEM images at the same area but along different recording directions enables three-dimensional determination of the stacking in phyllosilicates.

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The Miocene sedimentary strata are widely distributed in the Annaka-Tomioka area, northwestern Kanto. Workable several bentonite deposits that are interbedded in the middle Miocene sequence are formed by physical and chemical activities during burial diagenesis.
The middle Miocene sequence provides evidence of stratigraphical data, biohorizontal investigation and paleobathymetrical data. From these analytical research, the sedimentary age and paleoseadepth of these workable T-7, T-11 and T-14 bentonite beds are regarded as 13.5Ma/-175m, 15.2Ma/-500m and 15.8Ma/-200m respectively.
In this normal basin, which are consisted of mainly clastic sedimentary rocks and not effected by any volcanic activity or assuming thermal anomaly, equation (2) can be applicable to temperature estimation in each stratum. For the first input parameter, the heat flow has been held constant (87.9mW/m²) from burial age to present. For the second input parameter, the thermal conductivity of sandstone and mudstone depends on the porosity. Therefore, it can be made use of the data to calculate the primary thermal conductivities. For the third input parameter, the thicknesses of all burial strata are used thicknesses to restored at that age. In this paper, the method to restored have been adopted an exponential porosity-depth relationship.
Thermal history modeling of the main bentonite deposits during diagenesis can be determined by this system.

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