Miocene sandstones recovered from three Ocean Drilling Program (ODP) sites in the Japan Sea backarc basin during ODP Legs 127/128 provide comparative data on albitization of feldspar subjected to different burial conditions. Feldspars in volcaniclastic sandstones from Site 796 in the northern Japan Basin (burial temperatures less than -60°C) have not been albitized. Feldspars at the other two sites are albitized to various degrees, depending upon burial temperature, original composition of the feldspars, and crystallographic features such as twinning, zoning, cleavage planes, glass inclusions, and micropores. At Site 797 (Yamato Basin), volcaniclastic sandstones have been subjected to temperatures ranging from -120 to >150°C, owing in part to intrusion by sills. About 50 percent of-450 plagioclase feldspar grains examined in 750 analyses by use of the electron probe microanalyzer have been partially or completely replaced by albite (>Ab₉₅). A small number of K-feldspar grains (<-1-2%) are also replaced in part of albite. Selective albitization has been facilitated by the presence of glass inclusions, micropores, and twin and cleavage planes. Sandstones at Site 799 (Yamato Rise) are arkoses that have undergone maximum diagenetic temperatures of about 90-100°C. About 25 percent of -500 plagioclase grains examined in-800 analyses have been altered totally or in part to albite. A few K-feldspar grains (-1%) have also been partially replaced by albite. Albitization was enhanced by the presence of twin and cleavage planes and fractures.
Albitization occurs by a dissolution-reprecipitation process. Single, large grains of plagioclase or K-feldspar are commonly replaced by numerous, micron-size, elongated albite crystals (laths), all orientated in roughly the same direction. The dissolution that precedes albitization typically proceeds along crystallographic planes and commonly occurs as a result of congruent (stoichiometric) dissolution processes. Ca-rich plagioclase is particularly susceptible to such albitization; essentially all plagioclase in Site 797 and 799 sandstones more calcic than An 50 has been albitized.
Albitization has changed original chemical composition and altered the twinning and zoning characteristics of many of the plagioclase feldspars from Site 797 and 799. These diagenetic changes have reduced the usefulness of the feldspars for provenance determination.

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The Mahanadi delta in the east coast of Peninsular India has an arcuate shape, and covers an area of about 9, 000km² with a maximum width of 140km. Among the important geomorphic features recognized on the delta are active distributary channels, dead or defunct channels, ancient beach ridges, coastal sands, tidal flats, swamps, and spits. The sediments brought by the Mahanadi River are distributed by riverine and marine agents to give rise to a broad deltaic plain. Waves, winds and littoral currents have played an important role to rework the deltaic sediments and have been responsible for the development of the sea-marginal transition zone of the delta plain. Based on the disposition of the geomorphic features, four major stages are recognized in the evolution of the delta.

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The Pliocene Ohta Tephra Bed is distributed over a distance of more than 150km in central Japan. Several sedimentary facies can be recognized in this tephra bed. In terms of content, volcanic glass and pumice predominate (more than 99%). The former is roughly smaller than 0 phi, and the latter larger than 0 phi. Volcanic glass mean specific gravity of 2.25 is higher than pumice that of 1. 15. Particle falling velocity of the Ohta tephra can be described by:
Cd=26+24/Re, W=[-9η+{81η²+156ρa³(σ-ρ)g}^0.5]/39ρa
where σ and ρ are the particle and fluid densities respectively, g is the acceleration due to gravity, η is fluid dynamic viscosity, Re is grain Reynolds number, a is the particle radium, Cd is non-dimensional drag coefficient, and W is the falling velocity. This formula means the transition to turbulence is promoted at a lower Reynolds number than for the corresponding smooth spherical particles. More poorly sorting of this fluvial channel and bar facies can be explained by the above formula, which suggests that more varied grain in diameter can be deposited under a small falling velocity range. The association of sedimentary facies combined with semi-quantitative analysis for dispersive and hydraulic equivalence of volcanic glass and pumice particles reveals that the deposition of hyperconcentrated flood flow in this study is seem to be influenced by hydraulic equivalence. Grains of some channel fill facies are in hydraulic equivalence under tractive flow. However, grains of some channel fill facies are more closely in dispersive pressures, suggesting small grain flow occurred on a foreset surface of channel bar.

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The Upper Pleistocene Kioroshi Formation is distributed in the northern part of Chiba Prefecture, central Japan. The formation consists of mainly coastal and shallow marine deposits which accumulated during the last interglacial period. The deopositional system of beach-shoreface, formed during the high-stand, can be recognized in the upper part of the Kioroshi Formation. The Pleistocene beach facies is used as a marker for the paleo-highstand sea-level.
The mean uplifting and tilting rates of the study area (20×30km) since 125kyr. B. P. were estimated by comparing the present elevations of beach facies with an inferred initial form of the beach, deduced from the Holecene strand-plain.

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The early Pliocene Lower Shigarami Formation is well developed in the Takafu syncline of the northern Fossa Magna region. This formation is divided into the Gonda conglomerate and sandstone member in the southern part of this district and the Takafu mudstone member in the north. The both members show interfingering relationship each other. It has been stated that the former member deposited at fan delta environment and the latter at off-shore. In this study details of the depositional conditions in the two members were clarified as follows.
1. The Lower Shigarami Formation is composed of 11 sedimentary facies, which were formed under a fan delta system on the shelf and a channel system on the continental slope.
2. These sedimentary systems are descriminated as two stages; namely, Stage 1 and Stage 2. At the Stage 1, a fan delta prograded from the southeast and turbidites in the north of this district was supplied from a fan delta on the east. And at the last of Stage 1, outer shelf environment extended to all over this area. At the Stage 2, the sedimentary environment in the south changed from outer shelf to delta front due to fan delta progradation at the early, and delta plane extended to the north at the later.

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Two diatom bathymetric indices are proposed as proxies of water depth in sea bottom. They are defined as follows: Bd1=Xp/(Xs+Xp) and Bd2=(0.5Xt+Xp)/(Xs+Xt+Xp), where Xs, Xt and Xp are frequencies of diatom species characteristic to shelf, transitional and pelagic regions, respectively. The diatoms characterizing shelf regions include benthic diatoms such as Paralia sulcata and Actinoptychus senarius with low-salinity meloplanktonic diatoms, whereas the diatoms typical of pelagic regions are oceanic planktonic species such as Neodenticula seminae and Denticulopsis spp. The transitional assemblage is composed of Thalassionema nitzschioides that has a maximum abundance in the transitional area between neritic and oceanic regions. Of the two indices, Bd1 is more sensitive to a change in bathymetry, but has more limitted applicablity in bathymetric range. These two indices are useful indicators of bathymetry not only in the Recent Bering Sea, but also in a Middle Miocene sequence of the Taga Group in Joban area of Japan, and thus they seem to be potentially of wide application.

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Data on heavy minerals from the Valanginian-Cenomanian sedimentary rocks of the Lower Amur region are interpreted on the basis of actuallistic approach with the use of previous study results on heavy mineral assemblages from the modern deposits accumulated in the known plate-tectonic conditions. As a result, the following has been found out; Deposits of the Valanginian-Barremian ensimatic island arc and its adjacent marginal sea, Barremian-Albian active continental margin, and Albian-Cenomanian passive (or transform) continental margin were combined in terranes of the Lower Amur region. Major tectonic processes that resulted in these were large-scale strike-slip movements and accretion processes associated with oblique subduction, and some collisions among the arcs mentioned, continental margins, and rigid blocks of oceanic lithosphere.

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