The sedimentary complex of the Northern Subbelt of the Chichibu Belt in the Kanto Mountains is structurally divided into three geologic units, namely the Nishimikabo, Kashiwagi, Mamba-Kamiyoshida Units in ascending order. Radiolarians from the Mamba-Kamiyoshida Unit indicate the Middle Jurassic age. The Nishimikabo Unit is in fault contact with the Kashiwagi Unit. The Kashiwagi Unit is also in fault contact with the Mamba-Kamiyoshida Unit. These moderate to low angle faults strike WNW-ESE and dip southward. There is a possibility that the Mamba-Kamiyoshida Unit is thrust over the Kashiwagi Unit. The Nishimikabo Unit is composed mainly of mudstone with turbidite origin sandstone blocks, and these sediments are regarded as submarine slide deposits. The Kashiwagi Unit is composed of acidic tuff, chert and mudstone, and these sediments are regarded as pelagic and hemipelagic sediments. The Mamba-Kamiyoshida Unit is lithologically divided into the Mamba and the Kamiyoshida Subunits in ascending order. The Mamba Subunit is conformably overlain by the Kamiyoshida Subunit. The Mamba Subunit is composed mainly of basic tuff with limestone blocks and the Kamiyoshida Subunit is composed mainly of mudstone with chert and limestone blocks. These sediments could be submarine slide deposits with allochthonous blocks. It is interpreted that each geologic unit was deposited in a distinct sedimentary environment in the Northern Subbelt of the ChichibuBelt along the Kanna River. In reference to past problems in this area, the Sakahara Formation is correlated with the Kashiwagi Unit, The sedimentary complex of Northern Subbelt of Chichibu Belt is folded by WNW-ESE trending folds in general and the Chichibu Belt is in fault contact with the Sambasfawa Belt.

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Pattern of zonal distribution of the Sambagawa, Chichibu and Shimanto Terranes is disturbed in the central Kii Mountains where the Sambagawa Terrane is missing and the Chichibu Terrane rests on the Shimanto Terrane as a nappe. These Mesozoic accretionary complexes in the area are divided into nine geologic units; Daihugendake (Middle Triassic-Late Jurassic), Wasabidani (Late Jurassic or younger), Takahara (early Early-middle Early Cretaceous), Obadanigawa (Albian-Cenomanian), Akataki (Turonian), Makio (Coniacian-Santonian), Nakaguro, Heibara and Ogawa Formations. The Heibara and Ogawa Formations are correlated to the Akataki Formation and the Nakaguro Formation is correlated to the Makio Formation on the basis of lithologic similarity. The Daihugendake, Wasabidani and Takahara Formations belong to the Chichibu Terrane, while the Obadanigawa, Makio, Akataki, Nakaguro, Heibara and Ogawa Formations belong to the Shimanto Terrane. These units are tectonically stacked up to form a pile nappe structure, generally showing a younging age polarity from the upper unit to the lower one. Mappable geologic structures include P-thrusts (parallel to bedding planes within geologic bodies), C-thrusts (crossed bedding planes of foot wall bodies), high angle faults (nearly vertical), large-scale folds and medium-scale folds. The P-thrusts are regarded as original sole and roof thrusts which limit different-aged accretionary complexes. The C-thrusts cut the P-thrusts, indicating that they activated later than the P-thrusts. The Butsuzo Tectonic Line traced at the sole of the Chichibu Terrane is a representative for this category. The high angle faults strike E-W or NE-SW and include the Median Tectonic Line, Iro Fault, Natsumi Fault, Otaki Fault and Takahara Fault from north to south. The large-scale folds (6 km in wavelength) have NE-SW fold axes and control the distribution pattern of accretionary complexes; the Chichibu Terrane around a fold axis of synform while the Shimanto Terrane around axes of antiform. The medium-scale folds (2 km in wavelength) generally have E-W trending fold axes and are observed only within the Shimanto Terrane. On the basis of the relationships among the above-mentioned geologic structures, the following tectonic history is reconstructed: (1) Development of the P-thrusts related to the formation of the Chichibu-Shimanto accretionary complexes. (2) Deformation of accretionary complexes in the Shimanto Terrane (formation of the medium-scale folds). (3) Development of the C-thrust (primary C-thrust) between the Chichibu and Shimanto Terranes. (4) Development of the large-scale antiform-synform folds with NE -SW fold axes. (5) Development of the C-thrusts (secondary C-thrust) within the Shimanto Terrane. (6) Modification by the E-W to NE-SW trending high angle fault system.

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The remains of sand-eruptions are preserved in the limuro Formation exposed in the floor of the Tama River. This formation, a member of the Lower Pleistocene Kazusa Group, is distributed in the Tama Hills district. It is composed of massive sandy mudstone with several intercalations of fine to medium sandstone. The total thickness is about 45m. The remains of sand-eruptions are located near the middle of the formation. Two different types of sand-eruption structures are recognized. Type I occurs sporadically, and shows a tubular to columnar form. Typell occurs along small faults or fissures. Type I are subdivided into A〜D subtypes, based on the shape of the transverse section, and the presence of a central hole. Thus, a tube with ellipsoidal profile comprises subtype I-A; a tube with circular profile subtype I-B; a multi-layered tube, subtype I-C; and columnar, subtype I-D. Type II is subdivided into an elongate lenticular subtype (II-A), and subtype II-B clastic dykes. Some members of subtype I -C have an upper funnel-shaped form, which might result from the sudden release of pressure during the final stage of sand-eruption. Subtype I-C with a multi-layed inner structure indicates several episodes of sand-eruption. As these structures are often accompanied by small faults or fissures, it is assumed that sand-eruption might occur repeatedly at the same time as fissuring of sediments by earthquake activity, which controlled the form of sand-eruptions. The sedimentary facies and fauna of the limuro Formation show that these eruptions happened in shallow water near the coast, during the Early Pleistocene.

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Cordierite and cummingtonite occur in tuff blocks in the Nodono Formation. The blocks mainly consist of pumice, glass, plagioclase and quartz, with subordinate vocanic debris, and accessary biotite, cordierite, hypersthene, augite, hornblende, cummingtonite and opaque mineral. Cordierite occurs as euhedral crystals (less than 3mm) or fragments with a thin glass layer on the surface, and is often twinned, and exhibits distinct pleochroism from dark blue to colorless. The unit cell constants are a0=17.138(5)Å, b0=9. 748(2)Å, c0=9.327(7)Å, and V=1558.1(7)Å^3. The distortion index (Δ) is 0.29. The refractive indices are α=1.534(1), γ=1.551(1) and α-γ=0.017. The chemical formula is Na0.04 (Mn0.10 Mg1.48 Fe0.52) Al2.93(Si4.98All.02) O18・nH2O. Cummingtonite usually occurs as fragments (less than 3mm×0.7mm), and which occasionally show polysynthetic twinning. It is pleochroic from brownish green to grayish green.The unit cell constants are a0=9.508(1)Å, b0=18.083(3)Å, c00=5.311(4)Å, β=102.25(1)°, and V=892.4(2)Å^3. The chemical formula is (ÅNa_0.14 Ca0.02) (Ca0.05 Mn0.35 Fe1.60) (Fe0.65 Mg4.17 Ti0.03 Al0.15) (Si7.65 Al0.35) O22 (OH)2. Cordierite and cummingtonite found in the Nodono Formation show almost the same properties as those found in the Joetsu ash and in the Takigasawa ash, apart from the distortion index of cordierite. Based on stratigraphy and mineralogy, it is likely that cordierite and cummingtonite have the same origin as those of the Joetsu ash and the Takigasawa ash. The difference in distortion index suggests that the cordierite from Nodono may have been annealed at lower temperature during redenosition.

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The present study of ostracode faunas from the Eocene rocks exposed along the El Sheikh Fadl-Ras Gharib stretch in eastern Egypt has resulted in, as shown below, the establishment of biozones and the delineation of the distribution of paleoenvironments which prevailed during this period of time. Forty-two ostracode species have been discriminated in samples collected from 11 sections in the study area. Of these samples 43 which yielded 100 or more ostracode specimens have been grouped under five biotopes as the result of cluster analysis. These biotopes are rock bodies characterized by particular ostracode faunas, and thus provide kernels of three assemblage-and one acme-zones of the middle Eocene, and one assemblage-zone of the lower Eocene. In consequence, general paleoenvironments prevailing in the study area during Eocene time can be presumed by stratigraphic and geographic distributions of these biozones.

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Sequence stratigraphy is a study of genetically related strata within a chrono-stratigraphic framework, which is defined by erosion or nondeposition surfaces, or their correlative conformities. The fundamental unit of the sequence stratigraphy is the depositional sequence, bounded by unconformities and their correlative conformities. A depositional sequence is interpreted to be deposited between an eustatic fall and the next in a subsided basin. Depositional sequences have a hierarchical internal structure. A bed is the fundamental building block, and successions of beds form sedimentary facies. Assemblages of process-related facies make up depositional systems. A linkage of contemporaneous depositional systems is the systems tract. During the interactions of subsidence, sediment input, and sea level change, systems tracts are progressively stacked forming depositional sequences. The systems tracts are identified and correlated on the basis of their facies and bounding discontinuities. Most of the discontinuities form as aresult of fluctuations in relative sea level. The unconformities (subaerial erosion surfaces) and regressive surfaces of erosion are formed during relative sea level falls. The ravinement surfaces (tansgressive surfaces of erosion) are formed during relative sea level rise. In many cases, the unconformities are destroyed by successive transgression and are replaced by ravinement surfaces. The recognition and discussion of the facies and discontinuities are important for the sequence stratigraphic analysis. The reconstruction of the hierarchical structure from outcrops or well cores, leads us to the detail discussion of eustasy and tectonics.

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