Since the end of the 1970's, many new informations about stratigraphy and age of the Mesozoic in Hokkaido have been accumulated. These data are very important to examine the geologic history of Hokkaido. This paper referred to stratigraphy, age, facies, correlation and tectonic setting of the Mesozoic in Hokkaido, as summarized below. i) "Meso-Paleozoic systems" of the Oshima-Rebun Belt are melange formed during the late Jurassic. ii) The Cretaceous granites and volcanogenic rocks in the Oshima-Rebun Belt are considered to represent the products of an active island arc. iii) The Cretaceous tectonic setting of the Sorachi-Yezo Belt was a residual forearc basin (Yezo Group) floored by a trapped oceanic crust (a greater part of the Sorachi Group). The trap of the oceanic crust is probably caused by a jump of plate boundary that took place toward the earliest Cretaceous from the Oshima-Rebun Belt to the western margin of the Hidaka Belt, iv) The Hidaka Supergroup which is correlative with the upper part of the Sorachi Group and Yezo Group is mainly melange presumably partially resulting from westward and partially from eastward subductions. v) The Yubetsu, Saroma and Nakanogawa Groups which are correlative with the upper part of the Yezo Group are forearc deposits connected with eastward subduction.

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Paleozoic to Mesozoic "geosynclinal" deposits, composed chiefly of sandstone, mudstone, siliceous shale, chert, limestone and greenstone, are widespread in the Mino terrane, central Japan. The history of geological studies of these deposits, especially from the micropaleontological standpoint is reviewed and some basic future problems are pointed out. Our knowledge on the geological age of "geosynclinal" deposits in the Mino terrane has accumulated with the progress of three kinds of biostratigraphical works: fusulinacean biostratigraphy mainly during the 1880's-1960's, conodont biostratigraphy prominently in the decade of the 1970's, and radiolarian biostratigraphy since the end of the 1970's. One of recent important findings is the existence of widespread Jurassic olistostrome complexes in this terrane; the olistostromes have varisized allochthonous blocks and sheets of Carboniferous to Triassic age. The timing and mode of emplacement of the olistostrome complexes are fundamental to the geological history of the Mino terrane.

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It has been deciphered that the Tamba Group consists of two distinct suites of stratigraphic successions (and Type I and Type II) and that Type II is distributed in the synform, while Type I is developed in the antiform. Type II is composed of mainly Permian (partly Late Carboniferous) chert-greenstone formation and Early to Middle Jurassic mudstone formation which includes olistostrome and these formations are tectonically repeated within this suite. Type I suite is mainly composed of Triassic to Early Jurassic chert formation and Late Jurassic siliceous-black shale formation (including olistostrome) and they are regarded to be repeated tectonically within this suite Type I and II suites are regarded to be formed separately in two mutually different paleo-oceanic sub-basins and the Type II suite tectonically overlies the Type I suite as a nappe, prior to the upright-folding, probably Late Jurassic or Cretaceous. Synforms and antiforms in the Tamba Belt reveal a strongly asymmetrical distribution of the strata between northern and southern wings, concerning the lithologic feature, limb-dipping and width of the two wings. These lines of evidence led to the following hypothesis: Type I and II suites are composed of tectonically repeated several units which dip gently southward, in the course of construction of the "two-storyed structure". Recently, it has been clarified that the Permian clastic formations are distributed in a certain belt along the south of the Maizuru Belt. These formations which are called Oi and Katsumi Formations are different from the Tamba Group and its equivelent in the Tamba Belt, while they have certain a similarity with the contemporaneous strata of the Maizuru Belt. On the other hand, the Kato Formation, which is distributed south of the Oi Formation, has a certain similarity with the Type II suite so far as its age and lithology are concerned. The presence of the Permian clastic facies along the southern margin of the Maizuru Belt offers a new important information in connection with the examination of the relationshio between the Tamba and the Maizuru Belts.

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Through intensive and extensive studies of radiolarian fossils, it has been recently revealed that the so-called Honshu geosynclinal deposits are mainly composed of the middle Mesozoic complexes associated with the upper Paleozoic and Triassic rocks. The Chichibu belt was formerly divided into the northern, middle and southern subbelts by the Kamanokawa-Sakashu thrust and the Uonashi-Kanbaradani-Junisha thrust respectively in Shikoku. However, the boundaries among them are modified on the basis of the recent stratigraphical results and of pre-Cretaceous terrane analysis. In the northern subbelt, lower to middle Jurassic olistostromes are widely distributed, which include olistoliths of late Paleozoic limestone-greenstone-chert and Triassic chert. The Paleozoic-Mesozoic complexes of the middle subbelt are composed of the lenticular bodies of the Kurosegawa tectonic zone, "the upper Paleozoic formations", the middle and upper Triassic formations, the middle to upper Jurassic formations and the Cretaceous formations. The Mesozoic complexes of the southern subbelt generally consist of sequences of three different types, i. e., middle Triassic to upper Jurassic chert-clastic sequences, Jurassic to lower Cretaceous olistostromes and the Torinosu Group (upper Jurassic-lowest Cretaceous). The olistostromes contain various kind of olistoliths such as late Paleozoic limestonegreenstone-chert, late Triassic limestone and middle Triassic to earliest Jurassic chert. The geologic structure in the northern subbelt is characterized by nappes and open upright folds. They were formed by the tectonic movements which may be correlated with the Ozu-Nagahama phase and the Hijikawa phase of the Sambagawa belt. In the middle sub-belt, main tectonic movements took place at Permian - earliest Mesozoic time and at late Jurassic-earliest Cretaceous time. Through the latter event, the Kurosegawa tectonic zone revealed the character of serpentinite melange zone. The southern subbelt is characterized by imbricate structure dipping northward which was originally constructed through the accretional process during Jurassic to early Cretaceous time. Then, it was reconstructed by the Paleogene tectonic movements. The pre-Cretaceous tectonic movements in the Chichibu belt are regarded as the events which took place in allochthonous state prior to its final fusion to the Paleo-Asian Continent.

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Recent researches on the Shimanto Belt in the Kii Peninsula, mainly on the Cretaceous Hidakagawa subbelt, was reviewed in this paper. The stratigraphy of the Paleogene in the southern subbelt, the Otonashigawa and Muro Groups, was already proposed by Hatenashi Research Group and Kishu Shimanto Research Group, the new occurrences of microfossils, however, suggest that the ages of the formations are older than those formerly estimated, as shown in Fig. 2. Recently, the Hanazono Formation formerly regarded as the Chichibu Paleozoic was included into the Hidakagawa subbelt, which the subbelt was subdivided, from north to south, into the Hanazono, Yukawa, Miyama, Ryujin and Nyunokawa Formations, and they were bordered each other by longitudinal faults. The ages of formations were determined by radiolarian fossils and the revised stratigraphy is shown in Fig. 2. The detailed research on the Miyama Formation has revealed that there exsist the chertgreenstones olistostromes, and that the Miyama Formation might be formed in or near a trench. It seems that the whole Hidakagawa subbelt was formed in the place between a continent and an ocean, accompanied with an oceanic plate subduction. There might be another source land to the south of the Shimanto basin at the latest Cretaceous age.

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The Archean sediments have nearly the same concentration of organic carbon as in the Phanerozoic sediments in spite of the poor organic production by Archean biota. This contradiction can be explained by the low rate of sedimentation in Archean time. The duration required for total influx of each element to the sea through the geologic history can be obtained by dividing the total influx by the annual supply of each element at the present time. The calculated values are much smaller than the history of the sea. This contradiction is also explained by the increase in the rate of sedimentation through the geologic history.

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