Modern Progress of Geology in Japan 1)

Modern Progress of Geology in japan 1)

Teiichi KOBAYASHI

In 1920 when the first Pan-Pacific Science Conference was held at Honolulu, there were in Japan only two geological institutes of the universities at Tokyo (founded in 1877) and Sendai (1912). The geological society of Tokyo, Japan (1893) has had no more than 400 members at that time, but now the number is increased as much as about five times. In addition, there are societies and associations of petrologists, mineralogists and economic geologists (founded in 1928, 940 members at present), volcanology (1931, 400), palaeontology (1935, 320), education of earth science (1948, 800), crystallography (1950, 350), mining geologists (1951, 1350), mineralogy (1952, 435), and so forth. They attain more than 15, if those of coal, petroleum and other branches of applied geology are taken into account. The number of geologists and parageologists in addition to mineralogists and palaeontologists is estimated to total no less than 4 , 000. It means the density of more than one geologist in every one hundred sq. km. The rate of increase of geologists is indeed incredibly rapid, if compared to the population which was doubled in Japan in last 55 years. 2) Beside the great expansion of the geological survey of Japan, several institutes were founded for geological researches. As the result of reforming the educational system after the second great war, govermental as well as private colleges and universities and accord- ingly their institutes or departments of geology have been propagated to more than 100. At present journals published from these surveys, institutes and societies far exceed 100. HUJIMOTO's Bibliography of Geology of Japan (1873-1955), 1956, is dealt with 180 journals including a few foreign ones. In Bibliography of Geological Sciences (1945-1955) which was compiled in 1957 as the memorial publication of the 75 th anniversary of the Geological Survey, 196 Japanese journals were referred to. This flood of publications is certainly puzzling workers. Therefore it is strongly required to publish a bibliography annually, as done from the U. S. Geological Survey for North America. ' The below mentioned are expedient compilations for stratigraphers and paleontologists.

1) This is a report of Standing Committee on Geology and Geophysics, Tenth Pacific Science Congress, Hawaii 1961, entitled " The Progress of Geology in Japan during the interval since the First Pacific Science Congress ". but slightly emended and annexed 2 tables. 2) History of the Geological Society of Japan. 60th Anniversary volume, (Japanese), 1953. Address of the Twenty-fifth Anniversary of the Palaeontological Society of Japan. T. KOBAYASHI. Trans. Proc. Pal. Soc. Japan, N. S. No. 41, 1961. 3) More convenient for the foreign reader are the followings : Bibliography of Japanese Palaeontology and Related Sciences, 1940-50. Compiled by R. ENDO. Palaeontological Society of Japan, Special Paper. No. 1, 1951. Titles and Abstracts in Japanese Journal of Geology and Geography, Vols. 1-31, 1922-60, Index to Vols. 1-20 (1922-47), 1955, Vols. 21-25, (1949-54), 1960, Vols. 26-30, (1955-59), 1961 . Titles of geological papers in 62 journals (exclusive of society periodicals and survey publications) are contained in vol. 24 J.J.G.G. (1954) and geological and geographical papers of 96 journals are in vol. 30 of the same journal (1959).

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Table 1. The Classification of the Cretaceous System in Japan.

Lexicon of Stratigraphic Names of Japan, Cenozoic Erathem, Parts 1-3 (A-N), 1954-59, published from Geol. Soc. Japan, (Japanese). Lexique Stratigraphique International, Vol. III, Asie, Fasc. 3a, Japon (K. KANEKO), 3b, Ryukyu (S. HANZAWA). Catalogue of Type Specimens of Fossils in Japan. Compiled by S. HANZAWA, K. ASANO and F. TAKAI. Pal. Soc. Japan, 25 th Anniversary Volume. The folowing publications may be suggested to the reader for tracing steps in the Geology of Japan. 1926. Geology and Mineral Resources of Japanese Empire, and annexed Geological Map, (1/2 , 000 , 000). Geol. Surv. Japan. 1931-34. Geology in Iwanami Lecture Series. (Japanese) Iwanami Book Co. 1932. Geology and Mineral Resources of Japan. 50 th Ann. Volume, Geol. Surv. Japan, (Japanese). 1941. The Sakawa Orogenic Cycle and its Bearing on the Origin of the Japanese Islands. T. KOBAYASHI. Jour. Fac. Sci. Imp. Univ. Tokyo, Sec. 2, Vol. 5, Pt. 7. 1942. Geologic Structure of Japan. Y. OTUKA. (Japanese). Dobun-Shoin. 1948. Geotectonics of the Japanese Islands, Vols. 1-2. T. KOBAYASHI. (Japanese). Meguro Book Co. 1950-54. Regional Geology of Japan. General Statement, (KOBAYASHI, 1951), Tohoku, (HANZAWA, 1954), Kwanto, (FujimoTo, 1951, 53), Chubu, (MAKIYAMA, 1950, 56), Kinki, (MATSUSHITA, 1953), Chugoku, (KOBAYASHI, 1950, 54), Shikoku, (K0BAYA- SHI, 1950, 54), Hokkaido and Kyushyu, (in preparation). (Japanese). Asakura Book Co.

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Table 2 . The Classification of the Cainozoic Group in Japan.

1956, 60. Geology and Mineral Resources of Japan with Geological Map of Japan, (1/ 2 , 000 , 000), Geol. Surv. Japan. Geological sheet maps of Japan (exclusive of Hokkaido)" in scale of 1/200,000 and their explanatory texts have been completed in 1919. Now those in 1/75,000 and 1/50,000 cover

1) Geological Map of Hokkaido (1/200,000) and its Explanatory Text (Japanese), 1953-58. Geolo- gical Survey of Hokkaido. Geology and Mineral Resources of Hokkaido. J. SUZUKI. " Dai-Nippon " published by Bummei Kyokwai . Bibliography of Geology of Hokkaido, 1936. Hokkaido Chishitsu-chosa-kai.

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one-quarter and 10% respectively, putting aside numerous unpublished sheet maps of which survey is already done. Besides, there are many geological maps of oil-fields, coal-fields, mining districts and so forth. The remaining part where one must rely on the old 11 200,000 scale map may be no more than 5% of the territory. Detailed informations of certain geological systems are available in the following works : 1927. Cretaceous Stratigraphy of the Japanese Islands. H. YABE. Sci. Rep. Tohoku Imp. Univ. Sendal, 2nd Ser. Vol. 11, No. 1. 1951. Triassic Stratigraphy of Japan. Compiled by 112 Committee, Japan Soc. Prom. Sci. Rep. Sp. No. A.a.l. Geol. Surv. Japan, (Japanese) 1954. The Cretaceous System in the Japanese Islands. Compiled by Cretaceous Research Comm. (Chairman, T. MATSUMOTO). Japan. Soc. Prom. Sci. 1960. Carboniferous System of Japan. Compiled by Carboniferous Research Subcomm. (Chairman, H. YABE). Rep. Sp. No. (D), A.a.l. V, Geol. Surv. Japan. 1961. The Middle Palaeozoic Group of Japan and its Bearing on her Geological History. T. HAMADA. Jour. Fac. Sci. Univ. Tokyo, Sec. 2, Vol. 13, Pt. 1. Forty years ago the oldest fossiliferous rock in Japan was Carboniferous, but Devonian and Silurian fossils were successively discovered by NODA (1934) and ONUKI (1937) in the Kitakami mountains. The existing knowledge of the two systems was recently summarized by HAMADA (1961). For the Carboniferous stratigraphy, see the committee report (1960). Corals and brachiopods were studied by YABE, HAYASAKA, MINATO and others, fusulinids by OZAWA, HANZAWA, FUJIMOTO, TORIYAMA and many others, and calcareous algae by R. ENDO, and KONISHI. The Akiyoshi, Akasaka, and other limestones and the Permo-Carboniferous group of the Southern Kitakami, the Kuma area of Kyusyu and other regions are now precisely zonated by means of fusulinids and other fossils. Of the Triassic system the Carnic stage was previously unknown and no Skytic fossil was described, but now the system of Japan devoid of the Rhaetic, is classified into 9 stages by ICHIKAWA. It is of great importance that the so-called Rhaeto-Liassic flora was proven to have appeared already in the Carnic in Japan. See Special Report of the system (1951) for details.1' Jurassic stromatoporoids were described by YABE and SUGIYAMA, corals by EGUCHI, ammonites by SATO and a few others, pelecypods by HAYAMI and some others. The stratigraphy of the system was greatly improved in recent years by KIMURA, TAMURA, MAEDA and others. The once schematized Cretaceous stratigraphy (1927) was greatly revised with a large amount of new data and the result is compiled in the committee report (1954). The system is now classified into 6 series with 2 or 3 stages in each. (See Table 1.) The advancement of the Tertiary stratigraphy was greatly accelerated by the investiga- tions of coal and petrolium prospecting (CEAC and PEAC). The system can be classfied into 14 stages. (See Table 2.) The Quaternary research became very active among geologists, palaeontologists, geographers, biologists, anthropologists, archaeologists and others

1) Recently KAMBE has ascertained that the Permo-Triassic boundary is indicated by weak discor - dance in the Maizuru zone and the Southern Kitakami and it is apparently concordant in Kyushu. The Triassic stratigraphy of the Maizuru zone was improved by NAKAZAWA and the Upper Triassic orogenic sedimentation analysed in detail by TOKUYAMA . 2) Regional Palaeoclimatology is briefly summarized in the article : The Climatic History of the Far East. T. KOBAYASHI and T. SHIKAMA. Descriptive Palaeoclimatology, 1961, Interscience Publishers, N. Y. -London .

6 Modern Progress of Geology in Japan 213 since the Japan Association for the Quaternary Research had been established in 1956.2) The Triassic, Cretaceous and Tertiary crustal movements were successively determined at some places by OZAWA, KOBAYASHI, IMAI and others in 1923-30. Ten years later KOBAYASHIschematized the tectonic development from the Chichibu geosyncline with three cycles of orogeny, causing the migration of geosyncline from the continental to the Pacific side. They are the Permo-Triassic Akiyoshi cycle, Jura-Cretaceous Sakawa cycle and the Cainozoic Oyashima crustal movements') (1941). These orogenies are each accompanied by metamorphism and plutonism. Therefore the three sets may be distinguished with prefixes, palaeo-, meso- and neo-. In addition, archaeplutonic and archaemetamorphic rocks are contained in Permian and older conglomerates, but their origin is still in chaos. The mountain structure yielded by these orogenies are essentially in coincidence with one another in having the metamorphosed axis and the granitized zone behind the axis. It has long been believed that the Sambagawa and Mikabu series are the oldest, being probably the Pre-Cambrian metamorphic rocks, but they are found to reveal the Sakawa axis. At one time after the war-end the Hida gneiss complex was insisted by some geologists and petrologists to exhibit the Pre-Cambrian basement, but in fact it belongs to the Akiyoshi granitized zone. Absolute chronology estimated by the K-Ar method (KUNO, MIYASHIRO, et al.) is as follows : Hida gneiss, (palaeoplutonism) : 180 mill. yrs. (170, 190, 175 or 180 myr.) Sambagawa schists, (mesometamorphism) : 90 mill. yrs. (82 or 94 myr.) Ryoke gneiss, (mesoplutonism) : 95 mill. yrs. (99, 101 or 91 myr.) Abukuma gneiss, (mesoplutonism) : 100 mill. yrs. The margin of error among the above estimates attain 20 mill. years or more, but these values are evidently all too far from Pre-Cambrian. The history of igneous activity and metamorphism is, however, going to be much better understood in relation to the tectonic development (KATO, SUZUKI, WATANABE, et al.). As the result the metallogenetic epochs and provinces can be schematized on the basis of these facts. They were illustrated in four maps of mineralization of (1) Palaeozoic, (2) Mesozoic and Palaeogene, (3) Neogene, (4) and Quanternary periods and published from the Geological Survey (1960).2) Finally a brief mention is added as to the Japanese contributions to the geology of the neighbouring territories. 1. Unpublished results achieved by Japanese geologists in Korea, Manchuria, North and South China and Formosa during the second great war and the history of research in the regional geology were compiled in three volumes of Geology and Mineral Resources of Eastern Asia by the compilation committes of the Tokyo Geographic Society. 2. Geological Sheet Maps of Korea and Manchuria (Scale 1/250,000) compiled by the same committee, 1955-60. 3. Geological Sheet Maps of Sachalin and the Kurile Islands (1/250,000) compiled by Y. SASA, T. NEMURO and T. KOIWAI, 1958-60. 4. Geology of South Korea, etc. T. KOBAYASHI. Jour. Fac. Sci. Univ. Tokyo, Sec. 2, Vol. 8, Pt. 4, 1953.

1) Because the Sakawa folded mountains had begun to suffer from fragmentation before its comple- tion, subsequent movements were greatly localized. In consequence the Cenozoic history is strongly complicated, as outlined by IKEBE (1956) in his paper. Cenozoic Geohistory of Japan. Proc. Eighth Pacif. Sci. Congr. 1953, Vol. 2, pp. 446-454, 1 chart. 2) See also Progress in Economic Geology (Editor, T. WATANABE), 1956, Fuzanbo Book Co. (Japanese).

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5 . A Contribution to the Geotectonics of North Korea and South Manchuria. T. KOBA- YASHI. Ibid. Vol. 10, Pt. 2, 1956. 6 . Geology of Eastern Asia, Vol. 1, T. KOBAYASHI. (Japanese). 1956. Asakura Book Co. 7. Lexique Stratigraphique International, Vol. III, Asie, Fascules 2a, Coree, (I. TATEIWA), 2b, Manchouris, (T. SAKAMOTO), 1956. The first three projects were facilitated with considerable assistance and valuable coope- ration of the Tokyo branch of the U. S. Geological Survey. The advancement in the regional geology in some past decades will emerge by a comparison of the above results with those in the following publications : 1926. Explanatory Statements of the Map of Geology and Mineral Resources of Taiwan (Formosa), (1/300,000), H. TAKAHASHI and Y. ICHIKAWA. (Japanese).Section of Commerce and Industry, Government-General of Taiwan. 1926. Geology and Mineral Resources of Korea. S. KAWASAKI. Geol. and Min. Resour - ces of the Japanese Empire, Pt. 2. 1933. A Sketch of Korea. T. KOBAYASHI. Am. Jour. Sci. Vol. 26. 1934, 39. Geology and Mineral Resources of Manchuria. R. ENDO. (Japanese). Sanshodo Book Co. 1937. The Petroleum Geology of South Sachalin. (Japanese). Jour. Geol. Soc. Japan, Suppl. to No. 530, Vol. 44. As to the Japanese contributions to the geology of the South Sea Islands the reader is referred to Annoted Bibliography of Geologic and Soil Literature of Western North Pacific Islands, compiled by the U. S. Geol. Surv. etc. 1956, and also Lexique Stratigraphique International, Vol. VI, Fasc. 2, Oceanie Proprement Dite, 1956. Petrology and Mineralogy were also greatly improved in Japan, by KOZU, TSUBOI, ITO and others. However, I shall render competent specialists the reviews of these untouched fields. The modern geology of Japan is now just about 100 years old, if its age be counted from the geological reconnaissance in Hokkaido by W. P. BLAKE and others (1862). It may not be too much saying that, contrary to the short time-length,the achievement in last four decades occupies more than three-quarters of the geology of Japan. It is then, a great interest to see the relative position of the modern geology in the History of Earth Sciences in Japan. As MOCHIZUKItells the story in his book of this title, 1948 ( Japanese, Heibon-Zensho), the history of Natural History goes back in Japan more than 10 centuries. The oldest literature dealing with minerals and written by a Japanese is Hirose WAKE' s Yakkyo-Taiso (Essentials of Medicines), which appeared in the eighth century, although minerals, rocks and fossils were little investigated from the genetical point of view in the ancient times.