出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.18, no.4, pp.284-284, 1906

著者

河本 大地

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.117, no.3, pp.xiii-xiv, 2008-06-25 (Released:2010-05-14)

著者

宇井 忠英

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.110, no.2, pp.285-288, 2001-04-25 (Released:2009-11-12)

参考文献数

5

被引用文献数

3

著者

日置 幸介

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.103, no.5, pp.522-527, 1994-10-25 (Released:2009-11-12)

参考文献数

17

被引用文献数

1 1

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Following an episode in Northeast Iceland known as the “Krafla Rifting Episode” 1975-1981, a transient accerelation of the spreading rate between the North American and Eurasian plates was observed by geodetic surveys 1987-1990 using Global Positioning System (GPS). This post-rifting crustal deformation can be interpreted as the response of the shallow elastic layer to the rifting episode (dyke intrusions) delayed by mechanical coupling with an underlying viscous layer. We also found a smaller amount of radial displacements possibly caused by the inflation of the magma chamber beneath the Krafla Caldera.

著者

小出 良幸

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.111, no.2, pp.317-317, 2002-04-25 (Released:2009-11-12)

被引用文献数

1

著者

森 和紀

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.116, no.1, pp.52-61, 2007-02-25 (Released:2009-11-12)

参考文献数

27

被引用文献数

2 2

---

Changes in the components of hydroclimatological characteristics including precipitation, evapotranspiration, and runoff over the last 100 years were investigated in the Kiso, Nagara, Ibi, and Kumozu River Basins as a case study. Annual precipitation in the study basin has tended to decrease since the first half of the 1970s. On the other hand, the smooth trend curve indicates that annual evapotranspiration has increased over the long term, especially since the 1980s. Smoothed secular changes in the difference between annual values of precipitation and potential evapotranspiration are analogous to those of annual precipitation. The average annual runoff ratio for each year has also shown a tendency to decrease during the last few decades. It is pointed out that the notable characteristics of current frequency-magnitude distributions in anrange in each year. Under conditions of extreme meteorological events that increased air temperature in the summer of 1994, river water quality showed a remarkable change compared to its average value in a normal year. The most striking feature due to high temperature was a very low value for the concentration of dissolved oxygen, especially in July and August. The facts identified in the present study provide a meaningful perspective of the possible consequences of global warming for hydrological processes, and are also useful basic data for evaluating the effects of future climate change on the aquatic environment.

著者

須田 耕樹 上野 健一

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.123, no.1, pp.35-47, 2014-02-25 (Released:2014-03-07)

参考文献数

24

被引用文献数

1 6

---

The distribution of weather divides in Japanese winters was identified using 30-year data of the Automated Meteorological Data Acquisition System (AMeDAS) operated by the Japan Meteorological Agency. Two kinds of weather divide were defined, one is a cloudy weather divide (CWD) determined by the high-frequency grids of large gradients in the sunshine duration distribution, and the other is a precipitation area border (PAB) where the edge of daily precipitation areas frequently appeared. The CWD appeared continuously in eastern Japan along the Pacific backbone ranges, but it was discontinuous in the central mountain ranges and western Japan. The CWD also appeared in Pacific coastal areas, such as east of Kamikouchi, south of the Kii Peninsula, and southeast of Shikoku Sanchi. The PAB overlapped with the CWD distribution in eastern Japan, and it was enhanced throughout the Sekigahara-Tamba Kochi and Chugoku Sanchi areas, but the CWD in pacific coastal areas was not associated with the PAB. Most of the weather divides were caused by the winter monsoon pressure pattern, and some PABs in northwestern Tohoku and Hokkaido areas occurred with passing pacific coastal extratropical cyclones. The distribution of the weather divides in cold-winter years was dependent on the dominance of Satoyuki/Yamayuki weather patterns, and weather divides became unclear in warm winters.

著者

宮地 政司

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.59, no.3, pp.61-63, 1950-06-30 (Released:2009-11-12)

---

最近測地学方面で行われた無線報時の利用による二, 三の研究成果を紹介し, 我國の無線報時の現況とその利用法の概要を述べ, それ藤広い分野を有つ地学のどこかで役立つ事を願5ものである。測定や観測を静的なものと動的なものに大別する事が出来る。歴史の示す様にそれは静から動へと発展している。近代の科学の発展はこの動的測定に負5ものが非常に多い様である。こゝでいう動的とは「時」の利用によるもので, それが無線報時の手段で簡單に自由にそして必要な精密さで利用出来る様になつたのは極めて最近でこゝ二三十年来の事である。先づ二, 三の最近の研究成果を述べてみよう。

著者

竹内 章

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.100, no.4, pp.540-551, 1991-08-25 (Released:2010-11-18)

参考文献数

62

被引用文献数

7 6

---

Central Japan has been tectonically situated at a triple juncture among Izu-Bonin, Northeast Japan, and Southwest Japan Arcs. Neotectonics of central Japan is geohistorically reexamined with the special reference to the results of ODP Leg126 transect of Izu-Bonin Arc. Three major points are claimed as follows:(1) The tectonic belt along eastern margin of Japan Sea (EMJS) is characterized by severe compressional deformation including thrusts and folds have developed within the Miocene rifted trough, Uetsu sedimentary basin, by a tectonic reversal which occurred at the end of Miocene around 6 Ma. Since then, the belt have behaved as a newly formed plate boundary between Eurasia and North America Plates.(2) During the period of 2.8-1.4 Ma, a bimodal volcanism occurred at the both flanks of the southern Hida Mountain Range. Area of such explosive acidic volcanism was bounded by a rift-like depression zone called “Omine Rift” was formed along the north-central segment of Itoigawa-Shizuoka Tectonic Line. This means that backarc rifting of Izu-Bonin arc forced the above colliding boundary between Northeast Japan and Southwest Japan to expand.(3) As for plate tectonic frame-work in central Japan, two possibilities are pointed out based on contemporal changes throughout central Japan.a) An eastward motion of Southwest Japan (EUR) has started at about 6 Ma, which immediately caused the jump of plate boundary from central Hakkaido to the EMJS following the tectonic reversal in the inner Northeast Japan arc.b) Philippine Sea plate has changed the direction of its movement from North-northeast to West-southwest around 3.5 Ma, which activated the backarc rifting of Izu-Bonin arc.

著者

加藤 茂

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.99, no.2, pp.Plate1-Plate3, 1990-04-25 (Released:2009-11-12)

著者

椚座 圭太郎 後藤 篤

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.119, no.2, pp.279-293, 2010-04-25 (Released:2010-07-06)

参考文献数

50

被引用文献数

19 39

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This paper examines the early stage of the geotectonic history of the Japanese Islands on the basis of finding hydrothermal jadeitite including zircons of ca. 520 Ma in serpentinite mélange of the Itoigawa-Omi area of the Hida-Gaien belt, Central Japan. Hydrothermal jadeitite contains euhedral jadeite in natrolite veins and patches, and consists of jadeite-albite and jadeite-natrolite without quartz. These minerals were crystallized from an aqueous fluid phase at the low-pressure and high-temperature side of the reaction boundary of albite = jadeite + quartz in the system NaAlSiO4-SiO2-H2O. The occurrence of rounded relict hornblende mantled by omphacite rimmed by fine-grained aggregates of jadeite in the matrix of jadeite and albite suggests a pervasive hydrothermal fluid flow, through which metabasite was extensively replaced by jadeitite. This rather high-temperature hydrothermal activity of ca. 520 Ma did not occur in an ordinary subduction zone but in a newly-formed mantle wedge suffering severe hydration from a subducting slab. Recently accumulated U-Pb ages of zircon of ca. 450-500 Ma from paleozoic sediments and granitic rocks of the Hida-Gaien belt were due to initiation of subduction followed by subduction zone magmatism. Protolith of serpentinite in the Hida-Gaien belt includes highly depleted harzburgite, thus requiring tectonic setting of a high-temperature-rift zone rather than a low-temperature-slow spreading ridge. Subduction was initiated at ca. 520 Ma along the boundary between low-density harzburgitic rift zone peridotite and lherzolitic spreading ridge peridotite with a slightly higher density, resulting in the common occurrence of harzburgitic serpentinite in the oldest part of the accretionary complex of Southwest Japan. An area including the Japanese Islands was born around the Yangtze block by the breaking up of the Rodinia supercontinent, because the oldest K-Ar age of biotite actinolit rock of 672 Ma (Matsumoto et al., 1981) and the subduction initiation of ca. 520 Ma are in accord with the paleogeographic history of the Yangtze block, and because ca. 300 Ma Renge schists of the Hida-Gaien belt did not suffer the ca. 280-200 Ma collision-type metamorphism of the Hida metamorphic belt that is an eastern extension of the suture between the Sino-Korea and Yangtze blocks.

著者

浜口 博之 長谷川 昭 植木 貞人 高木 章雄

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.97, no.4, pp.333-340, 1988-08-25 (Released:2011-02-17)

参考文献数

15

著者

早津 賢二 清水 智 板谷 徹丸

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.103, no.3, pp.207-220, 1994-06-25 (Released:2009-11-12)

参考文献数

52

被引用文献数

6 8

---

The Myoko volcano group, consisting of five stratovolcanoes, Myoko, Kurohime, Iizuna, Yakeyama and Madarao, is situated in the northern part of central Japan. Twenty one volcanic rocks from the early stage of volcanic successions of Myoko (5 samples), Kurohime (4 samples), Iizuna (9 samples) and Madarao (3 samples) were dated with K-Ar methods. On the basis of previously well studied geology and petrology of the volcano group and chronology of marker tephra layers in this area together with newly obtained K-Ar ages, volcanic history of the Myoko volcano group was discussed in detail. The results confirmed the genetical story of the volcanoes by Hayatsu (1985), i. e., the Myoko volcano has grown by four stages of active volcanisms with three distinctive pauses and each stage has a chemical fractionation trend from basalt to dacite through andesite during a volcanism, and other volcanoes were also in the same story though number of stages was variable : three for Kurohime and two for Iizuna and Madarao, and the fractionation trend was little changeable. This paper calls this type of volcano “poly-generation volcano”.Growth mechanism of the poly-generation volcano was also revealed in detail : life span of each generation, that is time span of each stage of activity, is nearly constant, 20-50 kyrs though some exceptions but total amount of volcanic ejecta decreases with time, e. g., 40-20-7-5 km3 for Myoko, and pause period between any two active volcanic stages decreases with time from 100-160 kyrs of early pause to ca. 10 kyrs of late one.This poly-generation volcano is common in Japan and should be studied in further detail from view points of igenous petrology and tectonics of magmatism as well as geothermal energy and volcanic hazards.

著者

米倉 二郎

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.61, no.1, pp.8-13, 1952-03-30 (Released:2009-11-12)

参考文献数

15

被引用文献数

3

---

The Roman field was planned by Agrimensores with an instrument “Groma.” They made at first straight roads pointing north and south was called Kardos and east west road was called Limes Decumanus. With these two roads as axis they divided their field into sections 2400 Roman feet (nearly equal to 710.4 metres) square which was called Centuria. One Centuria was also divided into 100 Heredia by small lanes. Each Heredium had 240 Roman feet square. (See Map I) It is said that Romulus, the founder of Rome, gave one Heredium to each of his people. One Heredium consisted of two Jugera, and one Jngerum was the area which two oxen could till in one day. One Jugerum had two Acti. One Actus was the area of 120 Roman feet square.We can find as yet in many plains of Italy and other European countries, for example in England, the remnant of the Roman field system. The township system of northern America may be said the hereditary of the Roman field system.Ancient Chinese in Chou Dynasty also planned their field by making the main road crossing each other at right. angles. The north-south road was called T'sien and the east-west one Me. Later on with these two roads as axis they divided the field with basic block of one Ri or 300 Pu (nearly equal to 414.5 metres) square, called Tsing-t'ien. One Tsing-t'ien was composed of nine Fu which was 100 Pu square. Fu means one family's holding, so one Tsing-t'ien was the ideal type of small village which had eight families settled themselves at central Fu section, and had to farm other eight Fus. (See Map II).The field planning of Romans and that of ancient Chinese both with their square shaped field can also be called as square field system, each resembling so much that it seems these two methods must have a common origin.This field system was planned at first in the suburbs of Rome and Loyang, capital of Chou Dynasty, in the age of their city state. Therefore the origin of the former system may be traced back to the Orient where the foremost city state blossomed in human history.The square field system was planned with great accuracy by survey and arranged irrigation ditches alongside the roads and lanes, also the standard shape of the field was decided by ploughing with two oxen.These characteristics of agriculture are just the same which Prof. Gordon Chiide has called as the second revolution of human civilization. He says that this city revolution has occured at first in Mesopotamia, Egypt and India relating each other, and from there it spread out all over the world.We have found not yet the exact remnant of the square field system in these oldest countries. But some inscribed tablets show the continuity of the method adopted for example, Agrimensores of Rome, elected boundary stones after surveying at the corners of the field, and in Mesopotamia we know there were also boundary stones, and in the Sumerian city state the people (Sûb-lugal) were provided with uniformed feud.Chinese Tsing-Vien system also propagated to the east Asian countries, and especially in Japan we have a typical square field system “Jori.” Yamato basin, Nara prefecture, famous with many old temples, is the district in which Jori system was being held perfectly, Naka Gaido, the north-south road which runs in middle of the basin, was the principal meridian, and Yoko. Ohoji, east-west road connecting Sakurai, Yagi, and Takata towns which runs rather southern part of the basin was the base line of Jori of Yamato. Ground Block of Joni was called Ri and was one Ri square, the length Ri which was introduced from Ti of Chinese but prolonged a little, was about 640 metres. (See Map III).

著者

田中 阿歌麻呂

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.18, no.6, pp.415-419, 1906

著者

青木 一勝 大藤 茂 柳井 修一 丸山 茂徳

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.119, no.2, pp.313-332, 2010-04-25 (Released:2010-07-06)

参考文献数

88

被引用文献数

15 24

---

The Sanbagawa metamorphic belt in SW Japan was previously considered to extend in the E-W direction from the Kanto Mountains to Kyushu Island, a distance > 800 km. However, Aoki et al. (2007) recently demonstrated that protoliths of metamorphic rocks in the Oboke area of the belt in central Shikoku accumulated at the trench after ca. 90-80 Ma. Furthermore, Aoki et al. (2008) showed that these rocks suffered blueschist metamorphism at 66-61 Ma, which differs from the timing of the Sanbagawa metamorphism. Thus, these results show that the Sanbagawa belt in Shikoku is a composite metamorphic belt. We, therefore, redefine the traditional Sanbagawa belt; the structurally upper part is the Sanbagawa metamorphic belt (sensu stricto). It formed as an accretionary complex at ca. 140-130 Ma and subsequently experienced BS-EC facies metamorphism at ca. 120-110 Ma (Okamoto et al., 2004). By contrast, the structurally lower segment termed the Shimanto BS facies metamorphic belt, formed as an accretionary complex after ca. 90-80 Ma and experienced peak metamorphism at ca. 60 Ma. Our observations have important implications for the lateral extension of these two metamorphic belts in SW Japan. The accretionary ages of the traditional Sanbagawa belt in the Kanto Mountains are younger than the Sanbagawa peak metamorphic age (Tsutsumi et al., 2009), clearly indicating that the entire region of Kanto Mountains Sanbagawa must belong to the Shimanto metamorphic belt. The same timing relationships were also found for the Sanbagawa belt on Kii Peninsula (Otoh et al., 2010). These results, therefore, indicate that the Shimanto metamorphic belt is exposed in Shikoku, Kii, and Kanto, thus the spatial distribution of Sanbagawa belt (ss) is less than half of its previous extent. The metamorphic grade of the Kanto Mountains in the Shimanto metamorphic belt ranges from pumpellyite-actinolite facies to epidote-amphibolite facies. Therefore, the higher-grade rocks of the Shimanto metamorphic rocks are exposed in the Kanto Mountains in comparison with Shikoku and Kii Peninsula. Hence, these two distinct BS-EA-EC (?) metamorphic belts are virtually equivalent in terms of spatial distribution, metamorphic range of grade, and facies series. Pacific-type orogenic belts typically comprise accretionary complex, high-P/T metamorphic belt, fore-arc sediments, and batholith belt landward from the trench (Maruyama et al., 1996). In SW Japan, the Sanbagawa belt (ss) is paired with the Ryoke low-P/T metamorphic belt and with the ca. 120-70 Ma Sanyo TTG batholith belt. Furthermore the related fore-arc basin may have developed penecontemporaneously with the Shimanto BS-EA orogeny, which is paired with the late Cretaceous to early Tertiary San-in TTG belt, which extending along the Japan Sea coast. In-between the intervening Izumi Group, a fore-arc basin deposit formed during the Campanian to Maastrichtian. Thus, these two groups of orogenic units, which formed during independent orogenies were both extensively modified during the opening of the Japan Sea ca. 20 Ma. The southward thrusting of the Ryoke and Cretaceous TTG belts over the Sanbagawa extended beyond the southern limit of the Sanbagawa, leading the up-down relationship of the Sanbagawa (ss) and the Ryoke belts.

著者

大川 通久

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.5, no.4, pp.194-196, 1893

著者

大藤 茂 下條 将徳 青木 一勝 中間 隆晃 丸山 茂徳 柳井 修一

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.119, no.2, pp.333-346, 2010-04-25 (Released:2010-07-06)

参考文献数

41

被引用文献数

33 44

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We measured the 206Pb/238U age distribution of detrital zircons in five psammitic schist samples from the Sanbagawa Belt in east-central Shikoku and the western Kii Peninsula to constrain their depositional age. The age-distribution diagrams for the five psammitic schist samples all show that detrital zircons of 100 to 90 Ma are most abundant and the age of the youngest zircon in each sample is less than 80 Ma. Considering the age of the retrogressive metamorphism of these psammitic schists, ca. 80-60 Ma, the protoliths age of the psammitic schists is constrained to 75-70 Ma, correlative to the age of the sandstone of the Middle Shimanto Belt (Yanai, 1984). A similar age-distribution has already been reported for two psammitic schist samples from the Central Unit of the Sanbagawa Belt in the Kanto Mountains (Tsutsumi et al., 2009). Thus the Sanbagawa Belt is most widely occupied by metamorphic rocks originating from rocks of the Middle Shimanto Belt. We also measured the 206Pb/238U age distribution of detrital zircons in Turonian sandstone from the Northern Shimanto Belt in the central Kii Peninsula. The age-distribution diagram shows that detrital zircons of around 128 Ma are most abundant and the age of the youngest zircon in the sample is about 100 Ma. A similar age-distribution has already been reported from a psammitic schist sample from the Southern Unit of the Sanbagawa Belt in the Kanto Mountains, overlying the Central Unit (Tsutsumi et al., 2009). The protolith age is still younger than the metamorphic age of the eclogites in central Shikoku, ca. 120-110 Ma (Okamoto et al., 2004), which occupy the uppermost portion of the Sanbagawa Belt. Although some previous studies suggested that the Sanbagawa Belt consists of metamorphosed Late Jurassic to Early Cretaceous accretionary complex, the present study shows that the belt is largely occupied by metamorphosed Late Cretaceous rocks: the Shimanto Metamorphic Rocks of Aoki et al. (2007). As a result, the Sanbagawa Belt consists of the following three units with different protolith ages: (1) Lower Unit of Shimanto Metamorphic Rocks with protoliths ages of 75-70 Ma and metamorphic ages of 70-60 Ma, (2) Upper Unit of Shimanto Metamorphic Rocks with protoliths ages of 95-85 Ma and metamorphic ages of 85-75 Ma, and (3) Sanbagawa Metamorphic Rocks (s.s.) with protoliths ages of Late Jurassic to Early Cretaceous and metamorphic ages of 120-110 Ma. The protoliths of the Upper and Lower units of the Shimanto Metamorphic Rocks are most likely rocks of the Northern Shimanto and Middle Shimanto belts, respectively.

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.15, no.3, pp.273a-274, 1903

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.19, no.10, pp.759a-759a, 1907