著者

保柳 睦美 内藤 誉三郎 和達 清夫 伏見 康治 矢澤 大二

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.89, no.1, pp.71-77, 1980

著者

和達 清夫 荒川 秀俊

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.63, no.3, pp.117-121, 1954

著者

和達 清夫

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.100, no.1, pp.1-2, 1991-02-25

著者

河角 廣

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.57, no.2, pp.93a-94, 1949

著者

田中 圭 中田 高 松浦 律子 田力 正好 松田 時彦

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.127, no.3, pp.305-323, 2018

被引用文献数

1

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<p> <i>Kambara Jishinyama</i> (earthquake-mound) located on the west bank of lower reach of the Fujikawa river, is widely believed to be a mound that was tectonically formed at the time of the 1854 Ansei Tokai earthquake. Using old maps and aerial photogtaphs, geomorphological changes around <i>Kambara Jishinyama</i> before and after the earthquake are examined. The Fujikawa river frequently flooded and the course on its west bank changed especially after construction of the <i>Karigane-zutsumi</i> (big bank) in order to protect farmland on its east bank. The area around the lower reach of the river was surveyed in 1803 for the <i>Dai Nihon Enkai Yochizu</i> large-scale map, which is the so-called <i>Ino-Daizu</i>. On that map, the river was at almost the same location as its present course. The historical road map (<i>Kaido-Ezu</i>) of <i>Tokaido</i>, which was the trunk road connecting Edo and Kyoto, illustrated in the same period as <i>Ino-Daizu</i>, shows that the Fujikawa river shifted its course close to the foot of river terraces at the west bank. Due to lateral erosion of the river, part of the <i>Tokaido</i> between the towns of Iwabuchi and Kambara collapsed several times. Subsequently, the road was diverted to the new route via Shinzaka as shown on the 1:20,000 scale topographic map published in 1890. A micro-landform classification map of the alluvial lowland of the west bank of the Fujikawa river based on interpretations of aerial photographs taken in 1952 and 1953 reveals that <i>Kambara Jishinyama</i> was located on one of the former mid-channel bars in the braided channels of the river before the 1854 Ansei Tokai earthquake. The earthquake caused a large landslide that dammed the Fujikawa river for a short period at the foot of Shiratori-yama to the north of Iwabuchi. The discharged flood water changed the river course close to the present stream. Geomorphic evidence for tectonic uplift does not exist around <i>Kambara Jishinyama</i>. The Koike river, a small stream flowing in the former main stream of the Fujikawa river, abandoned at the time of the Ansei Tokai earthquake, concordantly flows into the present main stream of the Fujikawa river showing that co-seismic uplift did not take place at the west bank. We conclude that <i>Kambara Jishinyama</i> was not tectonically formed by the earthquake, but is a product of the river course change.</p>

著者

久野 久

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.73, no.5, pp.279-280, 1964

被引用文献数

1

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Basalt magmas in Japan range in composition from tholeiite, passing through high-alumina basalt, to alkali basalt. Picrite basalt related to either of these three basalt magmas is scarcely represented. In Hawaii, both tholeiite and alkali basalt are closely associated with picrite basalt having bulk compositions intermediate between the ordinary basalt and peridotite. The Japanese basalt magmas are supposed to be produced by sudden release of stress attending the generation of the intermediate to deep-focus earthquakes. In such a case, there may be a certain limitation of the heat energy supply for melting the mantle peridotite ; only a few per cent of the peridotite would be melted to form the basalt magmas.<BR>The Hawaiian basalt magmas are supposed to be produced by the heat transfer due to convection current within the mantle. In such a case, there would be less limitation of the heat energy supply for melting ; a greater per cent of the peridotite would be melted, resulting in the production of picrite basalt magmas.

著者

宇佐美 龍夫

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.94, no.7, pp.656-664, 1986

著者

新谷 俊一 田中 和広

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.118, no.3, pp.340-349, 2009-07-07

参考文献数

20

被引用文献数

3 12

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&emsp;Mud volcanoes are structures formed as a result of the emissions on a land surface or the sea floor of argillaceous material, which is composed of erupting remobilized mud, petroliferous or magmatic gases, and high-salinity water. Recently, large constructions have been planned deep underground besed on the expectation of geological stability. Therefore, it is important to study the origin of erupted mud and groundwater and the depths from which they ascend when evaluating long-term stability. Three active mud volcanoes and a passive mud volcano are found in the Tertiary Shiiya Formation distributed in Tokamachi City, southern part of Niigata Prefecture. Detailed descriptions of the mud volcanoes are provided by Shinya and Tanaka (2005). However, the origin of erupted mud and the formation mechanism of abnormal pore water pressure have not yet been identified. The authors measured the oxygen and hydrogen isotopic ratio of groundwater and vitrinite reflectance of coal fragments separated from erupted mud of an active mud volcano to investigate the origin of erupted mud, particularly the depth of the origin, and the formation mechanism of abnormal pore water pressure. As a result, &delta;¹⁸O and &delta;D values of erupted water are 1.2&permil;, -5&permil; respectively, showing good agreement with those of the Nanatani Formation distributed at a depth of 3400 m in depth in the studied area. Vitrinite reflectance (Ro) shows a bimodal distribution (<i>i.e.</i>, 0.3-1.2% and 1.5-1.8%). Ro value of coal fragments sampled from the Shiiya Formation at the outcrop in the studied area are 0.3-0.45%. High Ro (1.5-1.8%) values of coal fragments are obtained in core samples at a depth of 4000 m in the Gimyo SK-1 oil well, which was excavated 2 km NW from the mud volcano. As a result of an investigation of erupted materials at the mud volcano, they were found to have originated at depths of from 3400 m to 4000 m in the studied area. Geothermal temperature of underground at depth of 3400 m to 4000 m in the in the studied area is estimated to be about 120&deg;C to 150&deg;C. Estimated temperature is high enough to cause diagenetic transition from smectite to illite. Transition from smectite to illite results in the release of a large volume of pore water into the sediment. It is concluded that dehydration due to mineral transition might be the major reason for abnormal pore water pressure formation at depths of 3500 m to 4000 m in the study area.

著者

井関 弘太郎 守屋 以智雄

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.77, no.3, pp.155-165, 1968

著者

米地 文夫

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.100, no.1, 1991-02-25

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.5, no.7, pp.361-362, 1893

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.5, no.3, pp.139-140, 1893

著者

西村 昭

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.107, no.1, pp.134-136, 1998-02-25 (Released:2009-11-12)

参考文献数

2

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深海の海底堆積物は, かつては微化石の標準層序の確立やマンガン団塊など海底鉱物資源関連の研究対象とされていたが, 現在では, 古気候や古環境の研究が活発になっている。海底堆積物の研究を古気候と関連させて考えると2つの視点がある。一つは古気候や環境変遷の記録としての堆積物で, もう一つは, 地球のシステムの物質循環の中で気候や環境の変化にかかわる堆積物である。地球環境問題の関連研究として, 深海堆積物の種類や分布, 形成過程と環境変遷について紹介した。

著者

日本地学史資料調査委員会

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.93, no.3, pp.168-181, 1984

被引用文献数

2 1

著者

早坂 一郎

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.82, no.1, pp.36-37, 1973

著者

早坂 一郎

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.55, no.7, pp.280-283, 1943

著者

早坂 一郎

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.38, no.7, pp.427-428, 1926

著者

宮下 純夫

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.98, no.3, pp.213-230, 1989

被引用文献数

5

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Magma reservoir models beneath ocean ridges are reviewed with reference to the spreading rates and the mode of fractional crystallization. Faster spreading rates (5cm/year) cause a large and long-lived magma chamber in which a thick plutonic sequence would be succesively produced away laterally from the chamber. Basalts extruded at fastspreading ridges underwent various degrees of low pressure fractionation causing conspicious chemical zonation in the chambers. On the other hand, small and transient magma chambers may be present beneath slow-spreading ridges. Comparatively less-evolved basalts, where petrological characteristics are governed mostly by the deep-seated processes such as degree of partial melting and polybaric fractionation, could appear at slow-spreading ridges because of absence of a large crustal magma chamber.<BR>Since sheeted dikes in ophiolites intruded vertically and the foliation of mantle tectonites were approximately horizontal in original, the configuration of the magma chamber interlayered between the tectonites and sheeted dike complex, if it existed, can be infered from the structure of a cumulate-gabbro sequence. The appearance of a thick plutonic sequence in the ophiolite where the crystallization order is olivine-plagioclase-clinopyroxene-orthopyroxene suggests that it was generated at a fast-spreading ridge. In such thick plutonic sequence, the fine-scale igneous layering (=time plane) obliquely across the major lithologic boundary of the plutonic sequence may reflect the horizontal chemical zonation of the magma chamber. On the other hand, the appearance of abundant whelritic cumulates crystallized at mantle deths and suffered high temperature deformation suggests that the ophiolite was generated at a slow-spreding ridge.<BR>Spreading rates of ancient ocean ridges at which the ophiolites were generated may be roughly estimated from the considerations on geochemical variation of the basaltic rocks. The occurrence of evolved basalts interpreted by extensive low pressure fractional crystallization suggests fast spreading rates, whereas the appearance of less evolved basalts showing complicated geochemical features such as different incompatible element ratios and crossing REE pattern suggests rather slow spreading rates.<BR>The studies on ophiolites would bring significant informations not only on the dynamic process beneath present-day ocean ridges but also on the tectonic framework and the evolution of ancient spreading center.

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.128, no.1, pp.Cover01_01-Cover01_02, 2019

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<p> 台風22号の通過後に冬型の気圧配置が強まり,近畿・東京地方では木枯らし1号が発表された.長野県北部にも季節風に伴う雪雲が侵入し,根子岳中腹から山頂では弱い降雪と霧氷が発生した.霧氷は短時間で広範囲の樹木に付着するため,低地から見上げると山頂が冠雪したと誤認されることもある.雪雲は背が低く,上空には青空が時折現れ,一方で上田盆地周辺は紅葉が見ごろだ.晩秋は中部山岳域北部の山々が彩を豊かにする季節である.</p><p>(写真・解説:上野健一 2017年10月30日撮影)</p>

著者

フローレス 慈英 松山 洋

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.130, no.3, pp.353-368, 2021-06-25 (Released:2021-07-20)

参考文献数

32

被引用文献数

2

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Precipitation on the Ogasawara (Bonin) Islands from summer to autumn depends the intensity, frequency and tracks of tropical cyclones (TCs), which are affected by El Niño/La Niña events (EN/LN). This study is the first to investigate the seasonal variability of the ratio of TCs approaching the Ogasawara Islands to the total number of TCs generated, and to calculate the ratio of TC-induced precipitation to total precipitation during EN/LN TCs extracted from within 300 km of Chichi-jima by QGIS, when they are defined as “TCs approaching Chichi-jima”. Using precipitation at Chichi-jima Observation Station, TC-induced precipitation is calculated when a TC is within 500 km of Chichi-jima. From August to November, the ratio of TCs approaching the Ogasawara Islands to the total number of TCs generated over the Western North Pacific is highest in October. For the same period, the number of TCs approaching the Ogasawara Islands per year during EN is more than that during LN. Reflecting the anomaly of sea surface temperature, the genesis position of TCs during LN shifts westward. TC-induced precipitation on Chichi-jima from August to October during EN is larger than that during LN. in particular, in September, TC-induced precipitation during EN is 40 mm more than that during LN. The former accounts for 61% of the total precipitation in September. These phenomena are explained by the fact that the genesis position of TCs shifts eastward or south-eastward during EN, keeping the central pressure of TCs approaching Chichi-jima lower than that during LN. Also, the presence time of a typhoon from its genesis until it enters the 500 km range of Chichi-jima is longer in EN than in LN. Within the 500 km range of Chichi-jima, the central pressure of a TC is lower in EN than in LN. All these contribute to a large volume of TC-induced precipitation on Chichi-jima during EN.