著者

福山 博

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.92, no.1, pp.55-67, 1983-02-25 (Released:2010-10-13)

参考文献数

11

被引用文献数

3 4

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Minami-Iwo volcano is located at the southern end of Izu-Bonnin volcanic chain, 1300km south of Tokyo. It consists of three major volcanic edifices; older volcano I (OV1), older volcano II (OV2), and younger volcano (YV). At the boundaries between OV1 and OV2 and OV2 and YV, pyroclastic materials are characteristically observed; scoria fall deposit between OV1 and OV2, and scoria fall deposit and pyroclastic flow deposit between OV2 and YV. Older volcanoes, OV1 and OV2, are wholly composed of lava flows with both aa and pahoehoe surface textures. Younger volcano (YV), on the other hand, consists mainly of scoriaceous agglutinate which made up the steep slope of the main Minami-Iwo volcano. The older volcanoes are cut by numerous dikes (115 all told) which are dominant at the south and southwest sea cliffs. Four specimens collected from OV1, OV2 and dikes show normal thermoremnant magnetic orientation suggesting the oldest age less than a few hundred thousand years. Rocks of Minami-Iwo volcano are ankaramite, olivine basalt, augite-olivine basalt and plagioclase phyric basalt. The petrographic features and the chemical composition show that the rocks of Minami-Iwo volcano are of alkali rock series. The basalt of alkali rock affinity is the first discovery for volcanoes located at the volcanic front in Japan.

著者

町田 洋 新井 房夫

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.88, no.5, pp.313-330, 1979-10-25 (Released:2009-11-12)

参考文献数

49

被引用文献数

45 27

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The eruptions of the Daisen Valcano (35°22'N, 133°33'E) were mainly rhyodacitic and of the paroxysmal type, producing several extensive sheets of tephra. The Kurayoshi pumice (DKP, for short), one of the excellent Late Pleistocene markers arising from the Daisen valcano, is rhyodacitic in composition with abundant hornblende and orthopyroxene crystals and relatively small amount of biotite. Its identification can be made from the above mentioned mineral assemblages as well as from the characteristic refractive index of orthopyroxene (γ=1.703-1.708) and of hornblende (n2 = 1.673-1.682) and the specific crystal habit of orthopyroxene. This pumice-fall deposit occurs on marine and fluvial terraces in the San'in and Hokuriku districts facing the Japan sea and extends eastward beyond the Northern Japan Alps to north Kanto plain as a thinner discontinuous layer. Stratigraphic relation with the dated tephra layers in north Kanto indicates that the pumice was probably deposited between about 47, 000 and 45, 000 years ago. That is, this pumiceous deposit is found at the intermediate horizon between Yunokuchi Pumice (UP, slightly younger than 49, 000 YBP) and Hassaki Pumice (HP, 40, 000-44, 000 YBP) in north Kanto, about 500 km far from the Daisen.Daisen Kurayoshi Pumice wonld be particularly valuable for establshing chronological framwork as a fundmental time-marker in arears where no suitable markers have yet been documented. Moranic deposit of the Murodo glacial advance at Mt. Tateyama, Northern Japan Alps, is mantled by this marker and overlies the Raicho-dai pumice-fall deposit, products of the earliest stage of volcanic activity of Tateyama III, which is correlated with the Omachi EPm deposit approximately 60, 000 years old. Distribution of these two unreworked tephras indicates that major valley glaciers had nearly disappeared by the times of these initial tephra falls. The glacial advance at Mt. Tateyama, the most extensive of the advances during Last Glacial age, therefore, apparently culminated between about 55, 000 and 50, 000 years ago. On the other hand, a filltop terrace repesented by Uwadan terrace along the River Joganji flowing from Mt. Tateyama, is covered by DKP and is nearly younger than the pyroclastic flow deposit of Tateyama III. Accumulation of the river of Uwadan stage is, therefore, simultaneous and probably associated with the Murodo glacial advance.

著者

山崎 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.45, no.2, pp.101-103, 1933-02-15 (Released:2010-10-13)

著者

松田 時彦 松浦 律子 水本 匡起 田力 正好

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.124, no.4, pp.657-664, 2015-08-25 (Released:2015-09-17)

参考文献数

18

被引用文献数

3

---

There are two emerged abrasion platforms on Enoshima Island, Kanagawa Prefecture, Southern Kanto district: the 4.0-meter-high Ryoshimachi surface, and the 1.0–1.3-meter-high Iwaya surface. Both emerged prior to the 1703 Genroku Earthquake. Considering uplift due to the 1923 Taisho Kanto Earthquake and non-seismic subsidence since the Genroku Era, uplift due to the 1703 Genroku Earthquake was 0.7 m or less, assuming that the height of Ryoshimachi surface before the Genroku Earthquake was 3 m or higher. This indicates that uplift of the Genroku Earthquake at Enoshima was smaller than that of the Taisho Earthquake, and the focal regions of the two earthquakes were different in the Sagami Bay. These two earthquakes are not repeating earthquakes at the Sagami Bay area.

著者

菅沼 悠介 川又 基人 白水 薫 小山 拓志 土井 浩一郎 金田 平太郎 青山 雄一 早河 秀章 小花和 宏之

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.126, no.1, pp.1-24, 2017-02-25 (Released:2017-04-20)

参考文献数

36

被引用文献数

6

---

Unmanned aerial vehicle-based “Structure from Motion” (UAV-SfM) photogrammetry is becoming increasingly important for obtaining high-definition topographic data in a variety of earth science research. Antarctica is one of the best fields in which UAV-SfM surveys are applied, because detailed geomorphological data are essential for reconstructing past Antarctic ice sheet changes and understanding landform evolution processes in a hyper-arid and hypothermal environment. However, application of UAVs in Antarctica has been limited because of difficulties arising from low temperatures and the restricted availability of the Global Navigation Satellite System (GNSS)-assisted navigation system at high latitudes. In this article, we provide methodological solutions for these difficulties, and report several preliminary results of UAV surveys in central Dronning Maud Land and the Soya Coast in East Antarctica. A digital elevation model (DEM) obtained in central Dronning Maud Land clearly shows 3D structures of polygons developed on glacial tills. At the Soya Coast, a DEM analysis reveals detailed geomorphological characteristics, such as moraine ridges originating from a former ice stream and differential erosion of the basement due to weathering. Based on these results, we suggest that the UAV survey has certain merits for conducting an efficient field survey in the extremely large areas of Antarctica within a limited time, and has great potential for reconstructing past Antarctic ice sheet changes and obtaining a further understanding of landform evolution processes.

著者

大森 房吉

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.32, no.3, pp.116-124, 1920

著者

加瀬 友喜

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.105, no.4, pp.512-515, 1996-08-25 (Released:2009-11-12)

参考文献数

19

著者

岡田 篤正 渡辺 満久 佐藤 比呂志 全 明純 曹 華龍 金 性均 田 正秀 池 憲哲 尾池 和夫

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.2, pp.111-126, 1994-04-25 (Released:2010-10-13)

参考文献数

51

被引用文献数

12 39

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Many distinct lineaments have been recognized by Landsat images in Korean Peninsula. The Yangsan fault system situated in the southeastern part of Korea is especially linear, continuously traceable for a long distance (about 200km), and particularly remarkable among these lineaments. The topographic expression of the Yangsan fault system is derived from the straightly stretching fault valley with wide shattered zones in the direction of NNE-SSW. This fault system extends for about 200km from the mouth of the Nagdong River west of Busan in the south to Yeondong in the north, and geologically separates Korean Peninsula from the Japan Sea. The amount of horizontal displacement may reach 30km. It is recognized as one of the most important faults in Korean Peninsula.From the interpretations of aerial photographs, and field surveys along the central part of the Yangsan fault system, the main results are summarized as follows:1. The Yangsan fault system has repeatedly moved in the late Quaternary. The lower to higher river terrace surfaces on this system show cumulative vertical offsets.2. The vertical component is upthrown on the east side from considering the terrace offset and the distribution of the mountainous lands. This vertical movement is reverse to the topographical situation on the meso-scale.3. The fault trace is extremely straight. The fault plane is almost vertical. The shatteredzone exceeds tens of meters in width with a remarkable fault gouge.4. The longer axis of flat clasts within the gravel observed in excavated the exploratory trench showed the re-arrangement along the fault. The predominantly right-lateral movements were recognized as the elongation of clayey parts and breccias in the fault gouge.5. From these characteristics, the Yangsan fault was clarified to be active with predominantly right-lateral movement. Estimated ages of terraces and its deposits give average rates of vertical and right slip on the Yangsan fault system at about 0.02-0.03mm/y, and at least 0.05-0.1mm/y, respectively.6. The fault topography is not found on the lower and lowest terraces. As the surface of the terrace has widely been cultivated as paddy fields for long historical time, lower fault scarplets less than a few meters high might have been modified or destroyed by the human actions. Therefore, we cannot mention the existence of the younger movement on the lower and lowest terraces.

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.122, no.3, pp.Cover03_1-Cover03_3, 2013-06-25 (Released:2013-07-08)

参考文献数

2

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(表面)太平洋プレート上部境界面から10km上方の曲面(地表面からほぼ40–120kmの深さ範囲)に沿うS波速度の分布(Nakajima and Hasegawa, 2010).S波速度をカラースケールで示す.太平洋プレートとフィリピン海プレートの接触域を2本の太い黒破線で囲んで示す.赤星印は1885年以降に南関東で発生した5つのM7級地震.ビーチボールは1921年竜ヶ崎地震(M7.0)(2通りの解を示す)と1987年千葉県東方沖地震(M6.7)のメカニズム解.黒丸は1987年千葉県東方沖地震の余震.(裏面)フィリピン海プレート東端部の蛇紋岩化域(茶色の領域).ピンク色の太い破線は蛇紋岩化域の西縁.フィリピン海プレート上面の深さ分布を灰色破線のコンターで示す.緑色の四角と丸は太平洋プレート上部境界面で発生した地震,灰色の点はフィリピン海プレートマントル内の地震.1921年竜ヶ崎地震と1987年千葉県東方沖地震に加え,フィリピン海プレートのマントル内の4つの地震のメカニズム解もビーチボールで示す.紫色の丸は1923年関東地震の約30時間後に発生したM7.1の余震.フィリピン海プレートはピンク色の太い破線を境にして2つに裂け,東側の蛇紋岩化域は西側の本体部分からとり残され,より遅い速度で沈み込んでいる.ピンク色の細い破線で囲んだ楕円はOkada and Kasahara(1990)が指摘した地震の空白域.(長谷川 昭)

著者

齋藤 有 田村 亨 増田 富士雄

出版者

Tokyo Geographical Society

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.114, no.5, pp.687-704, 2005-12-25

被引用文献数

3 12

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Hyperpycnal flow is one type of turbidity current, which is generated at a river mouth when the suspended sediment concentration of river discharge is so high that the density of the effluent exceeds the water of the receiving basin. Generations of this type of flow have become a common phenomenon recently. A lot of hyperpycnal flow deposits are expected to be preserved naturally in stratigraphic records. Hyperpycnal flow deposits (hyperpycnites) might become an innovative factor for turbidite paradigm considering the particularity of the flow, and bring facies analysis towards the next step. In this review paper, the criteria for identifying hyperpycnal flow deposits from strata are proposed by summarizing studies on hyperpycnal flow and its deposits. Typical characteristics of hyperpycnal flow include : (1) vertical succession composed of 2 parts, inversely-graded lower part and normally-graded upper part, (2) internal scour surface, (3) repetitive alternation of fine-grained and coarse-grained layers, or laminated and massive layers, (4) abrupt pinch-out of beds, and (5) inclusion of terrestrial materials such as leaves. Hyperpycnal flow gradually waxes and then wanes to terminate in response to flood conditions, resulting in (1). The internal scour surface (2) developed in accordance with the degree of waxing. Fluctuations of flow velocity and sediment concentration due to changes of river discharge and/or internal waves can occur during the flow event, and lead to repetitive alternation of (3). Because of the fresh interstitial water, the marine hyperpycnal flow might start to lift off after losing suspended sediments to the degree that the density of the flow is exceeded by ambient saline water. This results in (4) at the lifting point. Terrestrial materials referred to in (5) are the result of the fact that the hyperpycnal flow originated from terrestrial floods.<BR>A much wider variety of deposits, which form in one history of a turbidity current, than that expected from the Bouma sequence model, is shown. Exploration of the variety has just started.

著者

木川 栄一

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.104, no.3, pp.381-391, 1995-06-25 (Released:2009-11-12)

参考文献数

29

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The location of the magnetized rocks of the oceanic crust that are responsible for sea-floor spreading magnetic anomalies has been a long-standing problem in geophysics. The recognition of these anomalies was a keystone in the development of the theory of plate tectonics. Our present concept of oceanic crustal magnetization is much more complex than the original, uniformly magnetized model of Vine-Matthwes-Morley. Magnetic inversion studies indicated that the upper oceanic extrusive layer (layer 2A, 0.5 km thick) was the only magnetic layer and that it was not necessary to postulate any contribution from deeper parts of oceanic crust. Direct measurements of the magnetic properties from the sea floor, however, have shown that (i) the magnetization of layer 2A is insufficient to give the required size of observed magnetic anomalies and (ii) some contribution from lower intrusive rocks is necessary. Recent ODP studies reported high magnetization intensities in the gabbroic rocks and the peridotites. The source of the lineated magnetic anomalies must reside in most of the oceanic crust and in the upper portion of upper mantle.

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.17, no.4, pp.282a, 1905-04-15 (Released:2010-12-22)

著者

野上 道男

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.129, no.2, pp.263-274, 2020-04-25 (Released:2020-05-12)

参考文献数

10

被引用文献数

2 4

---

In order to measure the longitude difference between two distant sites, Inoh Tadataka and his technical team observed three lunar eclipses when surveying the Japanese Islands at the beginning of the 19th century, and left some observation records. The local times when the partial eclipses began and ended were measured with a pendulum clock. By introducing the equation of time to the calendar date of the observations, the time difference can be obtained between the local time observed by Inoh and the lunar eclipse timetable of NASA shown in Japanese Standard Time at 135E degrees of longitude. Consequently, the accuracy of the longitude survey performed by Inoh Tadataka is evaluated in comparison to the precise map of the Geographical Survey Institute.

著者

南 武志

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.5, pp.948-952, 2008-10-25 (Released:2010-04-27)

参考文献数

25

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The present study represents an attempt to determine the sources of vermilion found in ancient Japanese burial mounds prior to the emergence of the ancient Yamato dynasty. For this purpose, cinnabar ores were collected from Chinese and Japanese mines, and samples of vermilion were also collected from ancient tombs. When the vermilion collected from the tombs was studied morphologically, different particle sizes were observed. However, the particle size of the artificial vermilion was found almost same. The metal contents of cinnabar ores were different for each Japanese mine: Niu (Mie Pref.), Yamato Mercury (Nara Pref.), Sui (Tokushima Pref.), and Itomuka (Hokkaido Pref.) mines. Arsenic (As) content was highest in cinnabar ore from Niu mine; Mn and Fe contents were highest in Yamato Mercury mine; and, the Ba, Ca, Co, Cr, and Sr contents were highest in Sui mine. When analyzing the metal contents of vermilion collected from ancient tombs in Nara Prefecture, vermilion collected from Kurozuka, Kamotsuba, and Tomio-Maruyama tombs showed a high As content, and vermilion from Tenjinyama tomb showed a high Mn content. Thus, the possibility was suggested of identifying the original vermilion mine from the metal contents. However, it is difficult to set borderlines for the metal contents of vermilion to identify the source mine. So, the ratios of sulfur isotope (δ34S) in ores and vermilion were compared. A high δ34S value of +22.6 ± 3.6‰ was found for the ore of Wanshan of Guizhou and from +6 to +10.6‰ for Xunyang of Shaanxi in China, as opposed to low values ranging from -7.3 ± 1.9 to -2.1 ± 1.6‰ for Japanese mines. It is thought that δ34S values are suitable for determining the sources of vermilion found in ancient tombs. In addition, high ratios from +7.4 to +22.8‰ were found in 1st- and 2nd-century burial sites in northern Kyushu and San'in, and lower ratios from -8.4 to -2.0‰ were found in burial sites of the 2nd through 6th centuries in central Japan. Therefore, powerful local chiefs living in northern Kyushu and San'in areas might have obtained vermilion through relations with China, but chiefs living in central Japan might have used vermilion collected from Japanese mines. In conclusion, the sources of vermilion collected in ancient tombs can be determined by measuring δ34S values. An additional analysis of a lead isotope ratio, for example, might also be necessary to determine the source of vermilion.

著者

渡部 景隆

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.105, no.6, pp.694-702, 1996-12-25 (Released:2010-04-23)

参考文献数

16

被引用文献数

2 1

著者

田賀井 篤平

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.131, no.2, pp.133-146, 2022-04-25 (Released:2022-05-13)

参考文献数

41

被引用文献数

2 2

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The history of mineralogy can be traced back to the Greco-Roman period, from Theophrastos to Agricola. Linné, Cronstedt, and Werner established classical mineralogy. Crystallography developed with mineralogy, and classical crystallography was established by Haüy through Steno. In the 19th century, the discovery of X-rays by Röntgen and the discovery of X-ray diffraction by Laue gave birth to modern mineralogy and crystallography. A little later, electron diffraction was discovered, leading to the invention of the electron microscope. In Japan, Wada laid the foundations for mineralogy and crystallography.

著者

原田 豊吉 脇水 鐵五郎

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.3, no.9, pp.459-465, 1891-09-25 (Released:2010-10-13)

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.4, no.12, pp.585-586, 1892-12-25 (Released:2010-12-22)

著者

大上 宇市

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.7, no.1, pp.55a, 1895-01-25 (Released:2010-10-13)

著者

石川 一男

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.3, no.7, pp.368-372, 1891-07-25 (Released:2010-10-13)