著者

小山 真人

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.103, no.5, pp.576-590, 1994-10-25 (Released:2009-11-12)

参考文献数

56

被引用文献数

4 7

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Izu Peninsula and adjacent areas, which are located on the northern tip of the Izu-Bonin volcanic arc, are characterized by intense crustal movements and volcanic activity. Many geomorphological, geological, and geophysical data were collected from this area and various tectonic models were proposed to explain them systematically. These tectonic models can be classified into two categories : models 1 and 2. While model 1 regards the area as a single tectonic province, model 2 proposes two or more tectonic provinces, which are bounded by tectonic lines. Models 1 and 2 can be classified into models 1A and 1B, models 2A, 2B, 2C, and 2D, respectively. Model 1A hypothesizes an anticlinal bend of the Philippine Sea plate, which is being generated by the subductions along the Suruga and Sagami troughs. Model 1B emphasizes the crustal stress field generated by the collision of the Izu-Bonin volcanic arc with Japan arc and the slab-pull force along the Sagami trough. Since there are many local tectonic features that cannot be explained by model 1A or 1B, models 2A-2D were proposed. Model 2A divides the study area into two tectonic provinces : the northern province of compressive deformation by conjugate faults and the southern province of right-lateral shearing deformation. Model 2B divides the area into the eastern and western provinces, which are defined by sharp contrasts in the geologic structure, seismicity, crustal stress field, crustal movements, focal mechanisms of earthquakes, paleomagnetic directions, and volcanic activity. Many observations support the validity of the model 2B tectonic provinces. Model 2C introduces the hypothesis that the Izu-Bonin arc is being fractured into the inner and outer arcs because of a contrast in buoyancy. The existence of the estimated model 2C fracture, W est Sagami Bay Fracture, is still under debate. Model 2D regards the Higashi-Izu monogenetic volcano field, located in the eastern Izu Peninsula, as a field of crustal spreading. Model 2D proposes a key to understanding a sharp contrast in tectonic features between the eastern and western provinces of model 2B as well as the complex geometry of the Philippine Sea slab beneath the Japan arc.

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

横山 祐典

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.111, no.6, pp.883-899, 2002-12-25 (Released:2009-11-12)

参考文献数

62

被引用文献数

9 7

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Global ice volume during the last glacial stage was obtained using geological observations from the sites located away from the former glaciated regions. The advantage using such records is that the area has been less influenced from the readjustments of the crust due to glacial isostasy. However the effect is still not negligible in those areas and hence it is required to correct sea-level records for both glacio-and hydro-isostatic effect to extract past global ice volume information. The record shows progressive growth of global ice volume since the end of the Last Interglacial. Rapid fluctuations of the volume were also observed during the last ice age corresponding to the Heinrich events observed in the North Atlantic ocean as well as Dansgaard-Oschgar events seen in the Greenland Ice cores. The Last Glacial Maximum was ranged between 30, 000 years ago to 19, 000 years ago and ended by the rapid disintegration of the ice volume that corresponding to decrease of the ca. 10 m of ice-volume equivalent sea-level. Gradual sea-level rise was seen during the late glacial stage, except the time known as melt-water pulse la in the Barbados coral, but other catastrophic rises were not found in the records. Main phase of deglaciation was ended until ca. 7000 years ago, yet slight decrease in ice volume equivalent to the 3 m global sea-level has been occurred since then. Sea-level change namely global ice volume fluctuations had been played as major role for human migration from Africa to the other parts of the world during the last ice age. Therefore studies on coastline changes will provide an useful information for the research on spatial and temporal histories of past human life styles.

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

森本 良平 小坂 丈予 羽鳥 徳太郎 井筒屋 貞勝 浦部 和順 高橋 春男 岡田 義光 平林 順一 伊佐 喬三 磯部 宏

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.77, no.5, pp.255-283, 1968-10-25 (Released:2009-11-12)

参考文献数

25

被引用文献数

3 3

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Unusual uplift of the land was found about an insular active volcano Iwo-jima, Ogasawara archipelago, 1, 200 km south of Tokyo. Remarkable retreat of shore line was revealed by reviewing topographic maps and aerophotographs of the island. Some upward movements of the island are to be one of the most principal reasons of the retreat. As the clear evidences of the upheaval of the land, following phenomena were observed by the writers who investigated the island five times from 4th July to 23rd August 1968 : a) Sunken vessels and a landing craft have emerged on the western coastal beach of the island : b) Faults and cracks appeared on the abandoned run-way of the former Japanese Navy in the central part of the island ; c) Coastal reef emerged on the sea to connect off shore islet with the island ; d) New coastal terraces were formed on the sand beaches ; e) Fresh living corals were exposed on the sea.Results of the investigations are enumerated as follows : 1) About 8 m upheaval of the land since 1953-4 was revealed by levelling survey at the western coast of the island. 2) Amount of uplift observed on the above-mentioned run-way is smaller in its central part than in both terminals, maximum vertical displacement of the fault being 3 m. 3) Tide gauge installed at the western rocky coastrecorded slight relative down of sea level but further observation should be continued without disturbance by typhoon to obtain more reliable data. 4) No expected microseisms were recorded on the high sensitive electro-magnetic seismographs except 2 or 3 per day. 5) Temperature of the fumarolic gases were 95-123°C, 10-25°C higher than that observed in 1935. In spite of the rise in temperature, gases of so called high temperature type, such as sulphur dioxide and halogens, were not contained. 6) Composition of the sublimates also accords with these results of chemical analyses of the gases. 7) Content of each main component element and its ratio to other ones is quite variable in several hot springs whose pH values range from 2.1 to 6.8. 8) Analcite was identified by X-ray and DTA analyses in the tuff forming Moto-yama, an eastern main flat cone of the island. Genetic condition of the mineral inferred from its chemical composition may indicate submarine eruption of the volcano. 9) Three weak zones were recognized by the present investigations in addition to the two ones previously reported by Tsuya. Thus three are arranged radially through the center of the eastern main cone and the two are arranged concentrically around the foot of the same cone. From these weak zones phreatic explosions are expected in future, if they occur. 10) Nothing more than mere weak phreatic explosion was recorded through the historic activity of the volcano. Artificial filling up of the vent, such as the pavement of the surface often causes the small explosion at fumarole. 11) Submarine eruption recently found at the sea bottom, about 5.4 km NNE of the South Sulphur Island, about 50 km south of the island did not occur recently but must have repeated rather stationarily.According to the present investigations, no remarkable magmatic explosion could be expected except those small phreatic ones, same one of which has often occurred on the island. Chemical composition of the gases does not indicate any approach of hot magma to the surface.

著者

八木 勇治 菊地 正幸

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.112, no.6, pp.828-836, 2003-12-25 (Released:2009-11-12)

参考文献数

46

被引用文献数

1 5

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Resent studies on relationship between sites for co-seismic slip and a-seismic slip are reviewed. Through analysis of seismic wave and Global Positioning System (GPS) data set, the sites for co-seismic slip and a-seismic slip have been obtained in Hyuga-nada and Sanriku region. Those studies show three important results : (1) the sites for co-seismic slip, episodic a-seismic slip, and continuous a-seismic slip do not overlap but complementarily share the plate boundary : (2) after-slip (post-seismic slip) may play an important role especially in the triggering large earthquakes : (3) the depth range of a-seismic slip may be controlled by not only a thermal effect but also some other factors such as lateral heterogeneity of fluidpressure and serpentinization.

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.

著者

小原 一成

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.112, no.6, pp.837-849, 2003-12-25 (Released:2009-11-12)

参考文献数

20

被引用文献数

12 14

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Non-volcanic deep low-frequency tremors detected in southwest Japan are distributed in the forearc side along the strike of the descending Philippine Sea plate. The source depth of the tremor corresponds to the slab interface or the Moho discontinuity. The time sequence of the tremor activity is characterized by long durations from hours to weeks. The mobility and the successive occurrence of the tremor are thought to be related to the existence of fluid liberated from the slab by a dehydration process. The spatial distribution of the tremors is not homogeneous in a narrow belt but is spatially clustered. The major activity of the tremors with relatively long time durations is also clustered periodically, with a period of 2-3 months in the east and middle of Shikoku area and about 6 months in the west of Shikoku. On the other hand, tremors are sometimes triggered by local earthquakes or teleseismic waves. The periodicity of the tremor activity may represent a stable accumulation of fluid with a stable subduction process and the triggering phenomenon implies the unstable condition of the occurrence of tremors.

著者

原 辰彦

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.114, no.3, pp.323-337, 2005-12-25 (Released:2009-11-12)

参考文献数

25

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We review seismological studies on structure of the Earth's deep interior. First, we describe spherically symmetric Earth structure and discuss its geophysical implications. Second, we show three-dimensional mantle structure revealed by seismic tomography and discuss its geophysical implications. Then, we briefly review various anomalous and interesting features found in the lower mantle and the inner core.

著者

杉田 常吉

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.24, no.12, pp.845-852, 1912-12-15 (Released:2010-10-13)

著者

石原 舜三

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.142-143, 1998-02-25 (Released:2009-11-12)

参考文献数

4

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極東ロシアのシホテリアンからチュコーツクに至る地域は, 西方のシベリア地塊 (先カンブリア紀基盤) の周辺に古生代以降の堆積岩類が発達し, 主に中生代中一後期に火山深成岩活動を伴う地質的背景を有し, 下記の様に多様な鉱物資源が発見されている。1) 原生代中期の地溝帯 : アノーソサイトに伴われるチタン鉄鉱-燐灰石鉱床 (P2O540億トン), 花崗岩に付随するREE, Nb-Ta鉱床など。2) 原生代最末期-カンブリア紀初期の地溝帯 : 層状Fe-Mn鉱床, 堆積性Pb-Zn鉱床など。3) オルドビス-シルル紀の融合-衝突帯 : 花崗岩に伴われるSn, F, Nb-Ta鉱床など。蛍石鉱床は大規模で鉱量4,500万トン (CaF2 32%) 。4) ジュラ紀中期の鉱化作用 : 花崗岩活動に関係する若干のAu, Bi鉱床。5) ジュラ紀後期-白亜紀初期鉱化作用 : 花歯岩と火山岩活動に関係するSn, W, Uなどのスカルン, 鉱脈型鉱床。Wスカルン鉱床が大きい。6) 白亜紀後期-古第三紀の鉱化作用 : 花歯岩と火山活動に関係するSn, W, Pb-Zn, Au-Ag鉱脈型, 一部スカルン及び鉱染型鉱床。カバレロボのSn鉱床は金属量34万トンでロシア最大。他にもコムソモリスク西方に数鉱床群。ダルネゴルスクのPb-Zn鉱床はPb-Zn金属量100万トンクラス。コリマーマガダン地域のデュカートAg鉱脈 (図1) はロシア最大の銀鉱山 (Ag金属量18,000トン, Au約50トン) 。金鉱床としてはナタルカ (図1) が大きく, Au約500トン, シホテアリンではアムール河口域のムノゴベルシンノエ鉱脈でAu金属量100トン以上。

著者

吉田 明夫 外谷 健 吉田 真希子

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.113, no.1, pp.107-124, 2004-02-25 (Released:2009-11-12)

参考文献数

39

被引用文献数

1 1

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We investigated solar-cycle and semiannual variations of magnetic storms based on data observed at the Kakioka Magnetic Observatory since 1924. First, we show that magnetic storms with a peak value of ≥ 100 nT are considered to have been almost completely recorded for both types of storm, i.e., those with sudden commencement (Ssc) and those with gradual commencement (Sg). Using data for storms larger than 100 nT, we found that the variation of numbers of Ssc correlates well with that of the sunspot Wolf numbers, but that of Sg does not. The number of storms decreases linearly with the peak value in the semi-logarithmic plot. The inclination is steeper for Sg storms than for Ssc storms. The semiannual variation, that is, more storms are observed in spring and fall than in summer and winter, is clearly seen for storms with a peak value ≥ 100 nT for Sg, but it is recognized only for larger storms with a peak value ≥. 150 nT for Ssc. Concordant with the difference between Ssc and Sg in the semiannual variation, the decrease in the number of large storms in the semi-logarithmic plot is less in spring and fall than that in summer and winter for Ssc. Although such a difference is not apparently seen for Sg, the ratio of the number of storms with a peak value ≥ 150 nT to that of storms with a peak value between 100 nT and 150 nT is larger for spring and fall. We propose the hypothesis that the efficiency of magnetic reconnection depends on the three dimensional direction of the magnetic field in the solar wind relative to the geomagnetic field, and on the north-south symmetry of the geomagnetosphere when it is seen from the stream of the solar wind. We think these “equinoctial effects” are the main causes of the semiannual variation in the number of large magnetic storms. As for the Sudden Commencement (SC), the semiannual variation is not seen, but an annual variation with the number of SC being larger in summer is observed. The reason may be that the shock wave in the solar wind hits against the northern part of the geomagnetosphere in summer, and the southern part in winter.

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.27, no.2, pp.184a-185, 1915

著者

駒澤 正夫 ホセ パンティーク エディー リスタンコ

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.123, no.1, pp.133-142, 2014

被引用文献数

3

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イロシンカルデラの地下構造を把握するため1996年2月にBulusan火山およびその周辺で重力調査を実施した。測点は標高の低い山麓の道沿いに限られ,測定数は225点となった。火山の山体に近い密度である 2,300 kg/m³(2.3 g/cm³)の仮定密度のブーゲー異常図は,山体部に測点がなくても実際の重力異常を表すと考えられる。重力異常にはカルデラ壁に対応する急勾配がBulusan火山の東から南を経て西に存在することがわかった。しかし,カルデラの北縁については勾配構造が明瞭ではなかった。Irosin townは急勾配構造の内側にある低重力異常域にある。重力の3次元解析から得られた重力基盤にはカルデラ壁を含むカルデラ領域を示す直径 15 kmほどの円形構造があることがわかった。さらに,その円形構造の内側には直径 5 kmほどの急勾配の壁で仕切られた漏斗状(上下逆さまの円錐)の構造が存在し,深さは 1.5 kmに達することがわかった。つまり,イロシンカルデラは,陥没構造が一カ所だけ確認でき,大量の火山砕屑物の噴出を伴った大規模噴火(複数回の場合も含む)は,ごく狭い領域に限られることを示している。また,重力異常による質量欠損の計算から約 40 km³の領域から1.1 × 10¹⁰ トンの火山砕屑物を噴出したと推定され,既存のカルデラの直径と質量欠損の関係と整合的である。

著者

池上 隆

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.26, no.3, pp.181-191_2, 1914-03-17 (Released:2010-10-13)

著者

笠原順三

出版者

東京地学協会

雑誌

地学雑誌

巻号頁・発行日

vol.115, no.4, 2006

著者

長岡 信治 西山 賢一 井上 弦

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.4, pp.632-667, 2010-08-25 (Released:2010-11-08)

参考文献数

83

被引用文献数

4 6

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The Miyazaki Plain is situated at the western end of the forearc of the Southwest Japan Arc, and is one of the standard areas of the Quaternary system in Japan. Many tephra layers were supplied from volcanoes in the Ryukyu and Southwest Japan arcs during Quaternary. The authors establish the stratigraphy and chronology of sediments during middle Pleistocene to Holocene in the Miyazaki Plain using tephrochronological methods, and discuss landform development and tectonics. The sediments are subdivided into Kariya formation, Nojiri formation (the Highest terraces), the Higher terrace deposits, the Middle terraces deposits, the Lower terraces deposits, and the Holocene formation (alluvium plain). Kariya formation of 1 Ma-500 ka, is fluvial sediments which are partially accompanied by marine sediments. Nojiri formation is 500-300 ka old and fluvial and marine sediments form the highest terraces. Shiinoki member in Nojiri formation has a transgressive sediment and is correlated with MIS 9. The higher terraces are composed of Kukino fluvial terrace of 330-240 ka and Chausubaru fluvial terrace of 240 ka. The middle terraces consist of the four fluvial and marine terraces: Sanzaibaru terrace of 140-120 ka, Baba terrace of 110 ka, Nyutabaru terrace of 110-90 ka, Karasebaru terrace of 90 ka, and Saitobaru terrace of 90-80 ka. Sanzaibaru terrace with a thick transgressive sediment and well-developed marine terraces correlates with MIS 6-5e. Nyutabaru terrace is mainly fluvial accompanied partially by marine terraces, and emerged in MIS 5c. Baba and Saitobaru terraces are fluvial only. Saitobaru terrace with a gravel bed over 10-m thick indirectly corresponded to the transgression in MIS 5a. All of the lower terraces of 70-10 ka are fluvial, and are subdivided into ten terraces: Shimizu, Okatomi, Toyobaru 1, Toyobaru 2, Ikazuno, Oyodo, Fukadoshi 1, Fukadoshi 2, Mikazukibaru 1, and Mikazukibaru 2. Their steep longitudinal profiles indicate that sea-level when the terraces formed was lower than the recent one. This lower sea-level stage chronologically corresponds to MIS 4-2. Fukadoshi 1,2 terraces, the profile of which is the steepest of all the terraces, were formed in MIS 2, the last glacial maximum. Shimotajima marine terraces and recent alluvium correspond to Holocene high sea level and transgression in MIS 1. The tectonics of the Miyazaki Plain during the past 2 Ma are estimated from landforms and geological structures. During 2-1 Ma, the forearc basin beneath the sea was uplifted slowly and the Miyazaki Plain emerged. Then the left-lateral movement of Wanitsuka Mts block bordering the plain on the north formed the two pull-apart basins of the Kariya and Nojiri formations at the southern part of the plain during 1-0.3 Ma. The left-lateral movement was caused by the opening of the Okinawa Trough in the back arc of Ryukyu Arc. At 0.3 Ma, the Miyazaki plain suddenly began uplifting rapidly due to E-W trend compression. During 0.8-0.6 Ma, the movement direction of the Philippine Sea Plate changed from NW to WNW, and then the plate subducted obliquely along the Nankai trough. Consequently, the Southwest Japan forearc including the Miyazaki Plain decoupled from the inner arc, moving westward, and finally caused the E-W trend compression and uplifting around the Miyazaki Plain. The uplift rate of the southern part of the plain accelerated from 0.1 m/ka to 1 m/ka during the last 0.3 Ma at the southern part of the plain. In detail, the tectonical mode is domical uplifting the center, which is several kilometers off Miyazaki City in the Pacific Ocean. The domical uplifting and the increasing uplift rate relate to the isostasy of the subducting Kyushu-Palau Ridge on the Philippine Sea plate under the Miyazaki Plain or a rising serpentinite diapir in the crust of the Eurasia plate.

著者

薗部 龍一

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.53, no.8, pp.351-353, 1941-08-15 (Released:2010-10-13)

著者

谷内 達

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.91, no.1, pp.30-50, 1982

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One of the most important aspects of the mining activities in remote Australia since the 1960 's is large-scale infrastructure development by mining companies. This paper studies various types of infrastructure projects associated with the mining activities, from a viewpoint of development stages in terms of remoteness.<BR>Three study areas are selected; Pilbara region, Kalgoorlie region and Central Queensland, in order of remoteness. Mining railways and mining towns in the study areas are classified into three types, according to the extent of financial contribution by the mining companies.<BR>The railways of the first type are the iron are railways in Pilbara region. They are constructed, owned, operated and exclusively used by the mining companies. The railways of the second type are the coal railways in Central Queensland. They are constructed or upgraded, owned and operated by the government as a part of the State railway system, but are fully financed and almost exclusively used by the mining companies. The railways of the third type are the nickel railways in Kalgoorlie region. They are constructed and upgraded, owned and operated by the government, but are partly financed by the mining companies.<BR>The towns of the first type are the iron are mining towns in Pilbara region. They are company towns, which are constructed and managed by the mining companies. The towns of the second type are quasi-company towns, with a minor role of the government. Dampier and Wickham in Pilbara region and Kambalda near Kalgoorlie fall into this category. The towns of the third type are open towns, which are constructed and managed mainly by the governments with financial contribution by the mining companies. Port Hedland and Karratha in Pilbara region and the coal mining towns in Central Queensland fall into this category.<BR>These different types of infrastructure development can be interpreted as a reflection of different stages of regional development; the more developed, the less involved by mining companies. The idea is tested and supported by the historical cases in Mount Isa.<BR>One of the significant modifications of the development process mentioned above is an influence of the government policies, where higher priorities are given to more local participation in order to discourage influences of overseas capital, and to more local processing for the more value-added within the State or national economy. The reversed order of railway types against the general order of remoteness between Kalgoorlie region and Central Queensland can be partly explained by this point.<BR>A case study in this paper suggests that, from a viewpoint of regional development, infrastructure should not be simply defined by physical or institutional forms, but should be identified by examining actual functions. This functional concept of infrastructure would be useful for identifying the role of mining activities in regional development, especially in remote Australia.

著者

戎崎 俊一 西原 秀典 黒川 顕 森 宙史 鎌形 洋一 玉木 秀幸 中井 亮佑 大島 拓 原 正彦 鈴木 鉄兵 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.129, no.6, pp.779-804, 2020-12-25 (Released:2021-01-18)

参考文献数

94

被引用文献数

2

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Previously proposed hypotheses on the origin of life are reviewed and it is demonstrated that none of them can provide the energy flux of ionizing radiation (UV/X/γ photons, and high-energy charged particles and neutrons) required to synthesize organic materials as demonstrated by the experiments by Miller and Urey in 1953. In order to overcome this difficulty, Ebisuzaki and Maruyama, in 2017, proposed a new hypothesis called the “Nuclear Geyser Model” of the origin of life, in which high-energy flux from a natural nuclear reactor drives chemical reactions to produce major biological molecules, such as amino acids, nucleotides, sugars, and fatty acids from raw molecules (H2O, N2, and CO2). Natural nuclear reactors were common on the surface of Hadean Earth, because the 235U/238U ratio was as high as 20%, which is much higher than the present value (0.7%), due to the shorter half-life of 235U than 238U. Ebisuzaki and Maruyama further posited that aqueous electrons and glyceraldehyde play key roles in the networks of chemical reactions in a nuclear geyser and suggested that primordial life depended on glyceraldehyde phosphate (GAP) from the nuclear geyser system as energy, carbon, and phosphate sources, pointing to a possible parallelism with the anaerobic glycolysis pathway; in particular, the lower stem path starting from GAP through Acetyl Coenzyme A to produce ATP and reduction power. It is shown that microbes (members of candidate division OD1) inhabiting high alkali hot springs, a modern analogue of the Hadean Earth environment, do not possess genes associated with conventional metabolisms, such as those of the TCA cycle, but only have genes in the lower stem path of the glycolysis. This is named the “Hadean Primordial Pathway”, because it is believed that this striking result points to a plausible origin of metabolic pathways of extant organisms. Also proposed is a step-by-step scenario of the evolution of the metabolism: 1) Chemical degradation of GAP supplied from the nuclear geyser to lactate; 2) Catalytic reactions to produce reductive power and acetyl coenzyme A (or its primitive form) and self-reproductive reactions by ribozymes on the surface of minerals (pyrite and struvite), which precipitate in a nuclear geyser (RNA world); 3) Enzymatic reactions by proteins with pyrites and the struvite in their reaction centers (RNP world); and, 4) Metabolism of extant organisms with the full assembly of enzymes produced by translating molecular machines with information stored in DNA sequences (DNA world). It is further inferred that relics of primordial metabolic evolution in the Hadean nuclear geyser can be seen at the reaction centers of enzymes of both pyrite and struvite types, nucleotide-like molecules as a cofactor of the enzymes, Calvin Cycle of photosynthesis, and chemical abundance of cytoplasm.