DOCSLIB.ORG

Crustal Structure and Tectonics of the Hidaka Collision Zone, Hokkaido (Japan), Revealed by Vibroseis Seismic Re¯Ection and Gravity Surveys

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Crustal Structure and Tectonics of the Hidaka Collision Zone, Hokkaido (Japan), Revealed by Vibroseis Seismic Re¯Ection and Gravity Surveys ELSEVIER Tectonophysics 290 (1998) 197±210 Crustal structure and tectonics of the Hidaka Collision Zone, Hokkaido (Japan), revealed by vibroseis seismic re¯ection and gravity surveys Kazunori Arita a,Ł, Takashi Ikawa b,TanioItob, Akihiko Yamamoto c, Matsuhiko Saito a, Yasunori Nishida a, Hideyuki Satoh a,GakuKimurad,1, Teruo Watanabe a, Takeshi Ikawa e, Toru Kuroda e a Department of Earth and Planetary Sciences, Hokkaido University, Kita-ku, Sapporo 060, Japan b Department of Earth Sciences, Chiba University, Inage-ku, Chiba 263, Japan c Research Center for Earthquake Prediction, Hokkaido University, Kita-ku, Sapporo 060, Japan d Department of Earth Sciences, CIAS, University of Osaka Prefecture, Sakai-shi, Osaka 593, Japan e Japex Geoscience Institute Inc., Shinagawa-ku, Tokyo 140, Japan Received 21 November 1996; accepted 16 December 1997 Abstract This study is the ®rst integrated geological and geophysical investigation of the Hidaka Collision Zone in southern Central Hokkaido, Japan, which shows complex collision tectonics with a westward vergence. The Hidaka Collision Zone consists of the Idon'nappu Belt (IB), the Poroshiri Ophiolite Belt (POB) and the Hidaka Metamorphic Belt (HMB) with the Hidaka Belt from west to east. The POB (metamorphosed ophiolites) is overthrust by the HMB (steeply eastward-dipping palaeo-arc crust) along the Hidaka Main Thrust (HMT), and in turn, thrusts over the Idon'nappu Belt (melanges) along the Hidaka Western Thrust (HWT). Seismic re¯ection and gravity surveys along a 20-km-long traverse across the southern Hidaka Mountains revealed hitherto unknown crustal structures of the collision zone such as listric thrusts, back thrusts, frontal thrust-and-fold structures, and duplex structures. The main ®ndings are as follows. (1) The HMT, which dips steeply at the surface, is a listric fault dipping gently at a depth of ¾7 km beneath the eastern end of the HMB, and cutting across the lithological boundaries and schistosity of the Hidaka metamorphic rocks. (2) A second re¯ector is detected 1 km below the HMT re¯ector. The intervening part between these two re¯ectors is inferred to be the POB, which is only little exposed at the surface. This inference is supported by the high positive Bouguer anomalies along the Hidaka Mountains. (3) The shallow portion of the IB at the front of the collision zone has a number of NNE-dipping re¯ectors, indicative of imbricated fold-and-thrust structures. (4) Subhorizontal re¯ectors at a depth of 14 km are recognized intermittently at both sides of the seismic pro®le. These re¯ectors may correspond to the velocity boundary (5.9±6.6 km=s) previously obtained from seismic refraction pro®ling in the northern Hidaka Mountains. (5) These crustal structures as well as the back thrust found in the eastern end of the traverse represent characteristics of collisional tectonics resulting from the two collisional events since the Early Tertiary. 1998 Elsevier Science B.V. All rights reserved. Keywords: crustal structure; Hidaka Collision Zone; seismic re¯ection; gravity survey; collision tectonics; Hokkaido Ł Corresponding author. Tel.: C81 11 706-5305; Fax: C81 11 706-5305; E-mail: [email protected] 1 Present address: Geological Institute, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan. 0040-1951/98/$19.00 1998 Elsevier Science B.V. All rights reserved. PII S0040-1951(98)00018-3 198 K. Arita et al. / Tectonophysics 290 (1998) 197±210 1. Introduction Eastern Hokkaido is composed of Late Cretaceous to Palaeogene forearc sediments of the palaeo-Kuril The northern island of Japan, Hokkaido, is sit- arc±trench system (Kiminami and Kontani, 1983). uated at the conjunction of two active island Central Hokkaido, which geologically continues to arc±trench systems; the Northeast Honshu Arc± Sakhalin, has a complicated geological assemblage. Japan Trench and the Kuril Arc±Trench (Fig. 1a). It has been occupied by two subduction±accretion Hokkaido is divided into three major provinces with systems between the palaeo-Eurasian and palaeo- regard to its pre-Neogene geology, the trend of which North American Plates; the one in the west (the is oblique to these active arc±trench systems: West- Sorachi-Yezo Belt, the Idon'nappu Belt and the Hi- ern, Central and Eastern Hokkaido (Fig. 1b). Western daka Belt) is a N±S-trending, westward-subduct- Hokkaido, which is a northern extension of North- ing system of Late Jurassic to Palaeogene age, and east Honshu, consists of Jurassic accretionary com- the other in the east (the Tokoro Belt) is an east- plexes intruded by Cretaceous granitic intrusions. ward-subducting system of Cretaceous age (Fig. 1b Fig. 1. (a) Sketch map showing plate tectonic setting around Japanese islands. Thick lines and dotted line show present and Tertiary plate boundaries, respectively. (b) Geologic divisions of Central Hokkaido. Pro®ling lines Fig. 1cFig. 2a,b, and 3 are shown. Modi®ed from Kimura (1994). (c) Schematic geological cross-section of southern Central Hokkaido. POB D Poroshiri Ophiolite Belt, HMB D Hidaka Metamorphic Belt, HWT D Hidaka Western Thrust, HMT D Hidaka Main Thrust, TF D Tokachi Fault System. Cross-section line is shown in (b). Modi®ed from Kimura (1986). K. Arita et al. / Tectonophysics 290 (1998) 197±210 199 and c; Kiminami and Kontani, 1983; Sakakibara, Moriya, 1990; Miyamachi et al., 1994; Moriya et al., 1986). 1994; Ozel et al., 1996; Iwasaki et al., 1998); Central Hokkaido, especially its southern part, has (1) Beneath the Hidaka Collision Zone there are undergone two stages of collisions since the Early two seismic zones: a shallower zone (20 to 50 km Tertiary. The older oblique collision with a right- deep) likely related to the collision of the Eurasian lateral sense of motion between the palaeo-Eurasian and North American Plates, and a deeper zone (over and palaeo-North American Plates during the Palaeo- 70 km deep) related to the subduction of the Paci®c gene resulted in the amalgamation of the Hidaka Plate. Metamorphic Belt in the east and the Poroshiri Ophi- (2) In the southern Hidaka Mountains a low- olite Belt in the west. The younger collision was velocity zone (5.5 km=s) dips eastward from the caused by the westward migration of the Kuril fore- western coast, and reaches a depth of about 30 km arc plate which started in the Late Miocene due to beneath the Hidaka Mountains (Fig. 2a). the oblique subduction of the Paci®c Plate along the (3) The seismic velocity structure of both sides Kuril Trench (Fig. 1a; Kimura, 1986). The collision of the Hidaka Mountains is relatively clear, but that rapidly uplifted the Hidaka Metamorphic Belt as beneath the mountains is monotonous or not deter- well as the Poroshiri Ophiolite Belt, producing the minable (Fig. 2). present Hidaka Mountains. The process of collision (4) Lateral variation in seismic velocity due to between the Eurasian Plate and the North American different geological units is found across the Hidaka Plate (Kuril forearc plate) is still continuing. Collision Zone. In particular, seismic waves are at- Although the deformational features due to the tenuated under the Idon'nappu Belt on the western above two collisions are also observed in the So- part of the Hidaka Mountains. rachi-Yezo Belt, the Hidaka Mountains and their sur- (5) The Moho discontinuity is not clearly visible roundings in southern Central Hokkaido show typi- as it may be deeper than 50 km (Fig. 2a), although cally complex collisional features. They are therefore Miyamachi et al. (1994) reported a crustal thickness collectively termed as the Hidaka Collision Zone, of 32 km beneath the Hidaka Mountains. which provides favourable opportunities for studying the characteristics and structure of deep crust similar 2.2. Magnetotellurics to the Ivrea zone of the Alps and the Kohistan± Ladakh arc of the western Himalaya. It is impor- A recent magnetotelluric survey (Ogawa et al., tant to elucidate the present deep-crustal structure 1994) across the Hidaka Collision Zone (about 70 of the Hidaka Collision Zone in order to understand km north of the present survey area: Fig. 3) shows the arc±arc collisional mechanism and the formation that a 2-km high-resistivity (1000±2000 m) layer process of continental crust. Toward this end, we car- of high-grade Hidaka metamorphic rocks is followed ried out vibroseis seismic re¯ection pro®ling along by a relatively conductive (500±1000 m) layer of a 20-km-long traverse, and gravity measurements in accretionary prism at depths of 5 to 10 km, which the southern Hidaka Mountains. is underlain again by a high-resistivity (30,000 m) layer of probably high-grade metamorphic rocks. 2. Geophysical characteristics of the Hidaka This suggests an inter®ngered complex structure or Collision Zone crustal delamination beneath the Hidaka Collision Zone probably due to the above-mentioned two col- 2.1. Seismic refraction lision events. Seismic refraction experiments and natural earth- 3. Geological outline of the Hidaka collision zone quake data in and around the Hidaka Mountains have with special reference to the surveyed area revealed the following complicated tectonic features (e.g., Den and Hotta, 1973; Okada et al., 1973; The Hidaka Collision Zone is occupied by the Takanami, 1982; Fujii and Moriya, 1983; Moriya, N±S-trending accretionary and melange complexes 1983; Miyamachi and Moriya, 1984; Furumura and consisting of the Idon'nappu and Hidaka Belts (eg., 200 K. Arita et al. / Tectonophysics 290 (1998) 197±210 Fig. 2. (a) Seismic velocity structures (km=s) across the southern Hidaka Mountains (after Moriya et al., 1994). (b) Seismic velocity structures (km=s) across Central Hokkaido revealed by seismic refraction pro®ling (after Ozel et al., 1996). HMT D Hidaka Main Thrust. Both pro®ling lines are shown in Fig.
Load more

Recommended publications
  • Preliminary Notes on the Basic Inclusions Found in the Migmatite Area of the Hidaka Mountains, Hokkaido
    岩石鉱 物鉱床 学会 誌 60巻5号,1968年 研 究 短 報 文 PRELIMINARY NOTES ON THE BASIC INCLUSIONS FOUND IN THE MIGMATITE AREA OF THE HIDAKA MOUNTAINS, HOKKAIDO YONO TONOSAKI Institute of Earth Science,Hakodate Branch, Hokkaido Universityof Education Petrology of the metamorphosed calcareous concretions in hornfels of the southern part of the Hidaka Mountains was already investigated by Suzuki (1934). Similar studies were made in detail by Hunahashi et al. (1956), Asai (1956, 1958, 1959) and Hirota (1963) on various inclusions in gneisses and migmatites along the Horoman River, Hidaka Province. The writer discovered some basic inclusions consisting chiefly of biotite and amphibole in the migmatite area of the southern Hidaka Mountains. This is a very rare type of inclusions found in metamorphic rocks and migmatites in Hidaka. This paper briefly describes the petrographical nature of the basic inclusions. The various inclusions deriving from argillaceous sediments and calcareous concretions in Hidaka show usually a schistose or gneissose structure. Such inclusions occur as eye-shaped or dark ovoidal small patches intercalated between gneiss and hornfels fragments enclosed by metamorphic rocks and migmatites. The basic inclusions in question occur in the upper reaches of the Saruru River near Meguro, Hidaka Province. The area belongs to the eastern part of the regional Hidaka metamorphic complex. The basic inclusions are found only in tonalite (Hidaka research group, Hunahashi et al., 1967) and aplitic migmatite (Hunahashi and Igi, 1956; Igi and Hata, 1956), and always have lenticular forms of various sizes. A specimen of the basic inclusions was obtained from tonalite (Fig. 2). It was found as a xenolith-like rock in the coarse-grained tonalite.
    [Show full text]
  • Bus Stop: Oiwake Sta
    Issued by the Hokkaido Shinkansen × Nittan Regional Strategy Meeting. top last s fo te: The r No Sa pp HHR or o-b ou nd bu se s i s S a p p o r o F a c t HE o HOKKAIDO r y Sapporo Sta.・JR Sapporo Sta. Michi-no-Eki Abira D51 Station IBURI HIDAKA HM HMS HO HT HD HP HHD ST Location: Oiwake Kashiwagaoka 49-1, Abira Town HE HHR Nearest bus stop: Oiwake Sta. Oyachi Trm. Muroran Line Makomanai Shimukappu Sta. SM Subway Sta. Chitose Line Jozankei BUS函 館 本 線 MAP Natl. Highway 230 This roadside rest area sells local farm products and specialties of Abira Town. It also exhibits historical artifacts, including one of the best-preserved steam AP Sekisho Line RI & HIDAK S M locomotives in Japan. U A BU IB AREA Obihiro Sta. Bus Trm. Kutchan Sta. Kobushi-no-Yu Atsuma IB Oiwake Sta. Location: Hongo 229-1, Atsuma Town, Yufutsu County Lake Toya cruise AB Nearest bus stop: Rihabiri Center-mae Hidaka Trm. Nakayama Toge (pass) Abira HHD TH HTM SM Location: Toyako Onsen, Toyako Town Nearest bus stop: Toyako Onsen Bus Terminal Town Hidaka Town CTS Mukawa Town Chitose Sta. Minami-chitose Sta. Umi-no-Eki Plat Seaport Market Location: 2-5, Minato-machi 2-chome, Tomakomai City New Kimobetsu Nearest bus stop: Puratto Minato Ichiba-mae Chitose There are various baths. The dishes made from Atsuma Hobetsu Shutchojo HHY HN Daigaku CH MC Rusutsu Airport products are delicious. Enjoy Atsuma buta-don (pork CA CTS Seimon-mae over rice) and Mongolian barbecue.
    [Show full text]
  • Structural Heterogeneity in and Around the Fold-And-Thrust Belt of The
    Iwasaki et al. Earth, Planets and Space (2019) 71:103 https://doi.org/10.1186/s40623-019-1081-z FRONTIER LETTER Open Access Structural heterogeneity in and around the fold-and-thrust belt of the Hidaka Collision zone, Hokkaido, Japan and its relationship to the aftershock activity of the 2018 Hokkaido Eastern Iburi Earthquake Takaya Iwasaki1* , Noriko Tsumura2, Tanio Ito3, Kazunori Arita4, Matsubara Makoto5, Hiroshi Sato1, Eiji Kurashimo1, Naoshi Hirata1, Susumu Abe6, Katsuya Noda7, Akira Fujiwara8, Shinsuke Kikuchi9 and Kazuko Suzuki10 Abstract The Hokkaido Eastern Iburi Earthquake (M 6.7) occurred on Sep. 6, 2018 in the southern part of Central Hokkaido, Japan. Since Paleogene, this region has experienced= the dextral oblique transpression between the Eurasia and North American (Okhotsk) Plates and the subsequent collision between the Northeast Japan Arc and the Kuril Arc due to the oblique subduction of the Pacifc Plate. This earthquake occurred beneath the foreland fold-and-thrust belt of the Hidaka Collision zone developed by the collision process, and is characterized by its deep focal depth (~ 37 km) and complicated rupture process. The reanalyses of controlled source seismic data collected in the 1998–2000 Hokkaido Transect Project revealed the detailed structure beneath the fold-and-thrust belt, and its relationship with the aftershock activity of this earthquake. Our refection processing using the CRS/MDRS stacking method imaged for the frst time the lower crust and uppermost mantle structures of the Northeast Japan Arc underthrust beneath a thick (~ 5–10 km) sedimentary package of the fold-and-thrust belt. Based on the analysis of the refraction/wide- angle refection data, the total thickness of this Northeast Japan Arc crust is only 16–22 km.
    [Show full text]
  • Japan North-To-South 16 Days.Pdf
    Geo 1 Geo-Japan North-to-South 16 days Japan, where hills and mountains occupy more than 70% of the country, is one of the world‘s leading volcanic powers. Hokkaido:Akan Mashu National Park,which has two caldera terrains of Lake Kussharo and Lake Akan, is one of the largest national parks in Japan. You can visit former industrial remains like sulfur mining trace while climbing an active volcano where smoke rises. On the south side of Hokkaido, discover and experience the Toya-Usu UNESCO Geopark which is called a Living Volcano Museum. Touhoku:The Sanriku Geopark is Japan’s largest geopark, stretching some 220 km along the Pacific Coast of Aomori, Iwate and Miyagi Prefectures. From the pristine waters of Jodogahama Beach (literally ‘Paradise Beach’) to the mysterious hues of Ryusendo Limestone Cave’s underground lakes, the Sanriku Geopark is a breathtakingly beautiful world of blue! Oshima-Fuji-Hakone area: Experience life on a volcano-island at Oshima, then the culture born in the UNESCO Hakone Geopark in the foothills of that most iconic volcano Mt. Fuji. Kyusyu:Finish your journey in Kyushu with a visit to Aso Geopark, home to Japan’s largest active volcano. The Aso volcano is a beast that hasn’t only given birth to the dynamic caldera landscape of the Aso area, but also shaped much of Kyushu as we know it. Explore the flourishing nature and culture of Aso, vowen together by the overwhelming presence of Japan’s largest active volcano. 共同・協業販路開拓支援事業 1 Geo 1 Geo-Japan North-to-South 16 days Itinerary at a glance Day 1 Group meets at Memanbetsu
    [Show full text]
  • Mechanism of Long-Standing Cenozoic Basin Formation in Central Hokkaido
    Itoh et al. Progress in Earth and Planetary Science 2014, 1:6 http://www.progearthplanetsci.com/content/1/1/6 RESEARCH Open Access Mechanism of long-standing Cenozoic basin formation in central Hokkaido: an integrated basin study on an oblique convergent margin Yasuto Itoh1*, Osamu Takano2, Shigekazu Kusumoto3 and Machiko Tamaki4 Abstract The basin-forming process along a convergent margin off the eastern coast of Eurasia was pursued on the basis of geological, geochemical, and geophysical approaches. Central Hokkaido has been a site of vigorous tectonic events throughout the Cenozoic reflecting the long-standing subduction of oceanic plates in the region. Geochemical modeling provided an estimate of the eroded Paleogene unit in the study area. Data on the considerable thickness of the missing unit implied continued subsidence of the forearc region and its subsequent exhumation under the emergence of a compressive regime synchronous with the back-arc opening stage. Spatially large facies variety in the Paleogene system suggests that basin compartmentalization occurred as a result of the trench-parallel component of the plate convergence. Right-lateral motion seems to have been the dominant type in Hokkaido and the forearc of northeast Japan since the Late Cretaceous, except for a left-lateral episode during rapid subsidence of the Izanagi Plate around 110 Ma. Numerical modeling demonstrated that dextral slip on a bunch of longitudinal strike-slip faults restored the Neogenedepocenters in central Hokkaido, together with an east-west compressive regime related to an arc-arc collision. Keywords: Basin subsidence; Foreland basin; Modeling; Strike-slip basin; Subduction-related basin; Tectonics and sedimentation; Geochemistry; Maturation; Hokkaido Background focus here and elsewhere was on the central N-S elon- Hokkaido is an island presently located at a junction of gated depression adjacent to the arc-arc collision front the Kurile arc and northeast Japan arc (Figure 1).
    [Show full text]
  • Uplift of the Hidaka Collisional Orogen, Hokkaido, Japan Inferred from Stratigraphy and Thermochronology
    Title Uplift of the Hidaka Collisional Orogen, Hokkaido, Japan Inferred from Stratigraphy and Thermochronology Author(s) Kawakami, Gentaro; Ono, Masako; Ohira, Hiroto; Arita, Kazunori; Itaya, Tetsumaru; Kawamura, Makoto Citation Edited by Shunsuke F. Mawatari, Hisatake Okada., 121-125 Issue Date 2004 Doc URL http://hdl.handle.net/2115/38516 Type proceedings International Symposium on "Dawn of a New Natural History - Integration of Geoscience and Biodiversity Studies". 5- Note 6 March 2004. Sapporo, Japan. File Information p121-125-neo-science.pdf Instructions for use Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP Uplift of the Hidaka Collisional Orogen, Hokkaido, Japan Inferred from Stratigraphy and Thermochronology Gentaro Kawakami', Masako Ono', Hiroto Ohira3, Kazunori Arita4, Tetsumaru Itaya5 and Makoto Kawamura4 COE for Neo-Science of Natural History, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan 211idaka Mountains Center , Hidaka 079-2301, Japan 3Interdisciplinary Faculty of Science and Engineering , Shimane University, Matsue 690-8504, Japan 'Division of Earth and Planetary Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan sResearch Institute of Natural Sciences, Okayama University of Science, Okayama 700-0005, Japan ABSTRACT This paper reviews the stratigraphic and thermochronologic data concerning the exhumation his- tory of the Hidaka collisional orogen, Hokkaido, Japan. The Neogene sedimentary record of fore- land basin suggests that the topographic uplift of the orogen occurred in the Middle Miocene. The first occurrence of large amount of orogen-sourced granite clasts has been found in the Middle Mio- cene turbidites around 15 Ma. These granite clasts are S-type monzogranite-granodiorite, and show the Paleogene biotite K-Ar ages of 29-46 Ma.
    [Show full text]
  • Configuration of Migmatite Dome Comparative Tectonics of Migmatite in the Hidaka Metamorphic Belt
    Title Configuration of Migmatite Dome Comparative Tectonics of Migmatite in the Hidaka Metamorphic Belt Author(s) Kizaki, Koshiro Citation Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy, 15(1-2), 157-172 Issue Date 1972-03 Doc URL http://hdl.handle.net/2115/36009 Type bulletin (article) File Information 15(1-2)_157-172.pdf Instructions for use Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP CONFIGURATION OF MIGMATITE DOME COMPARATIVE TECTONICS OF MIGMATITE IN THE HIDAKA METAMORPHIC BELT by Koshiro KIzAKI (with 16 Text-Figures) (Contribution from the Department of Geology and Mineralogy, Faculty of Science, Hokkaido University, No, 1227 ) lntroduction The Hidaka metamorphic belt wliich represents the geological backbone of the Hokkaido is}and in northern Japan, is composed of various metamorphics and migmatites of pelitic and psamitic origin and a}so is characterizecl by thick sheets of basic intrusives which were metainorphosed to various aixtphibolites. Basic and ultrabasic plutonics as olivine gabbro, norite, gabbro and periodotite are significant in the belt. The core portion of the belt is occupied by the migmatites which are classified to biotite migmatite, cordierite migmatite and granitic migmatite of agmatitic, schollen, nebulitic and anatexitic natures, while sometimes of massive kind (Fig. I). The radiometric age of these migmatites indicates 30-40 my by K-A method (Kawano et al, 1967). So that with other geological informations, the age of the metamorphism and migmatization should be around from Cretaceous to Tertiary. The petrography of the metamorphic rocks and migmatites of the belt has been published by several authors (HiRoTA, l963, HuNAHAsHi, et al, l9S6, KizAKi, l964, ToNozAKi, 1965, etc.).
    [Show full text]
  • Memories of Japanese Military Horses Of
    Memories of Japanese Military Horses of World War II Aaron Skabelund [Brigham Young University] Introduction On August 10, 1977, the chief of a small rural railroad station near Honbetsu in central Hokkaido, the northernmost and second largest of Japan’s four main islands, discovered a wooden plank in a nearby field that triggered memories from over three decades earlier. As a railway employee during the war, Mori Hiroshi (1917-2003) moved hundreds of horses from an adjacent military horse ranch up the ramp and into boxcars, which carried them towards the front in China and elsewhere. When he found the plank – marked by countless horseshoe prints – Mori, as he recalled years later, felt like the spirits of the horses entered his body. The discovery led him to build a memorial for the horses a decade later near the by then abandoned station. Several local Honbetsu businessmen supported Mori with this project, including the manager of a draft horse-pulling (ban’ei keiba) competition course who provided land for the monument next to the track, which now too has disappeared. As the monument neared completion in 1988, Mori publically announced his plan in a letter to the daily Hokkaidō Shinbun (the prefectural broadsheet), which led people to send hundreds of letters, photographs, and items related to war horses from throughout Hokkaido and the country. The Honbetsu Town Historical Museum now displays some of those materials as part of a permanent exhibit. Over the last two decades, Mori’s experience and the outpouring of memories it elicited have led to a proliferation of war horse narratives in various cultural forms – newspaper and magazine articles, television specials, memoirs and book chapters, and a grade-school textbook story – and inspired the construction of other monuments, including one in Okinawa (an island chain south of Japan’s four main islands) built by veterans from Hokkaido of the Battle of Okinawa in 1990.
    [Show full text]
  • Foreland Basins at the Miocene Arc-Arc Junction, Central Hokkaido, Northern Japan
    Chapter 6 Foreland Basins at the Miocene Arc-Arc Junction, Central Hokkaido, Northern Japan Gentaro Kawakami Additional information is available at the end of the chapter http://dx.doi.org/10.5772/56748 1. Introduction A foreland basin can be defined as a linear depression formed from the flexure of foreland lithosphere under the load of an orogenic wedge. Various factors control the basin geometry and the stratigraphic architecture of the basin fill [1]. During the Miocene age, a series of foreland basins were formed in Hokkaido, the northern island of Japan, due to an arc-arc collision event [2–4]. The basin area has a total length of 400 km, and it is characterized by several rows of deep depressions stretched in a north-south direction and separated by topographic highs (Figure 1). The degree of total crustal shortening and exhumation by the collision event is larger in the southern region of the collision zone [5], and thus, the basin geometry and the stratigraphic/sedimentologic architecture of the basin fills vary among the depressions. Namely, the depression in the southern region has suffered progressive deformation due to thrust propagation, and the depocenter has migrated foreland- ward, a feature noted in many foreland basins [1]. In contrast, the depression in the northern region shows restrictive deformation and foreland-ward migration of depocenter. Thus, the initial geometry and stratigraphic architecture of the basin fill are well preserved even in the proximal margin of the basin. On the other hand, unlike the northern and southern regions, the depression located near the center of the foreland basin area has been affected by the existence of a projection on the foreland lithosphere.
    [Show full text]
  • On the Ice-Ages and Post Glacial Age of the Hidaka Mountain-Range
    Title Quaternary Geology of Hokkaido. 1st Report: On the Ice-ages and Post glacial age of the Hidaka Mountain-range Author(s) Hashimoto, Seiji; Minato, Masao Citation Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy, 9(1), 7-20 Issue Date 1955-03 Doc URL http://hdl.handle.net/2115/35878 Type bulletin (article) File Information 9(1)_7-20.pdf Instructions for use Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP QUA'TERNARY GEOMOGY CPF Eff0KKAffDO'K ist Rep. ort: On tke Iceptages aftd. Post glacial age o'x" tS}e ffirkaka moti.lttai{'iptrakge By' Seiji HASHIMOTe and Masao MINATO (With 10 Figures) Contribution fvom the DepaTtment of Geology and Mineralog'y, I]iaeulty of Scienee, Hokkaid6 UniversityL No. 531. 1. Ice ages of the ffidaka moufttain-range From its south-westem extremlty in tbe central vo]eanie highland area in Hokkaido (Daisetsusan National Park), the Hidaka mountain range extends south-ward with eentinuity foy 140 kms to Cape Eyimo. Throughout thls eourse the range styetehes as preeipitously as walls between the two adjaeent districts, Tol<achi, pla;m, to the east, and Hidaka low land area extending to the west. In the noythern part o£ the range, the higher peaks attain altitudes of 1900 to 2000 m, while sueh peaks in the southem part o£ the range, show elevations of 1700 to 1500m. Evidences o£ the former existenee of glaelescs have been diseovered at various localities in the range as shown in Ii'ig. 1. "" It is planned to publish in this series of papers: 1) Theiee-ages･ and post glaeial age of the Hndaka mountain range, 2) Terraee ehvonology in flol<kaido, 3) ?leistoeene and Holoeene volcanie aetivities in Hokkaido, 4) The Lowev Pleistocene deposits in Ilok- kaido, 5) Some biogeographical eonsiderationson .£aunal and fioral aspects of Hokkaido in relation to palaeogeog/ aphy o/f the Quatevnary age, 6) The Palaeolithie age in Hokkaido, and 7) The undeyground resourees in relation to the Quateynary geolog'y ln Hokl<aido.
    [Show full text]
  • Three Types of Greenstone from the Hidaka Belt, Hokkaido, Japan: Insights Into Geodynamic Setting of Northeastern Margin of the Eurasian Plate in the Paleogene
    Journal of Mineralogical and Petrological Sciences, J–STAGE Advance Publication, February 29, 2020 Three types of greenstone from the Hidaka belt, Hokkaido, Japan: Insights into geodynamic setting of northeastern margin of the Eurasian plate in the Paleogene Toru YAMASAKI* and Futoshi NANAYAMA*,** *Institute of Geology and Geoinformation, Geological Survey of Japan (AIST), Tsukuba 305–8567, Japan **Center for Water Cycle, Marine Environment and Disaster Management, Kumamoto University, Kumamoto 860–8555, Japan The Hidaka belt in Central Hokkaido, Japan, consists of an early Paleogene subduction complex, referred to as the Hidaka Supergroup, dominated by clastic rocks. The southern area of the Hidaka Supergroup is referred to as the Nakanogawa Group, which gradually leads to the high–temperature Hidaka metamorphic belt in the western part. We collected 17 samples of greenstone from the entire Hidaka belt and examined their whole– rock major and trace element geochemistry. Including those described in previous reports, three distinct types of greenstone exist in the Hidaka belt. Type 1 greenstone is an ocean island basalt–type greenstone. The multi– element and rare earth element (REE) patterns for this type of greenstone show a steep slope up to the left, with Ti/V > 62 and Zr/Nb < 15. Type 2 greenstone is a mid–ocean ridge basalt (MORB)–type greenstone that shows relatively flat chondrite–normalized REE patterns and a gentle slope up to the left on the normal–MORB– normalized multi–element patterns with Ti/V = 26–53 and Zr/Nb = 21–117. Type 3 greenstone shows multi– element and REE patterns similar to those of Type 1, but with a clear relative depletion of Nb, Ta, and Ti.
    [Show full text]
  • Chapter 3 Aircraft Accident and Serious Incident Investigations(P17
    Chapter 3 Aircraft accident and serious incident investigations Chapter 3 Aircraft accident and serious incident investigations 1 Aircraft accidents and serious incidents to be investigated <Aircraft accidents to be investigated> ◎Paragraph 1, Article 2 of the Act for Establishment of the Japan Transport Safety Board(Definition of aircraft accident) The term "Aircraft Accident" as used in this Act shall mean the accident listed in each of the items in paragraph 1 of Article 76 of the Civil Aeronautics Act. ◎Paragraph 1, Article 76 of the Civil Aeronautics Act (Obligation to report) 1 Crash, collision or fire of aircraft; 2 Injury or death of any person, or destruction of any object caused by aircraft; 3 Death (except those specified in Ordinances of the Ministry of Land, Infrastructure, Transport and Tourism) or disappearance of any person on board the aircraft; 4 Contact with other aircraft; and 5 Other accidents relating to aircraft specified in Ordinances of the Ministry of Land, Infrastructure, Transport and Tourism. ◎Article 165-3 of the Ordinance for Enforcement of the Civil Aeronautics Act (Accidents related to aircraft prescribed in the Ordinances of the Ministry of Land, Infrastructure, Transport and Tourism under item 5 of the paragraph1 of the Article 76 of the Act) The cases (excluding cases where the repair of a subject aircraft does not correspond to the major repair work) where navigating aircraft is damaged (except the sole damage of engine, cowling, engine accessory, propeller, wing tip, antenna, tire, brake or fairing). <Aircraft serious incidents to be investigated> ◎Item 2, Paragraph 2, Article 2 of the Act for Establishment of the Japan Transport Safety Board (Definition of aircraft serious incident) A situation where a pilot in command of an aircraft during flight recognized a risk of collision or contact with any other aircraft, or any other situations prescribed by the Ordinances of Ministry of Land, Infrastructure, Transport and Tourism under Article 76-2 of the Civil Aeronautics Act.
    [Show full text]