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The field trip will focus on the radiolarian response to global catastrophic events (e.g., bolide impact, large-scale volcanism, and anoxia) recorded in Triassic and Jurassic radiolarian chert of the Mino Belt, central Japan. The radiolarian chert of the Mino Belt records the sedimentary history of an oceanic plate in the Panthalassa Ocean prior to accretion at the trench. The topics presented and discussed in the field are: (1) the end-Permian mass extinction and recovery from the event; (2) Early Triassic anoxia and subsequent recovery in the Middle Triassic; (3) paleoenvironmental changes across the Early–Late Carnian boundary (Carnian Pluvial Event); (4) collapse of marine ecosystems triggered by a Norian impact event; (5) ocean acidification at the Triassic–Jurassic boundary; and (6) Early Jurassic (Toarcian) anoxia and the formation of black chert. In addition to these topics, this trip will consider aspects of the accretion process of oceanic plate sediments during the Middle to Late Jurassic., InterRed XV in Niigata 2017 Niigata University (JAPAN) Oct/22-Oct/27, 2017

Lithology and AMS14C ages of sediments accumulated in the dammed lake along the upper reach of the Sono River, Odai-cho, Mie Prefecture, central Japan are described at the two surface exposures and on the one drill core. The sediments are composed of bedded and laminated mud, silt and sand, top of which is covered by the debris flow deposits. Part of the laminations are interpreted as varves showing cyclic sedimentation of medium- to fine-grained clastic materials and very fine-graind clastics, algae, and siderite. Sporadic coarse-grained clastic interbeds showing graded bedding indicate the sedimentary events transporting the materials from the upper part of the basin by the turbidity corrents. The AMS 14C ages of wood fragments from the surface exposures range from 20440 to 20910 BP, while those from drill cores are from 21100 to 211900 BP. These ages indicate the sediment accumulation rate of the dammed lake is ca 20 mm/year., 地すべりにより形成された天然ダムは上流側にせき止め湖を形成する.三重県大台町の薗川上流では，過去のせき止め湖を埋積したせき止め湖堆積物が地表の2カ所で観察される.また，地表露頭の上流側で掘削したボーリングコアは，地表から深度約17mまでが土石流堆積物，その下位の深度約33mまでがせき止め湖堆積物からなる.せき止め湖堆積物は，層理・葉理の発達した泥層・シルト層からなり，砂層や礫質泥層を挟む.葉理の少なくとも一部は，砕屑粒子を含む粗粒部とシデライト濃集部を伴う細粒部からなり，年稿であると解釈できる.挟まれる粗粒層は級化層理を示し，上流部で発生したイベントによる堆積物と思われる.せき止め湖堆積物に含まれる木片の14C年代は，約20,000～22,000 BPで，せき止め湖堆積物の堆積速度は20mm/年程度と推定される., 名古屋大学年代測定総合研究センターシンポジウム報告

The AMS-14C ages of wood fragments and age of tephra in the sediments accumulated in the depression between the double ridges were determined in order to clarify the development history of the ridges northwest of Mt. Kanmuriyama, Gifu and Fukui prefectures. Nine boreholes arranged along the line perpendicular to the ridge were drilled by the hand auger boring. The westernmost K2 core with thickest sediments includes wood fragments suitable for the AMS-14C age determination at the depths of 82, 138 and 195 cm; they yield 1234-1060, 6161-5996 and 7931-7731 cal BP, respectively. The tephra layer recovered from the depth of 148 cm of the same core is correlated with the Kikai Akahoya tephra (K-Ah) about 7300 cal BP. The AMS-14C ages of wood fragments embedded at the depths of 90 and 112 cm in the K8 core located eastern part of the basin are 4091-3925 and 6179-5938 cal BP, respectively. However, the peak of content of volcanic glass originated from the K-Ah tephra appears between the two wood fragment horizons., 岐阜福井県境冠山北西に位置する二重山稜地形の発達過程を明らかにするため，凹地埋積堆積物中に含まれる木片のAMS-14C年代測定とテフラの年代決定を行った.おおよそ南北方向の稜線に直交する方向に9箇所ハンドオーガーボーリングを行いコアを採取した.堆積物の層厚が一番厚かった凹地西端のK2コアにおいては,深度82,138,195cmから木片を採取し,深度148cmからテフラを採取した.得られた木片のAMS-14C年代は上位から1234-1060,6191-5996,7931-7731cal BPであった.テフラについては,火山ガラスの屈折率を測定した結果,鬼界アカホヤ火山灰(K-Ah)に対比され,その降灰年代は7300cal BPであることが分かった.また,凹地東端に近いK8コアの深度90,112cmの層準から得られた木片の年代は,4138-3925cal BP,6179-5938cal BPで,その聞には,K-Ah起源の火山ガラスの含有率ピークがみられた., 名古屋大学年代測定総合研究センターシンポジウム報告

Steel concrete composite decks with concrete sandwiched between top and bottom steel plates. Placing highly flowable concrete inside therefore may produce a void between the top deck and concrete owing to the change in volume while the concrete hardens or the accumulation of air while the concrete is placed. The void may cause local damage to the pavement or top steel plate and is likely to deteriorate the durability of the deck. In order to identify the scale of void that may cause damage to steel plates, three-dimensional finite element analysis was conducted. As a result, it was found that cracking occurred at bolted connections on the top steel plate when a wheel load acted at a point at a depth of 3mm or greater where the void was larger than the spacing between bolts., 長崎大学工学部研究報告 Vol.39(72), pp.20-27; 2009

Based on the plant macrofossils discovered in the Kureha Hills, Toyama, Japan, a possible altitudinal vegetationsequence of Hokuriku Region during the Middle Pleistocene Period was reconstructed. Out of the fossilplants discovered and identified, five coniferous tree species were selected. They were Abies homolepis, A. veitchii, Picea jezoensis var. hondoensis, Pinus koraiensis, P. parviflora var. pentaphylla and Tsuga diversifolia. Based on the ecological amplitudes of the extant respective species against the Kira’s warmth index（Wi）, the climatic conditions of the Middle Pleistocene Period were inferred. Then mean annual temperature of the region during the Period was determined to be ca. 10.3℃ lower than the present days. This suggested that altitudinal belts of vegetation of the region were approximately 1,800 m lower than those of the present days. The implication of this would be that both evergreen broad-leaved forest belt and deciduous forest belt did not exist in the region at the time and coniferous forests started immediately from the sea coast extending up to ca. 500 m asl. Above the coniferous forest belt, a scrubby forest belt of Pinus pumila would have developed up to ca. 1,000 m asl., and further up an extensive alpine tundra vegetation would have occurred to the tops of the mountain ranges.

Koinami in Yatsuo Town, Toyama City, central Japan is located on a small flat basin along the Besso River surrounded by ridges about 600-800 m in altitude, south of the Toyama Plain. The ENE-WSW trending fault to the south of Koinami is the boundary between the Miocene Nirehara and Iwaine Formations to the north and the Tetori Group and the Funatsu Granite of Hida belt to the south. Many landslides are developed within the area underlain by the Iwaine Formation composed of volcanic and volcaniclastic rocks. One of the landslides, 500 in width and 800 m in length, dammed the Besso River and the dammed lake was filled in to form the Koinami flat basin. The buried forest composed of many stumps, about 2-5 m in diameter, were recovered from the lake sediments during the land improvement in 1977-79, one of which yields the AMS ^C age of 2475±30 BP. It is between the Final Jomon and Early Yayoi periods. Wood pillars with mortises were also recovered during the improvement, although the occurrence and the relationship with the stump-bearing formations are unclear. We couldn't determine the inducing cause of the landslide from the geomorphological and geological information now obtained from this area. If the slide was caused by an earthquake, the Atotsugawa fault is the most probable candidate causing the trigger earthquake for this landslide on the basis of the recurrence interval and the last event of the active fault., 第20回名古屋大学年代測定総合研究センターシンポジウム平成19(2007)年度報告 Proceedings of the 20th symposiumon on Chronological Studies at the Nagoya University Center for Chronological Research in 2007 日時:平成20 (2008)年1月10日(木)～11日(金) 会場:名古屋大学野依記念学術交流館 Date:January10th-11th, 2008 Venue:Nagoya Uhiversity Noyori Conference Hall

An image database has been constructed for the radiolarian fossils which have been studied by the staff members and students of Nagoya University in these decades. Of more than sixty thousands registered samples of SEM pictures in the Nagoya University Museum, 2596 samples were selected and grouped according to the localities of the fossils. The latest version of the database includes depository data, which show the place where the fossil bodies are stored in museum, and give us the way to access them. An original fossil body is placed on a stub for the SEM observation; the stub is stored within a plastic case, which is collectively stored in a cabinet. The depository system dealing with the fossil bodies, the original negative film, plastic case and cabinet in the museum, is briefly described together with several display pages of Rad-File (IDB), version 5.56., 国立情報学研究所で電子化したコンテンツを使用している。

Radiolarian biostratigraphic research is done for chert-clastic sequence of the Taukha terrane in the Koreyskaya River area, Far East Russia. Three successive radiolarian assemblages have been distinguished from the lower thrust sheet of the Gorbousha unit ; they are the Xitus gifuensis, Stichomitra doliolum and Pseudodictyomitra carpatica assemblages in ascending order. The lower two assemblages are extracted from the cherty part of the section, and the youngest one is from siliceous mudstone and black mudstone. The transitional facies of chert-clastic sequence in the sheet is late Late Tithonian in age. This age is different from that in the second thrust sheet of the Dalnegorsk area which is Late Kimmeridgian to Middle Tithonian. Therefore the approach of the Gorbousha unit-bearing oceanic plate to the subduction zone ranges in age, at least, from Late Kimmeridgian to Berriasian. The difference of age in two different thrust sheets possibly indicates that the duplication of chert-clastic sequences in the Gorbousha unit resulted from successive accretion of oceanic plate., 国立情報学研究所で電子化したコンテンツを使用している。

[論文]

We describe variations of floral traits of Dryas octopetala L. along a snowmelt gradient within and among three sites : 1) the Subarctic Latnjajaure in northernmost Sweden, 2) the High Arctic Longyearbyen and 3) Ny-Alesund, Svalbard in Norway, also High Arctic. Dryas octopetala had two types of flowers, hermaphrodite flowers and male flowers, lacking any gynoecium. The frequency of male flowers was higher in late snow-melt habitats (i. e. late flowering populations) both at Latnjajaure and Ny-Alesund. Male flowers were significantly lighter in dry weight than hermaphrodite flowers; the difference was larger in the High Arctic than in the Subarctic, suggesting a higher resource limitation in male flowers in the High Arctic. Flower weight also varied among the three sites, and showed a significant difference along the latitudinal gradient both in hermaphrodite and male flowers. In the hermaphrodite flowers, the gynoecium dry weight differed among the three sites, being significantly heavier at Latnjajaure than at Longyearbyen and Ny-Alesund. As a result, the "femaleness" (gynoecium weight/androecium+gynoecium weight) showed significantly higher values at Latnjajaure than at Longyearbyen and Ny-Alesund. Thus, the floral allocation to female function in D. octopetala decreases with an increase in latitude from the Subarctic to the High Arctic. Gender variation of flowers is a size-dependent phenomenon; a positive correlation between flower size and femaleness was observed within each site.

An attempt has been made to characterize and categorize some selected vascular species in the Ny-Alesund area, Svalbard, in relation to soil moisture conditions. A total of sixty releves were established to describe the floristic structures of plant communities. At each releve site, one soil core sample in a 100ml metal container was collected to determine soil physical properties. Samples were oven-dried for 48 hours at 105℃. Moisture content was measured and soil moisture index was calculated for each releve. Based on the index, sixty releves were divided into five soil moisture classes. Throughout the sixty releves, twenty-five species of vascular plants were recognized. Of them, eleven species were selected for this study. They were Salix polaris, Oxyria digyna, Polygonum viviparum, Cerastium arcticum, C. regelii, Saxifraga caespitosa, S. cernua, S. nivalis, S. oppositifolia, Dryas octopetala, and Cassiope tetragona. These were the species that occurred in more than eleven releves out of the sixty. Their frequencies against the soil moisture classes were counted. Ecological distribution curves were constructed for the species. From the distribution pattern, especially the amplitude and the mode position on the moisture classes, the species were classified into six categories as follows, i. e., euryhygrotopic xerophyte, euryhygrotopic mesophyte, euryhygrotopic hygrophyte, stenohygrotopic xerophyte, stenohygrotopic mesophyte, and stenohygrotopic hygrophyte.

Preface: Le Tour de Mino We make the six-day-long excursion that nearly northeast-southwest traverses the central Japan. The trip starts from the Takayama area in Hida Massif, travels down to south in Mino Massif, and ends at the Neo area. The excursion focuses upon the observation and discussion of the lithology and structure of the Permian to Jurassic rocks of the Mino belt, the most thoroughly studied, Jurassic subduction-generated accretionary complex of Japan. The rocks to examine during the excursion include Permian basaltic rocks, chert, and shallow-marine carbonates, Triassic to Jurassic chert and related siliceous rocks, and Jurassic terrigenous clastic rocks. Having a Panthalassic affinity, the accreted rocks of the Mino belt could offer a unique opportunity to realize similarities and dissimilarities between the Panthalassic rocks and Tethyan rocks. We also make several stops to observe high T/P metamorphic rocks of the Hida belt with a Sino-Korean (North China) affinity, Upper Paleozoic sedimentary and volcanic rocks of the Hida-gaien belt, and Jurassic granitic rocks in Hida Massif. The Hida-gaien belt is lying between the Hida belt to the north and the Mino belt to the south. We also observe post-orogenic, Late Jurassic-Early Cretaceous fluvial-lacustrine sediments covering older rocks of the Hida and Hida-gaien belts.

[論文] Articles

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議室