巻号一覧
62 巻 (2008)
- 6 号 p. 375-
- 5 号 p. 305-
- 4 号 p. 251-
- 3 号 p. 157-
- 2 号 p. 97-
- 1 号 p. 1-
62 巻, 4 号
選択された号の論文の7件中1～7を表示しています
- |<
- <
- 1
- >
- >|
-
高島累層研究会 , 冨田 克敏, 中野 聰志原稿種別: 本文
2008 年 62 巻 4 号 p. 251-252
発行日: 2008/07/25
公開日: 2017/05/16
ジャーナル オープンアクセスPDF形式でダウンロード (889K) -
川辺 孝幸, 風岡 修, 香川 淳, 楠田 隆, 古野 邦雄, 吉田 剛原稿種別: 本文
2008 年 62 巻 4 号 p. 253-255
発行日: 2008/07/25
公開日: 2017/05/16
ジャーナル オープンアクセスPDF形式でダウンロード (1564K) -
Binyam W. WOLDEMICHAEL, Jun-Ichi KIMURA原稿種別: 本文
2008 年 62 巻 4 号 p. 257-271
発行日: 2008/07/25
公開日: 2017/05/16
ジャーナル オープンアクセスThe remobilized Pre-Neoproterozoic and juvenile Neoproterozoic systems of the Western Ethiopian Shield consist of three N-S trending terrains. These are the western migmatitic gneissic terrain(WMGT), the central meta-volcano-sedimentary terrain(CVST), and the eastern migmatitic gneissic terrain(EMGT). The CVST contains a suture zone of ultramafic-metasedimentary complexes in its eastern half, whereas metavolcanics predominate in the western half. The CVST and its adjacent areas often contain syn- to post-tectonic gabbroic to granitic intrusions. The petrography and major and trace element compositions of intrusions in and around the CVST in the Ghimbi-Nedjo area were examined to determine their petrogenesis and the tectonic setting in which they were emplaced. The Bikilal-Ghimbi, Gombo Kora, and Daleti gabbros intruded within the EMGT do not preserve melt composition. In contrast, the Senbet-Dura and Gebeya-Kemisa diorites that were intruded in the boundary between WMGT and CVST, the Wayu-Meni gabbro in the CVST metavolcanics, and the Kemashi diorite in the CVST suture zone all preserve primary melt compositions. Multi-element plots indicate that all the intrusions in the CVST metavolcanics and the boundary between the WMGT and CVST have arc-type and back arc basin-type magma affinities, showing enrichment in large ion lithophile elements and Nb-Ta depletion. Conversely, gabbros from the EMGT and one diorite body in the CVST suture zone have ocean island tholeiite (OIT)-type magma affinities. These two contrasting magma types intrude geologically differing units bordered by the ultramafic-metasedimentary suture zone. This suggests that accretion/intrusion of arc-back arc type plutons and OIT-type plutons occurred near the suture zone. Such a magmatic association is common in the Arabian-Nubian-Shield(ANS), and is interpreted to have formed in intra oceanic, convergent margin, and continental collision settings, with subsequent preservation along the suture zone in the Neoproterozoic. The West Ethiopian Shield thus formed as a part of the ANS during multi stage accretion and closure of the Mozambique Ocean in Neoproterozoic time.抄録全体を表示PDF形式でダウンロード (1935K) -
塩野 敏昭原稿種別: 本文
2008 年 62 巻 4 号 p. 273-285
発行日: 2008/07/25
公開日: 2017/05/16
ジャーナル オープンアクセス本論では,約1,000本のボーリング資料をもとに長野市北部地域の後背湿地堆積物の詳細な分布と層序を明らかにしてその堆積年代を考察した.また,N値や含水比の程度にもとづく軟弱地盤の細区分を行ない1941年に発生した長沼地震の被害と軟弱地盤との関係を検証した.得られた結論は以下のとおりである.1)長野市北部地域の後背湿地堆積物は,上位から第1粘土層,第2粘土層およびこれらに挟在される第1砂層,第2砂層,泥炭層に区分され,全層厚は最大40m近くに達する.第1粘土層は完新世(約1万年以降)に,第2粘土層は更新世の後期に対比される.2)後背湿地堆積物を工学的に評価し,N値4以下を示す軟質な第1粘土層とN値10以下を示す締りの緩い第1砂層を軟弱地盤と定義してその分布を明らかにした.本地域には北東-南西方向に延びる2列の地溝状を示す軟弱地盤地帯が存在し,それらの成因が長野盆地西縁断層に伴う盆地側の相対的な沈降によるものであることを述べた.3)長沼地震によって被災した地域は長野市北部の後背湿地堆積物と自然堤防の分布域に集中していることを明らかにした.被害状況と地盤の関係から盆地内における液状化被害は第1砂層を挟在する地域と一致し,揺れによる被害は,第1粘土層が分布する地域にあたるが,この状況をより詳しく見ると,被害は後背湿地堆積物の分布域の中央部よりもむしろ地溝状を示す軟弱地盤地帯の縁の部分に集中している.抄録全体を表示PDF形式でダウンロード (2788K) -
向井 理史, 小坂 共栄原稿種別: 本文
2008 年 62 巻 4 号 p. 287-291
発行日: 2008/07/25
公開日: 2017/05/16
ジャーナル オープンアクセスThe Miocene Uchimura Formation, which consists of the Miocene submarine volcanic rocks and the Lower Pleistocene volcanic rocks in the Chushin Highland are widely distributed in the northeastern part of the Utsukushigahara Plateau, Chushin Highland, central Japan. An andesite lava, which effused on land surface, was found out in about 3 km eastward of the Utsukushigahara Plateau. The K-Ar age for whole rock sample of the andesite lava taken from basal part of the lava flow deposits indicates 2.11±0.05 Ma in this study. According to the stratigraphical, petrographical and whole rock chemistry data, it is considered that the andesite lava belongs to the volcanic rocks in the Chushin Highland. The result is suggested that the volcanic activity in the Chushin Highland was initiated around 2.1 Ma. Consequently, it is clear that the volcanic activity in the Chushin Highland had took place both in the Upper Pliocene and Pleistocene.抄録全体を表示PDF形式でダウンロード (948K) -
高島累層研究会 , 冨田 克敏, 中野 聰志原稿種別: 本文
2008 年 62 巻 4 号 p. 293-296
発行日: 2008/07/25
公開日: 2017/05/16
ジャーナル オープンアクセスA crowd of large compact vivianite nodules has been found in the mud bed of the Takashima Formation, the Kobiwako Group, Kutsuki, Takashima City, Shiga Prefecture, Japan. The nodules are of variable shape from ball-like to stick-like. The biggest stick-like nodule is 15cm long and 4cm wide. They consist of many small globular grains, each of which is also composed of many blade-like vivianite crystals radically combined. Vivianite nodules have been associated with neighboring siderite grains and, moreover, each vivianite globular grain within a nodule contains siderite grains sporadically. Each siderite grain consists of aggregates of many platy crystals. These facts indicate that the vivianite was crystallized after the siderite formation.抄録全体を表示PDF形式でダウンロード (1128K) -
島津 光夫原稿種別: 本文
2008 年 62 巻 4 号 p. 297-302
発行日: 2008/07/25
公開日: 2017/05/16
ジャーナル オープンアクセスPDF形式でダウンロード (1555K)
- |<
- <
- 1
- >
- >|