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1.

論文(リポジトリ)

論文(リポジトリ)
野田, 篤 ; 利光, 誠一 ; 栗原, 敏之 ; 岩野, 英樹
出版情報: 地質学雑誌 — 地質学雑誌.  116  pp.99-113,  2010-02.  日本地質学会
本文リンク: http://hdl.handle.net/10191/26521
概要: 上部白亜系の和泉層群は横ずれ堆積盆を西から東へ埋積した地層と言われているが,四国の西部と東部とでは岩相や地質構造に違いがあり,堆積盆の埋積過程やテクトニクスが異なっていた可能性がある.今回,四国中央部の新居浜地域の和泉層群を調査し,北縁相の 楠崎層と主部相の磯浦層・新居浜層の3つの新しい地層名を定義した.新居浜層に挟在する珪長質凝灰岩を用いたフィッション・トラック年代は79.1±2.2 Maを示した.また,新居浜層の泥岩から産出した放散虫化石群集は,前期-中期カンパニアン階のDK群集帯に対比された.これらの結果は新居浜層の堆積年代が中期カンパニアン期であり,四国西部(松山地域)に分布する同層群とほぼ同時期に堆積したことを示唆している.本地域の和泉層群の岩相や地質構造は四国西部と東部に見られる同層群の両方の特徴を持っており,その堆積盆形成・埋積プロセスの過渡期に堆積した地層であると考えられる.<br />The Izumi Group, which occurs from western Shikoku to the Izumi Mountains, Kii Peninsula, comprises sediments deposited in a strike-slip basin during the Late Cretaceous. Some differences exist in the lithostratigraphy and geological structure of the group where it occurs in western and eastern Shikoku; consequently, outcrops in central Shikoku may record evidence of the transition between the two areas. We conducted stratigraphical and geochronological surveys as part of compiling the "Niihama" geological map, and defined the following new formations: the Kussaki, Isoura, and Niihama formations. Fission-track dating of felsic tuff beds in the Niihama Formation yielded an age of 79.1±2.2 Ma. The radiolarian assemblages within mudstone of the Niihama Formation are DK assemblages, corresponding to the early-middle Campanian. The combined age data indicate a middle Campanian age for deposition of the Niihama Formation. The present results suggest that the Izumi Group was simultaneously deposited in western and central Shikoku. The lithology and geological structure in the study area are comparable with those in western and eastern Shikoku, indicating that the analyzed rocks represent strata deposited during a transitional stage of basin development and basin fill. 続きを見る
2.

論文(リポジトリ)

論文(リポジトリ)
加々島, 慎一 ; 志村, 俊昭
出版情報: 地質学雑誌 — 地質学雑誌.  107  pp.515-530,  2001-08.  日本地質学会
本文リンク: http://hdl.handle.net/10191/17810
概要: The Late Cretaceous to Paleogene Iwafune granitoids of are distributed around the border between Niigata and Yamagata Pr efectures, Japan. The Budo Mountains is located in northern part of Niigata Prefecture and is exposed in an area covering more than 250 square kilometers. It consists of Iwafune granitoids, which are divided into six lithological types ; porphyritic biotite granite (PBG), biotite granite (BG), garnet two-mica granite (GTMG), two-mica granite (TMG), quartz diorite (QD) and granodiorite (GD). The six rock types can be assigned to three rock groups on the basis of petrological observations as follows : biotite granite group(BG-group ; PBG and BG), and tow-mica granite group (TMG-group;GTMG and TMG) and diorite group (D-group;QD and GD). Most of the granitoids in this area are attributed to BG-group. This group is composed of quartz, plagioclase, potassium feldspar, biotite and minor amounts of accessory minerals. Especially, the PBG contains potassium feldspar megacrysts and sometimes shows schlieren layering owing to the concentration of biotite and plagioclase. BG-group has medium SiO_2 content ranging from 69 to 77 weight percent and is peraluminous. Modal and bulk chemical compositions show that BG-group has curved trend. Mass balance calculation indicates that the BG-series magma can be derived from common parental magma through two-stage fractional crystallization of potassium feldspar, biotite and plagioclase. The first stage is characterized by plagioclase- and biotite-rich fractionation, and the second stage is characterized by fractionation of biotite and potassium feldspar more than plagioclase.<br />新潟県北部の蒲萄山塊には,後期白亜紀から古第三紀の岩船花崗岩類が分布する.蒲萄山塊南部の岩船花崗岩類は,斑状黒雲母花崗岩,黒雲母花崗岩,ざくろ石両雲母花崗岩,両雲母花崗岩,石英閃緑岩,花崗閃緑岩に区分された.これらは産状,構成鉱物,全岩-鉱物組成から3つの岩類に分けられる.主要岩相である斑状黒雲母花崗岩の結晶作用を検討した.モード組成および全岩化学組成から屈曲したトレンドが得られ,2段階の分別結晶作用が考えられる.マスバランス計算により,第1段階では斜長石と黒雲母が主な分別鉱物であり,第2段階では斜長石よりもカリ長石+黒雲母の分別が多かったことが導き出された. 続きを見る
3.

論文(リポジトリ)

論文(リポジトリ)
Rezanov, Andrey I. ; Shuto, Kenji ; Iizumi, Shigeru
出版情報: 地質学雑誌.  102  pp.828-831,  1996-09.  日本地質学会
本文リンク: http://hdl.handle.net/10191/17794
4.

論文(リポジトリ)

論文(リポジトリ)
松岡, 篤
出版情報: 地質学論集 — 地質学論集.  55  pp.17-26,  2000-01.  日本地質学会
本文リンク: http://hdl.handle.net/10191/6273
概要: 付加体研究における放散虫の役割について,生層序,古生物地理,放散虫含有量と堆積岩の物性という観点から研究成果をレビューするとともに,最近進めつつある検討例を紹介した.生層序学研究に基礎を置く放散虫年代学の進展により,付加体の成長速度や成長様 式について,定量的に議論を行うことが可能となった.古生物地理に関しては,今後この分野の研究が進展すると,付加体形成場の相対的位置関係を議論できるようになることを指摘した.また,“熱帯度”を表現するために,VEN(Vallupus/Eucyrtidiellum Number)という指標を提案した.放散虫の含有量と堆積岩の物性という点については,放散虫の絶滅事件により相対的に強度の弱い層準(下部トリアス系)が形成され,それが付加体形成時にデコルマ面として機能していることを例にあげた.また,付加体研究と古海洋学研究を有機的に結びつけていくことの重要性を強調した. / This paper reviews major roles of radiolarians in the study of accretionary complexes. The major roles include (1) age control, (2) spatial control and (3) mechanical control. The age control is related to radiolarian biostratigraphic investigations. The geochronologic calibration for zonal scheme makes it possible not only to give a basis for chronostratigraphic correlation among accretionary complexes but also to give data for the rate and mode of growth of accretionary complexes. The spatial control is connected to radiolarian paleobiogeographic research. Recognition of biogeographic realms offers a viewpoint for the relative position of the formation of accretionary complexes independent of other data such as paleomagnetic records. VEN (Vallupus(V)/Eucyrtidiellum(E) Number=V/(V+E)×100) is proposed as one of paleoceanographic parameter which indicates a tropical environment. Mechanical control is related to the physical properties of sedimentary rocks. Radiolarian evolutionary events such as mass extinction and change in abundance affect lithology, particularly in pelagic sediments because radiolarian skeletons are the major components among rock-forming materials. The fluctuation of radiolarian content in pelagic sediments changes the physical properties along a lithologic sequence. This lithologic variation has an essential meaning in accretionary events because physically weak horizons act as a decollement above which the sedimentary package is off-scraped from a subducting oceanic plate. The Lower Triassic siliceous claystone unit, which was formed due to the end Permian mass extinction, is a good example for a decollement horizon. 続きを見る
5.

論文(リポジトリ)

論文(リポジトリ)
梅津, 慶太 ; 栗田, 裕司
出版情報: 石油技術協会誌 — 石油技術協会誌.  72  pp.215-223,  2007-03.  石油技術協会
本文リンク: http://hdl.handle.net/10191/17774
概要: Palynostratigraphic investigation and age determination based on terrestrial palynomorphs are conducted on the nonmarine to shallow marine deposits of the Upper Cretaceous Kuji Group, Northeast Japan. Four palynostratigraphic assemblages are recognized in the group (assemblages A, B, C, and D, in ascending order). The variation of the assemblages are considered to depend on changes of paleovegetation and depositional environment of host sediments, Especially, the variation of assemblages A to C from marine-influenced deposits suggests a regional paleovegetational change represented by the increase of bisaccate pollen-producing conifers during the deposition of the Tamagawa Formation. The occurrence of angiosperm triprojectate pollen in the Kuji Group shows that the interval from the upper part of the Tamagawa Formation to the Sawayama Formation is confined to Santonian to lower Campanian. This contributes to dating of the potential source rock/reservoir packages within Cretaceous sediments in the Yezo forearc basin. 続きを見る
6.

論文(リポジトリ)

論文(リポジトリ)
高橋, 正道
出版情報: 石油技術協会誌 — 石油技術協会誌.  70  pp.37-46,  2005-01.  石油技術協会
本文リンク: http://hdl.handle.net/10191/17772
概要: A new assemblage of Late Cretaceous fossil plants (the Kamikitaba assemblage) was discovered from the Ashizawa Formation of Futaba Group (Early Coniacian;89Ma). The flora includes well-preserved mesofossils of angiosperm flowers, fruits, seeds, leaf fragments and woods. Some aspects on the origin of angiosperms and the vegetational consequences of Cretaceous and Paleogene flora are reviewed in the paper. 続きを見る
7.

論文(リポジトリ)

論文(リポジトリ)
Ito, Tsuyoshi ; Matsuoka, Atsushi
出版情報: Science reports of Niigata University. (Geology) — Science reports of Niigata University. (Geology).  32(Supplement)  pp.125-136,  2017-10.  新潟大学理学部
本文リンク: http://hdl.handle.net/10191/48675
概要: Ie Island in northwestern Okinawa Prefecture, Japan, mainly comprises of basement rocks (Gusukuyama Formation of the Sou thern Chichibu terrane) and the overlying Pleistocene Ryukyu Group. The bedded cherts of the Gusukuyama Formation in Mt. Gusuku in the central part of Ie Island have yielded radiolarians ranging from the Neoalbaillella optima Zone (Changhsingian, Lopingian, Permian) to the Kilinora spiralis Zone (JR6: Oxfordian, Upper Jurassic). Siliceous mudstones in the southern flank of Mt. Gusuku have yielded radiolarians of the Pseudodictyomitra carpatica Zone (KR1: uppermost Jurassic–lowermost Cretaceous). This age difference is assumed to indicate the presence of a thrust between Mt. Gusuku and the southern flank of the mountain. Red chert clasts are contained in the Pleistocene Ryukyu Group at Waji on the north coast of Ie Island, and Permian radiolarians have been obtained from chert clasts. In addition, a red bedded chert boulder at Waji yielded Cisuralian (Early Permian) radiolarians including dimorphic pair of Albaillella sinuata Ishiga and Watase.<br />InterRed XV in Niigata 2017 Niigata University (JAPAN) Oct/22-Oct/27, 2017 続きを見る