Reishi Takashima - Academia.edu (original) (raw)

Papers by Reishi Takashima

Research paper thumbnail of Large igneous province activity drives oceanic anoxic event 2 environmental change across eastern Asia

Communications earth & environment, Feb 19, 2024

Research paper thumbnail of Depositional Environments Revealed From Biomarkers in Sediments Deposited During the Mid-Cretaceous Oceanic Anoxic Events (OAEs) in the Vocontian Basin (SE France)

Research paper thumbnail of Application of MART Analysis to Infer Paleoseasonality in a Pleistocene Shallow Marine Benthic Environment

Research paper thumbnail of Decrease in volume and density of foraminiferal shells with progressing ocean acidification

Scientific Reports, Oct 7, 2021

Research paper thumbnail of Upper Albian to Lower Cenomanian biostratigraphy in the Oyubari area, Hokkaido, Japan: toward a Cretaceous biochronology for the North Pacific

Acta Geologica Polonica, Jun 30, 2003

Research paper thumbnail of Paleoenvironmental change during the mid-Cretaceous Oceanic Anoxic Event 1b

Annual Meeting of the Geological Society of Japan The 121st Annual Meeting(2014' Kagoshima), 2014

Research paper thumbnail of Origins of acritarchs found in sedimentary rocks deposited during the mid-Cretaceous Oceanic Anoxic Events (OAEs) and their contribution to primary production in the Cretaceous ocean

Annual Meeting of the Geological Society of Japan The 122nd Annual Meeting(2015' Nagano), 2015

Research paper thumbnail of Palaeoenvironment of a monospecific association of a new bryozoan species, Schizoretepora tamagawensis sp. n. (Phidoloporidae, Bryozoa), from the Miocene Tanosawa Formation, Northern Japan

Neues Jahrbuch für Geologie und Paläontologie, 2015

ABSTRACT A new species of Phidoloporidae (Bryozoa), Schizoretepora tamagawensis sp. n. is reporte... more ABSTRACT A new species of Phidoloporidae (Bryozoa), Schizoretepora tamagawensis sp. n. is reported from the Tanosawa Formation (Miocene) in northern Japan. This species is very similar to the Recent Schizoretepora tumescens (Ortmann, 1890). The unique occurrence in circular patches in an almost monospecific association indicates a shallow subtidal and soft substrate environment which limited the occurrence of other benthic species.

Research paper thumbnail of First record of a Cretaceous cheilostome bryozoan from Hokkaido, Japan

Cretaceous Research, Dec 1, 2006

Research paper thumbnail of Cretaceous warming and environmental changes linked to volcanism

Research paper thumbnail of Correlation and tephrochronology of tuffs based on trace element composition of apatite phenocrysts

テフラの対比は,第四系~鮮新統においては,地層の年代決定における重 要な手法として定着している.しかしながら,中新世より古い時代の凝灰岩 では,火山ガラスの大部分が変質しているため,火山ガラスの... more テフラの対比は,第四系~鮮新統においては,地層の年代決定における重 要な手法として定着している.しかしながら,中新世より古い時代の凝灰岩 では,火山ガラスの大部分が変質しているため,火山ガラスの形態,屈折率, 化学組成を用いたテフラの識別・対比は困難である.一方,近年,続成作用 に強いアパタイトの化学組成を用いた凝灰岩の対比が,北米や北欧地域にお いて盛んにおこなわれている(たとえば,Sell & Samson, 2011a, b).これら の研究の結果,従来,北米から北欧にかけて追跡され,顕生代最大の噴火の 産物と考えられてきたオルドビス紀の凝灰岩が,実は同時期の別々の噴火に よって形成されたことが明らかにされている(Sell & Samson, 2011a). 本研究では,アパタイトの微量元素組成(F, Cl, Mg, Mn, Fe, Y, Ceの含有量) を用いた凝灰岩の対比の有用性を検証するため,秋田県男鹿半島や宮城県鬼 首地域に露出するいくつかの第四紀広域テフラと,それぞれの給源火山の火 砕流堆積物に含まれるアパタイトを分析した.さらに,火山ガラスが変質し ている古い凝灰岩の対比・識別の可否を検討するために,中新統・室生火砕 流堆積物-石仏凝灰岩や古第三系根室層群,白亜系蝦夷層群に挟まる各凝灰岩 のアパタイトの微量元素組成も測定した.測定に際しては,東北大学金属材 料研究所の波長分散型EPMA(日本電子製 JXA-8530F)を用い,Goldoff et al. (2012)によって示されたアパタイトの分析条件で行った. 第四紀の各テフラおよび根室層群,蝦夷層群の各凝灰岩については,アパ タイトの各微量元素組成のグラフにおいて独自の領域にプロットされ,対 比・識別に極めて有効であることが分かった.蝦夷層群においては200km以 上離れたセクションや堆積相の異なるセクションでも凝灰岩を対比するこ とができた.室生火砕流堆積物については,およそ300mの厚さの溶結凝灰岩 うち,基底部,下部,中部~上部の3つの区間でアパタイトの化学組成が明瞭 に異なることが明らかになった.室生火砕流堆積物の遠方相と考えられてき た非溶結の石仏凝灰岩のアパタイトは,室生火砕流堆積物の下部のアパタイ トと組成が一致した.これらのことから,室生火砕流堆積物のうち,下部の ものが...

Research paper thumbnail of Variations in redox condition of marine environment recorded by organic geochemical proxies in sedimentary rocks deposited across the Cenomanian-Turonian boundary in the Yezo Group, Hokkaido, Japan

Research paper thumbnail of High-resolution analysis of the mid-Cretaceous Oceanic Anoxic Event 1b in the Vocontian Basin, Southeast France

Research paper thumbnail of Paleoenvironmental change across the mid-Cretaceous Oceanic Anoxic Event 2 based on benthic foraminiferal assemblage in the Northwest Pacific

Research paper thumbnail of Preliminary study of Cretaceous tephrochronology in Japan

Research paper thumbnail of Comparison of planktic foraminifer biostratigraphy and assemblages in the eastern equatorial Pacific from Middle to Late Miocene

Research paper thumbnail of Linkage between LIPs formation and environmental changes in Pacific during the Cretaceous OAE 2 . *

Mid Cretaceous period (120-90 Ma) is characterized by the greatest value in the rate of ocean cru... more Mid Cretaceous period (120-90 Ma) is characterized by the greatest value in the rate of ocean crust production over the past 150 million years. During this period, a lot of Large Igneous Provinces (LIPs) were emplaced in the Pacific, Atlantic and Indian oceans. Since the emplacement ages of the Cretaceous LIPs are concurrent with the Oceanic Anoxic Events (OAEs), various hypotheses explaining the linkage between the LIPs and OAEs have been proposed since the end of 1980’s. A popular hypothesis attributes the high productivity and thereby ocean anoxia to the increased supply of biolimiting metals into photic zone during the LIPs formation (e.g., Snow et al., 2005). Another hypothesis explains the reason of increased productivity that elevated sea level as well as pCO2 by LIPs eruption caused increase in global warming and continental runoff, which delivered terrestrial nutrient to ocean surface (e.g., Monteiro et al., 2012). In order to understand linkage between large volcanic erupt...

Research paper thumbnail of The Kellwasser Events in the Upper Devonian Xom Nha Formation, Central Vietnam

Journal of the Sedimentological Society of Japan, 2020

Research paper thumbnail of Decrease in volume and density of foraminiferal shells with progressing ocean acidification

Scientific Reports, 2021

Rapid increases in anthropogenic atmospheric CO2 partial pressure have led to a decrease in the p... more Rapid increases in anthropogenic atmospheric CO2 partial pressure have led to a decrease in the pH of seawater. Calcifying organisms generally respond negatively to ocean acidification. Foraminifera are one of the major carbonate producers in the ocean; however, whether calcification reduction by ocean acidification affects either foraminiferal shell volume or density, or both, has yet to be investigated. In this study, we cultured asexually reproducing specimens of Amphisorus kudakajimensis, a dinoflagellate endosymbiont-bearing large benthic foraminifera (LBF), under different pH conditions (pH 7.7–8.3, NBS scale). The results suggest that changes in seawater pH would affect not only the quantity (i.e., shell volume) but also the quality (i.e., shell density) of foraminiferal calcification. We proposed that pH and temperature affect these growth parameters differently because (1) they have differences in the contribution to the calcification process (e.g., Ca2+-ATPase and Ω) and (...

Research paper thumbnail of Upper Devonian carbonates encapsulating the Frasnian-Fammenian boundary in northern Vietnam

Journal of the Sedimentological Society of Japan, 2017

Research paper thumbnail of Large igneous province activity drives oceanic anoxic event 2 environmental change across eastern Asia

Communications earth & environment, Feb 19, 2024

Research paper thumbnail of Depositional Environments Revealed From Biomarkers in Sediments Deposited During the Mid-Cretaceous Oceanic Anoxic Events (OAEs) in the Vocontian Basin (SE France)

Research paper thumbnail of Application of MART Analysis to Infer Paleoseasonality in a Pleistocene Shallow Marine Benthic Environment

Research paper thumbnail of Decrease in volume and density of foraminiferal shells with progressing ocean acidification

Scientific Reports, Oct 7, 2021

Research paper thumbnail of Upper Albian to Lower Cenomanian biostratigraphy in the Oyubari area, Hokkaido, Japan: toward a Cretaceous biochronology for the North Pacific

Acta Geologica Polonica, Jun 30, 2003

Research paper thumbnail of Paleoenvironmental change during the mid-Cretaceous Oceanic Anoxic Event 1b

Annual Meeting of the Geological Society of Japan The 121st Annual Meeting(2014' Kagoshima), 2014

Research paper thumbnail of Origins of acritarchs found in sedimentary rocks deposited during the mid-Cretaceous Oceanic Anoxic Events (OAEs) and their contribution to primary production in the Cretaceous ocean

Annual Meeting of the Geological Society of Japan The 122nd Annual Meeting(2015' Nagano), 2015

Research paper thumbnail of Palaeoenvironment of a monospecific association of a new bryozoan species, Schizoretepora tamagawensis sp. n. (Phidoloporidae, Bryozoa), from the Miocene Tanosawa Formation, Northern Japan

Neues Jahrbuch für Geologie und Paläontologie, 2015

ABSTRACT A new species of Phidoloporidae (Bryozoa), Schizoretepora tamagawensis sp. n. is reporte... more ABSTRACT A new species of Phidoloporidae (Bryozoa), Schizoretepora tamagawensis sp. n. is reported from the Tanosawa Formation (Miocene) in northern Japan. This species is very similar to the Recent Schizoretepora tumescens (Ortmann, 1890). The unique occurrence in circular patches in an almost monospecific association indicates a shallow subtidal and soft substrate environment which limited the occurrence of other benthic species.

Research paper thumbnail of First record of a Cretaceous cheilostome bryozoan from Hokkaido, Japan

Cretaceous Research, Dec 1, 2006

Research paper thumbnail of Cretaceous warming and environmental changes linked to volcanism

Research paper thumbnail of Correlation and tephrochronology of tuffs based on trace element composition of apatite phenocrysts

テフラの対比は,第四系~鮮新統においては,地層の年代決定における重 要な手法として定着している.しかしながら,中新世より古い時代の凝灰岩 では,火山ガラスの大部分が変質しているため,火山ガラスの... more テフラの対比は,第四系~鮮新統においては,地層の年代決定における重 要な手法として定着している.しかしながら,中新世より古い時代の凝灰岩 では,火山ガラスの大部分が変質しているため,火山ガラスの形態,屈折率, 化学組成を用いたテフラの識別・対比は困難である.一方,近年,続成作用 に強いアパタイトの化学組成を用いた凝灰岩の対比が,北米や北欧地域にお いて盛んにおこなわれている(たとえば,Sell & Samson, 2011a, b).これら の研究の結果,従来,北米から北欧にかけて追跡され,顕生代最大の噴火の 産物と考えられてきたオルドビス紀の凝灰岩が,実は同時期の別々の噴火に よって形成されたことが明らかにされている(Sell & Samson, 2011a). 本研究では,アパタイトの微量元素組成(F, Cl, Mg, Mn, Fe, Y, Ceの含有量) を用いた凝灰岩の対比の有用性を検証するため,秋田県男鹿半島や宮城県鬼 首地域に露出するいくつかの第四紀広域テフラと,それぞれの給源火山の火 砕流堆積物に含まれるアパタイトを分析した.さらに,火山ガラスが変質し ている古い凝灰岩の対比・識別の可否を検討するために,中新統・室生火砕 流堆積物-石仏凝灰岩や古第三系根室層群,白亜系蝦夷層群に挟まる各凝灰岩 のアパタイトの微量元素組成も測定した.測定に際しては,東北大学金属材 料研究所の波長分散型EPMA(日本電子製 JXA-8530F)を用い,Goldoff et al. (2012)によって示されたアパタイトの分析条件で行った. 第四紀の各テフラおよび根室層群,蝦夷層群の各凝灰岩については,アパ タイトの各微量元素組成のグラフにおいて独自の領域にプロットされ,対 比・識別に極めて有効であることが分かった.蝦夷層群においては200km以 上離れたセクションや堆積相の異なるセクションでも凝灰岩を対比するこ とができた.室生火砕流堆積物については,およそ300mの厚さの溶結凝灰岩 うち,基底部,下部,中部~上部の3つの区間でアパタイトの化学組成が明瞭 に異なることが明らかになった.室生火砕流堆積物の遠方相と考えられてき た非溶結の石仏凝灰岩のアパタイトは,室生火砕流堆積物の下部のアパタイ トと組成が一致した.これらのことから,室生火砕流堆積物のうち,下部の ものが...

Research paper thumbnail of Variations in redox condition of marine environment recorded by organic geochemical proxies in sedimentary rocks deposited across the Cenomanian-Turonian boundary in the Yezo Group, Hokkaido, Japan

Research paper thumbnail of High-resolution analysis of the mid-Cretaceous Oceanic Anoxic Event 1b in the Vocontian Basin, Southeast France

Research paper thumbnail of Paleoenvironmental change across the mid-Cretaceous Oceanic Anoxic Event 2 based on benthic foraminiferal assemblage in the Northwest Pacific

Research paper thumbnail of Preliminary study of Cretaceous tephrochronology in Japan

Research paper thumbnail of Comparison of planktic foraminifer biostratigraphy and assemblages in the eastern equatorial Pacific from Middle to Late Miocene

Research paper thumbnail of Linkage between LIPs formation and environmental changes in Pacific during the Cretaceous OAE 2 . *

Mid Cretaceous period (120-90 Ma) is characterized by the greatest value in the rate of ocean cru... more Mid Cretaceous period (120-90 Ma) is characterized by the greatest value in the rate of ocean crust production over the past 150 million years. During this period, a lot of Large Igneous Provinces (LIPs) were emplaced in the Pacific, Atlantic and Indian oceans. Since the emplacement ages of the Cretaceous LIPs are concurrent with the Oceanic Anoxic Events (OAEs), various hypotheses explaining the linkage between the LIPs and OAEs have been proposed since the end of 1980’s. A popular hypothesis attributes the high productivity and thereby ocean anoxia to the increased supply of biolimiting metals into photic zone during the LIPs formation (e.g., Snow et al., 2005). Another hypothesis explains the reason of increased productivity that elevated sea level as well as pCO2 by LIPs eruption caused increase in global warming and continental runoff, which delivered terrestrial nutrient to ocean surface (e.g., Monteiro et al., 2012). In order to understand linkage between large volcanic erupt...

Research paper thumbnail of The Kellwasser Events in the Upper Devonian Xom Nha Formation, Central Vietnam

Journal of the Sedimentological Society of Japan, 2020

Research paper thumbnail of Decrease in volume and density of foraminiferal shells with progressing ocean acidification

Scientific Reports, 2021

Rapid increases in anthropogenic atmospheric CO2 partial pressure have led to a decrease in the p... more Rapid increases in anthropogenic atmospheric CO2 partial pressure have led to a decrease in the pH of seawater. Calcifying organisms generally respond negatively to ocean acidification. Foraminifera are one of the major carbonate producers in the ocean; however, whether calcification reduction by ocean acidification affects either foraminiferal shell volume or density, or both, has yet to be investigated. In this study, we cultured asexually reproducing specimens of Amphisorus kudakajimensis, a dinoflagellate endosymbiont-bearing large benthic foraminifera (LBF), under different pH conditions (pH 7.7–8.3, NBS scale). The results suggest that changes in seawater pH would affect not only the quantity (i.e., shell volume) but also the quality (i.e., shell density) of foraminiferal calcification. We proposed that pH and temperature affect these growth parameters differently because (1) they have differences in the contribution to the calcification process (e.g., Ca2+-ATPase and Ω) and (...

Research paper thumbnail of Upper Devonian carbonates encapsulating the Frasnian-Fammenian boundary in northern Vietnam

Journal of the Sedimentological Society of Japan, 2017