Pleistocene to Upper Miocene collodarians and spumellarians (polycystine radiolarians) from the western Indian Ocean, ODP Site 710
Kamikuri, S.; Matsuzaki, K.; M
Bull. Coll. Educ., Ibaraki Univ.（Nat. Sci）, 2024年04月
Middle to Lower Miocene Radiolarian Biostratigraphy in the West Pacific Warm Pool at the International Ocean Discovery Program (IODP) 363 Site U1490: A Report Presenting Preliminary Results.
Matsuzaki; K.; Kamikuri; S. Sagawa.
Proceedings of the International Ocean Discovery Program, 2023年03月, ［査読有り］
Environmental conditions during the deposition of the diatomite-organic rich marl alternance of the lower Messinian of the Lower Chelif Basin (Algeria) interpreted from microfossil assemblages and geochemistry.
Journal of African Earth Science, ラスト(シニア)オーサー
Journal of African Earth Science, 2022年05月, ［査読有り］
Tropical radiolarian biostratigraphy from the early to late Miocene at ODP Site 714 in the tropical Indian Ocean
Shin-ichi Kamikuri
Paleontological Research, 2022年03月, ［査読有り］
Les radiolaires messiniens du Dahra (Bassin du Bas Chelif, Algerie): systematique et interet biostratigraphique.
Ali Mokhtar Samet; Abbas Marok; Matias Reloid; Shin-ichi Kamikuri, ラスト(シニア)オーサー
Annales de Paleontologie, 2021年10月, ［査読有り］
An Austral radiolarian biozonation for the Paleogene
Hollis; C.; Pascher; K.M.; Sanfilippo; A.; Nishimura; A.; Kamikuri; S.; Shepherd; C.L.
Stratigraphy, 2020年10月, ［査読有り］
An integrated cross-latitude event stratigraphy for Paleogene radioalrians
Hollis; C.; Pascher; K.M.; Sanfilippo; A.; Nishimura; A.; Kamikuri; S.; Shepherd; C.L.
Stratigraphy, 2020年10月, ［査読有り］
Variation in the eastern North Pacific subtropical gyre (California Current system) during the Middle to Late Miocene as inferred from radiolarian assemblages
Shin-ichi Kamikuri; Isao Motoyama, 筆頭著者
Marine Micropaleontology, 2020年05月, ［査読有り］
Middle to late Miocene radiolarians at ODP Site 1021 in the eastern North Pacific
Kamikuri, S
Bulletin of the Geological Survey of Japan, 2019年, ［査読有り］
Radiolarian assemblages from the lower to middle Miocene at IODP Site U1335 in the eastern equatorial Pacific
Kamikuri, S
Bulletin of the Geological Survey of Japan, 2019年, ［査読有り］
青森県深浦地域に分布する新第三系層状マンガン鉱床の放散虫化石と地質年代
坂井志緒乃,伊藤 孝,上栗伸一,本山 功,小室光世, 責任著者
地質学雑誌, 2019年, ［査読有り］
Report of the 15th meeting of the International Association of Radiolarists (InterRad XV), 20 October-1 November, 2017, Niigata, Japan
Matsuoka A; organizing committee of the; InterRad XV
Science reports of Niigata University (Geology), 2018年
Paleoceanographic history of the Japan Sea over the last 9.5 million years inferred from radiolarian assemblages (IODP Expedition 346 Sites U1425 and U1430)Matsuzaki, K. M; Itaki, T; Tada, R; Kamikuri, S, ラスト(シニア)オーサー, Previous studies showed that the evolution of the Japan Sea paleoceanography since the Miocene has been influenced by the regional tectonism (e.g., opening/closing of the connecting seaways) and regional/global climate. In the Japan Sea, Expedition 346 of the Integrated Ocean Drilling Program (IODP) retrieved core sediments dating back to the Miocene at two sites (U1425 and U1430). In this study, we reconstruct shallow-to-deep-water hydrography of the Japan Sea during the Mio-Pliocene based on radiolarian assemblages at Sites U1425 and U1430 considering the local tectonism and changes in global/regional climate. Our data suggest that glacioeustatic sea-level changes have probably had an influence on the local paleoceanography between 9.5 and 7.0 Ma. Indeed, warm water probably flowed from the North Pacific into the Japan Sea when sea level was high via shallow central and eastern seaways. In addition, the sill depth of the northern seaway was probably close to 1000 m between 9.5 and 7.8 Ma and had probably allowed inflow of oxygen minimum zone water from the North Pacific to the Japan Sea when sea level was high. In contrast, our data imply that Cycladophora nakasekoi, an endemic species to the Japan Sea, dominated between 9.5 and 73 Ma when sea level was low. Our data also suggest a progressive shoaling of the sill for the period since 7.8 Ma and that global climatic events such as such the late Miocene cooling (7.5-55 Ma) and the early Pliocene warmth have had a sustained influence on the Japan Sea. During the mid-Pliocene, a deep cooling of the subsurface to intermediate water of the Japan Sea likely occurred because species related to subarctic subsurface to intermediate waters were dominant between 5 and 3.8 Ma. The Northern Hemisphere Glaciation (ca. 3.0-2.7 Ma) and Mid-Pleistocene Transition (1.2-0.8 Ma) have both likely intensified the cooling of the Japan Sea., SPRINGEROPEN
Progress in Earth and Planetary Science, 2018年,
［査読有り］ Reconstruction of oceanic circulation patterns in the tropical Pacific across the early/middle Miocene boundary as inferred from radiolarian assemblagesShin-ichi Kamikuri; Theodore C. Moore, Although there have been attempts to infer Neogene oceanic circulation patterns in the tropical Pacific on the basis of multiple marine proxies, oceanic circulation patterns across the early/middle Miocene boundary are still poorly understood despite paleoclimate having significantly changed during this interval. In this study, we reconstruct the changes in tropical oceanic circulation patterns in the Pacific across the early/middle Miocene boundary based on radiolarian assemblages obtained at Integrated Ocean Drilling Program Site U1335 in the eastern tropical Pacific.
The radiolarian upwelling taxa increased during four intervals (18.4-18.1 Ma, 16.9-15.7 Ma, 15.2-14.6 Ma, 14.2-13.4 Ma). Radiolarian temperature index (RTI) was calculated using the relative abundances of the warm water (cluster B1) and cool water taxa (cluster B2) in order to evaluate relative temperature fluctuations of the surface water. The sea surface temperature index was relatively high from 16.8 to 16.0 Ma and gradually decreased from 16.0 to 14.6 Ma. Subsequently, the temperature index decreased stepwise at 13.9 and 13.4 Ma and became relatively low from 13.4 to 12.7 Ma. Comparison of the RTI record in the eastern tropical Pacific to the climatic index based on the benthic foraminiferal delta O-18 record shows that variability in the two records-follows a roughly similar trend from the early to the middle Miocene. However, the sea surface temperature record does not indicate a sharp increase in warmth in the eastern tropical Pacific during the mid-Miocene climatic Optimum-1 (MMC0-1), as suggested by the benthic isotopic record. This is likely because of increased upwelling of cool, nutrient-rich water at this time.
Beginning in the latest early Miocene (similar to 17 Ma) radiolarian assemblages were dominated by different taxa in the eastern and western tropical Pacific. This pattern is interpreted as indicating a shallower thermocline in the east and a deeper thermocline in the west, based on the relative abundance of the upwelling taxa. There is an overall increasing trend in this difference since the latest early Miocene. We tie these events to the effective closure of the Indo-Pacific seaway and the development of a substantial western Pacific warm pool along with the development of a strong Equatorial Undercurrent., ELSEVIER SCIENCE BV
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY, 2017年12月,
［査読有り］ Radiolarian biostratigraphy from middle Miocene to late Pleistocene in the Japan SeaShin-Ichi Kamikuri; Takuya Itaki; Isao Motoyama; Kenji M. Matsuzaki, In the Integrated Ocean Drilling Program (IODP) Exp. 346, sampling by drilling was conducted at seven sites (U1422-U1427 and U1430) in the Japan Sea. Radiolarians in moderately well preserved states were found in most samples throughout the sequence in varying abundance. Forty-one radiolarian datum events were identified in this study, and the radiolarian zonation that best divides the middle Miocene to Pleistocene sequences with updated ages of radiolarian datum events (estimates based on the geomagnetic polarity time scale (GTS) 2012) was applied to the sedimentary sequences in the Japan Sea. Here, four new radiolarian zones are proposed for the Quaternary of the Japan Sea, and one zone is slightly revised to adjust for differences among other zones. The sequences collected at the sites extended from the Pleistocene Ceratospyris borealis Zone to progressively deeper zones as follows: Site U1427, four zones to the Pleistocene Schizodiscus japonicus; Site U1422, six zones to the late Pliocene Hexacontium parviakitaense Zone; Sites U1423, U1424 and U1426, eight zones to the early Pliocene Larcopyle pylomaticus Zone; and Sites U1425 and U1430, fourteen zones to the middle Miocene Eucyrtidium inflatum Zone. The absence or extremely rare occurrence of Stylatractus universus and E. matuyamai indicates that S. universus lived in the deep water of the northwestern Pacific and had not been able to migrate into the Japan Sea across the Tsugaru Strait since the Pliocene., PALAEONTOLOGICAL SOC JAPAN
PALEONTOLOGICAL RESEARCH, 2017年10月,
［査読有り］ Late Neogene radiolarian biostratigraphy of the eastern North Pacific ODP Sites 1020/1021Shin-Ichi Kamikuri, During Ocean Drilling Program Leg 167, Sites 1020/1021 were drilled to assess the paleoceano-graphic conditions within the northern region of the California Current. Radiolarian records from the upper middle Miocene to Pleistocene were obtained at Sites 1020/1021 cores in order to develop a correlation between Neogene biostratigraphic data and paleomagnetic chronostratigraphy. Of 66 radiolarian events identified during this study, 26 Pleistocene to late Miocene events were directly tied to the paleomagnetic stratigraphy, and 40 middle to late Miocene events were correlated with that result by second-order methods based on the diatom biostratigraphy. The updated ages of radiolarian bioevents were estimated based on the geologic time scale of Ogg (2012). Of these events, 12 bioevents that define low-latitude tropical radiolarian zones were either missing at Sites 1020/1021, or proved to have different ranges from those in the tropics. Using selected bioevents of the temperate and subarctic species, the studied sequences of Sites 1020/1021 were divided into fifteen radiolarian zones/subzones from the Eucyrtidium inflatum Zone to Botryostrobus aquilonaris Zone. Six new subzones were described: Hexacontium parviakitaense, Lamprocyclas hannai, Lithelius klingi, Dictyophimus splendens, Cycladophora cabrilloensis, and Collosphaera reynoldsi subzones. The Cycladophora funakawai Zone was proposed for the subarctic Northwest Pacific., PALAEONTOLOGICAL SOC JAPAN
PALEONTOLOGICAL RESEARCH, 2017年07月,
［査読有り］ Cenozoic biostratigraphy, chronostratigraphy and paleoceanography in the Boso Peninsula and Bandai Volcano in the Aizu region, East JapanIsao Motoyama; Takuya Itaki; Shin-ichi Kamikuri; Yojiro Taketani; Makoto Okada, The Boso Peninsula is a geologically active region where Cenozoic marine sediments formed in a wide variety of depositional and tectonic environments, including ocean basins, trench, trench-slope basins, forearc basins, and shelf to coastal zones. Radiolarians are key to dating most of these sedimentary rocks. In the northern part of the peninsula, Quaternary sedimentary sequences consisting mainly of siltstone and sandstone crop out along canyons of the Yoro and other rivers. There is no better place in the world than the Yoro canyon to correlate the Pleistocene geomagnetic polarity records to marine micro-biostratigraphy, oxygen isotope records, and radiometric ages from volcanic ash layers. This feature is of great benefit to establishing the boundary stratotype of the lower and middle parts of the Pleistocene Stage. In the more mountainous area to the south, visitors can trace the geological history back to middle Miocene through continuous sedimentary sequences. The earliest fossils imprinted in the rock of the peninsula are of early Cretaceous radiolarians from the Mineoka ophiolite complex. Since the Early Miocene the southern part of the peninsula was covered by seas and close to the trench where the Philippine Sea Plate subducts under the North American Plate. Continual subduction of the oceanic plate resulted in a pile of accreted Miocene sedimentary rocks in the southern part of the peninsula. Cover sediments unconformably resting on those accretionary prisms are thought to represent trench-slope basin deposits. Well-developed uplifted marine terraces in the southern portion of the peninsula represent the Holocene-continuing seismic activity associated with the earthquake cycle. Mount Bandai is a cone-shaped active stratovolcano. Past eruptions and collapses of mountain body formed a dammed lake, Lake Inawashiro, the fourth largest lake in Japan, to the south and created the numerous beautiful lakes in the forest land to the north. Bandai Volcano and its surrounding area was registered as a Japanese Geopark in 2011.InterRed XV in Niigata 2017 Niigata University (JAPAN) Oct/22-Oct/27, 2017, 新潟大学理学部
Science Report of Niigata University, 2017年,
［査読有り］ Radiolarian stratigraphy near the Eocene-Oligocene boundaryT. C. Moore; Shin-ichi Kamikuri; Andrea M. Erhardt; Jack Baldauf; Helen K. Coxall; Thomas Westerhold, Three sites from the equatorial Pacific (ODP 1218, IODP U1333, and U1334) are judged to have a complete stratigraphic sequence across the Eocene-Oligocene boundary. The sections of all three sites from similar to 40 Ma to similar to 30 Ma have been sampled and the samples merged into a single composite section with an average sample spacing <20 kyr. A total of 76 radiolarian species, species groups, and specific variant forms provide a detailed radiolarian stratigraphy across this climatically important boundary. Altogether 47 Eocene radiolarian species had their last appearance between similar to 40 Ma and the end of the final step of the Eocene-Oligocene climate transition, many of them in discreet episodes of extinction that grew in magnitude as the transition was approached. First appearance datums appear to cluster at the base of the cool-down from the middle Eocene climate optimum and near the base of the Oligocene, following a maximum in radiolarian last appearances and coincident with relatively abundant diatoms. There appears to be little relationship between paleoproductivity as measured by barite accumulation rates and both first and last appearances of radiolarians. Diatoms are not common in the Eocene and their blossoming in the Oligocene is preceded by the major episodes of radiolarian extinctions. In the Oligocene radiolarian extinctions appear to be associated with low to moderate diatom abundance, whereas species first appearances seem to be associated with moderate to high diatom abundance. Neither paleoproductivity nor a competition for the dissolved silica (a resource necessary for diatom frustule and radiolarian test construction) appears to control the episodic extinction of radiolarians in the Eocene or the more dispersed loss of species in the Oligocene. (C) 2015 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
MARINE MICROPALEONTOLOGY, 2015年04月,
［査読有り］ Radiolarian assemblages during the middle-late Eocene transition at Site 1052, ODP Leg 171B, Blake Nose, western North Atlantic Ocean
Shin-ichi Kamikuri
News of Osaka Micropaleontologists, 2015年, ［査読有り］
Radiolarian magnetobiochronology and faunal turnover across the middle/late Eocene boundary at Ocean Drilling Program Site 1052 in the western North Atlantic OceanShin-ichi Kamikuri; Bridget S. Wade, Quantitative radiolarian assemblage analysis has been conducted on middle and upper Eocene sediments (Zones RP16 to RP18) from Ocean Drilling Program Site 1052 in order to establish the radiolarian magnetobiochronology and determine the nature of the faunal turnover across the middle/late Eocene boundary in the western North Atlantic Ocean. We recognize and calibrate forty-five radiolarian bioevents to the magneto- and cyclo-stratigraphy from Site 1052 to enhance the biochronologic resolution for the middle and late Eocene. Our data is compared to sites in the equatorial Pacific (Leg 199) to access the diachrony of biostratigraphic events. Eleven bioevents are good biostratigraphic markers for tropical/subtropical locations (south of 30 degrees N). The primary markers (lowest occurrences of Cryptocarpium azyx and Calocyclas bandyca) which are tropical zonal boundary markers for Zones RP17 and RP18 provide robust biohorizons for correlation and age determination from the low to middle latitudes and between the Atlantic and Pacific Oceans. Some other radiolarian bioevents are highly diachronous (<1 million years) between oceanic basins.
A significant faunal turnover of radiolarians is recognized within Chron C17n.3n (37.7 Ma) where 13 radiolarian species disappear rapidly in less than 100 kyr and 4 new species originate. The radiolarian faunal turnover coincides with a major extinction in planktonic foraminifera. We name the turnover phase, the Middle/Late Eocene Turnover (MLET). Assemblage analysis reveals the MLET to be associated with a decrease in low-mid latitude taxa and increase in cosmopolitan taxa and radiolarian accumulation rates. The MLET might be related to increased biological productivity rather than to surface-water cooling. (C) 2012 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
MARINE MICROPALEONTOLOGY, 2012年05月,
［査読有り］ Successive extinctions of muricate planktonic foraminifera (Morozovelloides and Acarinina) as a candidate for marking the base PriabonianBridget S. Wade; Vlasta Premec Fucek; Shin-ichi Kamikuri; Milos Bartol; Valeria Luciani; Paul N. Pearson, The formal placement of the Global Stratotype Section and Point (GSSP) for the base of the Priabonian (Upper Eocene) is currently under discussion. We suggest that two closely spaced extinctions of planktonic foraminifera at similar to 38 Ma offer excellent potential for long-distance correlation in marine strata. The double extinction, which occurred within 11 kyr, involved the loss of the distinctive 'muricate' taxa Morozovelloides and the large acarininids. We present detailed biostratigraphic analyses from the Adriatic Sea and re-evaluate the magnetobiochronology of the extinction of these muricate taxa from previous studies from Ocean Drilling Program Site 1052 (western North Atlantic) and the Alano di Piave Section (NE Italy). We show these bioevents are robust, synchronous across the Atlantic Ocean and among the best calibrated and most easily recognised foraminiferal biohorizons for the entire Cenozoic. The two separate but very closely spaced bioevents provide a means for testing for completeness in the proposed stratotype and other sections that contain these fossils. The muricate extinctions coincide with a large turnover in radiolarians, within the short Subchron Cl7n.3n, providing distinct correlation horizons in siliceous and terrestrial sediments. We propose that the lithological level at 57.62 m in the Alano Section associated with the HO of Morozovelloides crassatus define the base of the Priabonian and the Middle/Upper Eocene boundary., GEBRUDER BORNTRAEGER
NEWSLETTERS ON STRATIGRAPHY, 2012年,
［査読有り］ Evolutionary changes in the fossil radiolarian Stichocorys peregrina lineage on the basis of biometry in the eastern equatorial Pacific (IODP Site U1335) and Northeast Pacific (ODP Site 887)Shin-ichi Kamikuri, Stichocotys peregrina (Riedel) contributes to paleoceanography as a valuable stratigraphic tool for correlation of deep-sea siliceous sediments in world oceans and as a paleoceanographic indicator. This paper documents the evolutionary morphologic changes of the S. peregrina lineage from the middle Miocene to late Pliocene in the eastern equatorial and eastern North Pacific (IODP Site U1335 and ODP Site 887, respectively). The size and shape changes show that there are at least two geographical variations in the S. peregrina lineage. In the eastern equatorial Pacific, two significant morphological shifts took place about 11.0 and 7.0 Ma, but the morphology remained relatively stable from 7.0 to 3.0 Ma. Coincident with morphological changes in the S. peregrina lineage were changes in biogenic productivity. These changes suggest that there is a close correspondence between major paleoceanographic events in the late Neogene and evolutionary changes of the S. peregrina lineage in the low latitudes. In the high latitudes, the ratio of the third segment to fourth segment in width and height showed a maximum from 9.5 to 8.0 Ma, and decreased stepwise at about 8.0 and 6.5 Ma. However, the radiolarian data in the high latitudes do not show a clear relationship between the paleoceanographic events and size variation of this lineage. The evolutionary transition from Stichocotys delmontensis to S. peregrina can be used as a primary biostratigraphic marker in the low latitudes. However, it is not easy to use the evolutionary transition for biostratigraphic correlation and age determination in the high latitudes, because there is no obvious change in the ratio of the third to fourth segment widths that can be used to distinguish S. delmontensis from the descendant S. peregrina. (c) 2012 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Marine Micropaleontology, 2012年,
［査読有り］ Early and middle Eocene radiolarian biostratigraphy, IODP Leg 320 Sites U1331, eastern equatorial Pacific.
Shin-ichi Kamikuri; Theodore C. Moore; Kaoru Ogane; Noritoshi Suzuki; Heiko Päiko; Hiroshi Nishi, 筆頭著者
IODP Scientific Result, 2012年, ［査読有り］
Radiolarian magnetobiochronology and faunal turnover across the middle/late Eocene boundary and their implications for enhanced upwelling in the northwest Atlantic Ocean
Shin-ichi Kamikuri; Bridget S. Wade, 筆頭著者
Marine Micropaleontology, 2012年, ［査読有り］
Radiolarian stratigraphy across the Eocene/Oligocene boundary in the equatorial Pacific, Site 1218, U1333 and U1334.
Ted Moore; Shin-ichi Kamikuri, ラスト(シニア)オーサー
IODP Scientific Result, 2012年, ［査読有り］
Revised composite depth scales and integration of IODP Sites U1331, U1332, U1333,U1334 and ODP Sites 1218, 1219, 1220
Thomas Westerhold; Roy Wilkens; Heiko Päike; Mitch Lyle; Tom Dunkley Jones; Paul Bown; Ted Moore; Shin-ichi Kamikuri, ラスト(シニア)オーサー
IODP Scientific Result, 2012年, ［査読有り］
Early Eocene to early Miocene radiolarian biostratigraphy for the low-latitude Pacific OceanShin-ichi Kamikuri; Theodore C. Moore; Mitchell Lyle; Kaoru Ogane; Noritoshi Suzuki, A total of 226 early Eocene to early Miocene radiolarian datum events are identified and correlated with the geochronologic time scale at Sites U1331, U1332, and U1333 in the equatorial Pacific Ocean. Seven new radiolarian subzones are proposed for the low-latitude Oligocene: Eucyrtidium diaphanes Interval Subzone (RP22b); Calocycletta (Calocycletta) robusta Interval Subzone (RP22a); Lychnocanoma apodora Interval Subzone (RP21b); Theocyrtis annosa Interval Subzone (RP21a); Eucyrtidium plesiodiaphanes Interval Subzone (RP20c); Dorcadospyris pseudopapilio Interval Subzone (RP20b); Lithocyclia angusta Interval Subzone (RP20a). These subzones significantly improve the biostratigraphic resolution within the Oligocene (an average of one subzone per 1.6 million years [my]). Our study corroborates previous studies, which inferred that primary Oligocene datums were synchronous in the low-latitude Pacific. Four Eocene zones, Cryptocarpium ornatum (RP 19), Calocyclas bandyca (RP 18), Phormocyrtis striata striata (RP9), and Buryella clinata (RP8) are emended. Two new species/subspecies, Lychnocanoma klausi and Theocorys anaclasta clasta, are described., MICRO PRESS
Stratigraphy, 2012年,
［査読有り］ Early and Middle Eocene radiolarian assemblages in the eastern equatorial Pacific Ocean (IODP Leg 320 Site U1331): faunal changes and implications for paleoceanography
Shin-ichi Kamikuri; Theodore C. Moore; Mitchell Lyle; Kaoru Ogane; Noritoshi Suzuki, 筆頭著者
Marine Micropaleontology, 2012年, ［査読有り］
The successive extinctions of Eocene muricate planktonic foraminifera (Morozovelloides and Acarinina) and their stratigraphic utility for defining the base Priabonian
Bridget S. Wade; Vlasta Premec-Fucek; Shin-ichi, Kamikuri; Paul N. Pearson
Newsletters on Stratigraphy, 2012年, ［査読有り］
A Cenozoic record of the equatorial Pacific carbonate compensation depthHeiko Päiko et al.(全65人中35番目), Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth., NATURE PUBLISHING GROUP
Nature, 2012年,
［査読有り］ New late Neogene radiolarian species from the middle to high latitudes of the North PacificShin-ichi Kamikuri, Eighteen new late Neogene radiolarian species and a new subspecies from the Deep Sea Drilling Project (DSDP) Site 192, Ocean Drilling Program (ODP) Sites 884, 887 and 1151, located in the middle to high latitudes of the North Pacific, are illustrated and described, and redescription and comments of other 3 species are made. Stratigraphic ranges of all these species are also provided. The new species and subspecies are as follows: Acrosphaera muse, Amphisphaera nigriniae, Calocyclas motoyamai, Collosphaera mars, C. reynoldsi, Cycladophora funakawai, C. teocalli, Dendrospyris eurus, D. futaba, D. uruyaensis, Hexacontium minerva, H. dionysus, H. parviakitaensis, Joergensenium apollo, Lamprocyclas maritalis teraphimis, Lithelius klingi, Lychnocanoma kamtschatica, Spongodiscus cauleti and Stylochlamydium bensoni. The first occurrence of H. akitaensis and the last occurrences of H. parviakitaensis, E. japonicus and H. akitaensis are of potential biostratigraphic value in the middle to high latitudes of the North Pacific, because their events are synchronous. © 2009 Elsevier Masson SAS.
Revue de Micropaleontologie, 2010年,
［査読有り］ 釧路海底谷から採取された岩石試料の放散虫化石年代本山 功・上栗伸一・辻野 匠・川村喜一郎・三輪哲也, 北海道釧路沖の釧路海底谷において実施された「しんかい6500」の潜航調査（#1032，#1033，#1035）により採取された泥岩試料を分析した結果，年代決定に有効な放散虫化石が得られた．外縁隆起帯から採取された試料から産出した放散虫は後期始新世～漸新世，前期中新世及び中期中新世の年代を示す．隆起帯の陸側の前弧海盆からは，鮮新世またはそれ以降の年代を示す放散虫が得られた．, National Institute of Advanced Industrial Science and Technology, Geological Survey of Japan
地質調査研究報告, 2010年,
［査読有り］ 青森県津軽半島の下部中新統の地質とストロンチウム同位体年代上栗伸一・本山 功・中野孝教・小笠原憲四郎, 筆頭著者, 青森県津軽半島北西部に分布する磯松層は，権現崎層を不整合に覆い，下部より礫岩，砂岩ブロックを伴う凝灰岩，礫質砂岩，礫岩，泥岩からなり，海棲軟体動物化石を産する．磯松層の堆積相や層厚の特徴は，それがハーフグラーベン堆積物である可能性を示す．五所川原市磯松川上流に露出する磯松層中部から採取したカキ殻のストロンチウム同位体比（
87Sr/
86Sr）を測定した結果，20.4±0.2 Maの年代を得た．既存の放射年代データも合わせて，磯松層は前期中新世後期の約20－17 Maの範囲にあると結論づけた．磯松層から産出する貝化石は，津軽地域の新第三系で最も古い海棲動物化石の記録であり，前期中新世後期（約20－17 Ma）に津軽地域に新第三紀最初の海進が起こった可能性を示す．このイベントは日本海北部の玄武岩の形成年代に一致することから，磯松層を堆積させた海進は日本海拡大に関連したイベントである可能性が高い．, The Geological Society of Japan
地質学雑誌, 2010年,
［査読有り］ 北海道岩見沢幌向川流域の中新統の放散虫化石層序
久保田 資浩・本山 功・川村好毅・上栗伸一・小笠原憲四郎
石油技術協会誌, 2010年, ［査読有り］
The Pacific Equatorial Age Transect, IODP Expeditions 320 and 321: Building a 50-million-year-long environmental record of the Equatorial Pacific
Expeditions; Scientific Par
Scientific Drilling, 2010年
Pacific Equatorial Age Transect (PEAT)
Expeditions; Scientific Party
UK News letter, 2010年
Evolution of Eastern Pacific Warm Pool and upwelling processes since the middle Mioecne based on analysis of radiolarian assemblages: Response to Indonesian and Central American Seaways
Shin-ichi Kamikuri; Isao Motoyama; Hiroshi Nishi; Masao Iwai, 筆頭著者
Palaeogeography, Palaeoclimatology, Palaeoecology, 2009年, ［査読有り］
Neogene radiolarian biostratigraphy and faunal evolution rates in the eastern equatorial Pacific ODP Sites 845 and 1241Shin-ichi Kamikuri; Isao Motoyama; Hiroshi Nishi; Masao Iwai, 筆頭著者, Radiolarians from Sites 845 and 1241 in the eastern equatorial Pacific were examined in order to evaluate the role of paleoceanographic perturbations upon the general faunal evolutionary pattern of tropical planktonic organisms during the last 17 Ma. Radiolarian appearance and extinction rates indicate no periods of mass extinctions during the past 17 Ma. However, a relatively rapid replacement of the species in the radiolarian assemblages occurs near the middle-late Miocene boundary. This replacement event represents the gradual extinction of a number of radiolarian species and their gradual replacement by evolving new species. The modern equatorial circulation system wits formed near the middle-late Miocene boundary due to the closure of the Indonesian seaway. The minor faunal turnover appears to be associated with the formation of the modern equatorial circulation system near the middle-late Miocene boundary. Diatom assemblages in the equatorial Pacific became more provincial in character after about 9 Ma. The appearance and extinction rates of planktic foraminifers were relatively high near the middle-late Miocene boundary, and those of calcareous nannoplankton reached high values in the early late Miocene in the equatorial Pacific Ocean. Thus. faunal evolution from the middle Miocene type to late Miocene types occurred first, being followed by floral evolution. The middle-late Miocene boundary is not a sharp boundary for planktonic microfossils, but marks a time of transition critical for faunal and floral evolution in both siliceous and calcareous microfossil assemblages in the equatorial Pacific Ocean., INST PALEOBIOLOGII PAN
Acta Paleontologica Polonica, 2009年,
［査読有り］ Pacific Equatorial Transect I
Expedition; Scientists
IODP Preliminary Report, 2009年
Scientific report for Cruise CK09-03 Expedition 904
Hidetaka Nomaki; Kyoma Takahashi; Expedition; Scientists
D/V Chikyu JAMSTEC Expedition Science Report, 2009年
Proceedings of the Integrated Ocean Drilling Program
Expedition; Scientific Par
Initial Reports, 2009年
Proceedings of the Integrated Ocean Drilling Program, Initial Reports, vol 320/321
Expedition; Scientific Party
Proceedings of the Integrated Ocean Drilling Program, 2009年
Radiolarian assemblages in surface sediments along longitude 175°E in the Pacific OceanShin-ichi Kamikuri; Isao Motoyama; Akira Nishimura, 筆頭著者, This study of 24 surface sediment samples along longitude 175 degrees E between latitudes 48 degrees N and 14 degrees S in the western Pacific Ocean documents the relationship between the modern distribution of radiolarian assemblages and present oceanographic conditions. Ninety-two species were classified into eight clusters by using R-mode cluster analysis. Q-mode cluster analysis was used to distinguish five geographical zones, which were interpreted to represent the Tropical, Southern Subtropical, Northern Subtropical, Transitional, and Subarctic climatic zones. Species richness, diversity, and equitability are highest in the Tropical and Transitional Zones. We attempted to formulate new regression equations considering ecological information on the vertical distribution of radiolarian species. Transfer functions were derived from regression analysis of radiolarian assemblages to observed Sea Surface Temperature (SST) values. The transfer functions have a standard error of 1.16 degrees C in the estimate of winter SST, 0.81 degrees C in that of summer SST. (C) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Marine Micropaleontology, 2008年,
［査読有り］ Effects of late Neogene climatic cooling on North Pacific radiolarian assemblages and oceanographic conditionsShin-ichi Kamikuri,Hiroshi Nishi,Isao Motoyama, 筆頭著者, Radiolarian census and abundance data were collected from three deep-sea cores drilled by the Ocean Drilling Program Sites 884, 887 and 1151 to investigate patterns of ecologic changes in space and time during the last 16 million years for the mid-latitude to subarctic North Pacific. High concentrations of radiolarians occurred between 9.0 and 2.7 Ma. Radiolarian species richness was highest in the early middle Miocene at each site and gradually decreased tip to about 7 Ma, coinciding with a well-established global cooling trend. A degree of overlap index calculated for radiolarian assemblages revealed 11 faunal change events, of which 8 corresponded to global cooling events and expansions of polar ice sheets. Three of the faunal change events were observed within the peak of radiolarian accumulation rate and were ascribed to changes in primary productivity in the North Pacific rather than global climatic changes.
Our assemblage analyses revealed that north-soulb differentiation in radiolarian assemblages in the northwestern Pacific has existed since 16 Ma and became more distinct via major steps at 6.8 Ma and 2.7 Ma, coinciding with major glaciation events, and that east-west faunal contrasts in the subarctic region became obvious beginning at 11.7 Ma and changed to a different mode around 6.8 Ma. The observed east-west faunal differences possibly reflect east to west climate differences that were characterized by cooler temperatures in the east than the west during the late Miocene (11.7-6.8 Ma) and then by the opposite temperature trend (6.8 Ma-Recent). A severe glaciation at 2.7 Ma played a large role, particularly in temporal changes in radiolarian accumulation rate and assemblage composition. (c) 2007 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Palaeogeography, Palaeoclimatology, Palaeoecology, 2007年,
［査読有り］ 日本海における後期中新世以降の放散虫群集と海洋環境.上栗伸一・本山 功, 筆頭著者, Radiolarians live in a depth range from the surface to the great depths in the modern ocean, They, therefore, have much potential to reconstruct past vertical water structure as well as surface layer environments. To reconstruct paleoceanographic changes in the Japan Sea during the last 8 million years., we analyzed radiolarian assemblages in a deep-sea sedimentary sequence from the central part of the sea. Our results revealed that the surface layer changed from a warm condition in the late Miocene to a cooler one in the late Pliocene with some fluctuations and cooling steps that occurred at 6.5, 3.5 and 2.5 Ma. Warm water inflows from the south do not seem to have existed before the mid-Pliocene time. The signal of such inflow that can be comparable to the present-day Tsushima Current first appeared at 2.2 Ma. Occurrence of the deep as well as intermediate water species indicates the presence of deep and intermediate water masses comparable to those of the modern North Pacific before 2.5 Ma. The faunal composition of the deep and intermediate water species abruptly changed at 2.5 Ma, indicating that the formation of more oxygen-rich deep water initiated at that time in the sea. The reconstructed history of vertical water masses suggests exchanges of the deep water between the Japan Sea and the adjacent Pacific Ocean and, thus, deep channels are expected to have existed between them before the mid-Pliocene. Diversity of radiolarian assemblages in the Japan Sea was constantly lower than that of the North Pacific during the studied time interval., 日本古生物学会
化石, 2007年,
［査読有り］ Radiolarian faunal turnover across the Oligocene/Miocene boundary in the equatorial Pacific OceanShin-Ichi Kamikuri; Hiroshi Nishi; Theodore C. Moore; Catherine A. Nigrini; Isao Motoyama, The global warming trend of the latest Oligocene was interrupted by several cooling events associated with Antarctic glaciations. These cooling events affected surface water productivity and plankton assemblages. Well-preserved radiolarians were obtained from upper Oligocene to lower Miocene sediments at Ocean Drilling Program (ODP) Leg 199 Sites 1218 and 1219 in the equatorial Pacific, and 110 radiolarian species were identified. Four episodes of significant radiolarian faunal changes were identified: middle late Oligocene (27.5 to 27.3 Ma), latest Oligocene (24.4 Ma), earliest Miocene (23.3 Ma), and middle early Miocene (21.6 Ma). These four episodes approximately coincide with increases and decreases of biogenic silica accumulation rates and increases in δ18O values coded as "Oi" and "Mi" events. These data indicate that Antarctic glaciations were associated with change of siliceous sedimentation patterns and faunal changes in the equatorial Pacific. Radiolarian fauna was divided into three assemblages based on variations in radiolarian productivity, species richness and the composition of dominant species: a late Oligocene assemblage (27.6 to 24.4 Ma), a transitional assemblage (24.4 to 23.3 Ma) and an early Miocene assemblage (23.3 to 21.2 Ma). The late Oligocene assemblage is characterized by relatively high productivity, low species richness and four dominant species of Tholospyris anthophora, Stichocorys subligata, Lophocyrtis nomas and Lithelius spp. The transitional assemblage represents relatively low values of productivity and species richness, and consists of three dominant species of T. anthophora, S. subligata and L. nomas. The characteristics of the early Miocene assemblage are relatively low productivity, but high species richness. The two dominant species present in this assemblage are T. anthophora and Cyrtocapsella tetrapera. The most significant faunal turnover of radiolarians is marked at the boundary between the transitional/early Miocene assemblages. We also reviewed changes in other microfossil assemblages in the low latitudes during the late Oligocene through early Miocene. The microfossil assemblages of major groups show sequential changes near the Oligocene/Miocene (O/M) boundary (23.8 Ma). Many extinction events and some first occurrences of calcareous nannofossils and many occurrences of radiolarians are found from about 24.8 to 23.3 Ma, and first occurrences of planktic foraminifers and diatoms followed from 23.2 through 22 Ma. Hence, the O/M boundary is identified as a significant level for microfossil evolutions. © 2005 Elsevier B.V. All rights reserved.
Marine Micropaleontology, 2005年12月,
［査読有り］ Radiolarian faunal turnover across the Oligocene/Miocene boundary in the central eastern Pacific
Shin-ichi Kamikuri; Hiroshi Nishi; Theodore C. Moore; Catherine A. Nigrini; Isao Motoyama, 筆頭著者
Marine Micropaleontology, 2005年, ［査読有り］
Late Oligocene and early Miocene radiolarians from the Sites 1218 and 1219, central Pacific
Shin-ichi Kamikuri; Hiroshi Nishi; Theodore C. Moore; Catherine A. Nigrini; Isao Motoyama, 筆頭著者
ODP Scientific Results, 2005年, ［査読有り］
Middle Miocene to Pleistocene radiolarian biostratigraphy in the Northwest Pacific, Ocean Drilling Program Leg 186Shin-ichi Kamikuri; Hiroshi Nishi; Isao Motoyama; Saneatsu Saito, 筆頭著者, The Upper Cenozoic sedimentary sequences drilled at Sites 1150 and 1151, Ocean Drilling Program Leg 186, enabled establishment of radiolarian zonation and calibration of the age of bioevents in the forearc area of the northern Japan Islands. The sequences were divided into nine zones from the Pleistocene Botryostrobus aquilonaris Zone to the Upper Miocene Lipmanella redondoensis Zone at Site 1150, and 11 zones from the Pleistocene Stylatractus universus Zone to the Middle Miocene Dendrospyris? sakaii Zone at Site 1151. These zones correlate successfully with the studied sequences of many of deep-sea cores in the Northwest Pacific Ocean and with some sections of onshore Japan. Of 67 important radiolarian bioevents recognized during the study, 29 Pleistocene to Upper Miocene events were directly tied to the geomagnetic polarity time scale through the well-defined paleomagnetic polarity records, and 21 Upper Miocene events were calibrated based on the diatom biostratigraphy. Of these events, 24 geographically widespread events were selected to test synchroneity and usefulness as time-horizons within the mid-to-high latitude of the Northwest Pacific, involving eight other offshore and onshore sections. Examination showed that most of the zonal boundary events are synchronous within the considered region, and that many diachronous events, most of which are eliminated from the zonal scheme, are unreliable events linked to rare and sporadic occurrences of the species. Radiolarian biostratigraphy of the studied cores clearly indicates three major hiatuses in the Middle Pleistocene, Late Miocene and late Middle Miocene. The latter two hiatuses can be correlated to two global oceanic hiatuses, NH6 and NH3, respectively., WILEY-BLACKWELL
The Island Arc, 2004年,
［査読有り］ Middle Miocene to Pleistocene magneto-biostratigraphy of ODP Sites 1150 and 1151, northwest Pacific: Sedimentation rate and updated regional geological timescaleIsao Motoyama; Nobuaki Niitsuma; Toshiaki Maruyama; Hiroki Hayashi; Shin-ichi Kamikuri; Masamichi Shiono; Toshiya Kanamatsu; Kaori Aoki; Chikako Morishita; Kyoko Hagino; Hiroshi Nishi and Motoyoshi Oda, Shipboard and shore-based investigation on siliceous and calcareous microfossil biostratigraphy, magneto-stratigraphy and tephrostratigraphy identified numerous datum events from the sedimentary sequences of Sites 1150 and 1151 drilled on the forearc basin of northern Japan by the Ocean Drilling Program Leg 186. Some 83 datum events were selected to construct new age-depth models for the sites. Based on the reliable magneto-stratigraphy from the Pleistocene to the Upper Miocene, which were correlated to the standard geomagnetic polarity timescale, and on excellent records of diatom and radiolarian biostratigraphy throughout the sequences, the shipboard age model was revised. Major revisions referred to stratigraphic position of the Miocene-Pliocene boundary that has been shifted more than 200 m downward in each sequence. The age-depth relations of the forearc sites represent drastic changes in the sedimentation rate-extremely high (40 cm/k.y. on average) in the Early Pliocene and low (less than 2 cm/k.y. on average) in the Middle Miocene-and several hiatuses exist throughout the sequence. The drastic changes can be related mostly to changes in diatom sedimentation and the tectonics of the Japanese Island Arc. Local ages for some foraminiferal, calcareous nannofossil and radiolarian bioevents are estimated from the age-depth models at each site. These newly calibrated bioevents and biozones as well as established diatom biostratigraphy are incorporated into the updated magneto-biochronologic timescale, which will contribute to an improvement in biochronologic accuracy of Neogene sediments in northern Japan and adjacent areas., WILEY-BLACKWELL
The Island Arc, 2004年,
［査読有り］
