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アルケノン生産種の多様性 -陸水域における温度プロキシとしての発展について- Diversity of long-chain alkenone producers -Developments of temperature proxy in inland waters-

Article
Hiroto Kajita, Hideto Nakamura
Chikyukagaku (Geochemistry), Accepted manuscript
Publication year: 2020

Reconstruction of Holocene Optimum paleoclimatic variations using long-chain n-alkanes and alkenones in sediments from Dabusu Lake, northeastern China

Article
Ken Sawada, Makiko Ono, Hideto Nakamura, Shafi Mohammad Tareq
Quaternary International, https://doi.org/10.1016/j.quaint.2020.03.011, Accepted manuscript
Publication year: 2020

Abstract

Long-chain n-alkanes and alkenones were analyzed in sediments from Dabusu Lake, northeastern China, from ca. 7.2–4.5 kyr BP (the Holocene Optimum) and the present. Long-chain n-alkanes are derived from leaf waxes of terrestrial vascular plants and aquatic macrophytes. Using n-alkane proxies such as Paq and average chain length (ACL) indices, variations in paleovegetation were reconstructed. The Paq values were generally low, indicating that aquatic macrophytes were a minor floral component in Dabusu Lake. The ACL data indicated that forest/grassland mixed vegetation occurred around the lake. From the alkenone distribution patterns (C37/C38, C40/C37, and %C37:4 ratios), the main alkenone producers were inferred to be Group II producers, especially Ruttnera lamellosa. We estimated water temperatures based on alkenone unsaturation indices (UK37 and UK’’37) using the temperature calibrations obtained from culture strains of R. lamellosa. The variation pattern of the UK’’37-based water temperatures was almost similar to that of the UK37-based pattern, although some spikes differed between the temperatures based on the two indices. The UK’’37-based water temperatures were lower from 7.2 to 6.2 kyr BP, and subsequently increased after 6.2 kyr BP. The alkenone-based temperatures were highest from 5.5 to 5.3 kyr BP, indicating that this maximal stage was the Holocene Thermal Maximum in the Dabusu region. The markedly decreasing spikes of UK’’37-based water temperatures in our study likely corresponded to the cooling events during the Holocene Optimum, as previously reported, especially Asian monsoon events (AM) 1 and Bond event 4 (BE4). Also, the increasing spike (7.2 kyr BP) in temperatures was possibly associated with the warming regime just after AM2. Moreover, the rapid increasing spikes of alkenone-based temperatures corresponded to those of Paq at 7.2 kyr BP (just after AM2) and 6.4 kyr BP. These results imply that the rapid warming reconstructed using alkenone-based temperatures might have resulted in increased precipitation around the lake at these ages, especially just after the AM2 cooling.

Genomic and geochemical identification of the long-chain alkenone producers in the estuarine Lake Takahoko, Japan: Implications for temperature reconstructions

Article
Hiroto Kajita, Hideto Nakamura, Naohiko Ohkouchi, Naomi Harada, Miyako Sato, Shun Tokioka, Hodaka Kawahata
Organic Geochemistry, in press
Publication year: 2020

Highlights

  • We discovered LCAs in the brackish Lake Takahoko, in northern Japan.
  • Two distinct Group II haptophytes are responsible for LCAs production.
  • Lake Takahoko may be suitable for alkenone paleotemperature reconstruction. 

Abstract

Identifying the lacustrine haptophyte species that produce long-chain alkenones (LCAs) is essential for using alkenone unsaturation ratios to create lake water temperature reconstructions. We discovered LCAs in the brackish Lake Takahoko in northern Japan. The identity of LCA-producing species was investigated using 18S ribosomal DNA (rDNA) and organic geochemical analysis. Two distinct genetic groups, termed as Tak-A and Tak-B, were identified within the Group II haptophyte phylotype. Tak-A was closely related to Hap-A, which was obtained from Lake George, USA; and Tak-B was identified as Isochrysis galbana. Because Hap-A and Isochrysis galbana have similar temperature calibrations, Tak-A and Tak-B were also expected to share similar calibrations. Therefore, the changes of their relative abundances in the lake should not significantly disturb paleotemperature reconstructions. The alkenone temperature recorded in the surface sediment corresponded to the lake temperature in early to late summer. This is likely related to the haptophyte bloom season in Lake Takahoko suggesting that this lake may be a viable location for creating an lacustrine alkenone paleotemperature record.

Plant-derived triterpenoid biomarkers and their applications in paleoenvironmental reconstructions: chemotaxonomy, geological alteration, and vegetation reconstruction

Article
Hideto Nakamura
Researches in Organic Geochemistry, 35(2): 11-35, 2019
Publication year: 2019

Abstract

Triterpenoids and their derivatives are ubiquitous in sediment samples. Land plants are major sources of non-hopanoid triterpenoids; these terpenoids comprise a vast number of chemotaxonomically distinct biomolecules. Hence, geologically occurring plant-derived triterpenoids (geoterpenoids) potentially record unique characteristics of paleovegetation and sedimentary environments, and serve as source-specific markers for studying paleoenvironments. This review is aimed at explaining the origin of triterpenoids and their use as biomarkers in elucidating paleoenvironments. Herein, application of plant-derived triterpenoids is discussed in terms of: (i) their biosynthetic pathways. These compounds are primarily synthesized via oxidosqualene cyclase (OSCs) and serve as precursors for a variety of membrane sterols and steroid hormones. Studies on OSCs and resulting compounds have helped elucidate the diversity and origin of the parent terpenoids. (ii) their chemotaxonomic significance. Geochemically important classes of triterpenoid skeletons are useful in gathering and substantiating information on botanical origin of these compounds, evolution and diversification of angiosperms, and organic matter preservation during different periods in geological history. (iii) current knowledge on their transformation into geoterpenoids via diagenetic alterations. This knowledge helped in paleoenvironmental reconstructions from the local depositional environments to paleoclimatic variations. This review focuses on triterpenoids as paleoenvironmental biomarkers, and consolidates relevant literature that can form the basis for developing tools and techniques for improved paleoenvironment reconstruction. Future investigations should focus on detecting as yet unknown classes of triterpenoids and their biosynthetic pathways, inclusion of this information in automated databases, and identification of geoterpenoids as potential biomarkers to further our understanding of paleoenvironments and paleoclimate.

Impact of metabolic pathways and salinity on the hydrogen isotope ratios of haptophyte lipids

Article
Gabriella M. Weiss, David Chivall, Sebastian Kasper, Hideto Nakamura, Fiz da Costa, Philippe Soudant, Jaap S. Sinninghe Damsté, Stefan Schouten, Marcel T. J. van der Meer
Biogeosciences Discussions, https://doi.org/10.5194/bg-2019-147, in review, 2019.
Publication year: 2019

Abstract

Hydrogen isotope ratios of biomarkers have been shown to reflect water isotope ratios, and in some cases correlate significantly with salinity. The δ2H-salinity relationship is best studied for long-chain alkenones, biomarkers for haptophyte algae, and is known to be influenced by a number of different environmental parameters. It is not fully known why δ2H ratios of lipids retain a correlation to salinity, and whether this is a general feature for other lipids produced by haptophyte algae. Here, we analyzed δ2H ratios of three fatty acids, brassicasterol, long-chain C37 alkenones and phytol from three different haptophyte species grown over a range of salinities. Lipids synthesized in the cytosol, or relying on precursors of cytosolic origin, show a correlation between their δ2H ratios and salinity. In contrast, biosynthesis in the chloroplast, or utilizing precursors created in the chloroplast, yields lipids that do not show a correlation between δ2H ratios and salinity. This leads to the conclusion that location of metabolism is the first-order control on the salinity signal retained in δ2H ratios of certain lipids. Additionally, we found that δ2H ratios of alkenones from batch cultures of the Group II haptophyte species Tisochrysis lutea correlate positively with temperature, contrary to findings from cultures of Group III haptophytes, but retain a similar response to nutrient availability in line with other Group III haptophytes.

Establishment of Upper Cretaceous bio- and carbon isotope stratigraphy in the northwest Pacific Ocean and radiometric ages around the Albian/Cenomanian, Coniacian/Santonian and Santonian/Campanian boundaries

Article
Reishi Takashima, Hiroshi Nishi, Toshiro Yamanaka, Yuji Orihashi, Yasuyuki Tsujino, Xavier Quidelleur, Keiichi Hayashi, Ken Sawada, Hideto Nakamura, Takuto Ando
Newsletters on Stratigraphy, 52(3): 341–376, 2019
Publication year: 2019

Abstract

The Yezo Group, exposed in Hokkaido, northern Japan, is one of the few strata that recorded Cretaceous paleo-oceanographic changes in the Pacific Ocean. Although the group yields abundant marine macro- and microfossils, sporadic occurrences of age-diagnostic species in several stratigraphic intervals has prevented high-resolution international biostratigraphic correlation. The proposed integrated bio- and carbon isotope stratigraphy of the Yezo Group, which is exposed in northwest Hokkaido, enables high-resolution international stratigraphic correlation spanning from Upper Albian to Lower Campanian. The correlation of the present study identifies the detailed stratigraphic horizons of the Albian/Cenomanian, Cenomanian/Turonian, Turonian/Coniacian, Coniacian/Santonian, and Santonian/Campanian boundaries, as well as the Late Cretaceous paleo-environmental events in the Yezo Group. The Yezo Group is also important in order to complement the chronometric age of the Cretaceous geologic time scale because the group includes numerous felsic tuffs. The U-Pb zircon ages of some of these tuffs, which are interbedded near the Albian/Cenomanian, Coniacian/Santonian and the Santonian/Campanian boundaries in the Yezo Group, are dated at 99.7±0.3 Ma (Quidelleur et al. 2011), 86.87±0.60/0.67 (internal/total error) Ma and 84.7±0.7/1.8 (internal/total error) Ma, respectively. These radiometric ages are consistent with the latest age model of the Cretaceous time scale.

Alkenediones and their unsaturation ratios in the Miocene to Pleistocene sediments from the Northeastern Atlantic

Conference
Satoshi Furota, Hideto Nakamura, Ken Sawada
In: 29th International Meeting on Organic Geochemistry; Sep 2019; Gothenburg, Sweden.
Publication year: 2019

Abstract

Alkenone unsaturation indices (UK’ 37 and UK 37) in marine sediments have been extensively used for reconstructing paleo-sea surface temperature (SST). The long-chain alkenones are produced by haptophytes, especially Emilinia huxleyi and Gephyrocapsa oceanica, in present oceans, and the unsaturation indices-T calibrations are based on the physiological features of these present alkenone producers. However, these species occurred since the Pleistocene, and thus, it needs to confirm applicability of the unsaturation indices-T calibrations in the sediment older than the Pleistocene. Long time-scale variations in compositions of the alkenones as well as related compounds such as alkenoates and their unsaturation ratios provide considerable insights for evaluating the reliable application of the T calibrations to older sediments.
Our recent researches have reported a distinctive compound, C38 di-unsaturated (C38: 2) alkenedione, from the Miocene to Pliocene sediments recovered from the NE Atlantic (Furota et al., 2016). The alkenedione shares the most characteristics in molecular structure with the alkenones, but it has not been identified from the present alkenone producers. Moreover, the alkenedione/alkenone ratios tend to increase in the older sediments, and the comparison with the coccolithophorid calcareous nannofossil assemblage implied that the alkenedione was produced only by the ancient alkenone producers like genus Reticulofenestra. Thus, the alkenedione can be a key compound to study the physiological features of the ancient alkenone producers.

地衣類ハナゴケ属およびオオロウソクゴケ属から検出された脂肪族炭化水素:化学分類・環境指標の可能性 Aliphatic hydrocarbons identified in lichen genus Cladonia and Xanthoria : Potential for their chemotaxonomic and environmental indicators

Article
Ikeda A. Masashi, Hideto Nakamura, Ken Sawada
Researches in Organic Geochemistry, 34(2): 15-28, 2018
Publication year: 2018

Abstract

Aliphatic hydrocarbons were analyzed in 3 species (Cladonia vulcani, Cladonia scabriuscula, and Xanthoria sp.) of lichens collected from Hokkaido and Hyogo Prefectures, Japan. Molecular composition of n-alkanes is likely influenced by precipitation, as the long chain n-alkanes are produced under arid environments. Alkenes such as heptadecene are also detected as major components in these samples. Molecular composition of these alkanes is different between the genus Xanthoria and Cladonia, suggesting that the composition is influenced by taxonomic diversity. Molecular composition of the aliphatic hydrocarbons other than n-alkanes and alkenes detected are far different between the genera Xanthoria and Cladonia, but are almost similar in these 2 species of the genus Cladonia, potentially depending on taxonomy at the genus level. From these results, we predict that the alkenes, as well as other aliphatic hydrocarbons, can be useful as a chemotaxonomic marker, while the composition of n-alkanes can be an environmental indicator.

北海道苫前地域のセノマニアン/チューロニアン境界堆積岩中の地衣類バイオマーカーによる古環境・古生態変動の復元 Paleoenvironmental and paleoecological variations recorded by lichen biomarkers in the sediments deposited across the Cenomanian-Turonian boundary in the Tomamae area, northern Hokkaido, Japan

Conference (in Japanese)
Masashi Ikeda, Ken Sawada, Takuto Ando, Hideto Nakamura, Reishi Takashima, Hiroshi Nishi
In: Annual Meeting of the Geological Society of Japan, The 125th Annual Meeting (2018' Sapporo-Tsukuba), R23-O-10, Sapporo-Tsukuba, Japan, Sep 2018
Publication year: 2018

中海Nk3地点における湖底表層コアの岩相,年代,古環境変化 Lithofacies, dating and recorded paleoenvironment in surface core sediment of St. Nk3 in Lake Naka-umi, Shimane Prefecture.

Conference (in Japanese)
Kotaro Hirose, Koji Seto, Akira Tsujimoto, Hirdeto Nakamura, Takuto Ando, Hiroaki Shakutsui, Minami Aoki, Toshiaki Irizuki, Kazuo Kamura
In: Annual Meeting of the Geological Society of Japan, The 125th Annual Meeting (2018' Sapporo-Tsukuba), R22-P-6, Sapporo-Tsukuba, Japan, Sep 2018
Publication year: 2018

中海・瀬戸内海の表層堆積物を用いたケロジェン・パリノモルフ観察法の検討 Examination for observations of kerogen and palynomorph in the surface sediment from Lake Nakaumi and the Seto Inland Sea

Conference (in Japanese)
Yuki Hattori, Ken Sawada, Takuto Ando, Hideto Nakamura, Kotaro Hirose
In: Annual Meeting of the Geological Society of Japan, The 125th Annual Meeting (2018' Sapporo-Tsukuba), R12-O-6, Sapporo-Tsukuba, Japan, Sep 2018
Publication year: 2018

Variability of alkenone producers recorded in brackish lacustrine sediments of Lake Nakaumi, western Japan

Conference
Hattori, Y., Sawada, K., Ando, T., Nakamura, H., Hirose, K.
In: American Geophysical Union, Fall Meeting 2018, abstract #PP31E-1717, Dec 2018
Publication year: 2018

Long-chain alkenones, haptophyte-derived biomarkers, is a powerful tool for reconstructing sea surface temperature. Despite increasing reports of non-marine occurrence of alkenones, application of alkenone proxies in the settings are still challenging. Because the temperature calibrations of the alkenone unsaturation indices (UK37, UK’37) vary depending on the taxonomic differences of the alkenone producers, identification of the producer is a key to apply the calibrations for the coastal/lacustrine settings. The phylogeny of the alkenone producers is largely divided into three family-level groups, namely the Groups I – III (Theroux et al., 2010). In Japanese lakes, the Group I alkenone producer is identified in Lake Toyoni (Hokkaido) and Ichi-no-Megata (northeastern Japan) (Longo et al. 2018). Here we report the third example of lacustrine alkenone in Japan, which revealed from the analysis of ca. 1.8 m sediment core taken from Lake Nakaumi, western Japan. The L. Nakaumi is a coastal brackish lake and lagoonal in origin. Its water changed oligohaline to polyhaline by intrusion of seawater from Japan Sea. evaluated the source species of alkenones in Lake Nakaumi from the composition of alkenone and related compounds, and water temperature were preliminary reconstructed by selecting applicable calibrations.

The long-chain alkenones were detected in all samples from the 1.8 m core taken from near the center of L. Nakaumi (17NK-3 core). The alkenone compositions are clearly different between the samples above and below the horizons around 20 cm depth. corresponding to the horizon in about 1960s. Below 20 cm depth , the di-unsaturated alkenones such as C37:2 alkenones are dominant, and the UK’37 are higher. Meanwhile, above 20 cm depth, the C37:3 alkenones are dominant and C37:4 and C40 alkenones are relatively abundant, resulting contrastingly lower UK’37 and UK37 values. By comparing with chemotaxonomic features of known alkenone producers as reported previously , we estimate that the main alkenone producers in sediments below and above the horizons in about 1960s are Group III species (including marine producers: e.g. Emiliania huxleyi and Gephyrocapsa oceanica ) and Group II species (coastal and lacustrine producers: e.g. Ruttnera lamellosa and Isochrysis garbana), respectively.

Terrestrial environmental changes reconstructed by non-vascular plant biomarkers across the Cenomanian/Turonian boundary in the Tomamae area, northern Hokkaido, Japan

Conference
Masashi Ikeda, Ken Sawada, Takuto Ando, Hideto Nakamura, Reishi Takashima, Hiroshi Nishi
In: American Geophysical Union, Fall Meeting 2018, abstract #PP51E-1174, Dec 2018
Publication year: 2018

The Cretaceous is an interval of great interest for understanding the ecological evolution in terrestrial areas under hothouse condition. The reconstruction and ecological interpretation of the Cretaceous vegetation were performed by paleobotanical and palynological investigations, and recently, by organic geochemical analysis using terrestrial plant-derived biomarker. Records based on plant fossils and biomarkers are dominated by those of vascular plants, especially gymnosperm and angiosperm. In our works, we focus on the other members of terrestrial ecosystem, such as lichens and fungi to cover better scope of paleoecosystem on land. In addition, such organisms include pioneer species, which can grow in extreme environments. Hence retrieving paleontological information on such organisms has potential to piece out paleoecosystem reconstruction especially at the timing after severe environmental disturbance and paleoecology under extreme environments. Thus, we analyzed terrestrial biomarkers related to non-vascular plant, thallophyte, in sediments across the Cenomanian/Turonian boundary (CTB) of the Yezo Group distributed in the Tomamae area, northern Hokkaido, to reconstruct paleoenvironment and paleovegetation, and to examine the applicability for these indicators.

The CTB is known as an interval of the oceanic anoxic event (OAE) 2. In the study area, the OAE2 level reached about 700 m. Each phase of OAE2 was determined by δ13C of wood. By the sterane and hopane analyses, it shows immature of organic matter in the sediments. Perylene and dibenzofurans could be detected from all samples across the CTB. The perylene is thought to be mainly originated from terrestrial fungi. The dibenzofurans are known to be produced by plants, fungi and lichens, while the dibenzofurans having alkyl groups, especially at positions 1 and 9, are thought to be derived from lichens. Thus, the 1-methyl dibenzofuran ratio (1-MDBF ratio) was proposed as an indicator of lichen vegetation. The 1-MDBF ratios vary in the sediment across the CTB; the ratios increase during the 1st build up stage, consistently low values during the Trough, and tend to increase from the 2nd build up to Plateau stages. It is presumed that the variations are attributed to environmental and climatic changes in paleo-Hokkaido across the CTB.

Novel alkenone-producing strains of genus Isochrysis (Haptophyta) isolated from Canadian saline lakes show temperature sensitivity of alkenones and alkenoates

Article
Hiroya Araie*, Hideto Nakamura*, Jaime L. Toney, Heather A. Haig, Julien Plancq, Takashi Shiratori, Peter R. Leavitt, Osamu Seki, Ken-ichiro Ishida, Ken Sawada, Iwane Suzuki, Yoshihiro Shiraiwa (*Equal contribution.)
Organic Geochemistry 121: 89-103, 2018
Publication year: 2018

Highlights

  • Novel LCA-producing strains from Canadian lakes established as unialgal cultures.
  • Seven strains were categorized in the Isochrysis clade using genomic analysis.
  • One strain produces C41 and C42 alkenones that are sensitive to temperature changes.
  • New alkenoate-based indices from isolated strains for temperature reconstructions.

Abstract

Alkenone-producing species have been recently found in diverse lacustrine environments, albeit with taxonomic information derived indirectly from environmental genomic techniques. In this study, we isolated alkenone-producing algal species from Canadian saline lakes and established unialgal cultures of individual strains to identify their taxonomical and molecular biological characteristics. Water and sediments collected from the lakes were first enriched in artificial seawater medium over a range of salinities (5–40 g/L) to cultivate taxa in vitro. Unialgal cultures of seven haptophyte strains were isolated and categorized in the Isochrysis clade using SSU and LSU rRNA gene analysis. The alkenone distributions within isolated strains were determined to be novel compared with other previously reported alkenone-producing haptophytes. While all strains produced the typical C37 and C38 range of isomers, one strain isolated from Canadian salt lakes also produced novel C41 and C42 alkenones that are temperature sensitive. In addition, we showed that all alkenone unsaturation indices (e.g., UK37 and UK′37) are temperature-dependent in culture experiments, and that alkenoate indices (e.g., UA37UA37, RIA38 and A37/A38) provide alternative options for temperature calibration based on these new lacustrine algal strains. Importantly, these indices show temperature dependence in culture experiments at temperatures below 10 °C, where traditional alkenone proxies were not as sensitive. We hypothesize that this suite of calibrations may be used for reconstructions of past water temperature in a broad range of lakes in the Canadian prairies.

 

Higher plant triterpenoids bound in resistant macromolecules in extant and Pliocene fossil Liquidambar fruits

Article
Ken Sawada, Takaaki Arai, Hideto Nakamura, Minoru Tsukagoshi
Researches in Organic Geochemistry, 34(2): 37-45, 2018
Publication year: 2018

Abstract

Ester-bound compounds (compounds released by saponification) from the resistant macromolecules (RMMs) were analyzed in the extant and Pliocene fossil Liquidambar fruit from the Tokai Group distributed in Gifu Prefecture, central Japan. We compared the distributions of the ester-bound triterpenoids from the fossil with those of free and ester-bound triterpenoids of the extant fruits. The series of triterpenoid acids such as oleanolic and ursolic acids were identified in free compounds but hardly detected in ester-bound compounds from the extant Liquidambar samples. Most of free triterpenoids identified in the extant Liquidambar were also present in the fossil Liquidambar sample as the ester-bound compounds. These results indicate the occurrence of post-depositional incorporation of the free triterpenoids into the macromolecules such as the RMMs via ester bonds. Thus, it is suggested that the ester-bound triterpenoids in RMMs serve as excellent archives of the indigenous assemblage of triterpenoids. The class distributions of the oleanoids and ursanoids in the ester-bound compounds from the fossil sample are considerably different from those in the free polar compounds of the extant samples. Selective preservation of C-28 carboxyl group compared to C-3 oxygenated functions indicates that the triterpenoid acids were incorporated into RMM via ester-bound formed between C-28 carboxyl and hydroxyl groups of the RMM. These results indicate that the ester-bound triterpenoid acids obtained from the fossil sample are selectively preserved by incorporation into the RMM of the fruits.

Alkenone distribution and producers in Canadian lakes: Implications for palaeotemperature reconstructions

Conference
Plancq, J., Cavazzin, B., Steve, J., Haig, H., Leavitt, P., Araie, H., Nakamura, H., Shiraiwa, Y., Couto, J., Toney, J.L.
In: American Geophysical Union, Fall Meeting 2018, abstract #PP31E-1704, Dec 2018
Publication year: 2018

Alkenones are long-chain unsaturated ketones produced by a few number of haptophyte algae of the order Isochrysidale. The degree of unsaturation of C37 alkenones has been shown to vary as a function of the environmental temperature, and these lipids have been thus used for decades as a proxy for sea surface temperatures thanks to the unsaturation indices UK37 ([C37:2 – C37:4]/[C37:2 + C37:3 + C37:4]) and UK’37 ([C37:2]/[C37:2 + C37:3]). More recently, alkenones have been globally reported in freshwater and saline lakes, but their use as a proxy for terrestrial temperatures is hampered by the rather limited knowledge about the environmental factors controlling alkenone distribution and the haptophyte species that produce them. Here, 106 lakes from the Northern Great Plains in Saskatchewan, Canada were investigated for alkenone producers and composition.

The study of surface sediments indicate that 55% of the Canadian lakes contain alkenones, with very high concentrations (up to 2.3 mg/g of sediment) in 7% of the lakes. Statistical analyses reveal that salinity and stratification of the water column play key roles in determining alkenone presence and abundance, which is certainly linked to the ecology of the producing haptophyte species. Moreover, genomic analyses based on surface sediments from some lakes evidence the presence of four distinct species from Group I and Group II haptophytes. Even though calibration of the UK37 index was not possible from the study of the surface sediments, seven haptophyte strains were isolated from three Canadian lakes, and characterised by genomic analyses as belonging to the clade Isochrysis. The culture of these new species shows that not only the UK37 and UK’37, but also alternate indices based on alkenoates (esters with structure close to the alkenones), are temperature dependent.Taken together, these data bring new information on the production of lacustrine alkenones, and allow us to use these lipids for palaeoenvironmental reconstructions. A short core from one of the survey sites (Humboldt Lake) is being analysed to calibrate the alkenone proxy with historical climate records from the 20th century, a process which that will allow a longer temperature reconstructions in the Northern Great Plains.

北海道白亜系蝦夷層群函淵層に挟在する石炭層の有機物分析による堆積環境の復元 Reconstruction of sedimentary environment of coal beds by organic matter analyses of sediments from the Cretaceous Hakobuchi Formation, Yezo Group, Hokkaido, Japan

Conference (in Japanese)
Yuki Tateshita, Ken Sawada, Takuto Ando, Hideto Nakamura, Keiichi Hayashi
In: Annual Meeting of the Geological Society of Japan, The 124th Annual Meeting (2017' Ehime), R12-O-7, Ehime, Japan, Sep 2017
Publication year: 2017

Depositional environments and maturity evaluated by biomarker analyses of sediments deposited across the Cenomanian–Turonian boundary in the Yezo Group, Tomamae area, Hokkaido, Japan

Article
Takuto Ando, Ken Sawada, Hideto Nakamura, Keita Omatsu, Reishi Takashima, Hiroshi Nishi
Island Arc, 26(1):e12178, 2017
Publication year: 2017

Abstract

Biomarker analyses for evaluating maturity of organic matter and depositional environments such as redox conditions, were performed in sediments across the Cenomanian–Turonian boundary (CTB) in the Saku Formation of the Yezo Group distributed along the Shumarinai‐gawa River and the Omagari‐zawa River, both in the Tomamae area, Hokkaido, Japan. Maturity indicators using steranes and hopanes, show that organic matter in sediments from the Shumarinai‐gawa and Omagari‐zawa sections are of lower maturity than those from the Hakkin‐gawa section (Oyubari area). Moreover, the ββ hopane ratios clearly show that the maturity of the Shumarinai‐gawa samples is lower than that of the Omagari‐zawa samples. These variations in the maturity of organic matter presumably reflect the difference in their burial histories. The results for the pristane/phytane (Pr/Ph) ratios suggest that the Shumarinai‐gawa samples were deposited under dysoxic to anoxic environments across the CTB, while the depositional environments of the Omagari‐zawa samples were relatively oxic. By another paleoredox indicator using C35 homohopanoids including a homohopene index (HHenI), higher values are observed in the Shumarinai‐gawa section, particularly in the horizons of the preceding period and an early stage of the first negative shift phase and the latest oceanic anoxic event 2 (OAE2) interval. These results suggest that the Shumarinai‐gawa samples record dysoxic to anoxic environments across the CTB. In contrast, the signals for the C35 homohopanoid index values show a relatively oxic condition in the Omagari‐zawa section. The trends of stratigraphic variations in redox conditions are different from those in the OAE2 interval in the proto‐Atlantic and Tethys regions as reported previously. Hence, the redox variations in the Tomamae area were basically related to a local environmental setting rather than global anoxia. However, the prominent anoxic emphasis observed in the HHenI profile of the Shumarinai‐gawa section can be a distinctive, and possibly global, event in the North‐West Pacific just before the OAE2.

Long-chain alkenones and related distinctive compounds in the late Miocene and Pliocene sediments from the Gulf of Cadiz, eastern North Atlantic

Article
Satoshi Furota, Hideto Nakamura, Ken Sawada
Organic Geochemistry 101: 166-175, 2016
Publication year: 2016

Highlights

  • Long-chain alkenones were analyzed in a sediment core from the Gulf of Cadiz.
  • A mid-polar column enables separation between trans-C37:3 and cis-C37:2 alkenones.
  • Variations in C37/C38 alkenone ratios reflect taxonomic change of the producers.
  • An alkenedione, C38 di-unsaturated alkene-2,36-dione, was tentatively identified.
  • The alkenedione presumably originated from the ancient alkenone producer.

Abstract

Long-chain alkenones and related compounds were analyzed in Miocene and Pliocene sediments from the Gulf of Cadiz (GoC) in the eastern North Atlantic, which were obtained by Integrated Ocean Drilling Project (IODP) Expedition 339. Both GC and GC–MS analyses using non- and mid-polar columns were performed on the sediments. Isomeric cis-C37 alkenones were identified along with common trans-C37–C39 alkenones. The use of a mid-polar column resulted in the complete separation of the trans-C37 tri-unsaturated alkenone and the cis-C37 di-unsaturated alkenone and thus contributed to a more precise estimation of the alkenone-based paleotemperature. The reconstructed SSTs range from 26 to 28 °C during ca. 6–3 Ma in the GoC. These variations are concordant with global climate change during the period, particularly the Pliocene Climatic Optimum and the onset of sustained ice sheet growth in the northern hemisphere. The concentrations of C37–C39 alkenones and the C37/C38 alkenone ratios are lower during the late Miocene to early Pliocene and increase after ca. 4.2 Ma, which corresponds to the taxonomic change of the plausible alkenone producers from the genus Reticulofenestra to genera Gephyrocapsa and Reticulofenestra. Moreover, a C38 di-unsaturated alkene-2,36-dione was tentatively identified. Variations in the concentrations of a tentatively identified alkenedione are almost synchronous with those of other alkenones, and their relative abundances decrease after ca. 4.2 Ma. These results suggest that the alkenedione originated from the ancient alkenone producers such as the genus Reticulofenestra.

 

Composition of long chain alkenones and alkenoates as a function of growth temperature in marine haptophyte Tisochrysis lutea

Article
Hideto Nakamura, Ken Sawada, Hiroya Araie, Takashi Shiratori, Ken-ichiro Ishida, Iwane Suzuki, Yoshihiro Shiraiwa
Organic Geochemistry 99: 78-89, 2016
Publication year: 2016

Highlights

  • Haptophyte strain NIES-2590 was genetically identified as T. lutea.
  • T. lutea lacked C37:4 alkenones, and grew well between 15 °C and 35 °C.
  •  UK37 calibrations of Tisochrysis lutea strains CCMP463 and NIES-2590 were defined.
  • UK37  calibrations were distinct from the other Isochrysidaceae species.
  • They serve as the first UK37  calibrations empirically defined up to 35 °C.

Abstract

We investigated the compositions of long chain alkenones and alkenoates in cultured strains of the marine haptophyte Tisochrysis lutea CCMP463 and T. lutea NIES-2590 (formerly classified as Isochrysis galbana). Both T. lutea strains grown at various temperatures of 15–35 °C could be characterized by the lack of tetraunsaturated alkenones and alkenoates in comparison with strains in other genera Isochrysis and Ruttnera, which are classified in the same family Isochrysidaceae and order Isochrysidales that contain alkenone-producing haptophytes. We found that T. lutea has a distinct alkenone response to temperature, which is characterized by high U37K-temperature sensitivity at 15–30 °C and continuing sensitivity at warm-end temperatures over 30 °C, where the other species fail to adapt. Both strains showed similar trends in alkenone compositions and alkenone unsaturation index-temperature calibrations. In addition, both strains CCMP463 and NIES-2590 showed notably close phylogenetic relationships, even those that were collected from remote regions of the Atlantic Ocean, namely the Caribbean Sea and English Channel, where their habitats, particularly the sea surface temperature, are notably different. Considering previous published datasets, three genera, IsochrysisRuttnera and Tisochrysis, showed very different trends in the alkenone unsaturation index-temperature calibration. These results suggest that the lack of tetraunsaturated alkenones, warm-water oriented growth and the high sensitivity to growth temperature serve as distinct chemotaxonomic characteristics of T. lutea in the Isochrysidaceae family.

白亜系双葉層群から産出した炭化小型植物化石の抵抗性高分子組成から見た化学分類 Chemotaxonomy of plants by resistant macromolecular analysis of charred mesofossils from the Cretaceous Futaba Group

Conference (in Japanese)
Yuma Miyata, Ken Sawada, Kei Ikeda, Hideto Nakamura
In: Annual Meeting of the Geological Society of Japan, The 122nd Annual Meeting (2015' Nagano), R11-O-6, Nagano, Japan, Sep 2015
Publication year: 2015

北海道蝦夷層群 Cenomanian/Turonian 境界堆積岩の有機地球化学指標に記録された海洋の酸化還元環境変動 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.

Conference (in Japanese)
Ando Takuto, Ken Sawada, Nakamura Hideto, Miyata Yuma, Omatsu Keita, Reishi Takashima, Nishi Hiroshi
In: Annual Meeting of the Geological Society of Japan, The 122nd Annual Meeting (2015' Nagano), R22-O-16, Nagano, Japan, Sep 2015
Publication year: 2015

n-Nonacosadienes from the marine haptophytes Emiliania huxleyi and Gephyrocapsa oceanica

Article
Hideto Nakamura, Ken Sawada, Hiroya Araie, Iwane Suzuki, Yoshihiro Shiraiwa
Phytochemistry 111:107-113, 2015
Publication year: 2015

Highlights

  • E. huxleyi NIES837 and G. oceanica NIES1315 produces abundantly nonacosadienes.
  • Double bond positions in C29 alkenes were determined by MS of their DMDS adducts.
  • The most abundant C29 alkene isomer was determined as 2,20-nonacosadiene.
  • Nonacosadienes have potential for being distinct haptophyte biomarkers.

Abstract

The hydrocarbons in cultures of marine haptophytes Emiliania huxleyi NIES837 and Gephyrocapsa oceanica NIES1315 were analyzed, and nonacosadienes and hentriacontadienes were detected as the major compounds in both strains. C29 and C31 monoenes and di-, tri- and tetra-unsaturated C33 alkenes were also detected as minor compounds but not C37 and C38 alkenes. The positions of the double bonds in the C29 and C31 alkenes were determined by mass spectrometry of their dimethyl disulfide (DMDS) adducts. Among the four C29 alkenes identified, the most abundant isomer was 2,20-nonacosadiene, and the other three compounds were 1,20-nonacosadiene, 3,20-nonacosadiene and 9-nonacosene, respectively. Hitherto, 2,20-nonacosadiene and 3,20-nonacosadiene were unknown to be natural products. The double bond at the n-9 (ω9) position in these C29 alkenes is hypothesized to be derived from precursors of unsaturated fatty acids possessing an n-9 double bond, such as (9Z)-9-octadecenoic acid. Nonacosadienes have the potential for being used as distinct haptophyte biomarkers.

白亜系双葉層群芦沢層の堆積物および小型植物化石の結合態アルキル脂質分析:炭質物濃集層の成因 Analysis of alkyl lipids bound in sediment and plant mesofossils from the Cretaceous Futaba Group: Possible formation mechanism of organic matter-concentrated layer

Conference (in Japanese)
Yuma Miyata, Hideto Nakamura, Ken Sawada, Masamiti Takahashi
In: Annual Meeting of the Geological Society of Japan, The 121st Annual Meeting (2014' Kagoshima), R12-O-8, Kagoshima, Japan, Sep 2014
Publication year: 2014

北海道苫前地域に分布する蝦夷層群Cenomanian/Turonian境界堆積岩の有機地球化学分析による堆積環境・海洋生産変動の復元 Depositional environment and variation in primary production during the Cenomanian-Turonian boundary reconstructed by organic geochemical analysis of sedimentary rocks from the Yezo Group, Tomamae area, Hokkaido, Japan

Conference (in Japanese)
Takuto Ando, Hideto Nakamura, Ken Sawada, Reishi Takashima, Hiroshi Nishi
In: Annual Meeting of the Geological Society of Japan, The 121st Annual Meeting (2014' Kagoshima), R23-O-11, Kagoshima, Japan, Sep 2014
Publication year: 2014

北海道朱鞠内川セクションの Cenomanian-Turonian 境界イベント層準で見出された負の δ13C エクスカーションにともなう陸上植生変動 Recognition of vegetation change associated with negative d13C excursion at the bottom of the Cenomanian-Turonian boundary event: A molecular paleontological approach

Conference (in Japanese)
Hideto Nakamura, Ken Sawada, Takuto Ando, Reishi Takashima, Hiroshi Nishi
In: Annual Meeting of the Geological Society of Japan, The 121st Annual Meeting (2014' Kagoshima), R23-O-12, Kagoshima, Japan, Sep 2014
Publication year: 2014

ハプト藻の熱熟成実験による藻類脂質の分解・続成過程の検討 Examination of decomposition and diagenesis processes of algal lipid from Haptophyta by thermal maturation experiment

Conference (in Japanese)
Ryohei Abe, Ken Sawada, Hideto Nakamura, Hiroya Araie, Iwane Suzuki, Yoshihiro Shiraiwa
In: Annual Meeting of the Geological Society of Japan, The 121nd Annual Meeting (2014' Kagoshima), R12-O-4, Kagoshima, Japan, Sep 2014
Publication year: 2014

Stable carbon isotopic variation of long chain n-alkanoic acids in the equatorial Pacific sediments over the last 40 Ma: Implications for expansion of C4 grassland in South America

Article
Sinya Yamamoto, Ken Sawada, Hideto Nakamura, Madoka Kobayashi, Kimitaka Kawamura
Organic Geochemistry 76: 62-71, 2014
Publication year: 2014

Highlights

  • δ13C for n-alkanoic acids in equatorial Pacific sediments examined.
  • C30 and C32 n-alkanoic acids likely recorded terrestrial higher plant signals.
  • Meridional molecular variations suggest transport of plant wax from South America.
  • Contribution from C4 vegetation to the equatorial Pacific increased after 1.7 Ma.

Abstract

The stable carbon isotope ratio (δ13C) values of sedimentary long chain (> C20n-alkanoic acids from the equatorial Pacific (IODP Sites U1331–1338) were measured for historical reconstruction of C4 plant contribution from South America over the last 40 Ma. The values for C30 and C32 acids ranged between −36.9‰ and −25.4‰, suggesting that they likely originated from higher plant wax associated with C3-dominated vegetation. The molecular distribution of alkanoic acids in the sediments showed a marked change across the Intertropical Convergence Zone (ITCZ), indicating a potential contribution from the Northern Hemisphere to the sediments located at > 10°N. In contrast, the abundances of n-alkanoic acids significantly decreased in the sediments at < 10°N. The results suggest that the ITCZ may have acted as an effective barrier for the atmospheric transport of terrigenous biomarkers from the Northern Hemisphere, and the records presumably reflect the plant wax signal from the northern part of South America. The latitudinal variation in the δ13C values suggest that the differences in the core locations possibly caused north- and southward shifts of ca. −1.0‰/°N and ca. +0.5‰/°S from the equator, respectively. The corrected δ13C values of C30 and C32 acids did not cross the C3 end member threshold until 1.7 Ma, despite the onset of C4 plants in central South America at ca. 7 Ma. This implies that vegetation in the low latitudes of South America was less affected by hydrological changes induced by the uplift of the Andes during the late Miocene.

Paleovegetation changes recorded by n-alkyl lipids bound in macromolecules of plant fossils and kerogens from the Cretaceous sediments in Japan

Conference
Yuma Miyata, Ken Sawada, Hideto Nakamura, Reishi Takashima, Masamiti Takahashi
In: American Geophysical Union, Fall Meeting 2014, abstract #B21E-0096, Dec 2014
Publication year: 2014

Long chain alkenes, alkenones and alkenoates produced by the haptophyte alga Chrysotila lamellosa CCMP1307 isolated from a salt marsh

Article
Hideto Nakamura, Ken Sawada, Hiroya Araie, Iwane Suzuki, Yoshihiro Shiraiwa
Researches in Organic Geochemistry, Vol. 66, 90-97, 2014
Publication year: 2014

Highlights

  • Cultured Chrysotila lamellosa CCMP1307 produced high proportion of C37:4 alkenones.

  • C. lamellosa U37K values reproduced the typical values for C37:4-rich lakes.

  • UK37 calibration showed a better fit with temperature than UK′37 calibration.

  • The unsaturation degree of C31 alkenes was also controlled by growth temperature.

Abstract

The compositions of long chain alkenes, alkenones and alkenoates in a cultured strain of the haptophyte Chrysotila lamellosa CCMP1307, isolated from a salt marsh, were investigated. The biomarker patterns were distinctive and showed a high proportion of tetraunsaturated alkenones and alkenoates, with a pronounced proportion of C40 alkenones and a lack of C38 methyl and C39 ethyl alkenones. Linear regression of the alkenone unsaturation degree (UK37) with growth temperature (T) was obtained over the range of possible CCMP1307 growth temperature values (4–20 °C): UK37 = 0.045 × T (°C) − 1.016, (n = 13, r2 0.96), while the UK′37 values were weakly correlated with TUK′37 = 0.0035T (°C) + 0.0511 (n = 18, r2 0.70). The UK37 calibration exhibited a low y-intercept in comparison with that of a Chinese inland lake strain reported previously. The data show significant intraspecific variation in UK37 for C. lamellosa between strains from different geographic origins. C. lamellosa CCMP1307 reproduced typical UK37 values observed in C37:4 rich lakes, especially at lower temperature (< 15 °C). In addition, we identified C29:2, C31:1, C31:2 and C31:3 alkenes, and found that the unsaturation degree of C31 alkenes (U31en), calculated with C31:1 and C31:2 alkenes, might also be a useful index of growth temperature for the haptophyte C. lamellosa.

Cretaceous Record of Diatom Evolution Revealed by Biomarkers in the Northwest Pacific Margin

Conference
Hideto Nakamura, Ken Sawada, Takuto Ando, Reishi Takashima, Hiroshi Nishi
In: American Geophysical Union, Fall Meeting 2014, abstract #B21E-0095, Dec 2014
Publication year: 2014

Evaluation of paleoenvironment using terpenoid biomarkers in lignites and plant fossil from the Miocene Tokiguchi Porcelain Clay Formation at the Onada mine, Tajimi, central Japan

Article
Ken Sawada, Hideto Nakamura, Arai Takaaki, Minoru Tsukagoshi
International Journal of Coal Geology, 107: 78-89, 2013
Publication year: 2013

Abstract

We investigated terpenoid biomarkers in muds from lignite seams, clays from porcelain clay beds that slightly contain lignite, and from a conifer cone macrofossil from the Miocene Tokiguchi Porcelain Clay Formation of the Tokai Group in central Japan, as well as extant cones. The n-alkanes, n-alkanols (suberin origin), diterpenoids (conifer origin), hopanoids (bacteria origin) and steroids were mainly present in the lignite-containing muds and clays. On the other hand, the diterpenoids, triterpenoids (angiosperm origin), hopanoids and steroids were detected as major component in the conifer cone macrofossil. In addition, the diterpenoids were mainly detected in the extant conifer cones. The low hopane isomer ratios and the detection of biosterols are confirmed to be immature in the lignite, sediment and macrofossil in the formation. The stanol/sterol ratio values of the lignite-containing muds and clays are much higher than that of the macrofossil. The higher ratios in lignite-containing muds and clays are possibly attributed to enhanced microbial reduction of organic matter under reduced condition in the swampy environments. A large amount of angiosperm-derived triterpenoids detected in the conifer cone macrofossil are considered as contaminants in the sample from sedimentary organic particles originated from detrital waxes of angiosperms. Such contamination might occur by migration of organic compounds within sediment after deposition. The angiosperm-derived polar terpenoids may be hardly affected by contamination by migration of organic matter from the adjacent sediments because these are less abundant in the conifer macrofossil. Thus, it is suggested that the polar terpenoid biomarkers are more reliable as paleochemotaxonomic and paleovegetation indicators.

Highlights

► We analyze terpenoid in sediments of Miocene lignite and clay beds, and plant fossil.

► Coniferous diterpenoid is mainly detected in sediments in the lignite and clay beds.

► Low hopane isomer ratio and biosterol detection show the lignite seams are immature.

► Lower stanol/sterol ratios of lignite seams are due to microbial reduction in swamp.

► Angiosperm-derived triterpenoids are detected as contaminant in a conifer fossil.

Data report: revised composite depth scales for Sites U1336, U1337, and U1338

Reports
Wilkens, R.H., Dickens, G.R., Tian, J., Backman, J., and the Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.209.2013
Publication year: 2013

Abstract

The eastern equatorial Pacific (EEP) is one of the most dynamic regions of the open ocean. To fully appreciate the history of this area in the time domain, correlative and complete sedimentary records are required from multiple drill sites. One essential step for each site is the construction of an accurate composite depth scale, whereby selected intervals of successive cores from proximal holes are spliced together to render a full stratigraphic section. Here, we generate revised composite depth scales for Integrated Ocean Drilling Program (IODP) Sites U1336, U1337, and U1338, recovered during IODP Expeditions 320 and 321. Composite sections were generated using physical properties data overlain on high-resolution scanned images of adjacent core sections from all holes cored at a site. Coring disturbance, particularly deeper in the holes, prevented composite construction to total depth at each site. At Site U1336, utilizing two holes, the composite record reaches almost 135 m core composite depth below seafloor (CCSF). At Site U1337, with four holes, a depth of close to 450 m CCSF was reached with only three gaps. Using the three holes of Site U1338, a composite section of almost 400 m CCSF was developed with only two breaks. Composite depth records are crucial for working on these sites because sediment composition varies considerably over short (<30 cm) depth intervals. The composite gamma ray attenuation density records will be particularly important to a range of studies in the region because they can be coupled to those collected at earlier drill sites in the EEP.

東赤道太平洋における過去40Maの陸上植物由来脂肪酸の安定炭素同位体比変動 Stable carbon isotope ratios of terrestrial higher plant-derived n-fatty acids in the eastern equatorial Pacific sediments over the last 40 Ma

Conference (in Japanese)
Shinya Yamamoto, Ken Sawada, Hideto Nakamura, Madoka Kobayashi, Kimitaka Kawamura
In: Abstracts of Annual Meeting of the Geochemical Society of Japan 2012, 2P16, Fukuoka, Japan, Sep 2012
Publication year: 2012

北海道中部、白亜系堆積物中の陸上植物由来ケロジェンの抵抗性高分子分析:新しい古植生指標の提案

Conference (in Japanese)
Yuma Miyata, Ken Sawada, Hideto Nakamura
In: Abstracts of Annual Meeting of the Geochemical Society of Japan 2012, 3E16, Fukuoka, Japan, Sep 2012
Publication year: 2012

ハプト藻培養試料におけるステロイド分析:バイオマーカー指標の検討 Steroid analysis for cultures of Haptophyte algae: examination of potential for its biomarker proxy.

Conference (in Japanese)
Chisato Kanou, Ken Sawada, Hideto Nakamura, Yoshihiro Shiraiwa, Iwane Suzuki, Hiroya Araie
In: Abstracts of Annual Meeting of the Geochemical Society of Japan 2012, 2C04, Fukuoka, Japan, Sep 2012
Publication year: 2012

ハプト藻の長鎖アルケン組成の多様性 The variation in long-chain alkenes composition in alkenone-producing Haptophytes

Conference (in Japanese)
Hideto Nakamura, Ken Sawada, Chisato Kanou, Yoshihiro Shiraiwa, Iwane Suzuki, Hiroya Araie
In: Abstracts of Annual Meeting of the Geochemical Society of Japan 2012, 2C05, Fukuoka, Japan, Sep 2012
Publication year: 2012

Variations in terrigenous matter transport evaluated by plant terpenoid analysis in the Neogene eastern equatorial Pacific sediment

Conference
Hideto Nakamura, Ken Sawada, Shinya Yamamot, Madoka Kobayashi
In: American Geophysical Union, Fall Meeting 2012, abstract #PP51B-2123, Dec 2012
Publication year: 2012

Variations in sea surface temperature reconstructed by algal biomarker thermometry in the Neogene equatorial Pacific sediments

Conference
Ken Sawada, Hideto Nakamura, Sinya Yamamoto, Madoka Kobayashi
In: American Geophysical Union, Fall Meeting 2012, abstract #PP43B-2040, Dec 2012
Publication year: 2012

Revised composite depth scales and integration of IODP Sites U1331–U1334 and ODP Sites 1218–1220

Reports
Westerhold, T., Röhl, U., Wilkens, R., Pälike, H., Lyle, M., Jones, T.D., Bown, P., Moore, T., Kamikuri, S., Acton, G., Ohneiser, C., Yamamoto, Y., Richter, C., Fitch, P., Scher, H., Liebrand, D., and the Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.201.2012
Publication year: 2012

Abstract

To reconstruct the climate history of the equatorial Pacific, one major objective of the Pacific Equatorial Age Transect (PEAT) program is to compile a Cenozoic megasplice that integrates all available bio-, chemo-, and magnetostratigraphic data including key records from Ocean Drilling Program (ODP) Leg 199. In order to do so, extended postcruise refinements of the shipboard composite depth scales and composite records are required. Here, we present a revised depth scale of Integrated Ocean Drilling Program (IODP) Expedition 320 Sites U1331, U1332, U1333, and U1334 as well as Leg 199 Sites 1218, 1219, and 1220. The revised composite records were used to perform site-to-site correlation and integration of Leg 199 and Expedition 320 sites. Based on this decimeter-scale correlation, a high-resolution integrated paleomagnetic, calcareous nannofossil, and radiolarian stratigraphy for the equatorial Pacific is established that covers the time from 20 to 40 Ma. This sedimentary compendium from the equatorial Pacific will be the backbone for paleoceanographic reconstructions for the late Paleogene.

A Cenozoic record of the equatorial Pacific carbonate compensation depth

Article
Heiko Pälike, Mitchell W. Lyle, Hiroshi Nishi, Isabella Raffi, Andy Ridgwell, Kusali Gamage, Adam Klaus, Gary Acton, Louise Anderson, Jan Backman, Jack Baldauf, Catherine Beltran, Steven M. Bohaty, Paul Bown, William Busch, Jim E. T. Channell, Cecily O. J. Chun, Margaret Delaney, Pawan Dewangan, Tom Dunkley Jones, Kirsty M. Edgar, Helen Evans, Peter Fitch, Gavin L. Foster, Nikolaus Gussone, Hitoshi Hasegawa, Ed C. Hathorne, Hiroki Hayashi, Jens O. Herrle, Ann Holbourn, Steve Hovan, Kiseong Hyeong, Koichi Iijima, Takashi Ito, Shin-ichi Kamikuri, Katsunori Kimoto, Junichiro Kuroda, Lizette Leon-Rodriguez, Alberto Malinverno, Ted C. Moore Jr, Brandon H. Murphy, Daniel P. Murphy, Hideto Nakamura, Kaoru Ogane, Christian Ohneiser, Carl Richter, Rebecca Robinson, Eelco J. Rohling, Oscar Romero, Ken Sawada, Howie Scher, Leah Schneider, Appy Sluijs, Hiroyuki Takata, Jun Tian, Akira Tsujimoto, Bridget S. Wade, Thomas Westerhold, Roy Wilkens, Trevor Williams, Paul A. Wilson, Yuhji Yamamoto, Shinya Yamamoto, Toshitsugu Yamazaki, Richard E. Zeebe
Nature, 488: 609-614, 2012
Publication year: 2012

Abstract

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.

古代の堆積物中の陸上高等植物テルペノイドを用いた古植生解析 Reconstruction of paleovegetation based on terrestrial higher plant terpenoid analysis in ancient sediment

Article
Hideto NAKAMURA, Ken SAWADA
Chikyukagaku (Geochemistry), 44(4):205-219, 2010
Publication year: 2010

Abstract

Terrestrial higher plant terpenoids (HPTs) occurring in ancient marine and lacustrine sediments, are more refractory and constitute a more highly diversified family of molecules than the other terrestrial higher plant biomarkers including wax compounds and lignin phenols. Therefore, this HPT biomarker can be plant biogeochemical and paleontological indicators. Triterpenes such as oleanane are derived from various biological triterpenoids synthesized by almost all angiosperms. Diterpenenes such as retene are originated from abietane-type diterpenoids, which are constituents of gymnosperm, especially conifer. In pimarane and phyllocladane type diterpenoids, their precursors, source plants, and diagenetic products have been partly known. In addition, sesquiterpenoids are derived from both angiosperm and gymnosperm biosynthesized compounds. Several researchers have suggested that the HPT distributions were useful as the paleovegetation proxies for reconstructing the relative abundance of angiosperm to gymnosperm (e.g. angiosperm/gymnosperm index; AGI). Moreover, we recently examinated applicability of the indicator for angiosperm/gymnosperm ratio by using the HPTs in ancient plant fossils. In this paper, we review such HPT biomarkers and their applicability and reliability of the indicator as plant chemotaxonomy and paleovegetation in the ancient sediments.

Toward the Cenozoic Megasplice—high-resolution XRF core scanning data and improved composite records from IODP Expedition 320: implications for fine scale paleoceanography

Conference
Westerhold, T., Bown, P.R., Dunkley Jones, T., Lyle, M.W., Moore, T.C., Pälike, H., Roehl, U., Wilkens, R.H., and Expedition 320/321 Scientists
In: American Geophysical Union, Fall Meeting 2010, San Francisco, abstract #PP22B-04, Dec 2010
Publication year: 2010

The Pacific Equatorial Age Transect, IODP Expeditions 320 and 321: Building a 50-Million-Year-Long Environmental Record of the Equatorial Pacific

Article
Mitchell Lyle, Heiko Pälike, Hiroshi Nishi, Isabella Raffi, Kusali Gamage, Adam Klaus and the IODP Expeditions 320/321 Scientific Party
Scientific Drilling 9: 4-15, 2010
Publication year: 2010

Introduction

In March 2009, the R/V JOIDES Resolution returned to operations after its extended refit and began with a drilling program ideally suited to its drilling strengths, the Pacific Equatorial Age Transect (PEAT, IODP Exp 320/321; Fig. 1A).
The PEAT drilling program was developed to understand how a major oceanic region evolved over the Cenozoic Era (65–0 Ma) and how it interacted with global climate. It specifically targeted the interval between 52 Ma and 0 Ma and drilled a series of sites that originated on the paleoequator. These sites have since been moved to the northwest by plate tectonics. The equatorial Pacific is an important target for paleocean ographic study because it is a significant ‘cog’ in the Earth’s climate machine, representing roughly half of the total tropical oceans that in turn represent roughly half of the total global ocean area. Prior drilling in both the Deep Sea Drilling Project (DSDP) and the Ocean Drilling Program (ODP) outlined the changes that have occurred through the Cenozoic (e.g., van Andel et al., 1975; Pisias et al., 1995). Not only did the earlier work fail to cover sufficient time intervals but also many of the sites were cored with ‘first-generation’ scientific drilling technology with incomplete and disturbed sediment recovery and thus cannot be used for detailed studies. ODP Legs 138 and 199 provide the best sample material from previous drilling, but each leg recovered sections spanning less than 10 million years suitable for cyclostratigraphy (the use of earths orbital cycles, recorded in sediments, as a measure of time). Up until the PEAT program it was difficult to achieve more than a reconnaissance of the environmental changes that have occurred in the equatorial Pacific. The PEAT program was designed to augment previous drilling and collect undisturbed sediments that could be spliced into a continuous, high-resolution environmental record of the eastern equatorial Pacific for the entire period from 56–0 Ma to present.

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Site U1338

Book ChapterReports
Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.110.2010
Publication year: 2010

Site U1337

Book ChapterReports
Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.109.2010
Publication year: 2010

Site U1336

Book ChapterReports
Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.108.2010
Publication year: 2010

Site U1335

Book ChapterReports
Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.107.2010
Publication year: 2010

Site U1334

Book ChapterReports
Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.106.2010
Publication year: 2010

Site U1333

Book ChapterReports
Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.105.2010
Publication year: 2010

Site U1332

Book ChapterReports
Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.104.2010
Publication year: 2010

Site U1331

Book ChapterReports
Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.103.2010
Publication year: 2010

Reconstructing ocean carbonate compensation depth variability in the Oligocene and early Miocene

Conference
Edgar, K.M., Pälike, H., Wilson, P.A., and the IODP Expedition 320/321 Scientists
In: American Geophysical Union, Fall Meeting 2010, San Francisco, abstract #PP23A-1715, Dec 2010
Publication year: 2010

Methods

Book ChapterReports
Expedition 320/321 Scientists
In Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 332/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.102.2010
Publication year: 2010

Magnetostratigraphic records from Eocene–Miocene sediments cored in the equatorial Pacific: initial results from the Pacific Equatorial Age Transect (PEAT) IODP Exp 320/321

Conference
Ohneiser, C., Acton, G., Channell, J.E.T., Evans, H., Richter, C., Yamamoto, Y., Yamazaki, T., and the Expedition 320/321 Scientists
In: Australian Earth Sciences Convention (AESC) 2010, Canberra, Australia
Publication year: 2010

Faunal change of benthic foraminifera in CAE-3 (middle Eocene) in the eastern equatorial Pacific (IODP Exp 320)

Conference
Takata, H., Khim, B., Nomura, R., Tsujimoto, A., and the IODP Expedition 320/321 Scientists
In: American Geophysical Union, Fall Meeting 2010, San Francisco, abstract #PP23A-1729, Dec 2010
Publication year: 2010

Expedition 320/321 summary

Book ChapterReports
Pälike, H., Nishi, H., Lyle, M., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, 2010
In: Pälike, H., Lyle, M., Nishi, H., Raffi, I., Gamage, K., Klaus, A., and the Expedition 320/321 Scientists, Proc. IODP, 320/321: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.320321.101.2010
Publication year: 2010

Abstract

Integrated Ocean Drilling Program Expedition 320/321, “Pacific Equatorial Age Transect” (Sites U1331–U1338), was designed to recover a continuous Cenozoic record of the equatorial Pacific by coring above the paleoposition of the Equator at successive crustal ages on the Pacific plate. These sediments record the evolution of the equatorial climate system throughout the Cenozoic. As we gained more information about the past movement of plates and when in Earth’s history “critical” climate events took place, it became possible to drill an age transect (“flow-line”) along the position of the paleoequator in the Pacific, targeting important time slices where the sedimentary archive allows us to reconstruct past climatic and tectonic conditions. The Pacific Equatorial Age Transect (PEAT) program cored eight sites from the sediment surface to basement, with basalt aged between 53 and 18 Ma, covering the time period following maximum Cenozoic warmth, through initial major glaciations, to today. The PEAT program allows the reconstruction of extreme changes of the calcium carbonate compensation depth (CCD) across major geological boundaries during the last 53 m.y. A very shallow CCD during most of the Paleogene makes it difficult to obtain well-preserved carbonate sediments during these stratigraphic intervals, but Expedition 320 recovered a unique sedimentary biogenic sediment archive for time periods just after the Paleocene/Eocene boundary event, the Eocene cooling, the Eocene–Oligocene transition, the “one cold pole” Oligocene, the Oligocene–Miocene transition, and the middle Miocene cooling. Expedition 321, the second part of the PEAT program, recovered sediments from the time period roughly from 25 Ma forward, including sediments crossing the Oligocene/Miocene boundary and two major Neogene equatorial Pacific sediment sections. Together with older Deep Sea Drilling Project and Ocean Drilling Program drilling in the equatorial Pacific, we can delineate the position of the paleoequator and variations in sediment thickness from ~150°W to 110°W longitude.

Aliphatic and aromatic terpenoid biomarkers in Cretaceous and Paleogene angiosperm fossils from Japan

Article
Hideto Nakamura, Ken Sawada, Masamichi Takahashi
Organic Geochemistry 41(9): 975-980, 2010
Publication year: 2010

Abstract

The distributions of aliphatic and aromatic terpenoids in Cretaceous and Paleogene angiosperm fossils from Japan were investigated. Aliphatic A ring-degraded oleanane, ursane and lupane were found in all samples. In addition, aliphatic gymnosperm-derived diterpenoids were detected in significant quantities. Aromatic oleanane-type triterpenoids were the major components, with ursane- and lupane-type triterpenoids being minor compounds in all angiosperm fossils. In a Cretaceous gymnosperm fossil, major components included aliphatic labdane-, isopimarane- and abietane-type diterpenoids, aromatic abietane-type diterpenoids, and chrysene- and picene-type polyaromatic hydrocarbons (PAHs). Trace amounts of oleanane-, ursane- and lupane-type triterpenoids were also identified. It is likely that the aromatic triterpenoids were introduced to the gymnosperm fossil from the angiosperm-derived material in the sediments. We defined an angiosperm/gymnosperm index (al-AGI′) as an alternative to the aliphatic triterpenoid/diterpenoid ratio proposed in the literature. The al-AGI′ index may underestimate the angiosperm contribution, because the aliphatic angiosperm-derived triterpenoids are more readily converted to aromatic counterparts than the diterpenoids during diagenesis. An aromatic angiosperm/gymnosperm index (ar-AGI) can be calculated using aromatic diterpenoids and triterpenoids. We suggest that ar-AGI is best calculated using only the oleanane-, ursane- and lupane-type aromatic triterpenoids, and that the chrysene- and picene-type PAHs be excluded.

Magnetostratigraphic records from Eocene–Miocene sediments cored in the equatorial Pacific: initial results from the Pacific Equatorial Age Transect (PEAT) IODP Exp 320/321

Conference
Ohneiser, C., Acton, G., Channell, J.E.T., Evans, H., Richter, C., Yamamoto, Y., Yamazaki, T., and the Expedition 320/321 Scientists
Geological Society of New Zealand Miscellaneous Publications, 128A: 161.
Publication year: 2009

Geosciences ’09. Geological Society of New Zealand, New Zealand Geophysical Society joint conference, 23-27 Nov, Oamaru: Programme & Abstracts

Integrated Ocean Drilling Program Expedition 320 Preliminary Report, Pacific Equatorial Age Transect

Reports
Heiko Pälike, Hiroshi Nishi, Mitch Lyle, Isabella Raffi, Adam Klaus, Kusali Gamage, and the Expedition 320/321 Scientists
Integrated Ocean Drilling Program Preliminary Report 10.2204/iodp.pr.320.2009
Publication year: 2009

被子植物バイオマーカーを用いた北海道下部白亜系における被子植物の出現年代の検討 Examination of the use of angiosperm biomarkers to clarify the timing of angiosperm appearance in the Lower Cretaceous of Hokkaido, Japan

Conference (in Japanese)
Hideto Nakamura, Ken Sawada, Reishi Takashima
In: Annual Meeting of the Geological Society of Japan, The 115th Annual Meeting (2008' Akita), O-169, Akita, Japan, Sep 2014
Publication year: 2008

白亜紀木片化石の抵抗性高分子を構成する結合態脂肪酸および脂肪族アルコールの組成分布 : 分子古生物学的指標の検討 Distributions of fatty acids and alcohols bound in resistant macromolecules of the Cretaceous woody-fragment fossils : search for molecular paleontological indicators

Article
Hideto Nakamura, Ken Sawada
Researches in Organic Geochemistry, Vol. 22, 31-42
Publication year: 2007

Abstract

The chemical compositions of woody fossil fragments collected by picking manually and density centrifugation from sandstones of the Lower Cretaceous Yezo Group in Oyubari, central Hokkaido, Japan were analyzed by KOH/methanol hydrolysis (saponification) after solvent extraction. Organic compounds bound in macromolecules of the woody fragments with ester bonds, obtained by saponification, were mainly composed of short-chain (C14 to C18) fatty acids and series of n-alkanols ranging from C12 to C28 homologues. These ester bound constituents are attributed to moieties of polyester parts of selectively preserved resistant macromolecule like cutin or suberin. Even carbon-number predominance was observed in both compounds, which indicated that biological components were well preserved. The bound fatty acids showed similar distribution patterns among all samples, indicating that these moieties might have been altered by strong diagenetic processes. On the other hand, the distribution patterns of n-alkanols significantly varied. In particular, those of long-chain (>C20n-alkanols varied possibly depending on plant taxonomy. Thus, we suggest that these parameters are strongly useful as molecular paleobiological indicators for chemotaxonomic analyses. Also, the distributions of short-chain n-alkanols and the ratios of short to long-chain homologues are presumably useful indicators for diagenesis, taphonomy and environment.

Plant Polymer Palaeobiology- Aphidoidea (PL3-A) Project : Geochemical and Morphological Studies on Gall (-like) Fossils

Proceedings
Ken Sawada, Shin-ichi Akimoto, Minoru Tsukagoshi, Hideto Nakamura, Debora Suzuki
In: (Eds) Hisatake Okada, Shunsuke F. Mawatari, Noriyuki Suzuki, Pitambar Gautam: Origin and Evolution of Natural Diversity: Proceedings of the International Symposium, The Origin and Evolution of Natural Diversity, 1-5 Oct 2007 in Sapporo, Japan. ISBN: 978-4-9903990-0-9, pp. 171-174.
Publication year: 2007