著者

鶴巻 萌 齋藤 元文 丸山 茂徳 金井 昭夫

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.129, no.6, pp.881-898, 2020-12-25 (Released:2021-01-18)

参考文献数

49

被引用文献数

2 5

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It is well known that the evolution of life is affected by environmental factors, and this should be a fundamental perspective when investigating the origin of life; however, this perspective has not been fully addressed in biology. The Hadean Earth had a completely different surface environment from that of today, with no free oxygen, but instead a local environment rich in H2 which was generated by serpentinization, while energy–material circulation was driven by nuclear geysers. It is proposed that an anoxic hot-spring environment, with abundant hydrogen produced by serpentinization, was the birthplace of life. It is also proposed that the Hakuba hot spring in Nagano, Japan, is a Hadean-Earth-like environment with an H2-rich environment. A microbe found there, designated Hakuba OD1, is a member of the Candidate Phyla Radiation (CPR) bacteria group. In this review, CPR bacteria are described and their importance for the origin of life is discussed. The CPR is a bacterial supergroup consisting of dozens of phylum-level lineages of very small bacteria. This group was recently discovered with a metagenomics analysis that allowed unculturable environmental samples to be detected. Biochemical approaches to the CPR bacteria have not yet been successful because almost all the bacteria are unculturable or have not been isolated. However, with the development of massive parallel sequencing technology (next-generation sequencing), the phylogenetic characteristics of the CPR bacteria are becoming clear, and genomic analyses of these bacteria have led to unique discoveries. The sizes of the CPR bacterial genomes range from 400 to 1,500 kilobases (kb), and they contain approximately 400-1,500 genes. Thus, their genomes are remarkably small compared to other well-known and ordinary bacteria, represented by Escherichia coli, which have over 4,000 genes, but are similar to those of symbiotic or parasitic bacteria. The CPR bacterial genomes also lack many of the genes involved in essential metabolic pathways, such as the tricarboxylic acid (TCA) cycle and amino acid biosynthesis, so they seem to obtain their essential metabolites from their environments. It is proposed that this knowledge is important when considering the chemical changes that occurred on primitive Earth, which gave rise to the first forms of life through the processes of chemical evolution. Therefore, it is essential to understand the kinds of protein that are encoded in CPR bacterial genomes when studying the origin of life.

著者

丸山 茂徳

出版者

日本放射線安全管理学会

雑誌

日本放射線安全管理学会誌 (ISSN:13471503)

巻号頁・発行日

vol.8, no.2, pp.113-114, 2009 (Released:2011-12-07)

著者

磯崎 行雄 丸山 茂徳 柳井 修一

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.119, no.2, pp.378-391, 2010-04-25 (Released:2010-07-06)

参考文献数

72

被引用文献数

11 9

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A new historical review is presented on the progress of the geological sciences in Japan since the Meiji revolution in 1868. Geological knowledge, particularly studies of the geotectonic evolution and orogenic aspects, of the Japanese Islands has progressed through three distinct phases; (1) non-science stage, (2) colonial science stage, and (3) independent science stage, as modeled by Basalla (1967), who demonstrated a general pattern of transplanting cutting-edge scientific/technological knowledge from western Europe to the rest of the world. During the “non-science” stage from the 1860s to the 1890s, major geological aspects of the Japanese Islands, together with discoveries of unusual rocks, fossils etc., were initially described by foreign geologists (e.g. E. Naumann). In contrast, almost nothing was contributed by domestic geologists. During the “colonial science” stage, from the 1900s to the 1980s, research and education systems were transplanted effectively from western European countries. For example, applying the purely imported concept of geosyncline, the geotectonic history of the Japanese Islands was summarized for the first time by domestic geologists (e.g., Kobayashi, 1941; Minato et al., 1965 etc.). The almost unidirectional acceptance of plate tectonics also followed at this stage, with the exception of the rare but outstanding contribution of A. Miyashiro during the 1960s-1970s. During the “independent science” stage from the 1980s, various new ideas and original techniques in geology were proposed by Japanese geologists with lesser help from the western countries than before; i.e., practical criteria for identifying ancient accretionary complex, exhumation tectonic of ultrahigh to high-P/T metamorphic rocks, and subhorizontal growth framework of subduction-related orogens. Furthermore, in the first decade of the 21st century, the geological science in Japan entered stage of (4), “exporting science” with the introduction of new paradigms, such as the application of detrital zircon chronology to subduction-related orogens, which efficiently recognizes new geotectonic subdivisions and allows paleogeographical reconstruction with much higher resolution than before. These new paradigms (ideas, techniques) from Japan are now on sale for applying to the rest of the world.

著者

佐藤 友彦 吉屋 一美 丸山 茂徳

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.128, no.4, pp.571-596, 2019-08-25 (Released:2019-09-20)

参考文献数

109

被引用文献数

11 11

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Phylogenetic analysis is one of the useful tools available for revealing the evolution of life on the Earth; however, it has difficulty in principle distinguishing old and new genomes just by comparing phylogenomic trees. To overcome this difficulty, a new method is introduced which utilizes the Earth's history derived from geologic information to trace genomic evolution. This idea is inspired by Darwin's natural selection, and explains how living organisms change with the environment. In other words, life's genome does not change if the environment remains the same. A key is the birthplace of life on Hadean Earth, which is thought to be an ultra-reducing environment with H2 produced in abundance through serpentinization. OD1 is a potential microbe that has survived on the Earth since the Hadean. Its habitat, Hakuba-Happo in Japan, is a unique serpentinite-hosted hydrothermal system on land, and it has avoided evolution by remaining in a super-reducing environment from the Hadean to the present. OD1 is regarded as a “living fossil” of the Hadean microbe. Ultra-reducing environments have disappeared over the Earth's history. How has OD1 survived since the Hadean to the present? A possible scenario is proposed based on Plate Tectonics. OD1 habitats have gone through the following transitions: (1) super-reducing environment in a natural nuclear geyser on a primordial continent in the Hadean; (2) serpentinite-hosted hydrothermal system along a mid-oceanic ridge transform fault during the Archean-Proterozoic; (3) subduction-accretion and escape from oxygenated Phanerozoic ocean floor; and, (4) jacked up by growth of accretionary complexes and taking refuge in a hydrothermal system above a volcanic front. OD1 habitats have been reduced with geological age as free oxygen has increased in the surface environment. OD1 may be a “living microfossil” of the Hadean, making its way continuously through ultra-reducing environments on a tightrope.

著者

吉屋 一美 佐藤 友彦 大森 聡一 丸山 茂徳

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.128, no.4, pp.625-647, 2019-08-25 (Released:2019-09-20)

参考文献数

77

被引用文献数

4 4

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The Hadean surface was mainly covered by three kinds of rock: komatiite, KREEP basalt, and anorthosite, which were remarkably different from those on the modern Earth. Water–rock interactions between these rocks and water provided a highly reducing environment and formed secondary minerals on the rock surface that are important for producing metallo-enzymes for the emergence of primordial life. Previous studies suggest a correlation with active sites of metallo-enzymes and sulfide minerals based on an affinity with their structure, but they do not discuss the origins of metallic elements contained in these minerals, which are critical to understand where primordial life was born. Secondary minerals formed through water–rock interactions of komatiite in a nuclear geyser system are investigated, followed by a discussion of the relationship between active sites of metallo-enzymes and secondary minerals. Instead of komatiite, we used serpentinite collected from Hakuba Happo area, Nagano Prefecture in central-north Japan, which is thought to be one of the Hadean modern analogues for the birthplace of life. Several minor minerals were found, including magnetite, chromite, pyrite, and pentlandite, in addition to the major serpentine minerals. Pentlandite is not been mentioned in previous studies as a candidate for supplying important metallic elements to form metallo-enzymes in previous studies. It also acts as a catalyst for hydrogen generation, because it closely resembles the structural features of an active site of hydrogenases. Nickel-iron sulfide, pentlandite, is considered to be one of the important minerals for the origin of life. In addition, what kinds of minor mineral would be obtained from water–rock interactions of these rocks is estimated using a thermo-dynamic calculation. KREEP basalt contains large amounts of iron, and it could be useful for producing metallo-enzymes, especially for ferredoxins, an electron transfer enzymes associated with the emergence of primordial life.

著者

丸山 茂徳 戎崎 俊一 大島 拓

出版者

日本地球惑星科学連合

雑誌

日本地球惑星科学連合2016年大会

巻号頁・発行日

2016-03-10

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生命の起源は、おそらく生物学者だけでは解けない問題だろう。この問題は、生物学のみならず、天文学、地球物理学、化学、地質学などを総動員した超学際研究によってのみ解明できるはずである。われわれは、地球史研究を通して、生命を育んだ器としての地球の歴史を、横軸46億年研究と特異点研究の2つの手法を利用して解明してきた。そこから導かれる生命誕生場はどのようなものであり、最初の生命はどのようなものだったのかをまとめたのが、地球生命誕生の3段階モデルである。本モデルでは、生命は、第一次生命体、第二次生命体を経て第三次生命体(原核生物)が誕生したことを提唱する。以下に、各段階における生命体について詳述する。第一次生命体は、それぞれの個体そのものだけでは生存できなかったが、多数が外部共生することによって生き延びることが可能であった生物群だと考える。第一次生命体が持っていたワンセットの遺伝子をミニマム遺伝子と考える。おそらく、ミニマム遺伝子は約100個の遺伝子からなっており、「膜+代謝+自己複製」を可能にした。しかし、生存するためには細胞外共生をする必要があった。当時、ミニマム遺伝子の周囲には、この微小生態系の100倍以上の量のオルガネラ(現代のウイルスに酷似の状態)が存在していたが、これらの微小生態系が活動するためには、連続してエネルギーを供給することが必要で、当時の冥王代地球表層では太陽エネルギーが利用できなかった。その代わりに、地下の自然原子炉から供給される強力なエネルギーによって地表と間欠泉内部をつなぐ環境でのみ存在が可能だった。自然原子炉間欠泉は、熱湯が周期的に噴出するため、内部の温度は100℃が上限がとなる。従って、高温によるRNAの損傷を受けることは少なかった。 間欠泉から地表に投げ出される第一次生命体は、地表に降り注ぐ原始太陽風(現在の1000倍の放射線)によって分解され死滅する。それによって、これらはタールと化す。冥王代表層環境の厚い大気(CO2100気圧)が薄くなり、次第に太陽が顔を出し始めると、可視光(太陽エネルギー)を利用することができるようになった新しい生命(第2次生命体)が生まれる。これは地下の自然原子炉間欠泉で生まれた第一次生命体を基本とし、太陽からの弱い電磁エネルギーを利用するために、半導体(FeSなど)を利用した反応システムを創り出した。第一次生命体に引き続き、第二次生命体も無限に近い種類のアミノ酸の高次有機物からできるので、第二次生命体の多様性はさらに増加し、種類は無数にあったと考えられる。第二次生命体も細胞外共生していた。原始海洋は猛毒(pH<1、超富重金属元素濃度、塩分濃度は現在の5-10倍)である。したがって、淡水をたたえる湖沼環境で生まれた第二生命体は、原始海洋に遭遇すると大量絶滅する。大陸内部のリフト帯の湖沼環境で生まれた生命体は、リフトが割けて海洋が浸入することによって大量絶滅を起こすことになる。このプロセスが何度も繰り返され、幾度となく第二次生命体は大量絶滅を経験する。一方、プレート運動によって、海洋の重金属は鉱床として硫黄とともに固定され、マントルへプレートと共に沈み込むことによって海洋から取り除かれていった。更に、陸地の風化浸食運搬作用によって、細かく砕かれた大陸の岩石と海洋が反応することによって、海洋の中性化が進む。このように浄化されていった海洋にやがて適応した生命体は遺伝子の数を桁違いに増加して、細胞壁を作り、耐性強化した。これが真正細菌でシアノバクテリアの起源だと考えられる。 こうして、原始生物は、生き延びるための防御構造を、次々と発明して、遺伝子数を急増させた。理論的に可能なアミノ酸の種類はほぼ無限(1020)に近いが、現代地球の生物は20種類のアミノ酸だけを使う。これは、第二次生命体が、無限に近い種類のアミノ酸を組み合わせたものであったが、猛毒海洋への適応戦略で淘汰された結果であろう。これが地球型生命体の起源である。

著者

丸山 茂徳

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.121, no.6, pp.1090-1106, 2012-12-25 (Released:2013-01-07)

参考文献数

52

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The geotectonic division of the Japanese islands has been proposed by Isozaki and Maruyama (1991) such that the eastern extension of the Dabie-Sulu 240-220 Ma collisional UHP-HP belt (DSB) passes through the Korean peninsula to Japan. The corresponding belt in Japan is the Higo-Unazuki-Hitachi-Takanuki belt (HUHTB), because the protoliths are a unique A-type (platform sediments) and the metamorphic facies series belongs to the intermediate-pressure type, in addition to 240-220 Ma of metamorphic ages. Ishiwatari and Tsujimori (2012) claim that Maruyama et al. (2011) did not evaluate a new proposal by Ishiwatri and Tsujimori (2003), who proposed that the DSB extends not to the HUHTB but to the Sangun belt in a complex manner because of the promontory nature of the continental margin. This is a Q-A report requested by Ishiwatari and Tsujimori (2012). In this paper the author first introduces a classification of orogenic belts based on protoliths and its great significance for understanding the history of complex orogenic belts, following the original article by Maruyama et al. (1996), in addition to current topics on the role of tectonic erosion. Preceding the final formation of the collisional orogen, the Pacific-type orogen must have been present structurally above the collisional orogen against the hanging wall of the continent or arc. If not, it suggests the presence of tectonic erosion. Moreover, the size of any of regional metamorphic belt, arc, and TTG belt could be an excellent indicator of the scale of tectonic erosion. The Triassic DSB continues not to Sangun belt, but to the HUHTB, for four reasons: first, the protolith of those belts, second; the nature of regional metamorphism along intermediate-pressure type; third, structural units above and below the HUHTB; and finally, paleogeographic reconstruction of the Triassic North and South China cratons. The tectonic juxtapositions of the four so-called Sangun BS belts —450 Ma, 340 Ma, 250-210 Ma, and 170-180 Ma— against the HUHTB in a narrow zone as klippes can best be interpreted by extensive tectonic erosion.

著者

丸山 茂徳

雑誌

日本地球惑星科学連合2018年大会

巻号頁・発行日

2018-03-14

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地球上で生命が誕生するためには、満足しなければならない条件が少なくとも9つある。その9つとは、(1)エネルギー源(電離放射線と熱エネルギー)、(2)栄養塩の供給(リン、カリウム、レアアース元素など)、(3)生命構成主要元素の供給、(4)CH4, HCN, NH3などの還元ガスの濃集、(5)膜やRNAを合成するための乾湿サイクル、(6)非毒性の湖水環境、(7)Naの少ない水、(8)非常に多様な環境、(9)周期的環境、である。この9つの条件に基づいて、これまでに提案されてきた生命誕生場;(1)ダーウィンの提案したWarm Little Pondとそこから派生した生命のスープ仮説、(2)パンスペルミア、(3)火星説、(4)深海熱水系説、(5)島弧のヒューマロール仮説、(6)自然原子炉間欠泉説、を検証してみる。我々の考える最も理想的な生命誕生場は冥王代の表層環境に普遍的に存在したと考えられる自然原子炉間欠泉説である。この説が提案する生命誕生場は、生命誕生場に必要な9つの条件をすべて満たし、生命誕生のための「ゆりかご」を提供することができる。世界の地質記録に基づいて考えると、冥王代地球における環境変動が一連の前駆的化学進化を支配したと考えられる。そして、環境変動への受動的応答として生命が誕生したと考えられる。 生命の起源に代表される複雑系科学に取り組む際に重要なことは、カール・ポッパーが提案した検証可能性である。検証可能性を踏まえてモデルを提案することによって、生命の起源の解読が可能になるはずである。

著者

丸山 茂徳 横山 哲也 澤木 佑介 大森 聡一 鳴海 一成 ドーム ジェームズ 丹下 慶範

出版者

東京工業大学

雑誌

新学術領域研究(研究領域提案型)

巻号頁・発行日

2014-07-10

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本計画研究班では、地球史研究から導かれる「生命誕生の器」としての原始地球表層環境を定量的に復元し、冥王代地球表層環境進化の過程を具体的に解明することを目的としている。H29年度の研究は主に5つのテーマで実施された。[1]生命誕生場と生命誕生のプロセスの解明:生命が誕生するためには、水があるだけでは不十分で、それ以外にも複数の環境条件が満たされることが必要である。そこで、諸条件の中から生命誕生場に必要な9つの条件を抽出してまとめた。[2]白馬地域の地質の継続調査と古環境の分類:冥王代類似環境としての白馬地域の特殊な水環境について比較分析し、水環境場を4つのタイプに分類した。白馬で特徴的な蛇紋岩熱水系温泉水は、高アルカリかつ水素ガスを大量に含んでおり、特に、H2を含むため貧酸素水であり、そのため冥王代型の微生物生態系が形成されていることが明らかになった。[3]オクロの自然原子炉の研究:ガボン国内の数地域で露頭周辺の調査を集中的に行い、最適と思われる掘削地点を三か所抽出した。[4]地球の起源と新たな太陽系惑星形成論の展開:太陽系進化の初期条件を決めるうえで、太陽系組成ガスから凝縮した最古の物質であるCAIの理解を深めることが重要である。そこで、始原的隕石ALLENDEに含まれる3種類のCAIに注目し、それらの核合成起源Sr同位体異常(μ84Sr)を高精度で測定した。その結果、μ84Sr値の大きさはFTA > Type B > FSの順であることが判明した。[5]継続的なブレインストーミングの実施:2件の国際ワークショップと4件の国内向けワークショップ実施した。

著者

丸山 茂徳 林 衛 中村 保夫

出版者

実業公報社

雑誌

地質ニュース (ISSN:00094854)

巻号頁・発行日

no.497, pp.18-33, 1996-01

著者

佐藤 友彦 磯崎 行雄 小宮 剛 丸山 茂徳

出版者

日本地質学会

雑誌

日本地質学会学術大会講演要旨 (ISSN:13483935)

巻号頁・発行日

vol.115, 2008-09-15

著者

林 衛 丸山 茂徳

出版者

日本地質学会

雑誌

日本地質学会学術大会講演要旨

巻号頁・発行日

vol.99, 1992-03-25

著者

青木 一勝 大藤 茂 柳井 修一 丸山 茂徳

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.119, no.2, pp.313-332, 2010-04-25 (Released:2010-07-06)

参考文献数

88

被引用文献数

15 24

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The Sanbagawa metamorphic belt in SW Japan was previously considered to extend in the E-W direction from the Kanto Mountains to Kyushu Island, a distance > 800 km. However, Aoki et al. (2007) recently demonstrated that protoliths of metamorphic rocks in the Oboke area of the belt in central Shikoku accumulated at the trench after ca. 90-80 Ma. Furthermore, Aoki et al. (2008) showed that these rocks suffered blueschist metamorphism at 66-61 Ma, which differs from the timing of the Sanbagawa metamorphism. Thus, these results show that the Sanbagawa belt in Shikoku is a composite metamorphic belt. We, therefore, redefine the traditional Sanbagawa belt; the structurally upper part is the Sanbagawa metamorphic belt (sensu stricto). It formed as an accretionary complex at ca. 140-130 Ma and subsequently experienced BS-EC facies metamorphism at ca. 120-110 Ma (Okamoto et al., 2004). By contrast, the structurally lower segment termed the Shimanto BS facies metamorphic belt, formed as an accretionary complex after ca. 90-80 Ma and experienced peak metamorphism at ca. 60 Ma. Our observations have important implications for the lateral extension of these two metamorphic belts in SW Japan. The accretionary ages of the traditional Sanbagawa belt in the Kanto Mountains are younger than the Sanbagawa peak metamorphic age (Tsutsumi et al., 2009), clearly indicating that the entire region of Kanto Mountains Sanbagawa must belong to the Shimanto metamorphic belt. The same timing relationships were also found for the Sanbagawa belt on Kii Peninsula (Otoh et al., 2010). These results, therefore, indicate that the Shimanto metamorphic belt is exposed in Shikoku, Kii, and Kanto, thus the spatial distribution of Sanbagawa belt (ss) is less than half of its previous extent. The metamorphic grade of the Kanto Mountains in the Shimanto metamorphic belt ranges from pumpellyite-actinolite facies to epidote-amphibolite facies. Therefore, the higher-grade rocks of the Shimanto metamorphic rocks are exposed in the Kanto Mountains in comparison with Shikoku and Kii Peninsula. Hence, these two distinct BS-EA-EC (?) metamorphic belts are virtually equivalent in terms of spatial distribution, metamorphic range of grade, and facies series. Pacific-type orogenic belts typically comprise accretionary complex, high-P/T metamorphic belt, fore-arc sediments, and batholith belt landward from the trench (Maruyama et al., 1996). In SW Japan, the Sanbagawa belt (ss) is paired with the Ryoke low-P/T metamorphic belt and with the ca. 120-70 Ma Sanyo TTG batholith belt. Furthermore the related fore-arc basin may have developed penecontemporaneously with the Shimanto BS-EA orogeny, which is paired with the late Cretaceous to early Tertiary San-in TTG belt, which extending along the Japan Sea coast. In-between the intervening Izumi Group, a fore-arc basin deposit formed during the Campanian to Maastrichtian. Thus, these two groups of orogenic units, which formed during independent orogenies were both extensively modified during the opening of the Japan Sea ca. 20 Ma. The southward thrusting of the Ryoke and Cretaceous TTG belts over the Sanbagawa extended beyond the southern limit of the Sanbagawa, leading the up-down relationship of the Sanbagawa (ss) and the Ryoke belts.

著者

大藤 茂 下條 将徳 青木 一勝 中間 隆晃 丸山 茂徳 柳井 修一

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.119, no.2, pp.333-346, 2010-04-25 (Released:2010-07-06)

参考文献数

41

被引用文献数

33 44

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We measured the 206Pb/238U age distribution of detrital zircons in five psammitic schist samples from the Sanbagawa Belt in east-central Shikoku and the western Kii Peninsula to constrain their depositional age. The age-distribution diagrams for the five psammitic schist samples all show that detrital zircons of 100 to 90 Ma are most abundant and the age of the youngest zircon in each sample is less than 80 Ma. Considering the age of the retrogressive metamorphism of these psammitic schists, ca. 80-60 Ma, the protoliths age of the psammitic schists is constrained to 75-70 Ma, correlative to the age of the sandstone of the Middle Shimanto Belt (Yanai, 1984). A similar age-distribution has already been reported for two psammitic schist samples from the Central Unit of the Sanbagawa Belt in the Kanto Mountains (Tsutsumi et al., 2009). Thus the Sanbagawa Belt is most widely occupied by metamorphic rocks originating from rocks of the Middle Shimanto Belt. We also measured the 206Pb/238U age distribution of detrital zircons in Turonian sandstone from the Northern Shimanto Belt in the central Kii Peninsula. The age-distribution diagram shows that detrital zircons of around 128 Ma are most abundant and the age of the youngest zircon in the sample is about 100 Ma. A similar age-distribution has already been reported from a psammitic schist sample from the Southern Unit of the Sanbagawa Belt in the Kanto Mountains, overlying the Central Unit (Tsutsumi et al., 2009). The protolith age is still younger than the metamorphic age of the eclogites in central Shikoku, ca. 120-110 Ma (Okamoto et al., 2004), which occupy the uppermost portion of the Sanbagawa Belt. Although some previous studies suggested that the Sanbagawa Belt consists of metamorphosed Late Jurassic to Early Cretaceous accretionary complex, the present study shows that the belt is largely occupied by metamorphosed Late Cretaceous rocks: the Shimanto Metamorphic Rocks of Aoki et al. (2007). As a result, the Sanbagawa Belt consists of the following three units with different protolith ages: (1) Lower Unit of Shimanto Metamorphic Rocks with protoliths ages of 75-70 Ma and metamorphic ages of 70-60 Ma, (2) Upper Unit of Shimanto Metamorphic Rocks with protoliths ages of 95-85 Ma and metamorphic ages of 85-75 Ma, and (3) Sanbagawa Metamorphic Rocks (s.s.) with protoliths ages of Late Jurassic to Early Cretaceous and metamorphic ages of 120-110 Ma. The protoliths of the Upper and Lower units of the Shimanto Metamorphic Rocks are most likely rocks of the Northern Shimanto and Middle Shimanto belts, respectively.

著者

丸山 茂徳

出版者

日経サイエンス

雑誌

日経サイエンス (ISSN:0917009X)

巻号頁・発行日

vol.32, no.4, pp.46-55, 2002-04

被引用文献数

4

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火星の表層は赤茶け,猛烈な暴風と低温にしばしば見舞われる。表面には海はおろか液体の水すらない。

著者

齋藤 拓也 渋谷 岳造 小宮 剛 上野 雄一郎 丸山 茂徳 黒澤 正紀

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 日本地質学会第118年学術大会・日本鉱物科学会2011年年会合同学術大会(水戸大会) (ISSN:13483935)

巻号頁・発行日

pp.84, 2011 (Released:2012-03-27)

参考文献数

4

著者

ジェームズ・ ドーム 丸山 茂徳

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.127, no.5, pp.609-618, 2018-10-25 (Released:2018-11-14)

参考文献数

32

被引用文献数

2 2

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Habitable Trinity is a new concept for a habitable environment proposed by Dohm and Maruyama (2015). This concept indicates that the coexistence of an atmosphere, an ocean, and a landmass, accompanied by a continuous circulation of material among these three components driven by the Sun, is one of the minimum requirements for life to emerge and evolve. Because a life body consists of carbon (mainly from the atmosphere), oxygen (mainly from an ocean), hydrogen (mainly from an ocean), nitrogen (mainly from the atmosphere), and various nutrients (supplied from a landmass), the presence of water alone is not a sufficient condition. The Habitable Trinity concept can also be applied to other planets such as Mars, Europa, and Titan, and even exoplanets, as a useful index in the quest for life-containing planetary bodies.

著者

丸山 茂徳 生駒 大洋 玄田 英典

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 (ISSN:13483935)

巻号頁・発行日

vol.2007, pp.86, 2007

著者

石川 智子 上野 雄一郎 小宮 剛 吉田 尚弘 丸山 茂徳

出版者

一般社団法人日本地球化学会

雑誌

日本地球化学会年会要旨集 2009年度日本地球化学会第56回年会講演要旨集

巻号頁・発行日

pp.41, 2009 (Released:2009-09-01)

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後期原生代エディアカラ紀から顕生代初期カンブリア紀にかけて、生物進化と地球化学の両面で大規模な変動が起きたと考えられいる。特に先カンブリア紀/カンブリア紀境界(Pc/C境界)前後において海洋の無機炭素同位体比は大きく変動しており、当時の海洋の炭素循環の著しい変化が予想される。一般に、海洋の炭素循環の定量化には当時の海洋の有機炭素同対比の情報も必要不可欠であるが、Pc/C境界前後の有機炭素同対比が無機炭素同位体比と共に一地域で報告された例はほとんどない。そこで我々は、南中国・三峡地域において掘削により採取された連続試料を用いてPc/C境界前後の高時間分解能の有機炭素同位体比化学層序を求めた。得られた無機・有機炭素同位体比の関係性を基に、数値計算を行い当時の海洋の炭素循環について定量的に議論する。

著者

戎崎 俊一 西原 秀典 黒川 顕 森 宙史 鎌形 洋一 玉木 秀幸 中井 亮佑 大島 拓 原 正彦 鈴木 鉄兵 丸山 茂徳

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.129, no.6, pp.779-804, 2020-12-25 (Released:2021-01-18)

参考文献数

94

被引用文献数

2

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Previously proposed hypotheses on the origin of life are reviewed and it is demonstrated that none of them can provide the energy flux of ionizing radiation (UV/X/γ photons, and high-energy charged particles and neutrons) required to synthesize organic materials as demonstrated by the experiments by Miller and Urey in 1953. In order to overcome this difficulty, Ebisuzaki and Maruyama, in 2017, proposed a new hypothesis called the “Nuclear Geyser Model” of the origin of life, in which high-energy flux from a natural nuclear reactor drives chemical reactions to produce major biological molecules, such as amino acids, nucleotides, sugars, and fatty acids from raw molecules (H2O, N2, and CO2). Natural nuclear reactors were common on the surface of Hadean Earth, because the 235U/238U ratio was as high as 20%, which is much higher than the present value (0.7%), due to the shorter half-life of 235U than 238U. Ebisuzaki and Maruyama further posited that aqueous electrons and glyceraldehyde play key roles in the networks of chemical reactions in a nuclear geyser and suggested that primordial life depended on glyceraldehyde phosphate (GAP) from the nuclear geyser system as energy, carbon, and phosphate sources, pointing to a possible parallelism with the anaerobic glycolysis pathway; in particular, the lower stem path starting from GAP through Acetyl Coenzyme A to produce ATP and reduction power. It is shown that microbes (members of candidate division OD1) inhabiting high alkali hot springs, a modern analogue of the Hadean Earth environment, do not possess genes associated with conventional metabolisms, such as those of the TCA cycle, but only have genes in the lower stem path of the glycolysis. This is named the “Hadean Primordial Pathway”, because it is believed that this striking result points to a plausible origin of metabolic pathways of extant organisms. Also proposed is a step-by-step scenario of the evolution of the metabolism: 1) Chemical degradation of GAP supplied from the nuclear geyser to lactate; 2) Catalytic reactions to produce reductive power and acetyl coenzyme A (or its primitive form) and self-reproductive reactions by ribozymes on the surface of minerals (pyrite and struvite), which precipitate in a nuclear geyser (RNA world); 3) Enzymatic reactions by proteins with pyrites and the struvite in their reaction centers (RNP world); and, 4) Metabolism of extant organisms with the full assembly of enzymes produced by translating molecular machines with information stored in DNA sequences (DNA world). It is further inferred that relics of primordial metabolic evolution in the Hadean nuclear geyser can be seen at the reaction centers of enzymes of both pyrite and struvite types, nucleotide-like molecules as a cofactor of the enzymes, Calvin Cycle of photosynthesis, and chemical abundance of cytoplasm.