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Origin of the Earth:A proposal of new model called ABEL

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Geoscience Frontiers 2017年第2期8卷 253-274页

作者： Shigenori maruyama Toshikazu Ebisuzaki Earth-Life Science Institute Tokyo Institute of Technology Institute for Study of the Earth's Interior Okayama University RIKEN

The Earth was born as a dry planet without atmosphere and ocean components at 4.56 Ga,with subsequent secondary accretion of bio-elements,such as carbon（C）,hydrogen（H）,oxygen（O）,and nitrogen（N） which peaked at 4.37-4.20 *** two-step formation model of the Earth we refer to as the advent of bio-elements model（ABEL Model） and the event of the advent of bio-elements（water component） as ABEL *** is clear that the solid Earth originated from enstatite chondrite-like dry material based on the similarity in oxygen isotopic composition and among other *** the other hand,Earth＇s water derives primarily from carbonaceous chondrite material based on the hydrogen isotopic *** present our ABEL model to explain this enigma between solid Earth and water,as well as secondary accretion of oxidizing bio-elements,which became a precursor to initiate metabolism to emerge life on a highly reductive *** ABEL Bombardment had not occurred,life never would have emerged on the ***,ABEL Bombardment is one of the most important events for this planet to evolve into a habitable *** chronology of ABEL Bombardment is informed through previous researches of the late heavy bombardment and the late veneer *** Bombardment is considered to have occurred during 4.37-4.20 Ga,which is the concept to redefine the standard late heavy bombardment and the late veneer ***,ABEL Bombardment is the trigger of the transition from stagnant lid tectonics to plate tectonics on this planet because of the injection of volatiles into the initial dry Earth.

关键词： Origin of Earth and life Advent of bin-elements (ABEL)Origin of water on the Earth ABEL Bombardment Habitable Trinity planet Initiation of plate tectonics

United theory of biological evolution:Disaster-forced evolution through Supernova,radioactive ash fall-outs,genome instability,and mass extinctions

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Geoscience Frontiers 2015年第1期6卷 103-119页

作者： Toshikazu Ebisuzaki Shigenori maruyama RIKEN 2-1Hirosawa Earth-Life Science Institute Tokyo Institute of Technology

We present the disaster-forced biological evolution model as a general framework that includes Darwinian ＂phylogenic gradualism＂, Eldredge-Gould＇s ＂punctuated equilibrium＂, mass extinctions, and allopatric, parapatric, and sympatric speciation. It describes how reproductive isolation of organisms is established through global disasters due to supernova encounters and local disasters due to radioactive volcanic ash fall-outs by continental alkaline volcanism. Our new evolution model uniquely highlights three major factors of disaster-forced speciation： enhanced mutation rate by higher natural radiation level, smaller population size, and shrunken habitat size （i.e., isolation among the individual pop- ulations）. We developed a mathematical model describing speciation of a half-isolated group from a parental group, taking into account the population size （Ne）, immigration rate （m）, and mutation rate （μ）. The model gives a quantitative estimate of the speciation, which is consistent with the observations of speciation speed. For example, the speciation takes at least 105 generations, if mutation rate is less than 10 3 per generation per individual. This result is consistent with the previous studies, in which μ is assumed to be 10 3-10-5. On the other hand, the speciation is much faster （less than l0S generations） for the case that μ is as large as 0.1 in parapatric conditions （m 〈 μ）. Even a sympatric （m ~ 1 ） speciatiou can occur within 103 generations, if mutation rate is very high （μ- 1 mutation per individual per generation）, and if Ne 〈 20-30. Such a high mutation rate is possible during global disasters due to supernova encounters and local disasters due to radioactive ash fall-outs. They raise natural radiation level by a factor of 100-1000. Such rapid speciation events can also contribute to macro-evolution during mass extinction events, such as observed during the Cambrian explosion of biodiversity. A similar rapid speciation （though in a much smaller scale）

关键词： Speciation Supernova encounter Continental alkaline volcanism Cichlid Great African ape Cambrian explosion

Origins of building blocks of life: A review

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Geoscience Frontiers 2018年第4期9卷 1117-1153页

作者： Norio Kitadai Shigenori maruyama Earth-Life Science Institute Tokyo Institute of Technology

How and where did life on Earth originate？ To date, various environments have been proposed as plausible sites for the origin of life. However, discussions have focused on a limited stage of chemical evolution, or emergence of a specific chemical function of proto-biological systems. It remains unclear what geochemical situations could drive all the stages of chemical evolution, ranging from condensation of simple inorganic compounds to the emergence of self-sustaining systems that were evolvable into modern biological ones. In this review, we summarize reported experimental and theoretical findings for prebiotic chemistry relevant to this topic, including availability of biologically essential elements（N and P） on the Hadean Earth, abiotic synthesis of life＇s building blocks（amino acids, peptides, ribose, nucleobases, fatty acids, nucleotides, and oligonucleotides）, their polymerizations to bio-macromolecules（peptides and oligonucleotides）, and emergence of biological functions of replication and compartmentalization. It is indicated from the overviews that completion of the chemical evolution requires at least eight reaction conditions of（1） reductive gas phase,（2） alkaline pH,（3） freezing temperature,（4）fresh water,（5） dry/dry-wet cycle,（6） coupling with high energy reactions,（7） heating-cooling cycle in water, and（8） extraterrestrial input of life＇s building blocks and reactive nutrients. The necessity of these mutually exclusive conditions clearly indicates that life＇s origin did not occur at a single setting; rather, it required highly diverse and dynamic environments that were connected with each other to allow intratransportation of reaction products and reactants through fluid circulation. Future experimental research that mimics the conditions of the proposed model are expected to provide further constraints on the processes and mechanisms for the origin of life.

关键词： Astrobiology Biochemistry Chemical evolution Extraterrestrial life Hadean Earth Hydrothermal systems

Nuclear geyser model of the origin of life:Driving force to promote the synthesis of building blocks of life

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Geoscience Frontiers 2017年第2期8卷 275-298页

作者： Toshikazu Ebisuzaki Shigenori maruyama RIKEN Earth-Life Science Institute Tokyo Institute of Technology

We propose the nuclear geyser model to elucidate an optimal site to bear the first *** model overcomes the difficulties that previously proposed models have *** geyser is a geyser driven by a natural nuclear reactor,which was likely common in the Hadean Earth,because of a much higher abundance of 235U as nuclear *** nuclear geyser supplies the following：（1）high-density ionizing radiation to promote chemical chain reactions that even tar can be used for intermediate material to restart chemical reactions,（2）a system to maintain the circulation of material and energy,which includes cyclic environmental conditions（warm/cool,dry/wet,etc.）to enable to produce complex organic compounds,（3）a lower temperature than 100℃ as not to break down macromolecular organic compounds,（4）a locally reductive environment depending on rock types exposed along the geyser wall,and（5）a container to confine and accumulate volatile *** five factors are the necessary conditions that the birth place of life must *** the nuclear geyser can meet all five,in contrast to the previously proposed birth sites,such as tidal flat,submarine hydrothermal vent,and outer *** nuclear reactor and associated geyser,which maintain the circulations of material and energy with its surrounding environment,are regarded as the nuclear geyser system that enables numerous kinds of chemical reactions to synthesize complex organic compounds,and where the most primitive metabolism could be generated.

关键词： Origin of life Chemical evolution Natural nuclear reactor Aqueous electron Radiation chemistry

Formation of anorthosite on the Moon through magma ocean fractional crystallization

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Geoscience Frontiers 2017年第2期8卷 299-308页

作者： Tatsuyuki Arai Shigenori maruyama Department of Earth and Planetary Sciences Tokyo Institute of Technology2-12-10okayamaMeguro-kuTokyo 152-8551Japan Earth-Life Science Institute Tokyo Institute of Technology2-12-1 OokayamaMeguro-kuTokyo 152-8551Japan

Lunar anorthosite is a major rock of the lunar highlands,which formed as a result of plagioclasefloatation in the lunar magma ocean（LMO）.Constraints on the sufficient conditions that resulted in the formation of a thick pure anorthosite（mode of plagioclase 〉95 vol.%） is a key to reveal the early magmatic evolution of the terrestrial *** form the pure lunar anorthosite,plagioclase should have separated from the magma ocean with low crystal *** networks of plagioclase and mafic minerals develop when the crystal fraction in the magma（φ） is higher than ca.40-60 vol.%,which inhibit the formation of pure *** contrast,when φ is small,the magma ocean is highly turbulent,and plagioclase is likely to become entrained in the turbulent magma rather than separated from the *** determine the necessary conditions in which anorthosite forms from the LMO,this study adopted the energy criterion formulated by *** composition of melt,temperature,and pressure when plagioclase crystallizes are constrained by using MELTS/pMELTS to calculate the density and viscosity of the *** plagioclase starts to crystallize,the Mg~# of melt becomes 0.59 at 1291 *** density of the melt is smaller than that of plagioclase for P 〉 2.1 kbar（ca.50 km deep）,and the critical diameter of plagioclase to separate from the melt becomes larger than the typical crystal diameter of plagioclase（1.8-3 cm）.This suggests that plagioclase is likely entrained in the LMO just after the plagioclase starts to *** the Mg~# of melt becomes 0.54 at 1263 C,the density of melt becomes larger than that of plagioclase even for 0 *** the Mg~# of melt decreases down to 0.46 at 1218 C,the critical diameter of plagioclase to separate from the melt becomes 1.5-2.5 cm,which is nearly equal to the typical plagioclase of the lunar *** suggests that plagioclase could separate from the *** of the differences between the Earth and the Moon is the presenc

关键词： Moon Anorthosite Magma ocean MELTS Fractional crystallization

Changes in lamellar microstructure by parallel twinning during creep in soft PST crystal of TiAl alloy

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中国有色金属学会会刊：英文版 2002年第4期12卷 561-568页

作者： H.Y.Kim K.maruyama DepartmentofMaterialScience GraduateSchoolofEngineeringTohokuUniversity02AobayamaSendai980－8579Japan DepartmentofMaterialScience GraduateSchoolofEngineeringTohokuUniversity02AobayamaSendai980－8

Compression creep tests of a Ti-48%Al (mole fraction) alloy were carried out at 1?150?K with soft-orientated PST crystal. Parallel twinning took place during the creep. Changes in lamellar microstructure caused by the parallel twinning were investigated, and their effects on creep deformation behavior were discussed. The results show that the parallel twinning occurs in an early stage of creep, and makes significant contribution to creep strain in the domains favorably oriented for the twinning. The nucleation of parallel twins finishes at a strain of about 3%. There is a critical resolved shear stress for parallel twinning, and it is about 50?MPa in the Ti 48%Al PST crystals at 1?150?K. The activity of parallel twinning increases with increasing applied stress or in a coarse lamellar material. The addition of parallel twins reduces the average value of lamellar spacing. In general, the refinement of lamellar structure should improve creep resistance. However the strengthening by parallel twinning is not evident in creep of the soft PST crystals because the soft deformation modes are the dominant deformation mode in the crystals.

关键词：显微结构 TiAl合金软PST晶体蠕变孪晶

Triggers and sources of volatile-bearing plumes in the mantle transition zone

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Geoscience Frontiers 2015年第5期6卷 679-685页

作者： Inna Safonova Konstantin Litasov Shigenori maruyama V.S.Sobolev Institute of Geology and Mineralogy SB RAS Novosibirsk State University Earth-Life Science Institute Tokyo Institute of Technology

The paper discusses generation of volatile-bearing plumes in the mantle transition zone(MTZ) in terms of mineral-fluid petrology and their related formation of numerous localities of intra-plate bimodal volcanic series in Central and East *** plume generation in the MTZ can be triggered by the tectonic erosion of continental crust at Pacific-type convergent margins and by the presence of water and carbon dioxide in the *** probable sources of volatiles are the hyclrated/carbonated sediments and basalts and serpentinite of oceanic slabs,which can be subducted down to the deep *** erosion of continental crust supplies crustal material enriched in uranium and thorium into the mantle,which can serve source of heat in the *** heating in the MTZ induces melting of subducted slabs and continental crust and mantle upwelling,to produce OIB-type mafic and felsic melts,respectively.

关键词： Asis Pacific-type convergent margin Continental cr

Expanding-contracting Earth

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Geoscience Frontiers 2013年第3期4卷 341-347页

作者： Taku Tsuchiya Kenji Kawai Shigenori maruyama Geodynamic Research Center Ehime UniversityMatsuyamaEhime 790-8577Japan Department of Earth and Planetary Sciences Tokyo Institute of TechnologyMeguroTokyo 152-8551Japan Department of Earth Science University of CaliforniaSanta Barbara 93106CAUSA

The Earth was born from a giant impact at 4.56 Ga. It is generally thought that the Earth subsequently cooled, and hence shrunk, over geologic time. However, if the Earth＇s convection was double-layered, there must have been a peak of expansion during uni-directional cooling. We computed the expansion- contraction effect using first principles mineral physics data. The result shows a radius about 120 km larger than that of the present Earth immediately after the consolidation of the magma-ocean on the surface, and subsequent shrinkage of about 110 km in radius within about 10 m.y., followed by gradual expansion of 11 km in radius due to radiogenic heating in the lower mantle in spite of cooling in the upper mantle in the Archean. This was due to double-layered convection in the Archean with final collapse of overturn with contraction of about g km in radius, presumably by the end of the Archean. Since then, the Earth has gradually cooled down to reduce its radius by around 12 km. Geologic evidence supports the late Archean mantle overturn ca. 2.6 Ga, such as the global distribution of super-liqnidus flood basalts on nearly all cratonic fragments （〉35 examples）. If our inference is correct, the surface environment of the Earth must have undergone extensive volcanism and emergence of local landmasses, because of the thin ocean cover （3-5 km thickness）. Global unconformity appeared in cratonic fragments with stromatolite back to 2.9 Ga with a peak at 2.6 Ga. The global magmatism brought extensive crustal melting to yield explosive felsic volcanism to transport volcanic ash into the stratosphere during the catastrophic mantle overturn. This event seems to be recorded by sulfur mass-independent fractionation （SMIF） at 2.6 Ga. During the mantle overturn, a number of mantle plumes penetrated into the upper mantle and caused local upward doming of by ca. 2-3 km which raised local landmasses above sea-level. The consequent increase of atmospheric oxygen enabled life evolutio

关键词： Mantle overturn Expanding Earth Global unconformity Nutrients Eukaryotes

Reactions between olivine and CO2-rich seawater at 300℃:Implications for H2 generation and CO2 sequestration on the early Earth

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Geoscience Frontiers 2017年第2期8卷 387-396页

作者： Hisahiro Ueda Yusuke Sawaki Shigenori maruyama Department of Earth and Planetary Sciences Tokyo Institute of Technology2-12-1 OokayamaMeguro-kuTokyo 152-8551Japan Earth-Life Science Institute Tokyo Institute of Technology2-12-1 OokayamaMeguro-kuTokyo 152-8551Japan

To understand the influence of fluid CO2 on ultramafic rock-hosted seafloor hydrothermal systems on the early Earth,we monitored the reaction between San Carlos olivine and a CO2-rich NaCl fluid at 300 C and 500 *** the experiments,the total carbonic acid concentration（∑XO2） in the fluid decreased from approximately 65 to 9 mmol/*** minerals,magnesite,and subordinate amount of dolomite were formed via the water-rock *** H2 concentration in the fluid reached approximately 39 mmol/kg within 2736 h,which is relatively lower than the concentration generated by the reaction between olivine and a CO2-free NaCl solution at the same *** seen in previous hydrothermal experiments using komatiite,ferrous iron incorporation into Mg-bearing carbonate minerals likely limited iron oxidation in the fluids and the resulting H2 generation during the olivine *** carbonate mineralogy over the temperature range of natural hydrothermal fields,H2 generation is likely suppressed at temperatures below approximately 300℃ due to the formation of the Mg-bearing ***,H_2 concentration in fluid at 300℃ could be still high due to the temperature dependency of magnetite stability in ultramafic ***,the Mg-bearing carbonates may play a key role in the ocean-atmosphere system on the early *** studies suggest that the subduction of carbonated ultramafic rocks may transport surface CO2 species into the deep *** process may have reduced the huge initial amount of CO2 on the surface of the early *** approximate calculations demonstrate that the subduction of the Mg-bearing carbonates formed in komatiite likely played a crucial role as one of the CO2 carriers from the surface to the deep mantle,even in hot subduction zones.

关键词： Olivine CO2-rich condition Early Earth Hydrothermal alteration Serpentinization Experiment