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...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 Ga.This 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 Bombardment.It is clear that the solid Earth originated from enstatite chondrite-like dry material based on the similarity in oxygen isotopic composition and among other isotopes.On the other hand,Earth＇s water derives primarily from carbonaceous chondrite material based on the hydrogen isotopic ratio.We 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 planet.If ABEL Bombardment had not occurred,life never would have emerged on the Earth.Therefore,ABEL Bombardment is one of the most important events for this planet to evolve into a habitable planet.The chronology of ABEL Bombardment is informed through previous researches of the late heavy bombardment and the late veneer model.ABEL 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 models.Also,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.展开更多
Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet.Here we speculate the processes that led to the birth of early life on Earth and its aftermath, fi...Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet.Here we speculate the processes that led to the birth of early life on Earth and its aftermath, finally leading to the evolution of metazoans.We evaluate：（1） the source of nutrients,（2） the chemistry of primordial ocean,（3） the initial mass of ocean,and（4） the size of planet.Among the life-building nutrients,phosphorus and potassium play a key role.Only three types of rocks can serve as an adequate source of nutrients：（a） continent-forming TTG（granite）,enabling the evolution of primitive life to metazoans;（b） primordial continents carrying anorthosite with KREEP（Potassium,Rare Earth Elements, and Phosphorus） basalts,which is a key to bear life;（c） carbonatite magma,enriched in radiogenic elements such as U and Th,which can cause mutation to speed up evolution and promote the birth of new species in continental rift settings.The second important factor is ocean chemistry.The primordial ocean was extremely acidic（pH = 1-2） and enriched in halogens（CI,F and others）,S,N and metallic elements（Cd,Cu,Zn,and others）,inhibiting the birth of life.Plate tectonics cleaned up these elements which interfered with RNA.Blue ocean finally appeared in the Phanerozoic with pH = 7 through extensive interaction with surface continental crust by weathering,erosion and transportation into ocean.The initial ocean mass was also important.The birth of life and aftermath of evolution was possible in the habitable zone with 3-5 km deep ocean which was able to supply sufficient nutrients. Without a huge landmass,nutrients cannot be supplied into the ocean only by ridge-hydrothermal circulation in the Hadean.Finally,the size of the planet plays a crucial role.Cooling of massive planets is less efficient than smaller ones,so that return-flow of seawater into mantle does not occur until central stars finish their main sequence.Due to the suitable size of Earth,the dawn of Phan展开更多
基金supported by Grant-in-Aid for Scientific Research on Innovative Areas(Grant Nos.26106002 and 26106006)
文摘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 Ga.This 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 Bombardment.It is clear that the solid Earth originated from enstatite chondrite-like dry material based on the similarity in oxygen isotopic composition and among other isotopes.On the other hand,Earth＇s water derives primarily from carbonaceous chondrite material based on the hydrogen isotopic ratio.We 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 planet.If ABEL Bombardment had not occurred,life never would have emerged on the Earth.Therefore,ABEL Bombardment is one of the most important events for this planet to evolve into a habitable planet.The chronology of ABEL Bombardment is informed through previous researches of the late heavy bombardment and the late veneer model.ABEL 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 models.Also,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.
文摘Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet.Here we speculate the processes that led to the birth of early life on Earth and its aftermath, finally leading to the evolution of metazoans.We evaluate：（1） the source of nutrients,（2） the chemistry of primordial ocean,（3） the initial mass of ocean,and（4） the size of planet.Among the life-building nutrients,phosphorus and potassium play a key role.Only three types of rocks can serve as an adequate source of nutrients：（a） continent-forming TTG（granite）,enabling the evolution of primitive life to metazoans;（b） primordial continents carrying anorthosite with KREEP（Potassium,Rare Earth Elements, and Phosphorus） basalts,which is a key to bear life;（c） carbonatite magma,enriched in radiogenic elements such as U and Th,which can cause mutation to speed up evolution and promote the birth of new species in continental rift settings.The second important factor is ocean chemistry.The primordial ocean was extremely acidic（pH = 1-2） and enriched in halogens（CI,F and others）,S,N and metallic elements（Cd,Cu,Zn,and others）,inhibiting the birth of life.Plate tectonics cleaned up these elements which interfered with RNA.Blue ocean finally appeared in the Phanerozoic with pH = 7 through extensive interaction with surface continental crust by weathering,erosion and transportation into ocean.The initial ocean mass was also important.The birth of life and aftermath of evolution was possible in the habitable zone with 3-5 km deep ocean which was able to supply sufficient nutrients. Without a huge landmass,nutrients cannot be supplied into the ocean only by ridge-hydrothermal circulation in the Hadean.Finally,the size of the planet plays a crucial role.Cooling of massive planets is less efficient than smaller ones,so that return-flow of seawater into mantle does not occur until central stars finish their main sequence.Due to the suitable size of Earth,the dawn of Phan
