1.Introduction.Since the Industrial Revolution,the partial pressure of atmospheric carbon dioxide(pCO_(2))has increased markedly,rising from approximately 280 ppm(1 ppm=1μL/L)to about 420 ppm.This escalation has inte...1.Introduction.Since the Industrial Revolution,the partial pressure of atmospheric carbon dioxide(pCO_(2))has increased markedly,rising from approximately 280 ppm(1 ppm=1μL/L)to about 420 ppm.This escalation has intensified global warming,with 2024 the hottest year on record since 1850.The global mean temperature now stands 1.46℃ above the pre-industrial average(1850-1900),a value already approaching the 1.5℃ threshold set by the Paris Agreement(NOAA,2025).展开更多
Over the past 500 million years in Earth's history,five mass extinctions("Big Five")have been identified,each with an extinction rate of exceeding 75%of marine species[1].Abrupt climatic and environmenta...Over the past 500 million years in Earth's history,five mass extinctions("Big Five")have been identified,each with an extinction rate of exceeding 75%of marine species[1].Abrupt climatic and environmental changes attributed to intra-or extraterrestrial events were proposed to cause these mass extinctions.Today the world is likely facing an ongoing biotic crisis,the socalled sixth mass extinction[2],due to the accelerated climate and environmental changes resulting from various anthropogenic activities.It is estimated that the average rate of vertebrate species loss in the last century is 100 times greater than the background rate[2].Deciphering the causes and mechanisms of past mass extinctions therefore is of great importance,as it provides critical knowledge for understanding the pattern and underlying mechanism of current biodiversity loss.展开更多
The Cryogenian Sturtian(717–660 Ma)and Marinoan glacial deposits(∼650–635 Ma),typically consisting of alternating layers of glaciogenic diamictite and clast-free lithofacies,indicate dynamic glaciers or glacial-int...The Cryogenian Sturtian(717–660 Ma)and Marinoan glacial deposits(∼650–635 Ma),typically consisting of alternating layers of glaciogenic diamictite and clast-free lithofacies,indicate dynamic glaciers or glacial-interglacial cycles during the global glaciations.This may result from ice sublimation in tropics under a Snowball Earth condition.However,this model fails to explain the deposition patterns observed in mid-latitude continents.We propose the presence of unfrozen oceans while the continents are covered,i.e.,the icy-continents.The open-ocean condition requires low atmospheric pCO_(2)level.We argued that the mantle CO_(2)degassing could be counterbalanced by a growing pool of dissolved organic carbon(DOC)in the deep ocean,maintaining a small marine dissolved inorganic carbon(DIC)pool and a low atmospheric pCO_(2)level.The persistent marine productivity in the open ocean would support the expanded DOC pool due to reduced ocean ventilation and limited terrestrial inputs of oxidants.However,the global glaciation with open oceans was climatically unstable.The fluctuation of the DOC pool on a local or regional scale likely contributed to the frequent glacial-interglacial oscillations recorded in the rock records.Additionally,the expansion of the DOC pool removed seawater nutrients,e.g.,phosphorus(P),and insufficient nutrient supply prevented the transfer of mantle-degassing carbon as DOC,ultimately leading to the termination of global glaciation.The turnover of the DOC pool,caused by deep ocean ventilation in the deglacial period,significantly increased the atmospheric pCO_(2)level.This event was followed by intense continental weathering,increased seawater pH,recovery of primary productivity,cap carbonate precipitation,and eventually,the emergence of new life forms and innovations in the biosphere.展开更多
This paper briefly introduces the conception and research history of the Great Oxidation Event(GOE) in the early Paleoproterozoic and summarizes the primary geological and geochemical records of this event. On the bas...This paper briefly introduces the conception and research history of the Great Oxidation Event(GOE) in the early Paleoproterozoic and summarizes the primary geological and geochemical records of this event. On the basis of these, we overview the significant progress in three fields of the GOE: the timing and process of its startup, its mechanisms, and its climatic-ecological effects. The records of mass-independent fractionation of sulfur isotopes suggest that the startup of the GOE might be multi-episodic, which is obviously inconsistent with the single-episodic opinion obtained from atmospheric model simulations. The fundamental mechanism of the GOE was the source of the atmospheric Oexceeding the sink, but it remains uncertain whether it was due to the increase in the source or the decrease in the sink. The GOE substantially affected the climate,biological evolution, and biogeochemical cycles, but the specific processes remain elusive. In consideration of the current progress, we propose four aspects for future explorations, including the construction of geological and geochemical proxies for extremely low atmospheric oxygen content(pO), how the GOE changed the evolutions of Earth’s habitability and the processes in deep Earth, and constraining the mechanism of the GOE by coupling geological events with different time scales.展开更多
The origin of sedimentary dolomite has become a long-standing problem in the Earth Sciences.Some carbonate minerals like ankerite have the same crystal structure as dolomite,hence their genesis may provide clues to he...The origin of sedimentary dolomite has become a long-standing problem in the Earth Sciences.Some carbonate minerals like ankerite have the same crystal structure as dolomite,hence their genesis may provide clues to help solving the dolomite problem.The purpose of this study was to probe whether microbial activity can be involved in the formation of ankerite.Bio-carbonation experiments associated with microbial iron reduction were performed in batch systems with various concentrations of Ca^(2+)(0–20 mmol/L),with a marine iron-reducing bacterium Shewanella piezotolerans WP3 as the reaction mediator,and with lactate and ferrihydrite as the respective electron donor and acceptor.Our biomineralization data showed that Ca-amendments expedited microbially-mediated ferrihydrite reduction by enhancing the adhesion between WP3 cells and ferrihydrite particles.After bioreduction,siderite occurred as the principal secondary mineral in the Ca-free systems.Instead,Ca-Fe carbonates were formed when Ca^(2+)ions were present.The CaCO_(3) content of microbially-induced Ca-Fe carbonates was positively correlated with the initial Ca2+concentration.The Ca-Fe carbonate phase produced in the 20 mmol/L Ca-amended biosystems had a chemical formula of Ca_(0.8)Fe_(1.2)(CO_(3))_(2),which is close to the theoretical composition of ankerite.This ankeritelike phase was nanometric in size and spherical,Ca-Fe disordered,and structurally defective.Our simulated diagenesis experiments further demonstrated that the resulting ankerite-like phase could be converted into ordered ankerite under hydrothermal conditions.We introduced the term“proto-ankerite”to define the Ca-Fe phases that possess near-ankerite stoichiometry but disordered cation arrangement.On the basis of the present study,we proposed herein that microbial activity is an important contributor to the genesis of sedimentary ankerite by providing the metastable Ca-Fe carbonate precursors.展开更多
The Ediacaran Period(~635–539 Ma)was a critical time in Earth history due to large increases in atmospheric and oceanic oxygen levels and rapid evolution of early animals[1].It was also an interval of major climatic ...The Ediacaran Period(~635–539 Ma)was a critical time in Earth history due to large increases in atmospheric and oceanic oxygen levels and rapid evolution of early animals[1].It was also an interval of major climatic and geochemical perturbations,such as the~580-Ma Gaskiers Glaciation[2](Fig.S1 online)and the late Ediacaran Shuram Excursion(SE;also known as DOUNCE or EN3 in South China,see Fig.S2 online),which was the largest negative carbonate carbon isotope(δ13Ccarb)excursion in Earth history[3,4].In contrast to established redox,biological,and C-cycling records for the Ediacaran,however,no secular,high-resolution paleotemperature record with climatic significance has been reported to date,impeding our understanding of the relationships among major environmental,biological,geochemical,and climatic processes and milestones.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42425305,42293290,and 42172216).
文摘1.Introduction.Since the Industrial Revolution,the partial pressure of atmospheric carbon dioxide(pCO_(2))has increased markedly,rising from approximately 280 ppm(1 ppm=1μL/L)to about 420 ppm.This escalation has intensified global warming,with 2024 the hottest year on record since 1850.The global mean temperature now stands 1.46℃ above the pre-industrial average(1850-1900),a value already approaching the 1.5℃ threshold set by the Paris Agreement(NOAA,2025).
基金supported by the National Natural Science Foundation of China(42025703,42325202,and 42277072)。
文摘Over the past 500 million years in Earth's history,five mass extinctions("Big Five")have been identified,each with an extinction rate of exceeding 75%of marine species[1].Abrupt climatic and environmental changes attributed to intra-or extraterrestrial events were proposed to cause these mass extinctions.Today the world is likely facing an ongoing biotic crisis,the socalled sixth mass extinction[2],due to the accelerated climate and environmental changes resulting from various anthropogenic activities.It is estimated that the average rate of vertebrate species loss in the last century is 100 times greater than the background rate[2].Deciphering the causes and mechanisms of past mass extinctions therefore is of great importance,as it provides critical knowledge for understanding the pattern and underlying mechanism of current biodiversity loss.
基金supported by the National Natural Science Foundation of China(42225304 and 42293291).
文摘The Cryogenian Sturtian(717–660 Ma)and Marinoan glacial deposits(∼650–635 Ma),typically consisting of alternating layers of glaciogenic diamictite and clast-free lithofacies,indicate dynamic glaciers or glacial-interglacial cycles during the global glaciations.This may result from ice sublimation in tropics under a Snowball Earth condition.However,this model fails to explain the deposition patterns observed in mid-latitude continents.We propose the presence of unfrozen oceans while the continents are covered,i.e.,the icy-continents.The open-ocean condition requires low atmospheric pCO_(2)level.We argued that the mantle CO_(2)degassing could be counterbalanced by a growing pool of dissolved organic carbon(DOC)in the deep ocean,maintaining a small marine dissolved inorganic carbon(DIC)pool and a low atmospheric pCO_(2)level.The persistent marine productivity in the open ocean would support the expanded DOC pool due to reduced ocean ventilation and limited terrestrial inputs of oxidants.However,the global glaciation with open oceans was climatically unstable.The fluctuation of the DOC pool on a local or regional scale likely contributed to the frequent glacial-interglacial oscillations recorded in the rock records.Additionally,the expansion of the DOC pool removed seawater nutrients,e.g.,phosphorus(P),and insufficient nutrient supply prevented the transfer of mantle-degassing carbon as DOC,ultimately leading to the termination of global glaciation.The turnover of the DOC pool,caused by deep ocean ventilation in the deglacial period,significantly increased the atmospheric pCO_(2)level.This event was followed by intense continental weathering,increased seawater pH,recovery of primary productivity,cap carbonate precipitation,and eventually,the emergence of new life forms and innovations in the biosphere.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41821001, 42172216, 41873027)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB26000000)the 111 Project of China (Grant No. BP0820004)。
文摘This paper briefly introduces the conception and research history of the Great Oxidation Event(GOE) in the early Paleoproterozoic and summarizes the primary geological and geochemical records of this event. On the basis of these, we overview the significant progress in three fields of the GOE: the timing and process of its startup, its mechanisms, and its climatic-ecological effects. The records of mass-independent fractionation of sulfur isotopes suggest that the startup of the GOE might be multi-episodic, which is obviously inconsistent with the single-episodic opinion obtained from atmospheric model simulations. The fundamental mechanism of the GOE was the source of the atmospheric Oexceeding the sink, but it remains uncertain whether it was due to the increase in the source or the decrease in the sink. The GOE substantially affected the climate,biological evolution, and biogeochemical cycles, but the specific processes remain elusive. In consideration of the current progress, we propose four aspects for future explorations, including the construction of geological and geochemical proxies for extremely low atmospheric oxygen content(pO), how the GOE changed the evolutions of Earth’s habitability and the processes in deep Earth, and constraining the mechanism of the GOE by coupling geological events with different time scales.
基金This research was jointly supported by the National Natural Science Foundation of China(Grant Nos.42272046,42293292 and 42072336)the National Key R&D Program of China(Grant No.2022YFF0800304)the 111 Project(Grant No.BP0820004).
文摘The origin of sedimentary dolomite has become a long-standing problem in the Earth Sciences.Some carbonate minerals like ankerite have the same crystal structure as dolomite,hence their genesis may provide clues to help solving the dolomite problem.The purpose of this study was to probe whether microbial activity can be involved in the formation of ankerite.Bio-carbonation experiments associated with microbial iron reduction were performed in batch systems with various concentrations of Ca^(2+)(0–20 mmol/L),with a marine iron-reducing bacterium Shewanella piezotolerans WP3 as the reaction mediator,and with lactate and ferrihydrite as the respective electron donor and acceptor.Our biomineralization data showed that Ca-amendments expedited microbially-mediated ferrihydrite reduction by enhancing the adhesion between WP3 cells and ferrihydrite particles.After bioreduction,siderite occurred as the principal secondary mineral in the Ca-free systems.Instead,Ca-Fe carbonates were formed when Ca^(2+)ions were present.The CaCO_(3) content of microbially-induced Ca-Fe carbonates was positively correlated with the initial Ca2+concentration.The Ca-Fe carbonate phase produced in the 20 mmol/L Ca-amended biosystems had a chemical formula of Ca_(0.8)Fe_(1.2)(CO_(3))_(2),which is close to the theoretical composition of ankerite.This ankeritelike phase was nanometric in size and spherical,Ca-Fe disordered,and structurally defective.Our simulated diagenesis experiments further demonstrated that the resulting ankerite-like phase could be converted into ordered ankerite under hydrothermal conditions.We introduced the term“proto-ankerite”to define the Ca-Fe phases that possess near-ankerite stoichiometry but disordered cation arrangement.On the basis of the present study,we proposed herein that microbial activity is an important contributor to the genesis of sedimentary ankerite by providing the metastable Ca-Fe carbonate precursors.
基金supported by the National Natural Science Foundation of China(41825019,42130208,41821001,and 42102343)the Programme of Introducing Talents of Discipline to Universities(BP0820004)+1 种基金China Postdoctoral Science Foundation(2020M682515)an award from “Laboratoire Excellence”LabexMER(ANR-10-LABX-19)。
文摘The Ediacaran Period(~635–539 Ma)was a critical time in Earth history due to large increases in atmospheric and oceanic oxygen levels and rapid evolution of early animals[1].It was also an interval of major climatic and geochemical perturbations,such as the~580-Ma Gaskiers Glaciation[2](Fig.S1 online)and the late Ediacaran Shuram Excursion(SE;also known as DOUNCE or EN3 in South China,see Fig.S2 online),which was the largest negative carbonate carbon isotope(δ13Ccarb)excursion in Earth history[3,4].In contrast to established redox,biological,and C-cycling records for the Ediacaran,however,no secular,high-resolution paleotemperature record with climatic significance has been reported to date,impeding our understanding of the relationships among major environmental,biological,geochemical,and climatic processes and milestones.
