The Neoarchaean to Palaeoproterozoic Transvaal Supergroup of the Kaapvaal Craton,southern Africa,is one of the best-preserved and most complete stratigraphic records across a critical in juncture in the Earth’s history.
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
During Earth’s 4.6 billion-year history,its surface has experienced environmental changes that drastically impacted habitability.The changes have been mostly attributed to near-surface processes or astronomical event...During Earth’s 4.6 billion-year history,its surface has experienced environmental changes that drastically impacted habitability.The changes have been mostly attributed to near-surface processes or astronomical events with little consideration of Earth’s deep interior.Recent progresses in high-pressure geochemistry and geophysics,however,indicate that deep Earth processes may have played a dominant role in the surface(Mao and Mao,2020).展开更多
The carbon cycle is an important process that regulates Earth's evolution.We compare two typical periods,in the Paleoproterozoic and Neoproterozoic,in which many geological events occurred.It remains an open quest...The carbon cycle is an important process that regulates Earth's evolution.We compare two typical periods,in the Paleoproterozoic and Neoproterozoic,in which many geological events occurred.It remains an open question when modern plate tectonics started on Earth and how it has influenced the carbon cycle through time.In the Paleoproterozoic,intense weathering in a highly CO_(2)and CH_(4)rich atmosphere caused more nutritional elements to be carried into the ocean.Terrestrial input boosted high biological productivity,deposition of sediments and the formation of an altered oceanic crust,which may have promoted an increase in the oxygen content.Sediment lubrication and a decrease in mantle potential temperature made cold and deep subduction possible,which carried more carbon into the deep mantle.Carbon can be stored in the mantle as diamond and carbonated mantle rocks,being released by arc and mid-ocean ridge outgassing at widely different times.From the Paleoproterozoic through the Neoproterozoic to the Phanerozoic,the carbon cycle has promoted the evolution of a habitable Earth.展开更多
This paper compiles lithostratigraphic and geochronological data obtained for the Palaeoproterozoic glacial diamictite-bearing successions,and thereby provides insights into understanding the geological processes caus...This paper compiles lithostratigraphic and geochronological data obtained for the Palaeoproterozoic glacial diamictite-bearing successions,and thereby provides insights into understanding the geological processes causing the Huronian Glaciation Event.The majority of evidence for appearances of this glaciation event can be related to the Kenorland supercontinent breakup,allied to significant atmospheric change,as well as blooms of biogeochemical oxygenic photosynthesis.In this paper,the Huronian Glaciation Event is constrained to have occurred synchronously during 2.29-2.25 Ga,accompanied by dramatic environmental changes characteristic of the Great Oxidation Event which includes the pre- 2.3 Ga hydrosphere oxidation and the post-2.3 Ga atmosphere oxygenation.展开更多
A paleosol horizon is described from the contact of the Sausar Group(w2400 Ma) and its basement(Tirodi Gneiss; 〉2500 Ma) in Central India. Physical evidence of pedogenesis is marked by the development of stress c...A paleosol horizon is described from the contact of the Sausar Group(w2400 Ma) and its basement(Tirodi Gneiss; 〉2500 Ma) in Central India. Physical evidence of pedogenesis is marked by the development of stress corrosion cracks, soil peds, corestone weathering and nodular rocks. XRD and SEM-EDX data indicate the presence of siderite, ankerite, uraninite, chlorite, alumino-silicate minerals, ilmenite,rutile and magnetite, in addition to quartz, feldspar and mica. The chemical index of alteration, the plagioclase index of alteration, and the chemical index of weathering show an increasing trend from parent rock to the paleosol and indicate a moderate trend of weathering. The A-CN-K plot indicates loss of feldspars, enrichment in Al2O3 and formation of illite. Different major element ratios indicate baseloss through hydrolysis, clay formation, leaching of some elements, and more precipitation with good surface drainage. The paleosol is depleted in HREE in comparison to the parent rock indicating high fluid-rock interaction during weathering. The paleosol samples show flat Ce and Eu anomalies, low SREE, and high(La/Yb)N, indicative of a reducing environment of formation. Reducing condition can also be inferred from the concentration of elements such as V, Co, Cu, Pb, and Zn in the paleosol profile. Although enriched in Fe and Mg, the overall geochemical patterns of the paleosol indicate oxygen deficient conditions in the atmosphere and development by weathering and leaching processes associated with high precipitation and good surface drainage at the time of development of this paleosol during the Archeane Paleoproterozoic transition.展开更多
文摘The Neoarchaean to Palaeoproterozoic Transvaal Supergroup of the Kaapvaal Craton,southern Africa,is one of the best-preserved and most complete stratigraphic records across a critical in juncture in the Earth’s history.
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support of National Science Foundation of China Grant No:U1930401
文摘During Earth’s 4.6 billion-year history,its surface has experienced environmental changes that drastically impacted habitability.The changes have been mostly attributed to near-surface processes or astronomical events with little consideration of Earth’s deep interior.Recent progresses in high-pressure geochemistry and geophysics,however,indicate that deep Earth processes may have played a dominant role in the surface(Mao and Mao,2020).
基金funded by the National Key Research and Development Program of China(Grant No.2019YFA0708501)。
文摘The carbon cycle is an important process that regulates Earth's evolution.We compare two typical periods,in the Paleoproterozoic and Neoproterozoic,in which many geological events occurred.It remains an open question when modern plate tectonics started on Earth and how it has influenced the carbon cycle through time.In the Paleoproterozoic,intense weathering in a highly CO_(2)and CH_(4)rich atmosphere caused more nutritional elements to be carried into the ocean.Terrestrial input boosted high biological productivity,deposition of sediments and the formation of an altered oceanic crust,which may have promoted an increase in the oxygen content.Sediment lubrication and a decrease in mantle potential temperature made cold and deep subduction possible,which carried more carbon into the deep mantle.Carbon can be stored in the mantle as diamond and carbonated mantle rocks,being released by arc and mid-ocean ridge outgassing at widely different times.From the Paleoproterozoic through the Neoproterozoic to the Phanerozoic,the carbon cycle has promoted the evolution of a habitable Earth.
基金funded by the National 973-Program(Project Nos.2012CB416602,2006CB403508)National Natural Science Foundation of China(Nos.40352003,40425006,40373007)Frontier Field Project of the State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences
文摘This paper compiles lithostratigraphic and geochronological data obtained for the Palaeoproterozoic glacial diamictite-bearing successions,and thereby provides insights into understanding the geological processes causing the Huronian Glaciation Event.The majority of evidence for appearances of this glaciation event can be related to the Kenorland supercontinent breakup,allied to significant atmospheric change,as well as blooms of biogeochemical oxygenic photosynthesis.In this paper,the Huronian Glaciation Event is constrained to have occurred synchronously during 2.29-2.25 Ga,accompanied by dramatic environmental changes characteristic of the Great Oxidation Event which includes the pre- 2.3 Ga hydrosphere oxidation and the post-2.3 Ga atmosphere oxygenation.
文摘A paleosol horizon is described from the contact of the Sausar Group(w2400 Ma) and its basement(Tirodi Gneiss; 〉2500 Ma) in Central India. Physical evidence of pedogenesis is marked by the development of stress corrosion cracks, soil peds, corestone weathering and nodular rocks. XRD and SEM-EDX data indicate the presence of siderite, ankerite, uraninite, chlorite, alumino-silicate minerals, ilmenite,rutile and magnetite, in addition to quartz, feldspar and mica. The chemical index of alteration, the plagioclase index of alteration, and the chemical index of weathering show an increasing trend from parent rock to the paleosol and indicate a moderate trend of weathering. The A-CN-K plot indicates loss of feldspars, enrichment in Al2O3 and formation of illite. Different major element ratios indicate baseloss through hydrolysis, clay formation, leaching of some elements, and more precipitation with good surface drainage. The paleosol is depleted in HREE in comparison to the parent rock indicating high fluid-rock interaction during weathering. The paleosol samples show flat Ce and Eu anomalies, low SREE, and high(La/Yb)N, indicative of a reducing environment of formation. Reducing condition can also be inferred from the concentration of elements such as V, Co, Cu, Pb, and Zn in the paleosol profile. Although enriched in Fe and Mg, the overall geochemical patterns of the paleosol indicate oxygen deficient conditions in the atmosphere and development by weathering and leaching processes associated with high precipitation and good surface drainage at the time of development of this paleosol during the Archeane Paleoproterozoic transition.