The Great Oxidation Event(GOE)during the early Paleoproterozoic represents the first significant buildup in Earth’s atmospheric oxygen and resulted in a series of significant changes in the Earth’s surface environme...The Great Oxidation Event(GOE)during the early Paleoproterozoic represents the first significant buildup in Earth’s atmospheric oxygen and resulted in a series of significant changes in the Earth’s surface environment.Among them is the 2.22(or 2.33)–2.06 Ga Lomagundi-Jatuli Event(LJE),which is globally,the largest magnitude and longest duration,marine carbonate positive carbon isotope excursion(δ^(13)C_(V-PDB)>10‰)known.This event has attracted the attention of scholars all over the world.However,except for a high positive carbon isotope excursion(δ^(13)C_(V-PDB)>10‰)recently identified from marine carbonate rocks within the Daposhan Formation in the lower Fanhe Group(or the Sanchazi Group)in the Longgang Block in the northeast North China Craton(NCC),Paleoproterozoic carbonates in the NCC are characterized by a low-amplitude positive carbon isotope excursion(δ^(13)C_(V-PDB)<5‰).This feature is significantly different from the high positive carbon isotope excursion characteristics of carbonates deposited during the LJE period in other cratons.To determine whether there are large-scale and reliable sedimentary records of the LJE in the NCC and the reasons for the low positive δ^(13)C excursion of the Paleoproterozoic carbonates obtained by the previous studies,we conducted field investigations,carbon-oxygen isotopes,and whole-rock major and trace element geochemical analyses of Liaohe Group carbonate rocks from the Anshan area in the northwestern margin of the Jiao-Liao-Ji Belt in the northeast NCC.Our results show that the Gaojiayu Formation of the Liaohe Group in the Anshan area has high positive δ^(13)C_(V-PDB) values from 8.6‰ to 12.4‰ and δ^(18)O_(V-SMOW) values of 17.9‰-27.4‰(δ^(18)O_(V-PDB) values ranging from−12.6‰to -3.4‰).This provides solid evidence for the preservation of reliable sedimentary records of the LJE in the northeastern NCC.Deposition of the high positive δ^(13)C excursion(>10‰)of marine carbonate rocks occurred at about 2.15 Ga.Lithological comparisons of展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.41920104004,U2244213,41725011)the Fundamental Research Fund of Chinese Academy of Geological Sciences(Grant No.JKYZD202320)。
文摘The Great Oxidation Event(GOE)during the early Paleoproterozoic represents the first significant buildup in Earth’s atmospheric oxygen and resulted in a series of significant changes in the Earth’s surface environment.Among them is the 2.22(or 2.33)–2.06 Ga Lomagundi-Jatuli Event(LJE),which is globally,the largest magnitude and longest duration,marine carbonate positive carbon isotope excursion(δ^(13)C_(V-PDB)>10‰)known.This event has attracted the attention of scholars all over the world.However,except for a high positive carbon isotope excursion(δ^(13)C_(V-PDB)>10‰)recently identified from marine carbonate rocks within the Daposhan Formation in the lower Fanhe Group(or the Sanchazi Group)in the Longgang Block in the northeast North China Craton(NCC),Paleoproterozoic carbonates in the NCC are characterized by a low-amplitude positive carbon isotope excursion(δ^(13)C_(V-PDB)<5‰).This feature is significantly different from the high positive carbon isotope excursion characteristics of carbonates deposited during the LJE period in other cratons.To determine whether there are large-scale and reliable sedimentary records of the LJE in the NCC and the reasons for the low positive δ^(13)C excursion of the Paleoproterozoic carbonates obtained by the previous studies,we conducted field investigations,carbon-oxygen isotopes,and whole-rock major and trace element geochemical analyses of Liaohe Group carbonate rocks from the Anshan area in the northwestern margin of the Jiao-Liao-Ji Belt in the northeast NCC.Our results show that the Gaojiayu Formation of the Liaohe Group in the Anshan area has high positive δ^(13)C_(V-PDB) values from 8.6‰ to 12.4‰ and δ^(18)O_(V-SMOW) values of 17.9‰-27.4‰(δ^(18)O_(V-PDB) values ranging from−12.6‰to -3.4‰).This provides solid evidence for the preservation of reliable sedimentary records of the LJE in the northeastern NCC.Deposition of the high positive δ^(13)C excursion(>10‰)of marine carbonate rocks occurred at about 2.15 Ga.Lithological comparisons of
