2.0 Ga orogenic graphite deposits and associated 13C-enriched meta-carbonate rocks from South China Craton:Implications for global Lomagundi event  

作　　者：Yihe Li Madhusoodhan Satish-Kumar Sasidharan Kiran Chuanhui Wan Jianping Zheng 

机构地区：[1]Institute of Geophysics and Geomatics,Hubei Subsurface Multi-scale Imaging Key Laboratory,China University of Geosciences,Wuhan 430074,China [2]Department of Geology,Faculty of Science,Niigata University,Niigata 950-2181,Japan [3]Graduate School of Science and Technology,Niigata University,Niigata 950-2181,Japan [4]Eighth Geological Brigade of Hubei,Xiangyang 441000,China [5]School of Earth Sciences,State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China

出　　处：《Geoscience Frontiers》2022年第4期181-192,共12页地学前缘（英文版）

基　　金：financial support from National Natural Science Foundation of China(41802200);Natural Science Foundation of Hubei Province(2020CFB863);China Scholarship Council(201906415017);China University of Geosciences Wuhan(CUGQY1938);the partial support through JSPS KAKENHI Grant Numbers JP15H05831 and 20KK0081;a PhD scholarship support from Niigata University;financial support from National Natural Science Foundation of China(41520104003);China University of Geosciences Wuhan(CUGCJ1709)。

摘　　要：The Lomagundi(-Jatuli)event,characterized by extremely high positive global inorganic carbon isotope excursion at about 2.2 billion years ago,is pivotal in investigating the causes and consequences of great oxygenation event,inventory and sequestration of carbon on the Earth’s surface,evolution of life,and more profoundly tectonic control on Earth’s environment.However,the reasons that caused the isotopic excursion are not resolved yet.Herein,we report the discovery of meta-carbonate rocks with distinct positive carbon isotopic excursion from the Paleoproterozoic continental collision zone of the Kongling Complex,South China Craton.The δ^(13)C_(V-PDB) values for meta-carbonate rocks show positive values in the range from+5.5‰to+11.6‰,whereas the δ^(13)C_(V-PDB) values of associated graphite deposits range from-25.8‰to-9.5‰.Zircon U-Pb-Hf isotopes from zircon-bearing meta-carbonate sample yielded weighted average _(207)Pb/_(206)Pb age of 2001.3±9.5 Ma,with correspondingε_(Hf)(t)range from-7.05 to-3.16,comparable to the values of local 2.9–2.6 Ga basement rocks.Geochemical characteristics of meta-carbonate rocks,such as their rare earth element patterns and the trace element parameters of La,Ce,Eu,and Gd anomalies and Y/Ho ratio,suggest that the carbonate deposition took place in passive continental margin in association with large volumes of organic carbon.The extensive graphite deposits from Kongling Complex in South China Craton,their equivalents in the North China Craton and elsewhere across the globe prove that the burial of ^(12)C-enriched organic carbon has eventually resulted in the global enrichment of ^(13)C in the atmospheric CO_(2),which is recorded in the marine carbonate rocks.Isotopic mass balance estimates indicate that more than half of the organic carbon was buried during the oceanic closure.Hence,the observed global shift could be directly related to the continent collision event in greater China,thus resolving the long-standing paradox of the Lomagundi global positive carbon is

关 键 词：Positive carbon isotope excursion Lomagundi(-Jatuli)event Kongling Complex South China Craton Marine carbonate 

分 类 号：P619.252[天文地球—矿床学]