大氧化事件在山西滹沱群中的记录:碳酸盐岩碳同位素资料分析  

Records of the Great Oxidation Event in the Hutuo Group,Shanxi,China:A reassessment of the δ^(13)C_(carb) data

作　　者：陈威宇 陈衍景[1] CHENWeiYu;CHENYanJing(MOE Key Laboratory of Crustal and Orogenic Evolution,Peking University,Beijing 100871,China)

机构地区：[1]北京大学造山带与地壳演化教育部重点实验室,北京100871

出　　处：《岩石学报》2018年第12期3709-3720,共12页Acta Petrologica Sinica

基　　金：国家重点基础研究发展计划"973"项目(2012CB416602)资助

摘　　要：古元古代早期爆发了全球性大氧化事件(GOE),诱发了休伦冰川事件(Huronian Glaciation Event,HGE)和2. 3～2. 06Ga的拉玛岗地-瓦图里碳酸盐碳同位素正漂移事件(Lomagundi-Jatuli Event,LJE)。滹沱群是华北克拉通最具代表性的古元古代沉积地层,变质程度最低,地层学研究程度高,是探索GOE以及HGE和LJE的理想研究对象。通过总结和分析滹沱群碳酸盐岩碳同位素研究结果,我们发现:(1)滹沱群主体未显示δ^(13)C_(carb)正漂移现象,但下部大石岭组有高达3. 5‰的δ^(13)C_(carb)正异常;(2)显示δ^(13)C_(carb)正异常的大石岭组可能形成于2. 08Ga之前,未显示δ^(13)C_(carb)正异常的东冶亚群可能形成于2. 06Ga之后;(3)五台地区记录休伦冰川事件的冰碛岩应发育在大石岭组之下,即四集庄组砾岩。总之,滹沱群形成于2. 3Ga之后,下部豆村亚群沉积于HGE或LJE期间,可能保留了更显著的δ^(13)C_(carb)正漂移信息及冰川沉积记录,中部的东冶亚群沉积于LJE之后,不存在δ^(13)C_(carb)正漂移。The Great Oxidation Event(GOE)happened in Palaeoprotorozoic era induced the global Huronian Glaciation Event(HGE)which was followed by the global positive δ^13 Ccarb excursion event(Lomagundi-Jatuli Event,LJE)around 2.3~2.06Ga.TheHutuo Group is the most representative and least metamorphosed Paleoproterozoic sedimentary sequence in North China Craton.It iswell investigated in stratigraphy,and taken as the best window to insight GOE,HGE and LJE in China.Based on a compilation andsynthesis of the available δ^13 Ccarb data of the Hutuo Group,we propose that:(1)the global positive δ^13 Ccarb excursion is not recorded inthe Hutuo Group,except for the Dashiling Formation,whose δ^13 Ccarb values are up to+3.5‰;(2)the Dashiling Formation displayedweakly positive δ^13 Ccarb excursion and possibly deposited before 2.08Ga,whilst the Dongye Subgroup without positive δ^13 Ccarb excursionmight deposit after 2.06Ga;and(3)a glacigenic diamictite succession recording the HGE could be observed below the DashilingFormation,most likely,the Sijizhuang Formation conglomerate suite.Therefore,the Dongye Subgroup deposited after LJE does notshow positive δ^13 Ccarb excursion;the Doucun Subgroup,as the lower portion of the Hutuo Group,deposited during HGE and LJE,maypreserve the positive δ^13 Ccarb excursion and glacial sedimentation;and the Hutuo Group generally deposited after 2300Ma.

关 键 词：古元古代 碳同位素正漂移事件 大氧化事件 滹沱群 华北克拉通 

分 类 号：P597.2[天文地球—地球化学]