摘要
发生在古元古代早期的大氧化事件(Great Oxidation Event,GOE)是地球演化历史上里程碑式的重大地质事件,对表生环境、生物演化及矿产资源和能源矿产的形成均具有深远的影响。虽然中国学者基于华北克拉通古元古代沉积记录及全球对比,在20世纪80年代后期较早地提出了古元古代早期(~2.3 Ga)地球表生环境突变的创新性观点,但由于中国境内古元古代沉积地层普遍遭受后期变形变质作用改造且连续性差,近20多年来大氧化事件的重要成果均是基于南非、西澳、北美及北欧等境外地质记录的研究。近10多年来,中国境内的华北克拉通及扬子克拉通等地陆续发现了一些较为完整的大氧化事件的沉积记录,如华北克拉通北东部辽宁鞍山地区“北辽河群”和铁岭凡河盆地凡河群下部(三岔子群)、华北克拉通中部的滹沱群及扬子克拉通西南缘滇中地区的易门群;在塔里木克拉通东南缘古元古代晚期壳源火成碳酸岩内也发现了一些大氧化事件记录的信息。这些发现为在中国境内开展大氧化事件研究提供了重要机遇。相对国外古元古代地层剖面,中国境内普遍缺失大氧化事件早期(2.43~2.2 Ga)的地质记录,大部分地层均沉积于2.2 Ga之后,特别是华北克拉通北东部及扬子克拉通西南缘的古元古代地层厚度大,变质程度较低,具有开展大氧化事件从中期至结束(2.2~2.06 Ga)演化过程研究的地域优势。未来需要在古元古代黑色页岩沉积环境、成因及其与海相碳酸盐岩碳同位素组成正漂移的关系,洛马贡迪−贾图利事件末期碳同位素组成正漂移结束的原因,碳−氧同位素化学地层与年代学相结合开展区域地层对比,变质作用对海相碳酸盐岩碳−氧同位素组成的影响,海相碳酸盐岩经历深熔作用形成壳源火成碳酸岩过程中碳−氧同位素变化行为,以及大氧化事件及洛马贡迪−贾图利事件的多学科综合研究及新地质−地球化学指标等方面开展深入研究,以便为更全面认识大氧化事件的成因机制、起始时限及资源环境效应提供依据。
[Objective]The Great Oxidation Event(GOE)during the early Paleoproterozoic represents one of the most significant geological events in Earth’s history and has profound impacts on Earth’s surface environment,biological evolution,and the formation of mineral resources and energy reserves.Chinese scholars innovatively proposed the hypothesis of a dramatic shift in Earth's surface environment at around 2.3 Ga in the late 1980’s,mainly based on sedimentary records from the North China Craton and global correlations.However,due to the pervasive deformation,the high-grade metamorphism,and the poor continuity of the Paleoproterozoic sedimentary sequences in China,most critical achievements in the GOE research obtained over the past two decades have predominantly relied on the well-preserved overseas geological records from South Africa,Western Australia,North America,and Northern Europe.[Methods]Geological and geochemical research over the last decade in China has identified some relatively complete sedimentary records of the GOE from the North China and Yangtze cratons,such as the"North Liaohe Group"in the Anshan area of northeastern Liaoning Province,the lower Fanhe Group(Sanchazi Group)in the Fanhe Basin of Tieling,the Hutuo Group in the central part of the North China Craton,and the Yimen Group in central Yunnan Province on the southwestern margin of the Yangtze Craton.Evidence related to the GOE has also been documented from the late Paleoproterozoic crustalderived carbonatites on the southeastern margin of the Tarim Craton.These discoveries provide crucial opportunities for studying the GOE and the Lomagundi-Jatuli Event(LJE)in China.[Results]Compared with the Paleoproterozoic sections used for GOE studies overseas,most of the Paleoproterozoic sequences in China were deposited after 2.2 Ga,and generally lack geological records from the early stage of the GOE(2.43~2.2 Ga).Notably,the Paleoproterozoic successions in northeastern North China Craton and the southwestern Yangtze Craton are characterized by great thickness and low metamorphic grade,offering invaluable opportunities for investigating the middle-to late-stage evolutionary processes of the GOE(2.2~2.06 Ga)in China.[Conclusion]Future research on the GOE and LJE records in China should focus on:(1)the depositional environment and genesis of Paleoproterozoic black shales and their relationship with the positive carbon isotopic excursions in marine carbonates;(2)the mechanisms for termination of the Lomagundi-Jatuli marine carbonate positive carbon isotopic excursion;(3)integrated chemostratigraphy based on marine carbonate carbon-oxygen isotopes and geochronological studies for regional stratigraphic correlation;(4)the effects of metamorphism on the carbon-oxygen isotope composition of marine carbonates;(5)the behavior of carbon and oxygen isotopes during the anatexis of marine carbonates to form crust-derived carbonatites;and(6)the use of multidisciplinary integrated methods and new geological-geochemical proxies for studying the GOE and LJE.[Significance]Such studies based on geological records in China will provide a more comprehensive understanding of the mechanism,timing,and resource-environmental effects of the GOE and LJE during the early Paleoproterozoic.
作者
张拴宏
ZHANG Shuanhong(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;State Key Laboratory of Deep Earth and Mineral Exploration,Beijing 100081,China;Key Laboratory of Paleomagnetism and Tectonic Reconstruction,Ministry of Natural Resources,Beijing 100081,China)
出处
《地质力学学报》
北大核心
2025年第5期1063-1082,共20页
Journal of Geomechanics
基金
国家自然科学基金项目(U2244213,41920104004,41725011)
中国地质科学院基本科研业务费项目(JKYZD202320)。
关键词
大氧化事件
洛马贡迪−贾图利事件
地球宜居性
古元古代沉积记录
大气−海洋环境
Great Oxidation Event(GOE)
Lomagundi-Jatuli Event(LJE)
Earth's habitability
Paleoproterozoic sedimentary record
atmosphere-ocean environment
