华北及扬子克拉通中元古代年代地层格架厘定及相关问题探讨  

Revision of the Mesoproterozoic chronostratigraphic subdivision both of North China and Yangtze Cratons and the relevant issues

作　　者：苏文博[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《地学前缘》2016年第6期156-185,共30页Earth Science Frontiers

基　　金：国家自然科学基金项目(40772076;41272046);国家重点基础研究发展计划"973"项目(2011CB808800)

摘　　要：在系统分析近年华北和扬子克拉通典型地区中元古代（GTS2012,1 780～850 Ma）年代地层学进展基础上,详细厘定了其地层格架。确认华北克拉通中元古代早期地层（约1 780～约1 350 Ma）发育始于豫陕晋交界地区,其后沿＂华北中部造山带＂（TNCO：Trans-North China Orogen）再逐渐扩展到燕山及附近地区,但随后则普遍缺失了中期（约1 350～约1 100 Ma）纪录。其晚期沉积（〈1 100 Ma）见于胶辽徐淮、豫西南及燕山等地区。扬子克拉通的川滇交界地区出露有中元古代早期（约1 750～约1 450Ma）及晚期（〈1 100Ma）地层,中期沉积（约1 400～约1 150 Ma）主要见于神农架地区。华北与扬子两地的地层纪录具有良好的互补性,并有效涵盖了整个GTS2012全球地质年表所建议之＂中元古代＂（1 780～850 Ma）。这一新格架蕴含多方面重要命题：（1）地层学方面。在未来GTS2012中元古界内部＂系＂级单位再划分研究中,中国学者通过在上述两地对应地层序列中识别此间全球大火成岩省LIPs-地幔柱事件的沉积响应,可望从地球系统科学角度全面参与新建议各系底界的＂金钉子＂工作,并做出独特贡献。（2）早期真核生物演化及生物古地理方面。基于当前格架可以确认,山西永济汝阳群北大尖组以Tappania为代表的具刺大型疑源类生物群的时代应约为1650 Ma,为目前全球真核生物遗存最早出现层位,同时不排除华北南缘有可能是此类生物的起源区。结合其时空分布或可进一步推测,至少在约1 650～约1 450 Ma阶段,即哥伦比亚超大陆向罗迪尼亚超大陆过渡阶段,华北克拉通应与印度、澳大利亚、北美、西伯利亚等古陆互为近邻。（3）沉积-大地构造演化方面。中元古代华北及扬子克拉通均表现出＂三段式＂沉积过程,其沉降-隆起区均发生过＂跷跷板＂式转换,包括＂晋宁运动＂在内的关键时间节点均�Following synthesis of recent advances in geochronological research,the GTS2012（The Geological Time Scale 2012）Mesoproterozoic（1780-850 Ma）chronostratigraphic subdivision of the typical areas both on the North China Craton（NCC）and the Yangtze Craton（YC）of China have been revised thoroughly.It is now know that the early Mesoproterozoic deposits of NCC,between～1780Ma and～1350Ma,developed initially near the junction of Henan-Shanxi-Shaanxi Provinces,and then expended gradually northwards to the Yanshan Mountains and the adjacent areas along the Trans-North China Orogen（TNCO）.However,the middle Mesoproterozoic,～1350 Ma-～1100 Ma,are all absent through out the entire craton.In addition to the southwestern Henan（south NCC）and the Yanshan Mountains（north NCC）,the late Mesoproterozoic,younger than～1100Ma,occurs mainly in the elongated rift-related basin in the eastern NCC,named the JiaoLiao-Xu-Huai Sea,in the west Shandong,the southeast Liaoning-east Jilin,the north Jiangsu,and northeast Anhui Provinces.On the other hand,both the early（～1750 Ma-～1450 Ma）and the late（〈1100 Ma）Mesoproterozoic deposits are developed near the border of Sichuan and Yunnan Provinces,i.e.the Kang-Dian area,along the western margin of YC.The middle Mesoproterozoic,～1400 Ma-～1150 Ma,outcrops mainly in the Shennongjia area,west of Hubei Province,in the northern YC.It means that the Mesoproterozoic successions from the two cratons of China could complement each other to cover the entire proposed GTS2012 Mesoproterozoic Era,1780 Ma-850 Ma.Some relevant fundamental issues emerging from the updated chronostratigraphic framework are discussed in short：（1）Precambrian Stratigraphy：Due to the only one～1.0Ga long Rodinian Period proposed for the Mesoproterozoic Era with the same duration in the GTS 2012,aquadripartite intra-subdivision of the Systems（Periods）in this Erathem（Era）has been suggested by the author.All the new Systems（Periods）would be defined by the GSSPs（Global Stan

关 键 词：华北克拉通 扬子克拉通 中元古代 大火成岩省 真核生物群 宏观藻类 超大陆 

分 类 号：P534.3[天文地球—古生物学与地层学]