华北克拉通北缘燕辽裂陷槽中-新元古代地层年代学研究进展  

Recent advances in the study of the Meso-to Neoproterozoic chronostratigraphy of the Yanliao Aulacogen on the northern margin of the North China Craton

作　　者：李怀坤[1,2,3] 张健[1,3] 田辉[1,2,3] 周红英[1,3] 相振群[1,2,3] 刘欢 LI Huai-kun;ZHANG Jian;TIAN Hui;ZHOU Hong-ying;XIANG Zhen-qun;LIU Huan(Tianjin Centre,China Geological Survey,Tianjin 300170,China;Precambrain Geological Research Centre,China Geological Survey,Tianjin 300170,China;North China Center for Geoscience Innovation,China Geological Survey,Tianjin 300170,China)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]中国地质调查局前寒武纪地质研究中心,天津300170 [3]中国地质调查局华北科技创新中心,天津300170

出　　处：《地质调查与研究》2020年第2期127-136,共10页Geological Survey and Research

基　　金：中国地质调查局项目“中国大地构造演化和国际亚洲大地构造图编制(DD20190359、DD20190009)”。

摘　　要：作为国内中-新元古界的标准剖面,燕辽裂陷槽蓟县剖面的地层年代学研究历史悠久,一直是备受关注的基础地质问题。蓟县剖面第一个准确可靠的同位素年龄来自于陆松年和李惠民(1991)获得的大红峪组火山岩锆石U-Pb年龄(1625±6 Ma,TIMS),之后很长一段时间,地层年代研究并未获得真正意义上的突破。直到2007年,随着可作为关键测年对象的碎屑岩-碳酸盐岩地层中凝灰岩(斑脱岩)夹层被逐渐识别出来,才开始迎来燕辽裂陷槽中-新元古代地层年代及相关古生物、古环境、古地理研究的新热潮,主要进展包括:(1)常州沟组作为长城群的第一个组,其底界年龄~1650 Ma,比以往认识的1800 Ma要年轻150 Ma;(2)精确标定蓟县群(自下而上包括高于庄组、杨庄组、雾迷山组、洪水庄组和铁岭组)的时限1600~1400 Ma,与国际地层表的盖层系相对应;(3)下马岭组时限为1400~1320 Ma,而不是原来划归的新元古代青白口纪早期(1000~900 Ma)。与此同时,仍存在几个亟待解决的重要问题:(1)中元古代早期“长城系”(1800~1600 Ma)年代地层序列的厘定及其标准剖面的建立,包括“长城系”、“长城群”术语的取舍问题,因为存在年代地层术语“长城系”和岩石地层术语“长城群”重名的问题;(2)中元古代中晚期(1400~1000 Ma)“待建系”地层的确定,其纪级年代地层单位的建立和标准剖面的建立;(3)青白口系地层的厘定和标准剖面的建立,迄今为止华北克拉通仍未获得可靠的同位素年龄约束青白口纪(1000~800 Ma)地层。As the Meso-Neoproterozoic standard stratigraphic section of China,the Jixian Section outcropped in the Yanliao Aulacogen along the northern margin of the North China Craton has attracted broader interests in many study aspects,especially in chronostratigrahy.The first widely accepted accurate and reliable stratigraphic age is the zircon U-Pb age 1625±6 Ma by ID-TIMS for the volcanic rock in the upper part of the Dahongyu Formation of the Jixian Section obtained by Lu Songnian and Li Huimin in 1991.Subsequently,there has been no significant progress for a quite long period in the study of chronostratigraphy of the Yanliao Aulacogen.It is not until 2007 as the tuff(or bentonite,hydrothermally altered tuff)intercalations suitable for zircon U-Pb dating were gradually recognized from the clastic-carbonate strata that a series of breakthroughs achieved in chronostratigraphy and relevant domains such as paleontology,paleogeography and paleoenvironment for Jixian Section.The main advances are as follows:(1)the base age of the Changzhougou Formation,the lowest formation of the Changcheng Group,was determined at^1650 Ma,~150 m.y younger than the conventionally adopted age of 1800 Ma;(2)the time span of the Jixian Group(including the Gaoyuzhuang,Yanzhuang,Wumishan,Hongshuizhuang and Tieling formations in ascending order)was precisely determined at 1600~1000 Ma,perfectly correlating with the Calymmian of the International Stratigraphic Chart;(3)the time span of the Xiamaling Formation was 1400~1320 Ma instead of the previously adopted the early stage of the Neoproterozoic Qingbaikou Period(1000~900 Ma).On the other hand,several key problems remain yet and need to be tackled desperately:(1)the re-establishment of the early Mesoproterozoic Changcheng Series(1800~1600 Ma)and its standard section,including the choice of the terminology“Changcheng Series”and“Changcheng Group”due to the duplication of the chronostratigraphic term“Changcheng Series”and the lithostratigraphic term“Changcheng Group”;(2)the setup of

关 键 词：华北克拉通北缘 燕辽裂陷槽 中-新元古界 地层年代学 研究进展 

分 类 号：P597.3[天文地球—地球化学]