冀北滦平盆地大店子组叶肢介生物地层特征与陆相侏罗系—白垩系界线  

Conchostracan biostratigraphy of the Dadianzi Formation in the Luanping basin,northern Hebei,China and the boundary of continental Jurassic and Cretaceous strata

作　　者：牛绍武[1] 田树刚[2] 庞其清[3] 

机构地区：[1]中国地质调查局天津地质矿产研究所,天津300170 [2]中国地质科学院地质研究所,北京100037 [3]石家庄经济学院,河北石家庄050031

出　　处：《地质通报》2010年第7期961-979,共19页Geological Bulletin of China

基　　金：国家自然科学基金项目<侏罗系-白垩系界线过渡期大北沟阶至义县阶连续剖面及化石分带研究>(批准号:40472019);全国地层委员会项目<中国主要断代地层建阶研究>(编号:200113900076)联合资助

摘　　要：大店子组是滦平盆地大北沟组之上、西瓜园组之下的一个岩石地层单元,建组剖面在滦平火斗山乡大店子东沟。在滦平火斗山乡张家沟,该组自下而上可进一步划分为4个岩性段,产有丰富的叶肢介化石,统属于东方叶肢介群(Eosestheria Fauna)。加之狼鳍鱼Lycoptera和女星介Cypridea与之共生,构成典型的热河动物群(Jehol Fauna)。根据叶肢介化石组合序列、叶肢介动物群的发展阶段与可能的演化谱系,将大店子组自下而上连续划分为5个叶肢介带。在大北沟组与大店子组界线的上下,尼斯托叶肢介群(Nestoria Fauna)和东方叶肢介群(Eosestheria Fauna)相继发生了集群绝灭和集群新生的重大生物事件。老的动物群的集群绝灭和新的动物群的集群新生,预示着一个大的时代界线的存在。在大北沟组与大店子组界线上C/O同位素有一高异常值和明显的降温事件,这可能就是这一集群绝灭和集群新生重大生物事件的原因。这一降温事件与世界范围内侏罗纪—白垩纪之间的降温事件相吻合。据此,中国乃至东亚陆相侏罗系—白垩系界线应置于大北沟组与大店子组之间,并以东方叶肢介Eosestheria属的出现为特征,以古老东方叶肢介Eosestheria antiqua的首现为标志,为大北沟阶的结束与张家沟阶的开始。其界线候选层型初步定于滦平县火斗山乡张家沟下营-上营剖面第9层之底和滦平县火斗山乡小东沟剖面第10-2层之底。The Donggou section of Dadianzi Village in Luanping County, northern Hebei is the naming section of the Dadianzi For- marion by Mr. Wang Si-en in 1990 year. This formation may be divided in ascending order into four members in the Zhangjiagou section. At Xiaodonggou, Huodoushan Town, Luanping County, Northern Hebei a bed of subaqueos distributary channel conglomerate of the formation was deposited continuously with its underlying Dabeigou Formation,and it is the boundary stratotype of the Dabeigou Formation and the Dadianzi Formation. Abundant conchostracan fossils were found in the Dadianzi Formation of this section, including 7 genera and 47 species. From the base upward, the Conchostracan biostratigraphy of the Dadianzi Formation is divided into five conchostracan zones. Because of the event of drop in temperature and the event of vanish and newborn of conchostracan fauna between the Dabeigou Formation and Dadianzi Formation, the boundary of continental Jurassic-Cretaceous System is determined in the point between the Dabeigou Formation and Dadianzi Formation.

关 键 词：滦平盆地 大店子组 叶肢介 张家沟阶 侏罗系-白垩系界线 

分 类 号：Q915[天文地球—古生物学与地层学] P534.52[生物学—古生物学]