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在发现冀北滦平盆地陆相侏罗系—白垩系界线过渡地层连续沉积剖面的基础上,经沉积学、岩石地层学、层序地层学、旋回地层学、生物地层学、同位素测年和年代地层学等多学科多方法综合研究,建立完整地层层序,将滦平张家沟剖面选作陆相义县阶和侏罗系—白垩系界线候选层型剖面。研究取得的初期成果是:补充大北沟组和大店子组含义,将这2个组系统分为7个岩段,命名4个标志层;确定年代地层层序, 完善大北沟阶和义县阶定义内容;研究重点门类化石分布和演化,建立系统生物地层分带序列,包括7个介形虫带和6个叶肢介带;划分陆相生物群发展阶段,将侏罗系—白垩系界线置于“早期热河生物群”阶段的底部;开展旋回地层和层序地层学研究,建立地层等时格架,识别盆地演化的3个阶段和5个构造期;测得界线层型剖面点存在氧同位素高值异常;锆石~(206)Pb/~(238)U 测得张家口组顶部年龄为135.4±1.6 Ma,大北沟组中部为133.9±2.5 Ma 和130.1±2.5 Ma。综合多学科研究成果,将界线层型剖面点定在张家沟剖面第9层底,以介形虫化石 Cypridea stenolonga 的首现为标志。
Based on the continuous sedimentary profile of the continental Jurassic-Cretaceous boundary transitional formation in the Luanping basin of Hebei Province, the sedimentary facies, lithostratigraphy, sequence stratigraphy, cyclostratigraphy, biostratigraphy, isotope dating and Age stratigraphy and other multi-disciplinary and multi-method comprehensive study, the establishment of a complete sequence of stratigraphy, the Luanping Zhangjiagou profile was selected as Luxian County and Jurassic-Cretaceous boundary line candidate layer profile. The initial achievements made in the study are as follows: to supplement the meanings of the Dabeigou Formation and Dadianzi Formation, and divide the two groups of systems into seven rock sections and name four landmark layers; determine the sequence of the age stratigraphy and improve the Dabeigou order and Yixian order definition; research focus on the distribution and evolution of fossils, the establishment of the system bio-stratigraphic zoning sequence, including seven ostracods and six leaf extremity mesenchymal zone; division of continental fauna development stage, the Jurassic- The Cretaceous boundary line is located at the bottom of the “Early Jehol Biota” stage. Cyclone and sequence stratigraphy studies are conducted to establish the isochronal stratigraphic framework and to identify three stages and five tectonic periods of basin evolution. There was a high value of anomalous oxygen isotopes at the boundary of the stratigraphic layer. The top of Zhangjiakou Formation measured by zircon ~ (206) Pb / ~ (238) U was 135.4 ± 1.6 Ma, and the middle of Dabeigou Formation was 133.9 ± 2.5 Ma and 130.1 ± 2.5 Ma. According to the results of multidisciplinary research, the stratum layer profile point is set at the bottom of the ninth layer of Zhangjiagou profile and marked by the first occurrence of the fossil Cypridea stenolonga.