胶莱盆地白垩纪末期至古新世早期轮藻植物群与K/Pg界线

The Cretaceous-Paleogene boundary (K/Pg boundary) marks the beginning of the Cenozoic, and is one of the most important geological boundaries. The K/Pg boundary is recognized as the boundary clay and the GSSP for the base of Danian stage is at the base of the clay. However, it is difficult to find the boundary clay in non-marine strata. Charophytes are usually very abundant in the non-marine strata near the K/Pg boundary, and the significant changes of charophyte flora can help to recognize the K/Pg boundary. Currently, the identification of charophytes in China is usually based on individual gyrogonites but not the whole population. Such studies lack statistical measurements and a uniform taxonomic standard, and do not consider the population characteristics and intraspecific variation. So it is difficult to make an intercontinental charopyhte biostratigraphic correlation and calibrate the K/Pg boundary in China. This project intends to study the charophytes near the K/Pg boundary in the Jiaolai Basin (eastern Shandong Province, China). The identification of charophytes will be based on a population and the definition of every species will be established clearly. The paleoecological significance and paleogeographic distribution of each species will be discussed. The eurytopic and widely distributed speices will be used to do the intercontinental correlation, which will help to determine the age of bizones and further mark the K/Pg boundary in the Jiaolai Basin. Additionally, the relationship between evolution of charophytes and end-Createceous extinction will be explored.

白垩系-古近系界线（K/Pg界线）标志着新生代的开始，是最重要的地质界线之一。K/Pg界线粘土层是寻找该界线的标志，该粘土层的底界也是丹麦阶的开始，但这一界线粘土层在非海相地层中很难找到，使得非海相K/Pg界线难以确定。非海相盆地中，轮藻化石在该界线附近常十分繁盛，植物群的显著变化有助于K/Pg界线的识别。目前，中国轮藻化石的鉴定多以单个藏卵器为研究对象，缺乏科学的统计和测量，未考虑居群特征和种内变异，分类标准也未统一，导致中国难以用轮藻开展洲际生物地层对比及K/Pg界线的标定。本课题拟对山东省东部胶莱盆地K/Pg界线附近的轮藻化石进行研究，以居群为基础，明确属种定义，详细探讨各类型生存的古生态环境，分析其古地理分布；通过使用生态域广和地理分布广的轮藻化石进行洲际/区域对比，确定轮藻生物带的年限，进而标定K/Pg界线，并探索轮藻演化与白垩纪末期灭绝事件之间的联系。

白垩系/古近系界线（K/Pg界线）标志着新生代的开始，是最重要的地质界线之一。K/Pg界线粘土层是寻找该界线的标志，该粘土层的底界也是丹麦阶的开始，但这一界线粘土层在非海相地层中很难找到，使得非海相K/Pg界线难以确定。非海相盆地中，轮藻化石在该界线附近常十分繁盛，植物群的显著变化有助于K/Pg界线的识别。本项目首次报道山东省胶莱盆地K/Pg界线附近的轮藻植物群，基于2个钻井和1个剖面的材料，使用国际统一的分类学方法，共鉴定发现轮藻化石11属15种；探讨不同轮藻属种生存的古生态环境，分析古地理分布，建立Microchara gobica生物带和Microchara prolixa生物带；同时，使用国际统一分类学方法对松辽盆地的轮藻植物群进行研究，建立3个生物带，并与古地磁带进行对比，确定每个生物带的年代延限，该研究为胶莱盆地生物带的年代限定提供依据。胶莱盆地的K/Pg界线位于胶州组内部，即鲁科1井（LK-1）317 m附近或者以上，胶莱盆地JZK-2钻井的15 m处。胶莱盆地K/Pg界线的限定有利于进行界线附近全球气候事件对比，深入研究生物大灭绝对轮藻植物群的影响。