Geochemical environmental changes and dinosaur extinction during the Cretaceous-Paleogene (K/T) transition in the Nanxiong Basin, South China: Evidence from dinosaur eggshells  

作　　者：ZHAO ZiKui MAO XueYing CHAI ZhiFang YANG GaoChuang ZHANG FuCheng YAN Zheng 

机构地区：[1]Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China [2]Institute of High Energy Physics and Laboratory of Nuclear Analytical Techniques, Chinese Academy of Sciences, Beijing 100080, China [3]Institute of Geology, State Seismological Bureau, Beijing 100029, China

出　　处：《Chinese Science Bulletin》2009年第5期806-815,共10页

基　　金：Supported by National Natural Science Foundation of China (Grant No. 40472018);the Chinese Academy of Sciences (Grant No. 21039751)

摘　　要：The complex patterns of trace elements including Ir and isotope distributions in the three K/T sections of the Nanxiong Basin prove the existence of two environmental events in the latest Cretaceous and earliest Paleocene. The first geochemical environmental event occurred at about 2 Ma prior to the K/T boundary interval, where the dinosaur diversity was hardly reduced, except that a number of patho-logical eggshells appeared. The second one was larger and occurred just at and near the Creta-ceous-Paleogene (K/T) boundary. The extinction of the dinosaurs spread out within 250 ka with major extinction beginning at the boundary interval. This is even later than their extinction in Montana, North America and in India. The cause of the dinosaur extinction may be the result of a complex multiple events brought about by the coincidence of global environment change marked by multiple Ir and δ 18O anomalies, and environmental poisoning characterized by other trace elements derived from the local source. Successive short- and long-term conditions of geochemically induced environmental stress negatively affected the reproductive process and thus contributed to the extinction of the dinosaurs.The complex patterns of trace elements including Ir and isotope distributions in the three K/T sections of the Nanxiong Basin prove the existence of two environmental events in the latest Cretaceous and earliest Paleocene. The first geochemical environmental event occurred at about 2 Ma prior to the K/T boundary interval, where the dinosaur diversity was hardly reduced, except that a number of pathological eggshells appeared. The second one was larger and occurred just at and near the Cretaceous-Paleogene （K/T） boundary. The extinction of the dinosaurs spread out within 250 ka with major extinction beginning at the boundary interval. This is even later than their extinction in Montana, North America and in India. The cause of the dinosaur extinction may be the result of a complex multiple events brought about by the coincidence of global environment change marked by multiple Ir and δ^18O anomalies, and environmental poisoning characterized by other trace elements derived from the local source. Successive short- and long-term conditions of geochemically induced environmental stress negatively affected the reproductive process and thus contributed to the extinction of the dinosaurs.

关 键 词：白垩系-古近系界线 南雄盆地 恐龙蛋壳 微量元素 地球化学 环境变化 

分 类 号：Q915[天文地球—古生物学与地层学]