南雄盆地白垩纪-古近纪交界恐龙灭绝和哺乳动物复苏

发布时间：2018-12-16 15:50

【摘要】：南雄盆地白垩纪-古近纪(K/Pg)界线剖面脊椎动物化石(恐龙蛋壳和龟类骨化石)的地球化学研究结果表明,从白垩纪晚期到古近纪早期中国华南地区曾发生过3次以多个铱异常为标志的地球化学环境变化事件:第一次地球化学环境变化事件发生在67 Ma前,除了有很多蛋壳显示出病理组织结构特征外,由它们为代表的恐龙种群多样性并没有发生明显变化.第二次地球化学环境变化事件规模较大,正好发生在根据孢粉组合变化划分的K/Pg界线及其附近.恐龙在K/Pg交界开始灭绝,然后持续至古新世早期.这一灭绝过程大约经历了250 ka.恐龙灭绝的原因是多次以铱异常、微量元素异常和氧同位素异常为标志的环境变化引起的,短期和长期地球化学环境的不断恶化,使恐龙无法正常繁殖后代而逐渐灭绝.第三次地球化学环境变化事件出现在早-中古新世,表明当时的环境变化及其效应可能长时间推迟陆相生态环境的恢复和哺乳动物的完全复苏.南雄盆地获得的地球化学资料、恐龙渐变灭绝模式以及古新世哺乳类的复苏在年代上与印度德干火山喷发及持续时间比较一致.
[Abstract]:Geochemical studies of vertebrate fossils (dinosaur eggshells and tortoises) from the Cretaceous to Paleogene (K/Pg) boundary sections in the Nanxiong Basin indicate that, From the late Cretaceous to the early Paleogene, there were three geochemical environmental events in South China marked by multiple iridium anomalies: the first geochemical environmental change occurred before 67 Ma. With the exception of many eggshells showing histopathological features, the diversity of dinosaur populations represented by them has not changed significantly. The second geochemical environmental change event is of large scale, which happens in the K/Pg boundary and its vicinity according to the sporopollen assemblage variation. Dinosaurs began to die out at the K/Pg border and continued into the early Paleocene. This extinction process took about 250 ka.. The extinction of dinosaurs was caused by several environmental changes marked by iridium anomaly trace element anomaly and oxygen isotope anomaly. The deterioration of the geochemical environment in the short and long term caused the dinosaurs to become extinct gradually because they could not reproduce their offspring normally. The third geochemical environmental change event occurred in the early and Middle Paleocene, indicating that the environmental change and its effects at that time may delay the restoration of terrestrial ecological environment and the complete recovery of mammals for a long time. The geochemical data obtained in Nanxiong Basin, the gradual extinction model of dinosaurs and the recovery of Paleocene mammals are consistent with the eruption and duration of Degan volcano in India.
【作者单位】：中国科学院古脊椎动物与古人类研究所中国科学院脊椎动物演化与人类起源重点实验室;
【基金】：国家重点基础研究发展计划(2012CB821900) 国家自然科学基金(41202003,41172018)资助
【分类号】：Q915

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