论文部分内容阅读
本文总结了八个地区白垩纪—第三纪界线的生物地层资料,试图确定一个完整的连续剖面.其中,突尼斯的艾尔·凯夫剖面出露最厚,生物地层标志也最全,包括白垩纪最顶部的Micula Prinsii带;第三纪最下部Globigerina fringa带中的“界线粘土”以及Globigerina eugubina and pseudobulloides带.根据这一分带,笔者对比了各剖面的稳定同位素地层标志.资料表明,白垩纪最晚期和第三纪最早期海洋的同位素组成,差别极大.碳同位素的变化主要取决于海洋养分的变化,显然是全球性的,因而具有等时性.氧同位素的变化虽然也具全球性,但受古地理位置及古循环系统的局部影响.同位素地层与生物地层资料的一致性表明,第三系底部沉积物中的“白垩纪”超微化石,并非再搬运的,而是白垩纪—第三纪界线事件的幸存者,在第三纪最早期海洋中仍继续繁衍.这些孓遗种属在界线事件后几万年才发生灭绝,理应为事件造成的环境变化的结果,而不是事件本身引起的”灾变性”灭绝.
This paper summarizes the biogenic stratigraphic data of the Cretaceous-Tertiary boundary in eight regions in an effort to determine a complete continuous profile in which the El-Kef section of Tunisia is the thickest with the most biofacies markers including chalk The Micula Prinsii belt at the very top of the Cretaceous, the “Boundary Clay” in the Globigerina fringa belt at the lowest part of the Tertiary, and the Globigerina eugubina and pseudobulloides belt.According to this zonation, The isotopic composition of the latest marine and the earliest Tertiary is very different.The changes of carbon isotope mainly depend on the changes of marine nutrients, apparently global, and therefore has the same time .Although the oxygen isotope changes But is affected by the paleogeography and the local influence of the paleo-circulation system.The consistency between isotopic stratum and biostratigraphic data shows that “Cretaceous” ultrafine fossils in the bottom sediments of the Tertiary are not transported anymore, but rather chalk The Survivor of the Triassic-Tertiary Boundary continued to multiply in the earliest Tertiary marine oceans that were discovered only after tens of thousands of years of boundary events Extinct, as should the results of environmental change caused by the incident, rather than the event itself caused “catastrophic” extinction.