北半球白垩纪-古近纪之交生物灭绝期孢粉地层学

长期以来,科学家们对白垩纪-古近纪(K-Pg)之交陆地上生物大灭绝事件的趋势与灭绝速率争论不断。这些争论主要集中在脊椎动物上,尤其是非鸟恐龙。尽管如此,在理解K-Pg之交的生物响应以及相关的生态系统扰动时,植被的演化也是一个重要的组成部分。本文综述北半球内白垩纪晚期至古近纪Aquilapollenites古孢粉地理大区的孢粉地层学:在美国,晚白垩世生物组合以一系列关键门类的出现为标志,其中三冬期—坎潘期过渡期以Aquilapollenites以及相关的三突起型属的出现为标志,而马斯特里赫特阶的底界以睛形型的Wodehouseia属与Kurtzipitessp.的出现为标志;Wodehouseia spinata生物组合带以较大的个体与复杂的壁构造为特征,其中一系列的被子植物孢粉单元在K-Pg之交的记录中消失了,这使得K-Pg灭绝事件容易识别;具孔类花粉和Momipites与Caryapollenites两个属的关键种的出现,标志着古近纪孢粉植物群的复苏。近期的资料涵盖了北美大陆的大部分记录,而中国、欧洲和南半球的更多研究将更有助于理解全球陆地生物圈对K-Pg之交撞击事件的响应。

POLLEN AND SPORE STRATIGRAPHY OF THE CRETACEOUS-PALEOGENE MASS-EXTINCTION INTERVAL IN THE NORTHERN HEMISPHERE

For a long time,debate has taken place regarding the trends and extinction rates associated with the Cretaceous-Paleogene(K-Pg) mass extinction event on land.While mainly focused on vertebrates and more particularly non-avian dinosaurs,the dynamics of the plant cover remains nonetheless a major component of the biological response across the K-Pg interval and associated ecosystem destabilization.In this paper,we present a review of the late Cretaceous to Paleogene pollen and spore stratigraphy in the Northern Hemisphere Aquilapollenites paleophytogeographic province.In the United States of America,Late Cretaceous assemblages are marked by the appearance of a series of key taxa:the Santonian-Campanian transition is characterized by the appearance of Aquilapollenites and associated triprojectate genera,whereas the base of the Maastrichtian is marked by the appearance of the oculate genus Wodehouseia as well as Kurtzipites sp.The K-Pg extinction event remains easily identifiable in the palynological record with the disappearance of a series of angiospermous taxa,part of the Wodehouseia spinata Assemblage Zone,which are characterized by rela-tively large size and a complex wall structure.The recovery palynoflora in the Paleocene is represented by assemblages dominated by porate grains,with key species from the Momipites and Caryapollenites genera.As current data mostly cover the North American terrestrial record,more research efforts are needed in Chinese,European and Southern Hemisphere localities to provide for a better understanding of the global response of the terrestrial biosphere to the K-Pg impact event.