南半球白垩纪-古近纪之交生物灭绝期孢粉地层学

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

白垩纪-古近纪(K-Pg)生物大灭绝事件前后的孢粉植物群的变化,可以详细揭示植被对一场全球环境危机(6550万年前小行星撞击现今的墨西哥)的响应。在K-Pg界线处有一些植物门类灭绝了,因此孢粉地层学是确定非海相序列中白垩纪-古近纪界线的主要工具。南半球包括以下植物区:热带至亚热带棕榈植物大区,高纬度Nothofagidites/Proteacidites大区,以及一个含有混合的植物组分的过渡区域。在棕榈植物大区,一些马斯特里赫特期的关键物种在白垩纪-古近纪界线处灭绝了,包括Aquilapollenites magnus、Buttinia andreevi、Crassitricolporites brasiliensis、Proteaci ditesdehaani和Gabonisporis vigourouxii。在Nothofagidites/Proteacidites大区,Tricolporite slilliei、Triporopollenites sectilis、Quadraplanus brossus、Nothofagidites kaitangata和Grapnelispora evansii等物种最后出现于白垩纪-古近纪界线处。由此可见,我们需要对南半球与中国的K-Pg界线处的孢粉信息进行更详尽的分析,才能更详细地了解不同纬度、不同地点的植被对墨西哥尤卡坦撞击事件的响应。

The palynofloral changes around the Cretaeeous-Paleogene （K-Pg） mass extinction event reveal the fine details of vegetation response to a global environmental crisis-in this ease an asteroid impact in Mexico 65.5 million years ago. Due to the extinction of several plant taxa at the K-Pg boundary, palynostratigraphy is a prime tool for local- izing the Cretaceous-Paleogene boundary in non-marine successions. The Southern Hemisphere includes the tropical to sub-tropical Palmae Province, the high-latitude Nothofagidites/Proteacidites Province, and a transitional zone of mixed floristic composition. Maastriehtian key-species that go extinct at the Cretaceous-Paleogene boundary within the Palmae Province include Aquilapollenites magnus, Buttinia andreevi, Crassitricolporites brasiliensis, Proteacidites dehaani and Gabonisporis vigourouxii. In the Nothofagidites/Proteacidites Province, taxa such as Tricolporites lilliei, Triporopol- lenites sectilis, Quadraplanus brossus, Nothofagidites kaitangata, and Grapnelispora evansii have their last appearances at the boundary. It is obvious that more thorough analyses of the palynologieal signals across the K-Pg boundary in theSouthern Hemisphere and China are required to elucidate the detailed patterns of vegetation response at different latitudes and at varying distances from the impact site in Yucatan, Mexico.