The Cretaceous to Eocene: a biostratigraphical review and a new detailed palynostratigraphy of Greenland and adjacent areas

This paper compiles and correlates for the first time Cretaceous to Eocene palynostratigraphies across the Arctic. It focuses on Greenland and adjacent areas, including the Labrador–Baffin Seaway, onshore Nuussuaq Basin in central West Greenland, onshore southern East Greenland, central East Greenland, North-East Greenland, eastern North Greenland and the Danmarkshavn Basin, but also extends to the Canadian Arctic Archipelago and the Barents Sea region offshore Norway. The paper compiles data from more than three decades of detailed Arctic palynological analyses, based mainly on dinoflagellate cysts. It gives a historical overview of the Cretaceous to Paleogene palaeontological studies of Greenland and presents an overview of 85 palynological intervals and numerous bioevents. The palynological assemblages from the Labrador–Baffin Seaway, Nuussuaq Basin and north-east Baffin Bay reflect the opening of the Labrador–Baffin Seaway, from a brackish to freshwater environment in a large embayment in the Early Cretaceous to an open marine seaway in the Late Cretaceous. Assemblages reveal dinoflagellate cyst provincialism between the opening stages of the Labrador–Baffin Seaway and the already opened Greenland–Norwegian–Barents seaway. The Upper Cretaceous global Oceanic Anoxic Event 2 (OAE2) spanning the Cenomanian/Turonian boundary is recognised from Arctic Canada, north-east Baffin Bay, Nuussuaq Basin in central West Greenland, and North-East Greenland, and is mapped and correlated based on dinoflagellate cyst stratigraphy and carbon isotope (δ¹³C_org) curves. The dinoflagellate cyst assemblages of the Cretaceous/Paleogene boundary are correlated from the Labrador Sea across to the Nuussuaq Basin in central West Greenland; in both areas the earliest Danian palynological assemblage is represented by incoming warm-water species. The presence of the global Paleocene–Eocene Thermal Maximum (PETM) in the Paleogene successions in North-East Greenland and in exploration wells in the Labrador–Baffin Seaway is indicated by the incoming of the warm-water dinoflagellate cyst species <i>Axiodinium augustum</i>.

本研究首次对北极地区白垩纪至始新世的孢粉地层学（palynostratigraphies）进行系统整理与对比分析。研究聚焦格陵兰及其邻区，涵盖拉布拉多-巴芬海道（Labrador–Baffin Seaway）、西格陵兰中部陆上努苏阿克盆地（Nuussuaq Basin）、东格陵兰南部陆上、东格陵兰中部、东北格陵兰、北格陵兰东部以及丹马克斯哈文盆地（Danmarkshavn Basin），同时研究范围延伸至加拿大北极群岛与挪威近海的巴伦支海区域。本研究整合了三十余年来针对北极地区的详细孢粉学分析数据，分析对象主要为沟鞭藻囊孢（dinoflagellate cysts）。文中首先梳理了格陵兰地区白垩纪至古近纪古生物学研究的历史脉络，并概述了85个孢粉地层区间与众多生物事件。拉布拉多-巴芬海道、努苏阿克盆地以及巴芬湾东北部的孢粉组合，反映了拉布拉多-巴芬海道的演化过程：早白垩世时期，该区域处于大型海湾环境，水体从半咸水逐渐过渡为淡水；至晚白垩世则演变为开阔海洋海道。孢粉组合揭示，在拉布拉多-巴芬海道开启阶段与已形成的格陵兰-挪威-巴伦支海道之间，存在沟鞭藻囊孢生物地理分区性。跨越森诺曼阶/土仑阶界线的晚白垩世全球大洋缺氧事件2（OAE2），已在北极加拿大、巴芬湾东北部、西格陵兰中部努苏阿克盆地以及东北格陵兰地区被识别；该事件基于沟鞭藻囊孢地层学与有机碳同位素（δ¹³Corg）曲线完成了填图与对比。白垩纪/古近纪界线处的沟鞭藻囊孢组合，可从拉布拉多海对比至西格陵兰中部的努苏阿克盆地；两处区域的最早达宁期孢粉组合均以喜暖类群的首次出现为特征。东北格陵兰古近纪地层以及拉布拉多-巴芬海道勘探井中，古新世-始新世极热事件（PETM）的存在可通过喜暖沟鞭藻囊孢物种Axiodinium augustum的首次出现得到指示。