Abstract

The upper Paleocene to lower Eocene Margaret Formation exposed at Stenkul Fiord on southern Ellesmere Island, Nunavut, Canada, represents a nearly continuous terrestrial succession of microfossil-rich clastic sediments and coal. These strata were deposited at a time of extensive tectonic activity associated with Eurekan deformation. The precise chronology of the Eurekan deformation is poorly known. Prior studies at Stenkul Fiord provided a stratigraphic overview and relative age estimates for exposed strata but lack the absolute age control required to investigate the timing of deformation events. Strata at Stenkul Fiord preserve evidence of Arctic forests that may have grown during hyperthermal events that characterized the Paleogene, namely, the Paleocene-Eocene Thermal Maximum (PETM) and Eocene Thermal Maximum 2 (ETM2). A quantitative palynological approach is herein used to define a new higher-resolution biostratigraphic framework for the Margaret Formation strata at Stenkul Fiord. This resulting improved biostratigraphic framework is integrated with new absolute age control of 53.7 ± 0.06 Ma provided by U-Pb ID-TIMS of zircon preserved in an ash bed within the studied succession. Nine pollen zones are defined based on cluster analysis, NMDS ordination, first- and last occurrences of taxa, and angiosperm pollen taxa diversity (H′). The presence of thermophilic pollen taxa at Stenkul Fiord provides evidence of climates related to the globally warm climates during the early Paleogene.

摘要

在加拿大努纳武特埃尔斯米尔岛南部的 Stenkul 峡湾出露的上古新世至下始新世玛格丽特组代表了几乎连续的富含微化石的碎屑沉积物和煤的陆地序列。这些地层是在与 Eurekan 变形相关的广泛构造活动时期沉积的。尤里坎变形的精确年代学知之甚少。Stenkul Fiord 先前的研究提供了暴露地层的地层概况和相对年龄估计，但缺乏调查变形事件时间所需的绝对年龄控制。Stenkul Fiord 的地层保存了北极森林的证据，这些森林可能在古近纪超高温事件期间生长，即古新世-始新世热最大值 (PETM) 和始新世热最大值 2 (ETM2)。本文使用定量孢粉学方法为 Stenkul Fiord 的 Margaret 组地层定义新的更高分辨率生物地层框架。由此产生的改进的生物地层框架与由 U-Pb ID-TIMS 提供的 53.7 ± 0.06 Ma 的新绝对年龄控制相结合，该锆石保存在研究序列中的灰床中。根据聚类分析、NMDS 排序、首次和最后出现的分类群以及被子植物花粉分类群的多样性，定义了九个花粉区。由 U-Pb ID-TIMS 提供的 06 Ma 保存在研究序列内的灰床中的锆石。根据聚类分析、NMDS 排序、首次和最后出现的分类群以及被子植物花粉分类群的多样性，定义了九个花粉区。由 U-Pb ID-TIMS 提供的 06 Ma 保存在研究序列内的灰床中的锆石。根据聚类分析、NMDS 排序、首次和最后出现的分类群以及被子植物花粉分类群的多样性，定义了九个花粉区。H ')。Stenkul Fiord 嗜热花粉类群的存在提供了与古近纪早期全球温暖气候相关的气候证据。