Searching for the Terrestrial Paleocene/Eocene Boundary at the Canadian High Arctic: A Carbon Isotope Study

• Main Author: Kraus, Monica
• Format: Text
• Language: English
• Published: Bryant Digital Repository 2007
• Subjects: global warming; fossils; Carbon; Paleocene Eocene Thermal Maximum; PETM; Paleocene; Eocene; Cenozoic; carbon isotope; PETM boundary; climatic change; C isotope; Science; Technology; Arctic; Canadian Arctic Archipelago; Ellesmere Island; Nunavut; Arctic Archipelago; Global warming
• Online Access: https://digitalcommons.bryant.edu/honors_science/1; https://digitalcommons.bryant.edu/cgi/viewcontent.cgi?article=1000&context=honors_science

The Paleocene Eocene Thermal Maximum (PETM) is a rare climatic event in the history of the Earth, which marks the abrupt transition from the Paleocene to Eocene of the Cenozoic era with a rapid increase in global surface temperatures of up to 5-8&#;C. The PETM marks the warmest climates in the past 65 million years and a world-wide negative excursion of stable carbon isotopes (δ13C). To determine the location of the Paleocene-Eocene (P/E) boundary in high-latitudinal non-marine strata and to examine the magnitude of vegetation and climatic change during the warming period, the bulk carbon isotope ratios were measured in coal samples taken from several well exposed outcrops at Stenkul Fiord, Ellesmere Island, Nunavut, Canadian Arctic Archipelago. The stratigraphic sections consist of three vertical sequences (SF-P, SF-M, and P Series) that have an approximate total thickness of 74.27 m, 73.18 m, and 145 m respectively. Extending from the lower part of the P-series outcrop, three horizontal sections were taken (1, 2, and 3 Series) each spanning approximately 1 km. The bulk δ13C in the samples ranged from -23.9‰ to -28.7‰ with a background fluctuation of less than 2‰. The PETM boundary is placed in the upper portion of the P-Series between P-58 and P-60 and also in the lower portion of the SF-M and SF-P series where a sharp decrease of δ13C of up to 4.7‰ is detected. This may provide an explanation for the differing conclusions drawn from a recent palynological study and a previously published record from the same sequence. Because the C isotope measurements were based upon Metasequoia-dominated plant matter, the variation of δ13C along the vertical sequence should reflect the change of δ13C of ancient atmospheric CO2, whereas the reduced variation of δ13C in the horizontal sequences may be due to compositional differences of ancient vegetation. This study is the first isotopically marked PETM in high latitude terrestrial outcrops from the High Artic that provides a stratigraphic framework under which the ...