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Synchronous Marine and Terrestrial Carbon Cycle Perturbation in the High Arctic During the PETM
Author(s) -
Cui Ying,
Diefendorf Aaron F.,
Kump Lee R.,
Jiang Shijun,
Freeman Katherine H.
Publication year - 2021
Publication title -
paleoceanography and paleoclimatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.927
H-Index - 127
eISSN - 2572-4525
pISSN - 2572-4517
DOI - 10.1029/2020pa003942
Subject(s) - carbon cycle , isotopes of carbon , algae , arctic , terrestrial plant , carbon fibers , canada basin , total organic carbon , environmental science , oceanography , geology , environmental chemistry , ecology , chemistry , ecosystem , biology , materials science , composite number , composite material
The Paleocene‐Eocene Thermal Maximum (PETM; 56 Ma) is considered to be one of the best analogs for future climate change. The carbon isotope composition (δ 13 C) of n ‐alkanes derived from leaf waxes of terrestrial plants and marine algae can provide important insights into the carbon cycle perturbation during the PETM. Here, we present new organic geochemical data and compound‐specific δ 13 C data from sediments recovered from an early Cenozoic basin‐margin succession from Spitsbergen. These samples represent one of the most expanded PETM sites and provide new insights into the high Arctic response to the PETM. Our results reveal a synchronous ∼−6.5‰ carbon isotope excursion (CIE) in short‐chain n ‐alkanes ( n C 19 ; marine algae/bacteria) with a ∼−5‰ CIE in long‐chain n ‐alkanes ( n C 29 and n C 31 ; plant waxes) during the peak of the PETM. Although δ 13 C n ‐alkanes values were potentially affected via a modest thermal effect (1‰–2‰), the relative changes in the δ 13 C n ‐alkanes remain robust. A simple carbon cycle modeling suggests peak carbon emission rate could be ∼3 times faster than previously suggested using δ 13 C TOC records. The CIE magnitude of both δ 13 C n ‐C19 and δ 13 C n ‐C29 can be explained by the elevated influence of 13 C‐depleted respired CO 2 in the water column and increased water availability on land, elevated p CO 2 in the atmosphere, and changes in vegetation type during the PETM. The synchronous decline in δ 13 C of both leaf waxes and marine algae/bacteria argues against a significant contribution to the sedimentary organic carbon pool from the weathering delivery of fossil n ‐alkanes in the Arctic region.