The benthic foraminiferal δ 34 S records flux and timing of paleo methane emissions

• Published in: Scientific reports Vol. 10; no. 1; p. 1304
• Main Authors: Borrelli, C, Gabitov, R I, Liu, M-C, Hertwig, A T, Panieri, G
• Format: Journal Article
• Language: English
• Published: England 28-01-2020
• ISSN: 2045-2322

In modern environments, pore water geochemistry and modelling simulations allow the study of methane (CH
) sources and sinks at any geographic location. However, reconstructing CH
dynamics in geological records is challenging. Here, we show that the benthic foraminiferal δ
S can be used to reconstruct the flux (i.e., diffusive vs. advective) and timing of CH
emissions in fossil records. We measured the δ
S of Cassidulina neoteretis specimens from selected samples collected at Vestnesa Ridge, a methane cold seep site in the Arctic Ocean. Our results show lower benthic foraminiferal δ
S values (∼20‰) in the sample characterized by seawater conditions, whereas higher values (∼25-27‰) were measured in deeper samples as a consequence of the presence of past sulphate-methane transition zones. The correlation between δ
S and the bulk benthic foraminiferal δ
C supports this interpretation, whereas the foraminiferal δ
O-δ
S correlation indicates CH
advection at the studied site during the Early Holocene and the Younger-Dryas - post-Bølling. This study highlights the potential of the benthic foraminiferal δ
S as a novel tool to reconstruct the flux of CH
emissions in geological records and to indirectly date fossil seeps.