A Pulse of Meteoric Subsurface Fluid Discharging Into the Chukchi Sea During the Early Holocene Thermal Maximum (EHTM)

• Published in: Geochemistry, Geophysics, Geosystems
• Main Authors: Ji‐Hoon Kim, Wei‐Li Hong, Marta E. Torres, Jong‐Sik Ryu, Moo‐Hee Kang, Dukki Han, Seung‐Il Nam, Jin Hur, Dong‐Chan Koh, Frank Niessen, Dong‐Hun Lee, Kwangchul Jang, James William Buchanan Rae, Meilian Chen
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: subsurface meteoric fluid discharge; Arctic element/carbon cycle; permafrost; EHTM; Chukchi Sea; Geophysics. Cosmic physics; QC801-809; Geology; QE1-996.5; Arctic; Arctic Ocean; Chukchi
• Online Access: https://doi.org/10.1029/2021GC009750; https://doaj.org/article/6860096e25734091bd3e9a4064c7d606

Abstract The response of Arctic Ocean biogeochemistry to subsurface flow driven by permafrost thaw is poorly understood. We present dissolved chloride and water isotopic data from the Chukchi Sea Shelf sediments that reveal the presence of a meteoric subsurface flow enriched in cations with a radiogenic Sr fingerprint. This subsurface fluid is also enriched in dissolved inorganic carbon and methane that bear isotopic compositions indicative of a carbon reservoir modified by reactions in a closed system. Such fluid characteristics are in stark contrast with those from other sites in the Chukchi Sea where the pore water composition shows no sign of meteoric input, but reflect typical biogeochemical reactions associated with early diagenetic sequences in marine sediment. The most likely source of the observed subsurface flow at the Chukchi Sea Shelf is from the degradation of permafrost that had extended to the shelf region during the Last Glacial Maximum. Our data suggest that the permafrost‐driven subsurface flow most likely took place during the 2–3°C warming in the Early Holocene Thermal Maximum. This time scale is supported by numerical simulation of pore water profiles, which indicate that a minimum of several thousand years must have passed since the cessation of the subsurface methane‐bearing fluid flow.