Publikationsdatum:
2021-09-12
Beschreibung:
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 oC warming in the Early Holocene Thermal Maximum (EHTM).
This time scale is supported by numerical simulation of pore fluid profiles, which indicate that
a minimum of several thousand years must have passed since the cessation of the subsurface
methane-bearing fluid flow.
Repository-Name:
EPIC Alfred Wegener Institut
Materialart:
Article
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