Abstract
In paleoenvironmental studies of marine sediments bioturbation is often neglected and/or only treated as a diffusion-like process affecting only the uppermost sediment with decreasing intensity with depth. Deep dwelling animals, like the Zoophycos producing animal, however, affect the sediment composition by transporting material over vertical distances of up to 1 m below the seafloor. In Arabian Sea sediment cores 70KL, 64KL and 57KL a significant downward transport of particles by Zoophycos can be observed. Within the Zoophycos burrows the faunal composition of both planktonic and benthic foraminiferal assemblages as well as the isotopic signature of foraminiferal carbonate differ significantly from the background sediment. Radiocarbon ages obtained from foraminiferal tests derived from the Zoophycos burrows reveal ages of up to 10 000 yr younger than those from the background sediment, indicating the time when the burrow was active. Faunal and isotopic compositions within the Zoophycos burrows resemble the surface sediment conditions at the time the Zoophycos producing animal lived. These features may result in misleading environmental interpretations regarding for example transfer functions of paleotemperature and -salinity or ventilation reconstructions. Moreover, the results show that Zoophycos bioturbation may significantly bias the radiocarbon age assessment for paleoenvironmental events if sampling is not carried out as careful to avoid possible incorporation of Zoophycos bioturbation material.
Published Version
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