Zoophycos in deep-sea sediments indicates high and seasonal primary productivity: Ichnology as a proxy in palaeoceanography during glacial-interglacial variations

摘要

Trace fossils provide valuable palaeoenvironmental information in hemipelagic settings. This is particularly true in the case of Zoophycos, an easily recognizable trace fossil in core. At IODP site U1385, Zoophycos was found throughout an interval representing 1.5Ma, covering 45 glacial-interglacial cycles mediated by obliquity (41ka) and short-term eccentricity (100ka). Zoophycos is most common in sediments deposited during glacial times and when the sedimentation rate was intermediate and primary production was high and seasonal. Occurrences of Zoophycos elsewhere support a similar relationship with seasonal organic-matter deposition. This is particularly significant considering that seasonality of organic-matter deposition is difficult to decipher from the sediment record. Zoophycos appears to represent a useful proxy to characterize high and seasonal organic-matter deposition and primary productivity in Neogene hemipelagic deposits.