Significance of the trace fossil Zoophycos in Pliocene deposits, Antarctic continental margin (ANDRILL 1B drill core)

• Published in: Antarctic Science
• Main Authors: Miller, Molly F., Cowan, Ellen A., Nielsen, Simon H.H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2009
• Subjects: Geology; Ecology, Evolution, Behavior and Systematics; Oceanography; Antarctic; Southern Ocean; McMurdo Ice Shelf; Antarc*; Antarctic Science; Antarctica; Ice Shelf
• Online Access: http://dx.doi.org/10.1017/s0954102009002041; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102009002041

Abstract Zoophycos is a complex three dimensional trace fossil that is abundant in deep ocean sediments worldwide, but has not been described previously from Cenozoic continental margin deposits of Antarctica. In the ANDRILL 1B core drilled through the north-west McMurdo ice shelf, Zoophycos occurs in a 17 m thick unit of interglacial sediments bounded above and below by glacial surfaces of erosion. This unit was deposited during the transition from the relatively warm Early Pliocene characterized by productive open waters to the cooler Late Pliocene with fluctuating subpolar ice sheets. Globally, Late Cenozoic Zoophycos are most abundant at great depths (> 1000 m), and where sedimentation rates and TOC levels are low; the Zoophycos producer, probably a worm-like animal, was (is) a slow colonizer. Application of these preferences to the ANDRILL 1B core indicates that the Zoophycos -bearing unit was deposited episodically, with sufficient time between events to allow for the slow processes of colonization and construction. The foray of Zoophycos producer into the relatively shallow ANDRILL 1B depths (200–1000 m) during the Pliocene documents “emergence” of benthic animals, supporting suggestions that the unique modern Antarctic and Southern Ocean faunas result from both “emergence” and “submergence” during the Cenozoic.