Nature 282, 63 - 65 (01 November 1979); doi:10.1038/282063a0

Response of deep-sea benthonic Foraminifera to development of the psychrosphere near the Eocene/Oligocene boundary

Bruce H. Corliss

Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543

A dominant feature of present-day thermohaline circulation in oceans is the production of cold Antarctic Bottom Water (AABW) in the Weddell and Ross Seas and along the continental margin off Antarctica. The cold, dense AABW formed at or near the surface sinks to abyssal depths and travels throughout the ocean basins. AABW circulation was suggested to have begun near the Eocene/Oligocene boundary with the development of the psychrosphere (lower cold layer of a two-layer ocean with temperatures <10°C) inferred from ostracode faunal data¹ and oxygen isotopic evidence from closely-spaced samples in DSDP site 277 (ref. 2). Previous studies suggested that the temperature change associated with the development of the psychrosphere caused a crisis for deep-sea ostrocodes¹ and deep-sea benthonic Foraminifera³. I consider here the response of benthonic Foraminifera to the development of the psychrosphere.

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