title: Impact of Antarctic Circumpolar Current development on late Paleogene ocean structure.
abstract: Global cooling and the development of continental-scale Antarctic glaciation occurred in the late middle Eocene to early Oligocene (~38 to 28 million years ago), accompanied by deep-ocean reorganization attributed to gradual Antarctic Circumpolar Current (ACC) development. Our benthic foraminiferal stable isotope comparisons show that a large δ(13)C offset developed between mid-depth (~600 meters) and deep (>1000 meters) western North Atlantic waters in the early Oligocene, indicating the development of intermediate-depth δ(13)C and O(2) minima closely linked in the modern ocean to northward incursion of Antarctic Intermediate Water. At the same time, the ocean's coldest waters became restricted to south of the ACC, probably forming a bottom-ocean layer, as in the modern ocean. We show that the modern four-layer ocean structure (surface, intermediate, deep, and bottom waters) developed during the early Oligocene as a consequence of the ACC.
authors: Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. katzm@rpi.edu
authors: Miriam E
authors: ME
authors: Katz
authors: Benjamin S
authors: BS
authors: Cramer
authors: J R
authors: JR
authors: Toggweiler
authors: Gar
authors: G
authors: Esmay
authors: Chengjie
authors: C
authors: Liu
authors: Kenneth G
authors: KG
authors: Miller
authors: Yair
authors: Y
authors: Rosenthal
authors: Bridget S
authors: BS
authors: Wade
authors: James D
authors: JD
authors: Wright