title: Hafnium isotope stratigraphy of ferromanganese crusts
abstract: A Cenozoic record of hafnium isotopic compositions of central Pacific deep water has been obtained from two ferromanganese crusts. The crusts are separated by more than 3000 kilometers but display similar secular variations. Significant fluctuations in hafnium isotopic composition occurred in the Eocene and Oligocene, possibly related to direct advection from the Indian and Atlantic oceans. Hafnium isotopic compositions have remained approximately uniform for the past 20 million years, probably reflecting increased isolation of the central Pacific. The mechanisms responsible for the increase in (87)Sr/(86)Sr in seawater through the Cenozoic apparently had no effect on central Pacific deep-water hafnium.
authors.affiliation: Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA. Institut fur Isotopengeologie und Mineralische Rohstoffe, Department fur Erdwissenschaften, ETH-Zentrum, NO C61, Sonneggstrasse 5, CH-8092 Zurich, Switzerland.
authors.initials: DC
authors.lastname: Lee
authors.initials: AN
authors.lastname: Halliday
authors.initials: JR
authors.lastname: Hein
authors.initials: KW
authors.lastname: Burton
authors.initials: JN
authors.lastname: Christensen
authors.initials: D
authors.lastname: Gunther