title: Seawater strontium isotopic variations from 2.5 million years ago to the present.
abstract: Measurements of marine carbonate samples indicate that during the past 2.5 million years the (87)Sr/(86)Sr ratio of seawater has increased by 14 x 10(-5). The high average rate of increase of (87)Sr/(86)Sr indicates that continental weathering rates were exceptionally high. Nonuniformity in the rate of increase suggests that weathering rates fluctuated by as much as +/-30 percent of present-day values. Some of the observed shifts in weathering rates are contemporaneous with climatic changes inferred from records of oxygen isotopes and carbonate preservation in deep sea sediments.
authors.forename: R C
authors.initials: RC
authors.lastname: Capo
authors.forename: D J
authors.initials: DJ
authors.lastname: Depaolo