A 35-million-year record of seawater stable Sr isotopes reveals a fluctuating global carbon cycle

Adina Paytan; Elizabeth M Griffith; Anton Eisenhauer; Mathis P Hain; Klaus Wallmann; Andrew Ridgwell

doi:10.1126/science.aaz9266

A 35-million-year record of seawater stable Sr isotopes reveals a fluctuating global carbon cycle

Science. 2021 Mar 26;371(6536):1346-1350. doi: 10.1126/science.aaz9266.

Authors

Adina Paytan¹, Elizabeth M Griffith², Anton Eisenhauer³, Mathis P Hain⁴, Klaus Wallmann³, Andrew Ridgwell⁵

Affiliations

¹ Institute of Marine Science, University of California Santa Cruz, Santa Cruz, CA 95064, USA. apaytan@ucsc.edu.
² School of Earth Sciences, The Ohio State University, Columbus, OH 43210, USA.
³ GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany.
⁴ Institute of Marine Science, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
⁵ Department of Earth Sciences and Planetary Sciences, University of California Riverside, Riverside, CA 92521, USA.

PMID: 33766882
DOI: 10.1126/science.aaz9266

Abstract

Changes in the concentration and isotopic composition of the major constituents in seawater reflect changes in their sources and sinks. Because many of the processes controlling these sources and sinks are tied to the cycling of carbon, such records can provide insights into what drives past changes in atmospheric carbon dioxide and climate. Here, we present a stable strontium (Sr) isotope record derived from pelagic marine barite. Our δ^88/86Sr record exhibits a complex pattern, first declining between 35 and 15 million years ago (Ma), then increasing from 15 to 5 Ma, before declining again from ~5 Ma to the present. Numerical modeling reveals that the associated fluctuations in seawater Sr concentrations are about ±25% relative to present-day seawater. We interpret the δ^88/86Sr data as reflecting changes in the mineralogy and burial location of biogenic carbonates.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.