Coupled evolution of temperature and carbonate chemistry during the Paleocene-Eocene; new trace element records from the low latitude Indian Ocean

James S. K. Barnet*, Dustin T. Harper, Leah J. LeVay, Kirsty M. Edgar, Michael J. Henehan, Tali L. Babila, Clemens Ullmann, Melanie J. Leng, Dick Kroon, James C. Zachos, Kate Littler

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)
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Abstract

The early Paleogene represents the most recent interval in Earth's history characterized by global greenhouse warmth on multi-million year timescales, yet our understanding of long-term climate and carbon cycle evolution in the low latitudes, and in particular the Indian Ocean, remains very poorly constrained. Here we present the first long-term sub-eccentricity-resolution stable isotope (δ13C and δ18O) and trace element (Mg/Ca and B/Ca) records spanning the late Paleocene-early Eocene (similar to 58-53 Ma) across a surface-deep hydrographic reconstruction of the northern Indian Ocean, resolving late Paleocene 405-kyr paced cyclicity and a portion of the PETM recovery. Our new records reveal a long-term warming of similar to 4-5 °C at all depths in the water column, with absolute surface ocean temperatures and magnitudes of warming comparable to the low latitude Pacific. As a result of warming, we observe a long-term increase in δ18Osw of the mixed layer, implying an increase in net evaporation. We also observe a collapse in the temperature gradient between mixed layer- and thermocline-dwelling species from similar to 57-54 Ma, potentially due to either the development of a more homogeneous water column with a thicker mixed layer, or depth migration of the Morozovellain response to warming. Synchronous warming at both low and high latitudes, along with decreasing B/Ca ratios in planktic foraminifera indicating a decrease in ocean pH and/or increasing dissolved inorganic carbon, suggest that global climate was forced by rising atmospheric CO2 concentrations during this time.

Original languageEnglish
Article number116414
Number of pages15
JournalEarth and Planetary Science Letters
Volume545
Early online date18 Jun 2020
DOIs
Publication statusPublished - 1 Sept 2020

Keywords

  • Trace elements
  • Paleoclimate
  • Paleoceanography
  • Paleogene
  • Paleocene-Eocene Thermal Maximum
  • Indian Ocean

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