Reevaluation of conflicting Eocene tropical temperature estimates: Molluskan oxygen isotope evidence for warm low latitudes

Research Article| November 01, 2001 Reevaluation of conflicting Eocene tropical temperature estimates: Molluskan oxygen isotope evidence for warm low latitudes Takuro Kobashi; Takuro Kobashi 1Department of Geology and Geophysics, Texas A&M University, College Station, Texas 77840, USA Search for other works by this author on: GSW Google Scholar Ethan L. Grossman; Ethan L. Grossman 1Department of Geology and Geophysics, Texas A&M University, College Station, Texas 77840, USA Search for other works by this author on: GSW Google Scholar Thomas E. Yancey; Thomas E. Yancey 1Department of Geology and Geophysics, Texas A&M University, College Station, Texas 77840, USA Search for other works by this author on: GSW Google Scholar David T. Dockery, III David T. Dockery, III 2Mississippi Office of Geology, Jackson, Mississippi 39289, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Takuro Kobashi 1Department of Geology and Geophysics, Texas A&M University, College Station, Texas 77840, USA Ethan L. Grossman 1Department of Geology and Geophysics, Texas A&M University, College Station, Texas 77840, USA Thomas E. Yancey 1Department of Geology and Geophysics, Texas A&M University, College Station, Texas 77840, USA David T. Dockery, III 2Mississippi Office of Geology, Jackson, Mississippi 39289, USA Publisher: Geological Society of America Received: 02 Mar 2001 Revision Received: 09 Jul 2001 Accepted: 11 Jul 2001 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2001) 29 (11): 983–986. https://doi.org/10.1130/0091-7613(2001)029<0983:ROCETT>2.0.CO;2 Article history Received: 02 Mar 2001 Revision Received: 09 Jul 2001 Accepted: 11 Jul 2001 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Takuro Kobashi, Ethan L. Grossman, Thomas E. Yancey, David T. Dockery; Reevaluation of conflicting Eocene tropical temperature estimates: Molluskan oxygen isotope evidence for warm low latitudes. Geology 2001;; 29 (11): 983–986. doi: https://doi.org/10.1130/0091-7613(2001)029<0983:ROCETT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Oxygen isotope data from planktonic foraminifera for the warm Eocene epoch suggest that tropical sea-surface temperatures (SSTs) may have been cooler than at present. Such data have stimulated various explanations involving, e.g., major changes in ocean heat transport. However, the planktonic data disagree with terrestrial climate proxies, which suggest significantly warmer low-latitude temperatures. We examined this discrepancy by analyzing seasonal oxygen isotope variations in shallow-marine mollusks from the Mississippi Embayment. Results indicate that mean annual SSTs decreased from 26–27 °C in the early Eocene to 22–23 °C in the Oligocene, agreeing well with temperatures inferred from terrestrial climate proxies. These cooling trends, with more significant winter cooling (5 °C) than summer cooling (3 °C), are consistent with the predicted consequences of decreasing atmospheric CO2 concentration through the Paleogene, suggesting that atmospheric CO2 change was a major controlling factor for Paleogene climate change. That winter SST estimates from the mollusks agree well with the foraminiferal SST estimates suggests that planktonic foraminiferal growth in low latitudes occurred mainly during the cooler winter months throughout the Eocene. We hypothesize that the unusual hydrography of Eocene oceans shifted foraminiferal productivity primarily to winter, biasing foraminiferal SST estimates of mean annual SSTs. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.