Orbital-scale climate change and glacioeustasy during the early Late Ordovician (pre-Hirnantian) determined from delta O-18 values in marine apatite Academic Article uri icon


  • This study focuses on the ~10 m.y. before the latest Ordovician (Hirnantian) glaciation; we test whether orbital-scale climatic fluctuations controlled the growth and melting of continental glaciers, resulting in glacioeustatic sea-level changes and the development of widespread marine sedimentary cycles. 18O values of conodont apatite from 14 Late Ordovician (Katian) cycles range from ~17% to 21%. Isotopic values decrease and are lowest in the deepest water facies and increase and are highest in shallow-water facies, supporting the hypothesis that glacioeustasy was the dominant control on water-depth changes. Measured intracycle 18O changes of 0.7%-2.5% were controlled by changes in ice volume (<60 m sea-level changes), sea-surface temperatures (<5 C), and potentially local increases in seawater evaporation during drier and/or windier glacial stages. These interpreted orbital-scale climate changes and resultant large glacial ice-volume changes support recent interpretations of a dynamic and prolonged Ordovician greenhouse to icehouse transition. 2013 Geological Society of America.

published proceedings


altmetric score

  • 11.5

author list (cited authors)

  • Elrick, M., Reardon, D., Labor, W., Martin, J., Desrochers, A., & Pope, M.

citation count

  • 59

complete list of authors

  • Elrick, M||Reardon, D||Labor, W||Martin, J||Desrochers, A||Pope, M

publication date

  • July 2013