- Friday, February 8, 2019
- 3:30 PM–4:30 PM
- North Hall 078
Please make plans to join us for the GEO Department Seminar on Friday afternoon from 3:30-4:30pm in North Hall 078. Refreshments will be provided.
Beyond δ18O: Applying “Clumped” and “Triple Oxygen” Isotopes to the Sedimentary Record
By Dr. Ian Winkelstern
The relative abundance of heavy oxygen isotopes in carbonates, measured as δ18O, has been the geochemical foundation of decades of sedimentological research. However, these data are dependent on many factors: salinity and global ice volume (in marine settings), evaporation and precipitation (in terrestrial settings), rock – water interaction (in diagenetic settings), and temperature (everywhere). Two new geochemical tools, “clumped” and “triple oxygen” isotopes, can circumvent these issues, enabling new insights into the environments of carbonate formation in sedimentary systems.
In this talk I will discuss how clumped isotopes enable direct measurement of paleotemperatures, and how I have used the technique to better understand Last Interglacial climate in Bermuda. There, remarkably cold temperatures may indicate rapid ice sheet melting when sea levels rose ~125 thousand years ago. Clumped isotopes can be sensitive to diagenetic alteration, and I will also outline my work testing the resilience of “clumped” signals in the subsurface of The Bahamas.
Finally, I will describe how the nascent field of triple oxygen isotopes offers unique opportunities to build quantitative records of paleohydrological change. By measuring rare 17O isotopes in lacustrine carbonates, it is now possible to measure past shifts in water delivery and evaporation. These two new approaches may revolutionize our ability to extract paleoenvironmental data from the sedimentary record.