Geobiology Seminar: "Triple oxygen isotopes in sedimentary and biogenic carbonates: New tools for paleoclimate, paleoecology, and paleo-carbon cycle research"


Tuesday, May 5, 2015, 12:00pm to 1:00pm


Haller Hall (Geology Museum)

Speaker: Benjamin Passey (Johns Hopkins University)


The study of triple oxygen isotope variations (D17O) in the hydrological cycle and atmosphere has progressed significantly in the last ten years, and new analytical methods permit high-precision triple oxygen isotope analysis of carbonates, hence extending triple oxygen isotope applications into the sedimentary record. I will discuss a number of emerging applications for this isotope system.In paleosol and lacustrine carbonates, D17O largely reflects the extent of evaporation of parent waters, and hence will be useful for assessing paleoaridity and paleohydrology.  It will also help to improve estimates of the δ18O of primary (unevaporated) meteoric precipitation, which is often used as a basis for paleoelevation and paleotemperature reconstruction.

In animal body waters, D17O largely reflects the extent of leaf water consumption, and correlates with relative humidity for leaf-consuming animals.  Thus D17O analysis of biogenic carbonates (tooth enamel, eggshell) will be useful for studying water balance ecology and climatic contexts of modern and fossil vertebrates.

In carbon cycle research, D17O of atmospheric O2 reflects the relative concentrations of CO2 and O2 in the atmosphere, and global primary productivity.  The atmospheric O2 signal is incorporated into animal body water via metabolism (CH2O + O2 ® CO2 + H2O). Biogenic carbonates record the body water signal and hence partly record the D17O of atmospheric O2.  Thus the D17O of fossil biominerals can help place constraints on key aspects of past carbon cycles.