Tuesday, March 13th, 2018

Special Tuesday Seminar

4:10 PM, 1314 EPS

“The neglected middle son: 17O in paleoclimate”

      – by Zach Sharp, University of New Mexico

It is now recognized that deviations from the Terrestrial Fractionation Line for the three oxygen isotope system are ubiquitous and have geological meaning. The d18O and d17O values of selected low temperature quartz and silica samples were measured in order to derive the quartz-water fractionation - temperature relationship for the three isotopes.
Application of the quartz-water triple isotope system to low temperature samples provides constraints of temperatures of formation and sources of water. Authigenic crystalline quartz appears to crystallize at 50°C, lower than previous estimates. The combined d18O and d17O values of samples considered to be in equilibrium with meteoric waters can be used to estimate both formation temperatures and the d18O value of the meteoric water. Unlike other multiple isotopes systems, such as combined H and O isotopes in cherts, the oxygen source and diagenetic potential for both 17O/16O and 18O/16O ratios are identical, simplifying interpretations from ancient samples.

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