60th Annual Report on Research 2015

Research is progressing well on the two primary approaches: pyrite framboids and stable isotopes.

Pyrite framboids, used to test the distribution of oxygen-poor water, ended up being extremely rare in strata equivalent to the anoxic event previously documented in northern Spain and northwestern Europe. This implies that anoxia was absent or very restricted in its temporal distribution at the two study sections, consistent with previous evidence from the sedimentary facies. We will continue to examine samples from strata below and above the Toarcian anoxic event to assess pyrite framboid content and, if present, size. This will enable us to test the unlikely possibility that low-oxygen conditions were developed at a different time in these localities.

The stable isotope research is at an earlier stage because of the pre-screening required before analysis. The shells have been identified (necessary to account for potential species-specific effects on the isotope composition), cut, and mounted to glass slides. We have begun screening the shells under the cathodoluminescence microscope to identify shells or regions of the shells that may have been diagenetically altered. Like the belemnite shells from these locations, shell preservation is generally good and appears suitable for further analysis. Cathodoluminescence will be completed in the next few months. We will then perform the stable isotope analyses to test for seasonal differences in seawater chemistry and compare models for ocean stratification, circulation, and generation of anoxia in nearby European basins.

The funds have supported two PhD students with stipends for one academic quarter and summer (only part of the summer stipend is included in the review period). Both are progressing well with their research and will be writing their qualifying proposals in the 2015-16 academic year. They attended the Geological Society of America annual meeting in fall 2014, which was a valuable networking and professional development experience.

The funds also were used to hire an undergraduate research assistant to help cut and mount samples to glass slides in preparation for cathodoluminescence screening. The work experience in the winter and spring of 2015 helped her obtain a summer internship position at the Naval Postgraduate School. She will graduate in the spring of 2016 and is currently applying to graduate schools.