Geoscience Assistant Professor Ganqing Jiang and colleagues, in a recent paper in the Proceedings of the National Academy of Sciences (reprint), test the proposed linkages between redox changes in the oceans and biological evolution. Their study shows that pulsed oxidation is coupled with the development and diversification of multicellular life, in a transitional period between regimes in which carbon in the worlds oceans was dominated by dissolved organic carbon, to dominated by dissolved inorganic carbon. The research has important implications for the relationships between oxygenation of the world’s oceans and biological evolution.

Geoscience faculty members Michael Wells and Terry Spell, graduate student Tonia Arriola, and research scientist Kathleen Zanetti, in a recent paper in Tectonics (reprint), present the first successful applications of the UV and CO2 laser-probes to ⁴⁰Ar/³⁹Ar in situ dating of fibrous strain fringes.  These results demonstrate feasibility of the method for future application, and document a previously unrecognized episode of mid-Cretaceous synconvergent gravitational spreading parallel to the Mesozoic Sevier orogenic belt, with implications toward understanding the driving forces for orogen-parallel extension in mountain belts worldwide.

In a paper in Geophysical Research Letters, Assistant Professor Matthew Lachniet has shown how climate dynamics affect rainfall over the isthmus of Panama. Lachniet looked at the stable oxygen isotope values of rainfall from Panama City, Panama over the period 1968-1999, and found that the variations are related to departures from normal of sea surface temperatures in both the Caribbean Sea and the Pacific Ocean. The stable isotopes in rainfall responded in opposite ways to a warming of the Caribbean Sea and the Pacific Ocean. The rainfall isotopes are related to the effects of anomalous atmospheric circulation that is set up during the warm and dry El Niño events of the Pacific Ocean. The results have implications for both modern climate dynamics, and for the interpretation of proxy records for past rainfall from Central America.

Geoscience faculty member Elisabeth (Libby) Hausrath and colleagues, in a recent paper in the journal Astrobiology (reprint), studied basalt and olivine weathering in the arctic Mars analog environment, Svalbard. They deployed CheMin, a miniature XRD scheduled to fly to Mars on the Mars Science Laboratory, and successfully detected olivine and weathering products in the field. Biological impacts were analyzed by XPS in samples buried for one year, and in long-term weathered samples, the relative dissolution rates of basalt glass and olivine were correlated to temperature. This suggests a relevant marker of different aqueous conditions on Mars.