New Paper Update: Reconstructing an Eocene Estuary using D47 and D17O

Postdoc Julia Kelson (joint SCIPP lab and IsoPaleoLab) recently published an exciting paper in the journal Geology looking at a large estuary that existed in Southern California during the Eocene. This work brings together multiple research groups in the department, and has built gradually over the years from Nathan Niemi originally setting out to study the Goler Formation, to Sierra adding d18O, d13C, and D47 results while she was still a postdoc, to Julia and Ben Passey adding D17O to round out the story.

We found covariation in d18O, d13C and d18Owater (derived from D47-temperatures), suggesting an estuarine environment with an isotopically depleted freshwater source. To be as isotopically depleted as measured, the freshwater was infered to come from high-elevation precipitation and potentially snowmelt. The including of D17O, which is an indicator of the amount of evaporation that a water mass has undergone, suggested that the inferred d18Owater of the freshwater source was actually overestimated (it should have been even lighter) due to evaporation. This led us to infer that paleoelevation may actually have been even higher at this time, to produce even more isotopically depleted precipitation.

Overall, this paper highlights the power of combining multiple isotopic proxy systems to answer climate,hydrology, and even tectonic, questions in the past. Great job Julia!


SCIPP Lab Fall Potluck

SCIPP Lab, circa October 2021. Left to right: Julia Kelson, Allison Curley, Jade Zhang, Jon Hoffman, Alex Quizon, Manmeet Singh, Samantha Davies, Sabrina Lanker, Cecilie Phillips, Lucas Gomes, and PI Sierra Petersen.

The SCIPP Lab gathered to welcome new members (4 undergrad UROP students and 2 new PhD students), say a bit of a goodbye to old members (Julia will be around less often in the coming months), and enjoy each other’s company and food and Sierra’s new back deck. This came together last minute as we realized the long late summer weather was going to abruptly become fall at any moment, but was by all accounts a huge success. We learned that ring toss is harder than it looks, and that SCIPP lab members are big fans of chips and dips of all sorts. We sampled multiple desserts baked by group members, all of which were delicious – even the mysterious pastry/nutella experimental creations of Alex. We also determined that we are surprisingly good at soccer as a group and are ready to challenge another research lab in the Earth department to a game when the time is right. We all agree – Sabrina will be the goalie.

Looking forward to a fun year with these folks!

New Paper Update: Synthesis of Paleosol Clumped Isotope Data

Julia Kelson (collaborator and now postdoc in the SCIPP group) published a compilation study of all published paleosol clumped isotope data to investigate whether any patterns could emerge regarding seasonal timing of formation or temperature biases. She updated older data using the Brand/IUPAC parameters and culled out early data that didn’t meet current data collection standards.

She found that paleosol carbonates tend to show a warm season bias, and calculated d18Owater values are related to d18Oprecipiation values from the season of carbonate formation.



Link to Paper

SCIPP Lab welcomes 4 new group members

The SCIPP Lab/Petersen Group is very excited to welcome four new members for the coming year. Julia Kelson will arrive as a postdoc under the NSF Postdoctoral Fellowship to study paleoclimate and paleohydrology using clumped and triple oxygen isotopes, in conjunction with the IsoPaleo Lab. Two incoming Masters students, Allison Curley and Heidi O’Hora, will be working on Cretaceous paleoclimate projects. Finally, undergraduate Steve Wedel will join our ranks to work on reconstructing climate during the Last Interglacial in Turks and Caicos.