PI Sierra Petersen joined forces with Professor Kate Huntington (University of Washington) to author a review article on all things carbonate clumped isotope thermometry for Annual Reviews of Earth Sciences.
While writing this article, we envisioned it being used as the handbook you’d give to a new graduate student or collaborator to get them up to speed on the current state of the field and how it got here. For students in particular, we wrote a “Student Companion” supplement that goes into class-lecture-level detail on a number of foundational concepts of clumped isotope thermometry. We had never seen this type of information collected into one place before and had always struggled on how to onboard new students efficiently.
We hope this article will be useful to the clumped community – old and new members!
PhD student Jade Zhang published her second paper, this one focusing on high-resolution clumped isotope sampling in bivalves.
High-resolution isotopic sampling along the direction of maximum growth of a mollusk (isotopic sclerochonology) has been done for many years using oxygen and carbon isotopes. This method can reveal seasonality of climate (via the d18O max, min, and range), mollusk growth rate, and more, but suffers from the same issues all oxygen isotope paleothermometry methods do – unknown d18Owater. Clumped isotope paleothermometry doesn’t have the same issues with uncertainty in d18Ow, but large historical sample size requirements have prevented much application of this powerful technique to mollusk sclerochronology.
With recent reductions in sample size, this new area of clumped isotope paleothermometry is increasingly being explored. In this study, Jade applies different subannual sampling methods (seasonally targeted vs. continuous sampling) to modern shells of the bivalve Lucina pensylvanica from sites around Florida and the Caribbean, testing which methods work best in higher (Florida) or lower (Caribbean) seasonality locations.
In the end, she proposes a trade-off between sampling resolution, sample size, machine precision with different sample sizes, and bivalve growth rate. This study both defines L. pensylvanica as a robust recorder of climate and also serves as a template for designing clumped isotope sclerochronology sampling strategies on other species.
The latest SCIPP-Lab paper comes from former SCIPP-lab postdoc Dr. Matt Jones (now at the Smithsonian Institute), publishing the work he did while at UM. Dr. Jones looked at fossil oysters from the Cretaceous Western Interior Seaway and used clumped isotope to reconstruct seaway temperatures during the time they lived.
We found that temperatures during the Cretaceous Thermal Maximum (Cenomanian-Turonian period, ~95 Million years ago) reached upper 20’s to lower 30’s Celsius in what is now modern day Utah and Wyoming. This is very hot! These water temperatures, which occurred in the mid-latitudes during the Cretaceous, are today only found in the warmest areas of the ocean like the Western Pacific Warm Pool. It makes you wonder how hot the tropics were if the mid-latitudes were >30C!! But that’s for another day…
Some Cenomanian-Turonian oyster fossils used in this studyShell cross section, showing growth banding (and some calcite veins).
SCIPP Lab members measuring section and collecting Plio-Pleistocene fossil shells
Four members of the SCIPP lab ventured to sunny, hot, humid (sooo humid so hot) Florida to gather shells from the Plio-Pleistocene for geochemical analysis. We spent 5 days in the Florida Shell and Fill quarry near Punta Gorda gathering as many fossils as we could. Graduate students Lucas Gomes, Allison Curley, and Jade Zhang accompanied Professor Sierra Petersen and collaborator Peter Riemersma (Grand Valley State University) for the week. Our local contact Roger Portell from the Florida Museum of Natural History joined the group for the first two days to help us get our bearings. A big shout out to the owners and operators of FL Shell – Joe, Jess, Marilyn, James, Ernesto!! Thank you for giving us access to this awesome site.
During the Plio-Pleistocene interval (around 0.1-3.5 Ma), the southern portion of Florida was underwater much of the time (excluding glacial intervals where seawater was trapped in ice sheets and sea level was lower). Studied formations (Ochape, Caloosahatchee, Bermont, and Fort Thompson) represent marine to shallow marine to beach environments. These formations are SO full of shells, it wasn’t a question of whether we would FIND any fossils, more like could we SAMPLE the right ones and keep track of where we found them. We got very picky about which were the “best” ones by the end of the week.
Grad Student Lucas Gomes describing the upper portion of the section. Grad student Jade Zhang points to an in-place coral we hope to date.
This site has an amazing diversity of shells. Literally hundreds of species. Some large, some small. We found everything from hand-span-sized scallops (Carolinapecten) to mm-sized micromollusks. Although larger shells appeared caked in mud and sand, when you wash them off, they’re actually filled with even smaller shells!
Fast growing scallop, Carolinapecten. Micromollusks washed out of a larger gastropod shell, inside a yogurt container for scale. Grad students Jade Zhang, Allison Curley, and Lucas Gomes organizing samples in the garage of our AirBNB in the evening. Great teamwork, great organization!
Whether it was the first real field work, or the first field work in a while, the grad student team did an amazing job with logistics, field sampling, and evening sample organization. Great job everyone! Very excited to see what science comes out of these (many many) samples. 🙂
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!
MGU (Michigan Geophysical Union) is a 1-day conference completely run by UM students, bringing together students studying earth sciences in the Earth and Environmental Science, Chemistry, and Climate and Space Sciences and Engineering departments across campus. This has historically just been a poster session, but this year a few live talks were held as well.
The SCIPP Lab had a very strong representation at MGU 2022! ALL members of the SCIPP Lab presented (4 grad, 4 undergrad posters) and Sierra volunteered as a judge. Two of our group members (Alex and Allison) were also on the organizing committee! Everyone did an awesome job creating their posters and presenting their results. Two of our undergrads were awarded “best undergrad presentation” awards! Congratulations Cecilie and Samantha!
1st Yr PhD student Alex Quizon presents modern gastropod clumped isotope calibration data to fellow graduate student. Of all the mollusks that have been calibrated and studied for clumped isotopes, marine gastropods have been largely left out. Preliminary work shows some species may have vital effects, but others do not. Identifying good target species can open up more fossil applications. Nice work Alex!Junior UG Samantha Davies presents her work reconstructing paleo-ocean temperatures at a new KPg boundary section in Mississippi to Professor Jenan Kharbush. She must have impressed Professor Kharbush, because she was chosen as one of the “best undergrad posters”!! We are thrilled that Samantha will be continuing this research at more Gulf Coastal Plain sites as part of her senior thesis research in the SCIPP lab next year. Freshman UG Manmeet Singh presents his work reconstructing paleo-ocean temperatures in the Maastrichtian Gulf Coastal Plain to Iso-Paleo-Lab grad student Nick Ellis (Passey Group). Amazing job Manmeet! 4th year PhD student Jade Zhang presents her work to lab neighbor Cameron Trip (Cole group). Jade is trying to figure out the best sampling and data processing strategy to extract temperature seasonality using D47. She is testing modern bivalves from the Atlantic/Caribbean where true seasonality is known. Then she hopes to apply these methods to fossils from Bermuda from the Last Interglacial to determine past seasonality. Freshman Cecilie Phillips presents her work to an Earth graduate student. Cecilie is working with PhD student Alex Quizon to reconstruct past ocean temperatures and seasonalities up and down the US East Coast during the Last Interglacial. Cecilie analyzed fossil clams of the genus Mercenaria at subannual resolution and found growth shut offs at colder temperatures in the high latitude sites. We are excited that Cecilie will be staying on to work in the SCIPP Lab next year to continue this project!Junior Sabrina Lanker explains her poster to SCIPP Lab grad student Lucas Gomes. Sabrina has been working with PhD student Jade Zhang to look at seasonality in fossil bivalves from Bermuda dating to the Last Interglacial. Nice work Sabrina!1st YR PhD student Lucas Gomes presents his work on climate in the early Pleistocene of Florida. Lucas is using high resolution (subannual) clumped isotope sampling to reconstruct mean annual conditions, and seasonality of temperature and d18Owater from a Plio-Pleistocene section in central Florida. This preliminary data will be leading to new field work in early May to collect more samples from this site. Can’t wait to continue and grow this project!3rd Yr PhD student Allison Curley explains her work on isotopic vital effects in bivalves to Professor Jena Johnson. Allison is studying mechanisms that produce different isotopic signatures in bivalve shells and how they can tell us about physiology, potentially in extinct taxa! Can’t wait to see this work published (soon!). Nice job Allison. SCIPP Lab represents! Left to right: Professor Sierra Petersen, Manmeet Singh (fr), Samantha Davies (soph/jr), Allison Curley (3rd yr PhD), Cecilie Philips (fr), Lucas Gomes (1st yr PhD), Sabrina Lanker (jr), Jade Zhang (4th yr PhD). Not pictured: Alex Quizon (1st yr PhD). So proud of the awesome SCIPP Lab representation!! You guys did great!And a silly one too 🙂
Photo credit for all photos (except the selfie) goes to MGU Photographer and Earth PhD student, Mike Machesky.
SCIPP Lab members Jade Zhang, Lucas Gomes, and Alex Quizon set out on a week of field work with UM Alum and SCIPP group collaborator Dr. Ian Winkelstern and two of his students from Grand Valley State University. The group is hoping to collect Pleistocene and Pliocene marine mollusks from the US East Coast. Good luck!
Despite setbacks due to COVID, our very own Heidi O’Hora submitted her masters thesis this week to graduate end-of-summer, and then turned around and submitted her manuscript to a top-tier journal for peer review and (hopefully) eventual publication in the scientific literature. Congratulations Heidi, you did it! We are so proud of the progress you’ve made over the past 2 years, especially considering it was such an unusual time.
Heidi’s thesis project involved reconstructing Late Cretaceous ocean temperatures in the modern-day region of Maastricht, the Netherlands. Her samples come from the type section of the Maastrichtian (ENCI quarry) among other locations. She found that temperatures in that area were much warmer than they are today (as expected for the greenhouse world of the Cretaceous) and that interactions between different water masses had a strong control on local ocean temperature and salinity.
Sliced Cittarium pica, showing location of high resolution d18Ocarb drilling (green) and seasonally-targetted D47 drilling (red)
Jade’s first paper is now published in the journal Paleooceanography and Paleoclimatology. Congrats Jade! In this work, Jade analyzed fossil shells of the species Cittarium pica, a large gastropod known as the Indian Top Shell. She sampled these shells along their spiral growth direction to reconstruct ocean temperatures and oxygen isotopic compositions (seawater d18O) throughout a few years of their lifetime. These shells date from the Last Interglacial (LIG) interval (~125,000 years ago), a period when global climate was 1-2 degrees warmer and sea levels were 6-9m higher. Despite overall global warmth, we found Bermuda was actually slightly cooler during the LIG, consistent with other records from the region. We also found unexpectedly high variability in d18Oseawater, which we linked to freshwater discharge from an underground aquifer into the near coastal areas.
SCIPP Lab is excited to announce that Sierra has been selected as a 2021 Sloan Research Fellowship.
Paraphrasing from the Sloan website…
The Sloan Research Fellowship seeks to stimulate fundamental research by early-career scientists and scholars of outstanding promise. These two-year, $75,000 fellowships are awarded yearly to 128 researchers in recognition of distinguished performance and a unique potential to make substantial contributions to their field. Their achievements and potential place them among the next generation of scientific leaders in the U.S. and Canada.
Sierra plans to use the funds to push forward our paleo-seasonality projects in the Pliocene and elsewhere.
