Category: Clumped

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New Paper Update: Clumped Isotope Review Article

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!

LINK TO PAPER: https://www.annualreviews.org/doi/abs/10.1146/annurev-earth-031621-085949

LINK TO STUDENT COMPANION: https://www.annualreviews.org/doi/suppl/10.1146/annurev-earth-031621-085949

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New Paper Update: Clumped isotope sclerochronology – a trade off between sampling resolution, precision, and growth rate

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.

LINK TO PAPER: https://www.sciencedirect.com/science/article/pii/S0009254123000463

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New Paper Update: Tropically Hot Cenomanian temperatures in the Western Interior Seaway

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 study

Shell cross section, showing growth banding (and some calcite veins).

LINK TO PAPER: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G49998.1/613546/A-tropically-hot-mid-Cretaceous-North-American

LINK TO UM PRESS RELEASE: https://news.umich.edu/bali-like-temperatures-in-wyoming-fossils-reveal-tropically-hot-north-america-95-million-years-ago/

LINKS TO OTHER PRESS: Futurity article, Science Daily article,

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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!

LINK TO PAPER: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G49634.1/612992/Looking-upstream-with-clumped-and-triple-oxygen

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New Paper Update: Subannual D47 reconstructs Last Interglacial climate and d18Owater variability in Bermuda

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.

LINK TO PAPER: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020PA004145

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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

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New Paper Update: Community-Wide Clumped Calibration Efforts

Sierra wrapped up a community-wide effort to reprocess and update clumped isotope calibration data from 11 different laboratories, including over 1200 individual replicates, to bring it into the same framework. This involved updating the fundamental parameters R13_VPDB, R17_VSMOW, R18_VSMOW, and λ used to calculate raw D47, using a consistent and updated set of theoretical equilibrium values (D47_TE) to tie things into the absolute reference frame, and applying a single set of acid fractionation factors (D*90-25) across all studies. We found that agreement is quite good between labs, once all the data processing is done uniformly and the “two-slope” or “multi-slope” problem that plagued the clumped community in the early days has all but disappeared in more recent studies.

Link to paper here

 

As part of this effort, we also developed a data template and began a relationship with the EarthChem database to house future clumped isotope datasets in a long-term storage location. For more information on that, see this page.