Research

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Publications

(Orcid: 0000-0001-6084-6858)

[6] Katz, S.A., Levin, N.E., Abbott, M.B., Rodbell, D.T., Passey, B.H., Katz, S.A. (2025) "Orbital forcing drives both the South American monsoon and local water balance in the central Andes during interglacials." Geophysical Research Letters, 52 (10.1029/2025GL116249).

Associated Data: All data: https://doi.org/10.7302/wzbz-v060

Clumped and triple oxygen isotope data : https://doi.org/10.60520/IEDA/113718

[5] Katz, S.A., Levin, N.E, Abbott, M.B, Rodbell, D.T., Passey, B.H., DeLuca, N.M., Larsen, D.J., Woods, A. (2024) “Holocene temperature and water stress in the Peruvian Andes: insights from lake carbonate clumped and triple oxygen isotopes.” Paleoceanography and Paleoclimatology, 39 (10.1029/2023PA004827).

Associated Data: All data: https://doi.org/10.7302/ct1w-sm35

Clumped and triple oxygen isotope data: https://doi.org/10.60520/IEDA/113158

Code: https://doi.org/10.5281/zenodo.10869051

[4] Katz, S.A. (2024) “Andean interglacial climate and hydrology over the last 650,000 years,” PhD Thesis, University of Michigan (https://dx.doi.org/10.7302/22975).

[3] Katz, S.A., Levin, N.E, Rodbell, D.T., Gillikin D.P., Aron, P.G., Passey, B.H., Tapia, P.M., Serrepe, A.R., and Abbott, M.B. (2023) “Detecting hydrologic distinctions among Andean lakes using clumped and triple oxygen isotopes” Earth and Planetary Science Letters, Vol 602 (doi.org/10.1016/j.epsl.2022.117927).

[2] Rodbell, D.T., Hatfield, R.G., Abbott, M.B., Chen, C.Y., Woods, A., Stoner, J.S., McGee, D., Tapia, P.M., Bush, M., Valero-Garcés, B.L., Lehmann, S.B., Mark, S.Z., Weidhaas, N.C., Hillman, A.L., Larsen, D.J., Delgado, G., Katz, S.A., Solada, K.E., Morey, A.E., Finkenbinder, M., Valencia, B., Rozas-Davila, A., Wattrus, N., Coleman, S.M., Bustamante, M.G., Kück, J., and Pierdominici, S. (2022) “700,000 years of tropical Andean glaciation,” Nature, Vol 607 (doi.org/10.1038/s41586-022-04873-0). My contribution to this work was primarily in the form of performing sedimentological and isotopic analyses.

[1] Bernasconi, S., Daëron, M., Bergmann, K.D., Bonifacie, M., Meckler, A.N., Affek, H.P., Anderson, N., Bajnai, D., Barkan, E., Beverly, E., Blamart, D., Burgener, L., Calmels, D., Chaduteau, C., Clog, M., Davidheiser-Kroll, B., Davies, A., Dux, F., Eiler, J., Elliott, B., Fetrow, A.C., Fiebig, J., Goldberg, S., Hermoso, M., Huntington, K.W., Hyland, E., Ingalls, M., Jaggi, M., John, C.M., Jost, A.B., Katz, S., Kelson, J., Kluge, T., Kocken, I.J., Laskar, A., Leutert, T.J., Liang, D., Lucarelli, J., Mackey, T.J., Mangenot, X., Meinicke, N., Modestou, S.E., Müller, I.A., Murray, S., Neary, A., Packard, N., Passey, B.H., Pelletier, E., Petersen, S., Piasecki, A., Schauer, A., Snell, K.E., Swart, P.K., Tripati, A., Upadhyay, D., Vennemann, T., Winkelstern, I., Yarian, D., Yoshida, N., Zhang, N., and Ziegler, M. (2021) “InterCarb: A community effort to improve inter-laboratory standardization of the carbonate clumped isotope thermometer using carbonate standards,” Geochemistry, Geophysics, Geosystems, Vol 2, Issue 5 (doi.org/10.1029/2020GC009588). My contribution to this work was primarily in the form of performing isotopic analyses.

~~~~~

in review

Katz, S.A., Bertacchi, A., Yarian, D.A., Wostbrock, J.A.G., "Triple oxygen and carbon isotope effects of chemical pretreatments on biominerals." Submitted Dec. 2025.

Invited Talks & Presentations

American Geophysical Union, AGU (December 2024) Orbital-pacing of South American Monsoon Strength and Regional Water Balance: New Evidence from Triple Oxygen Isotopes. Invited contribution for GC044 - Climate change, variability, and impacts in South America.

Colgate University, (September 2023) Andean interglacial climate and hydrology over the last 650,000 years. Invited seminar talk for undergraduate audience.

Great Lakes Coordinating Committee, Hydrology Subcommittee, (October 2021) Project Updates: Investigating Uncertainty Associated with the Great Lakes Water Balance. USACE-funded project update to the Hydrology Subcommittee.

Union College, (October 2020) Reconstructing precipitation δ18O from lacustrine carbonates using δ18O, Δ47, and Δ'17O: a modern case study from Junín, Peru with implications for paleoclimate. Invited seminar talk for undergraduate audience.

Conference proceedings (click to expand)

(2021-present, only; only first-author and research mentor abstracts are shown; see CV for complete list; § = undergraduate student mentee)

2026 (forthcoming)

Northeast Section Meeting of the Geological Society of America (March)

Katz, S.A., Koch, P.L, Yarian, D.A., Wostbrock, J.A.G. "Evidence of Increasing Aridification in the Southern United States since the Last Glacial: Leveraging Advances in Tooth Enamel Triple Oxygen Isotopes and Revisiting Paleontological and Archaeological Collections" [Poster presentation]

Link to abstract

Northeast Section Meeting of the Geological Society of America (March)

Katz, S.A., Levin, N.E., Passey, B.H., Rodbell, D.T., Abbott, M.B., Wostbrock, J.A.G., Smith, B., Rao, A. “Detrital Contributions to Lake Junín (Peru) During Glacial Periods Revealed by Clumped Isotopes: Application of a Two-Point Δ47 Mixing Model to Mixed-Source Carbonate and Implications for Isotope-Based Paleoclimate Reconstructions” [Oral presentation]

Link to abstract

2025

Geological Society of America (GSA) (October)

Katz, S.A., Bertacchi, A., Yarian, D., Wostbrock, J.A.G*."Triple Oxygen and Carbon Isotope Effects of Chemical Pretreatments on Biominerals" [Poster presentation] Link to abstract

*presenting author

2024

American Geophysical Union (AGU) (December)

Katz, S.A., Levin, N.E., Rodbell, D.T., Abbott, M.B., Passey, B.H., Katz, S.A."Orbital-pacing of South American Monsoon Strength and Regional Water Balance: New Evidence from Triple Oxygen Isotopes" [Invited presentation]

International Clumped Isotope Workshop, ICIW9 (August)

Katz, S.A., Levin, N.E., Passey, B.H., Rodbell, D.T., Abbott, M.B., Smith, G., Rao, A. “Application of a Two-Point D47 Mixing Model to Mixed-Source Lacustrine Carbonate and Implications for Isotope-Based Paleoclimate Reconstructions.” [Oral presentation]

Goldschmidt (August)

Katz, S.A., Levin, N.E., Abbott, M.B., Rodbell, D.T., Passey, B.H., Katz, S.A. “Triple oxygen isotopes reveal large, orbitally-paced swings in South American monsoon strength and regional water balance.” Link to abstract [Oral presentation]

2023

Geological Society of America (GSA) (October)

Katz, S.A., Levin, N.E., Abbott, M.B., Rodbell, D.T., Passey, B.H., “Large swings in tropical water balance during a ‘weak’ interglacial (MIS 15) suggest a link to precession-induced monsoon variability.” [Oral presentation]

Michigan Geophysical Union (MGU) Research Symposium, Ann Arbor, MI (April)

Katz, S.A., Levin, N.E., Abbott, M.B., Rodbell, D.T., Passey, B.H., “Andean interglacial climate during MIS‑15 (621–563 ka).” (doi.org/10.7302/7054 ) [Poster presentation]

2022

Michigan Geophysical Union (MGU) Research Symposium, Ann Arbor, MI (April)

Katz, S.A., Levin, N.E., DeLuca, N.M., Passey, B.H., Rodbell, D.T., Abbott, M.B “Temperature and water budget records from Holocene lake carbonates in the Peruvian Andes (Peru).” (doi.org/10.7302/4224) [Oral presentation]

2021

American Geophysical Union (AGU), (December)

Katz, S.A., Levin, N.E., DeLuca, N.M., Passey, B.H., Rodbell, D.T., Abbott, M.B “Holocene temperature and water budget records from the tropical-latitude Andes (11 °S) using clumped isotope (47) and triple oxygen isotope (17O) measurements of lake carbonates from Lake Junín and Laguna Pumacocha, Peru.” GC55C-0430 Link

Michigan Geophysical Union (MGU) Research Symposium, Virtual Conference (April)

Katz, S.A., Passey, B.H., and Levin, N.E., “A simple numerical model to predict the effect of moisture recycling on the triple oxygen isotope (17O) composition of downwind precipitation.” MGU Annual Meeting 2021. (doi.org/10.7302/879)

Michigan Geophysical Union (MGU) Research Symposium, Virtual Conference (April)

§ Andrews, K.S., Katz, S.A., Aron, P.G., Levin, N.E., “Spatial and temporal trends in stable oxygen isotopes of eggshells and waters” MGU Annual Meeting 2021. (doi.org/10.7302/879)

GitHub:

https://github.com/sarahakatz

Yale Postdoctoral Research

Reconstructing terrestrial aridity in northcentral Texas since the Last Glacial with tooth enamel triple oxygen isotopes

In this exciting new work, we are employing triple oxygen isotopes of tooth enamel from fossil localities in northcentral Texas to reconstruct terrestrial hydroclimate, specifically, relative humidity and aridity since before to the LGM. We sampled a variety of taxa that represent end-members in water use strategies, including beavers, mammoths, mastodons, white tailed deer, horses, camelids, and pronghorn.

This work builds upon advances in triple oxygen isotopes, including i) recent compilations of triple oxygen isotopes in modern herbivorous mammals (e.g., Lehmann et al., 2022, GCA), ii) triple oxygen enabled animal body water models (Kohn, 1996, GCA; Passey and Levin, 2021, RiMG; Hu et al., 2023, Chemical Geology). We are in the process of combining our isotopic data with these conceptual frameworks to generate quantitative RH estimates, which will be compared to the TraCE-21k climate model results for this region (He, 2011, PhD thesis).

Click here to read our abstract on this work for Northeast GSA.

Present day aridity index and modern samples analyzed in this work and that of Lehmann et al., 2022, GCA.

White tailed deer tooth from the Dallas, Texas region sampled at the SMU Shuler Museum of Paleontology.

TILDAS instrument used to make carbon and triple oxygen isotope measurements at the Yale DELTA Lab (Wostbrock Lab).

Fossil localities sampled in this work.

Effects of chemical pretreatments on biominerals

Triple oxygen isotope analysis of biominerals (e.g., tooth enamel, eggshell calcite) has rapidly expanded in the past decade. However, despite knowing that common chemical pretreatments can affect sample mineralogy, mineral structure, and carbon and oxygen isotope values, we lack information about the potential effect(s) of chemical pretreatments on biomineral triple oxygen isotope values. In this work, we applied common chemical pretreatments to a suite of modern and fossil biomineral samples to provide researchers within important and timely information about pretreatment effects on sample mineral structure and isotope values. This work is currently in review at Chemical Geology.

Michigan Postdoctoral Research

Example mixing model between authigenic and detrital carbonate in the Junin catchment (blue curve). A glacial sample with a clumped isotope temperature of 40C is projected onto the mixing model (orange square) to establish a detrital estimate.

In addition to preparing my final dissertation chapter for publication, my work on the Lake Junin core is continuing through a few new projects as a University of Michigan postdoc.

A new project that I am especially excited about establishes a framework for using clumped isotopes to screen lake sediment samples for detrital carbonate, using samples from the Junin core as a case study. High concentrations of clastic material within the the glacial intervals has inhibited prior carbonate isotope analysis, but I show that clumped isotope data and mixing models have the potential to improve the accuracy of paleoclimate interpretations during these intervals.

PhD Dissertation Chapters

Chapter 1 Detecting hydrologic distinctions among Andean lakes using clumped and triple oxygen isotopes

In this chapter, I analyzed triple oxygen isotopes and clumped isotopes from modern surface waters and lacustrine carbonates from four lakes. We show that clumped isotopes track environmental temperatures and triple oxygen isotopes track hydrology (i.e., evaporation) in each lake. Furthermore, the combination of clumped and triple oxygen isotopes allows us to faithfully reconstruct local precipitation δ18O from carbonates formed from evaporated lake waters. This modern calibration study provides critical context for burgeoning triple oxygen isotope paleoclimate work in lake systems.

Publication: doi.org/10.1016/j.epsl.2022.117927

AGU 2020 Abstract

Fieldwork in the Lake Junin Region, Peru, 2019

Chapter 2 Holocene temperature and water stress in the Peruvian Andes: insights from lake carbonate clumped and triple oxygen isotopes

Global climate during the Holocene is considered to have been relatively stable compared to the late Pleistocene. However, evidence from lacustrine records in South America suggests the tropical latitudes experienced significant water balance variability during the Holocene, rather than quiescence. In this study, we use clumped and triple oxygen isotopes to develop Holocene temperature and evaporation records from Lakes Junín, Pumacocha, and Mehcocha to build a more complete picture of paleo-hydroclimate, specifically changes in water balance (P–E), in this region.

Publication: 10.1029/2023PA004827

AGU 2021 Abstract

Selected Holocene climate records from South America.

Chapter 3

Core image credit: Junin working group

Orbital forcing drives both the South American monsoon and local water balance in the central Andes during interglacials

South American summer monsoon (SASM) strength tracks insolation on orbital timescales, linking global climate and continental hydrology. However, whether local water availability also responds to global climate forcings is unclear. Here, we present water balance records from Lake Junín, an Andean lake within the SASM domain. Local water balance and SASM strength is inferred from triple oxygen isotopes of lake carbonates during two interglacial periods (MIS 15, 621–563 ka; the Holocene, 11.7–0 ka). We find SASM strength and water balance both follow the precession-pacing of local summer insolation, with the driest conditions occurring at Lake Junín under weakened SASM (and vice versa). Further, the largest variations occur during MIS 15, when insolation was more variable than the Holocene. These results suggest that global climate influences South American hydrology on both the local and continental scales, with implications for tropical water resources, the atmospheric greenhouse effect, and ecosystem dynamics.

Publication DOI: 10.1029/2025GL116249

DOIs for supplemental data available: 10.7302/wzbz-v060 (all data; University of Michigan Deep Blue Repository) and 10.60520/IEDA/113718 (clumped and triple oxygen isotope data; Earth Chem Repository)

Other projects

Investigating Uncertainty Associated with the Great Lakes Water Balance

Fall 2022 | Supervisor: Drew Gronewold (UM SEAS)

I worked on developing code to incorporate Stage Fall Discharge equations into the Large Lakes Statistical Water Balance Model (L2SWBM), a Bayesian water balance model of the Laurentian Great Lakes. We expect that this will reduce uncertainties in flow estimates for both the St. Clair and Detroit Rivers.

Project funding to Drew Gronewold from the US Army Corps of Engineers.

Pictured: A channel flow measurement station at the US ACE lab in Ft. Wayne, Detroit, USA (SK, 2021).

Link to Drew's projects page

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