Publications

Peer-reviewed published articles

Ahm, Anne-Sofie C, Fralick, Philip; Higgins, John, 2026. As it ever was: Calcium isotope constraints on Mesoarchean seawater chemistry. Geology, 54, 195–199 https://doi.org/10.1130/G53945.1

Farrell, Ú. C., Olson, H. C., Thompson, M. O., Abshire, M. L., Adeboye, O. O., Ahm, A.-S. C., et al., 2026. The Sedimentary Geochemistry and Paleoenvironments Project Phase 2 data release: An open data resource for the study of Earth’s environmental history. Chemical Geology, 712, 123148. https://doi.org/10.1016/j.chemgeo.2025.123148

Lonsdale, M. C., Ahm, A.-S. C., Nelson, L. L., Thompson, J. W., Higgins, J. A., & Smith, E. F., 2026. Carbon isotope trends of Precambrian–Cambrian carbonates in southwestern Laurentia are robust to diagenetic overprinting. American Journal of Science, 326, Article 4. https://doi.org/10.2475/001c.155346

Ruiz, Daniel G., Goldblatt, Colin, Ahm, Anne-Sofie C., 2025. Chempath 1.0: An open-source pathway analysis program for photochemical models. Geoscientific Model Development, 18, 4433-4454. https://doi.org/10.5194/gmd-18-4433-2025

Nadeau, M. D., Murphy, J. G., Hagen, C. J., Wu, Z., Akhtar, A. A., Ahm, A.-S. C., Stolper, D. A., Maloof, A. C., & Higgins, J. A., 2025. Disentangling global geochemical change from local diagenetic alteration in shallow-water marine carbonates: A case study from OAE1a. Earth and Planetary Science Letters, 666, 119513. https://doi.org/10.1016/j.epsl.2025.119513

Akhtar, A., Ahm, Anne-Sofie C., Higgins, J.A., 2024. Geochemical fingerprints of early diagenesis in shallow-water marine carbonates: insights from paired δ44/40Ca and δ26Mg values. Geochim. Cosmo. Acta. 383, 57-69. https://doi.org/10.1016/j.gca.2024.08.002

Ruiz, Daniel G., Goldblatt, Colin, Ahm, Anne-Sofie C. 2024 Climate variability leads to multiple oxygenation episodes across the Great Oxidation Event. Geophysical Research Letters, 51, e2023GL106694. https://doi.org/10.1029/2023GL106694

Edmonsond, S., Matthew D. Nadeau, Andrew C. Turner, Ziman Wu, Emily C. Geyman, Anne-Sofie C. Ahm, Blake Dyer, Sergey Oleynik, David McGee, Daniel A. Stolper, John A. Higgins, Adam C. Maloof. 2024. Shallow carbonate geochemistry in the Bahamas since the last interglacial period. Earth and Planetary Letters 627, 118566 https://doi.org/10.1016/j.epsl.2023.118566

Ostrander, Chadlin M., Bjerrum, Christian J., Ahm, Anne-Sofie C., Stenger, Simon R., Butterfield, Nicholas J., Grotzinger, John P., El-Ghali, Mohamed, Harthi, Abdul R., Al-Rawahi, Zuwaina, Nielsen, Sune G. Widespread marine anoxia during generation of the Ediacaran Shuram carbon isotope excursion. 2020 Geobiology 21 (5). https://doi.org/10.1111/gbi.12557

Ruiz, Daniel G., Goldblatt, Colin, Ahm, Anne-Sofie C., 2023. Climate shapes the oxygenation of Earth's atmosphere across the Great Oxidation Event Earth and Planetary Science Letters 607. https://doi.org/10.1016/j.epsl.2023.118071

Geyman, Emily C., Wu, Ziman, Nadeau, Matthew D., Edmonsond, Stacey, Turner, Andrew, Purkis, Sam J, Howes, Bolton; Dyer, Blake, Ahm, Anne-Sofie C, Yao, Nan, 2022. The origin of carbonate mud and implications for global climate. PNAS 119, 43. https://doi.org/10.1073/pnas.2210617119 (download pdf)

Murphy, Jack G., Ahm, Anne-Sofie C., Swart, Peter K., Higgins, John A. 2022. Reconstructing the lithium isotopic composition (δ7Li) of seawater from shallow marine carbonate sediments. Geochim. Cosmo. Acta. 337, 140-154. https://doi.org/10.1016/j.gca.2022.09.019 (download pdf)

Bryant, Roger N., Present, Theodore M., Ahm, Anne-Sofie C., McClelland, Harry-Luke O., Razionale, Dan., Blättler, Clara L. 2022. Early diagenetic constraints on Permian seawater chemistry from the Capitan Reef. Geochim. Cosmo. Acta. 328. https://doi.org/10.1016/j.gca.2022.04.027 (download pdf)

Ahm, Anne-Sofie, Husson, Jon, 2022. Local and global controls on carbon isotope chemostratigraphy. Elements in Geochemical Tracers in Earth System Science, Cambridge University Press. https://doi.org/10.1017/9781009028882 (download pdf)

Busch, James F; Hodgin, Eben B; Ahm, Anne-Sofie C; Husson, Jon M; Macdonald, Francis A; Bergmann, Kristin D; Higgins, John A; Strauss, Justin V, 2022. Global and local drivers of the Ediacaran Shuram carbon isotope excursion. EPSL 579, 117368. https://doi.org/10.1016/j.epsl.2022.117368 (download pdf)

Farrell, Úna C. et al. 2021. The sedimentary geochemistry and paleoenvironments project. Geobiology 19, 545-556. https://doi.org/10.1111/gbi.12462 (download pdf)

Ahm, A-S. C., Bjerrum, C.J., Hoffman, P.F., Macdonald, F.A., Maloof, A.C., Rose, C.V., Strauss, J.V., Higgins, J.A. The Ca and Mg isotope record of the Cryogenian Trezona carbon isotope excursion. Earth and Planetary Science Letters V568, 117002, 2021. https://doi.org/10.1016/j.epsl.2021.117002 (download pdf)

Nelson, L. L., Ahm, A-S. C., Macdonald, F. A., Higgins, J. A., Smith, E. F., Fingerprinting local controls on the Neoproterozoic carbon cycle with the isotopic record of Cryogenian carbonates in the Panamint Range, California. Earth and Planetary Science Letters, 566, 116956, 2021. doi.org/10.1016/j.epsl.2021.116956 (download pdf)

Crockford, P.W, Kunzmann, M., Blättler, C.B., Boriana K-A., Murphy, J.G., Ahm, A-S. C., Sharoni, S., Halverson, G.P., Planavsky, N.J., Halvey, I., Higgins, J.A. Reconstructing Neoproterozoic seawater chemistry from early diagenetic dolomite. Geology, v. 49, 2021, doi.org/10.1130/G48213.1 (download pdf)

Bold, U., Ahm, A-S. C., Schrag, D. P., Higgins, J. A., Jamsran, E., Macdonald, F. A., Effect of dolomitization on isotopic records in Neoproterozoic carbonates of southwestern Mongolia. Precambrian Research, 350, 2020, doi.org/10.1016/j.precamres.2020.105902 (download pdf)

Gussone, N., Ahm, A-S. C., Lau, K. V., Bradbury, H. J., Calcium isotopes in deep time: Potential and limitations, Chemical Geology, 544, 2020, doi.org/10.1016/j.chemgeo.2020.119601 (download pdf)

Jones, D. S., Brothers, W. R., Ahm, A-S. C., Slater, N., Higgins, J. A., Fike, D. A., Sea level, carbonate mineralogy, and early diagenesis controlled δ¹³C records in Upper Ordovician carbonates, Geology, 48, 194-199, 2020, doi.org/10.1130/G46861.1 (download pdf)

Crockford, P. W., Wing, B. A., Paytan, A., Hayles, J. A., Middleton, J., Torres, M., Ahm, A-S. C., Caxito, F., Uhlein, G., Halverson, G. P., Horner, T. J., Barium-isotopic constraints on the origin of post-Marinoan barites, Earth and Planetary Science Letters, 519, 234-244, 2019, doi.org/10.1016/j.epsl.2019.05.018 (download pdf)

Ahm, A-S. C., Maloof, A. C., Macdonald, F. A., Hoffman, P. F., Bjerrum C. J., Bold, U., Rose, C. V., Strauss, J. V., Higgins, J. A., An early diagenetic deglacial origin for basal Ediacaran cap dolostones, Earth and Planetary Science Letters, 506C, 292-307, 2019, doi.org/10.1016/j.epsl.2018.10.046 (download pdf)

Ahm, A-S. C., Bjerrum, C. J., Blättler, C. L., Swart, P. K., Higgins, J. A., Quantifying early marine diagenesis in shallow water carbonate sediments, Geochimica et Cosmochimica Acta, 236, 140-159, 2018, doi.org/10.1016/j.gca.2018.02.042 (download pdf)

Higgins, J. A., Blättler, C. L., Lundstrom, E. A., Santiago-Ramos, D. P., Akhtar, A. A., Ahm, A-S. C., Bialik, O., Holmden, C., Bradbury, H., Murray, S. T., Swart, P. K., Mineralogy, early marine diagenesis, and the chemistry of shallow-water carbonate sediments, Geochimica et Cosmochimica Acta, 220, 512-534, 2018, doi.org/10.1016/j.gca.2017.09.046 (download pdf)

Ahm, A-S. C., Bjerrum C. J., Hammarlund, E. U., Disentangling the record of diagenesis, local redox conditions, and global seawater chemistry during the latest Ordovician glaciation, Earth and Planetary Science Letters, 459, 145-156, 2017, doi.org/10.1016/j.epsl.2016.09.049 (download pdf)

Manuscripts in review/pre-prints

Ruiz, D. G., Goldblatt, C., Spence, J., Kurucz, S., Ramsay, B., Fralick, P., & Ahm, A.-S. C. Contradicting redox proxies across the Great Oxidation Event: Insights from iodine and Ce anomalies. Geochimica et Cosmochimica Acta, under revision following review.