137-1 Donath Medal | Young Scientist Award: When and How Does Soil Carbonate Form? Using Clumped and Triple Oxygen Isotopes to Decode Terrestrial Paleoclimate Archives

Session: Joint SGD-SEPM-IAS Focus on the Sedimentary Record of Climate Change

Presenting Author:

Author:

Abstract:

Soil carbonates provide a valuable record of terrestrial response to (paleo-)climate change. However, our ability to fully leverage their carbon and oxygen stable isotope records to reconstruct terrestrial paleoclimate hinges upon understanding the proxy: when and how do soil carbonates form? Clumped and triple oxygen isotopes are providing new insights. Clumped isotopes constrain growth temperatures, giving the "when." I will discuss the emerging consensus that soil carbonates typically form in the warm season, with significant aberrations best explained by soil grain size and rainfall patterns. The clumped isotope evidence suggests that the timing of soil carbonate formation is set by soil drying and provides a means to predict seasonal bias in paleosols. We are probing the "how" with triple oxygen isotopes. Triple oxygen isotopes record the evaporative state of soil water when carbonate forms and thus constrain the relative importance of evaporative drying versus biological factors (transpiration, respiration) in driving soil carbonate formation. I will describe results of a recent study in dryland critical zones that tests the soil-drying-paradigm in pedogenic carbonates and their parent waters. These geochemical tools were initially developed for paleoclimate but are yielding new insights into modern process, which is in turn enhancing paleoclimatic interpretations.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-5805

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.