121-9 Quantifying Cave-Internal Alterations in Speleothems using Triple Oxygen Isotopes

Session: Caves and Karst Through Space and Time: Biogeochemistry, Climate, and Astrobiology

Presenting Author:

Annabel Wolf

Authors:

Wolf, Annabel¹, Cole, Julia E.², Allen, Matthew L.³, Geng, Jie⁴, Langston, Jada⁵, Passey, Benjamin H.⁶, Patterson, Elizabeth W.⁷, Baker, Jonathan L.⁸, Johnson, Kathleen R.⁹, McGee, David¹⁰, Griffiths, Michael¹¹

(1) University of Michigan, Ann Arbor, MI, USA, (2) University of Michigan, Ann Arbor, USA, (3) University of Michigan, Ypsilanti, MI, USA, (4) University of Michigan, Ann Arbor, MI, USA, (5) University of Michigan, Ann Arbor, MI, USA, (6) University of MichiganEarth and Environmental Sciences, Ann Arbor, MI, USA, (7) Lafayette College, Pennsylvania, USA, (8) University of Innsbruck, Innsbruck, Austria, (9) UC Irvine, Dept. of Earth System Science, Irvine, CA, USA, (10) MIT, Earth, Atmos. and Planetary Sciences, Cambridge, MA, USA, (11) William Paterson University, Environmental Science, Wayne, NU, USA,

Abstract:

Monsoons consist of local hydrology and large-scale monsoonal circulation, which can vary independently. This is a challenge for paleo-monsoon reconstructions, requiring careful consideration of various proxies. While stable oxygen isotopes (δ¹⁸O) in carbonates serve as one of the primary proxies for reconstructing large-scale monsoon circulation, they can be influenced by cave-internal processes, creating a bias towards local hydrological conditions. Current methods cannot separate the large-scale climate signal from localized (cave-specific) influences. This creates unexplained between-site discrepancies and leaves large uncertainties in our understanding of past climate variability. Theoretical frameworks suggest that triple oxygen isotopes (Δ'¹⁷O) can be used as a new tool to quantify nonclimatic cave-internal effects on δ¹⁸O. To evaluate the effects of strong cave-internal alterations on Δ'¹⁷O, we are using an ideal set of samples that have previously been interpreted as having altered δ¹⁸O. Although more data are needed, preliminary results suggest a positive slope caused by cave-internal processes, such as prior carbonate precipitation and/or degassing, consistent with model predictions. Triple oxygen isotopes will provide new insights into speleothem oxygen isotopes, improving our interpretation of past climate conditions. This is a crucial step in for our understanding of past climate variability, especially in monsoonal regions, where speleothems are commonly used.

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

doi: 10.1130/abs/2025AM-10021

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