75-36 Machine Learning Algorithms Successfully Predict Mantle Reservoirs of Basalts Using Trace Elements as Proxies for Isotopic Data

Session: Mineralogy, Geochemistry, Petrology, and Volcanology Student Session (Posters)

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Abstract:

Identifying mantle reservoirs is fundamental to understanding mantle evolution and heterogeneity as well as the origin of Mid-Ocean Ridge Basalts (MORBs) and Ocean Island Basalts (OIBs).  The most effective tracers of mantle reservoirs are isotopic ratios, which are minimally fractionated during melting and resistant to alteration.  However, isotopic analyses are costly. Bivariate plots of trace elements (TE) and their ratios have also been used as mantle reservoir signatures, but are more susceptible to fractionation and alteration, limiting their diagnostic power compared to isotopes. This study aims to classify mantle reservoirs using machine learning (ML) with TE data alone, reducing the need for costly isotopic data and overcoming the limitations of bivariate TE plots. We compiled global geochemical data from MORBs and OIBs representing four mantle reservoirs: Depleted Mantle (DM or DMM), Enriched Mantle 1 (EM1), Enriched Mantle 2 (EM2), and HIMU (high μ or high time-integrated ²³⁸U/²⁰⁴Pb). Using the H2O package in Python for automated ML (AutoML), we trained supervised algorithms to classify basalts into these reservoir types based on TE input variables. The best H2O model, a Stacked Ensemble, achieved classification accuracy of 72% for all test locations and 84% for typical locations, demonstrating that TEs can effectively serve as isotopic proxies and distinguish between different mantle reservoirs. We repeated this process using an expanded HIMU class in the training data, in order to improve classification performance on the minority class.  We developed two open-source classification tools, both Stacked Ensemble models: one classifier for all four mantle reservoirs and one optimized for the minority HIMU class. To our knowledge, this is the first ML classification tool that identifies mantle reservoirs using only TE data, offering a robust and cost-effective alternative to isotopic methods.

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

doi: 10.1130/abs/2025AM-10405

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