11:30 AM - 11:45 AM
[MTT42-09] Towards quantitative evaluation of the chondritic Earth model: A combined geo-neutrino, -physics, and -chemistry study
Keywords:geoneutrino, chondritic Earth, crustal modeling
Towards quantitative evaluation of the chondritic Earth model, we have conducted a combined geo-neutrino, -physics, and -chemistry study. We first developed a methodological framework to construct a 3-D crustal composition model by combining geological, seismic, and geochemical data (Takeuchi et al., 2019 PEPI). In this method, we utilized the Bayesian inference technique to model the 3-D lithology map by combining seismic data as “observation” with a prior model based on a geologic map of local deep crustal exposure. Besides, we constructed U and Th abundance distribution models for different rock types based on published geochemical data for rock samples. We adopted the gamma distribution for the elemental abundance modeling, whereas previous studies adopted normal and log-normal distributions. Importantly, the gamma distribution modeling allows to estimate the unbiased mean from rock sample data that could be distorted due to detection limit and outliers. This point is crucial but often overlooked in mass balance calculations of geochemistry and geophysics, as detailed in a companion presentation by Enomoto et al. By convolving the 3-D lithology model with the rock U and Th distribution models, we constructed 3-D probability density function (PDF) models of U and Th abundances in the Japan Arc crust, and then calculated crustal geoneutrino flux. This new methodology enables constructing a fully probabilistic flux model, but the uncertainties are large at ~70%. This is due to the difficulty in handling of correlations among all the PDFs at different locations in the flux integration: We conservatively assumed maximum correlations, leading to the large uncertainties. An investigation into the correlations is in progress. In this presentation, we report the current status and prospects of our interdisciplinary study.