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A Reference Earth Model for the Heat Producing Elements and Associated Geoneutrino Flux

Y. Huang1, V. Chubakov2, F. Mantovani2, R. L. Rudnick1, and W. F. Mcdonough1
1University of Maryland, College Park, MD 20742, USA
2Università degli Studi di Ferrara/ INFN, Ferrara, Italy

Geoneutrinos are electron antineutrinos emitted by beta-minus decays of naturally occurring radionuclides (e.g., heat producing element (HPEs), namely U, Th and K). The recent geoneutrino experimental results from KamLAND [1] and Borexino [2] detectors reveal the usefulness of analyzing the Earth’s geoneutrino flux, as it provides a constraint on the strength of the radiogenic heat power and this, in turn, provides a test of compositional models of the bulk silicate Earth (BSE). This flux is dependent on the amount and distribution of HPEs in the Earth’s interior.

We have developed a geophysically-based, three-dimensional global reference model for the abundances and distributions of HPEs in the BSE [3]. The structure and composition of the outermost portion of the Earth, the crust and underlying lithospheric mantle, is detailed in the reference model, this portion of the Earth has the greatest influence on the geoneutrino fluxes. The reference model combines three existing geophysical models of the global crust and yields an average crustal thickness of 34.4±4.1 km in the continents and 8.0±2.7 km in the oceans, and the total mass (in 1022 kg) of oceanic, continental and bulk crust is 0.67±0.23, 2.06±0.25 and 2.73±0.48, respectively. In situ seismic velocity provided by CRUST 2.0 allows estimates of the average composition of the deep continental crust by using new and updated compositional databases for amphibolite and granulite facies rocks, in combination with laboratory ultrasonic velocities measurements. An updated xenolithic peridotite database is used to represent the average composition of continental lithospheric mantle. Monte Carlo simulation is used to predict the geoneutrino flux at selected locations and to track the asymmetrical uncertainties of radiogenic heat power due to the log-normal distributions of HPE concentrations in crustal rocks.

AAPG Search and Discovery Article #90182©2013 AAPG/SEG Student Expo, Houston, Texas, September 16-17, 2013