Effect of tectonic processes on biosphere-geosphere feedbacks across a convergent margin

Fullerton, Katherine M.
Schrenk, Matthew O.
Yücel, Mustafa
Manini, Elena
Basili, Marco
Rogers, Timothy J.
Fattorini, Daniele
Di Carlo, Marta
D'Errico, Giuseppe
Regoli, Francesco
Nakagawa, Mayuko
Vetriani, Costantino
Smedile, Francesco
Ramirez, Carlos
Miller, Heather
Morrison, Shaunna M.
Buongiorno, Joy
Jessen, Gerdhard L.
Steen, Andrew D.
Martinez, Maria
de Moor, J. Maarten
Barry, Peter H.
Giovannelli, Donato
Lloyd, Karen G.
The subsurface is among Earth's largest biomes, but the extent to which microbial communities vary across tectonic plate boundaries or interact with subduction-scale geological processes remains unknown. Here we compare bacterial community composition with deep-subsurface geochemistry from 21 hot springs across the Costa Rican convergent margin. We find that cation and anion compositions of the springs reflect the dip angle and position of the underlying tectonic structure and also correlate with the bacterial community. Co-occurring microbial cliques related to cultured chemolithoautotrophs that use the reverse tricarboxylic acid cycle (rTCA) as well as abundances of metagenomic rTCA genes correlate with concentrations of slab-volatilized carbon. This, combined with carbon isotope evidence, suggests that fixation of slab-derived CO2 into biomass may support a chemolithoautotrophy-based subsurface ecosystem. We calculate that this forearc subsurface biosphere could sequester 1.4 x 10(9) to 1.4 x 10(10) mol of carbon per year, which would decrease estimates of the total carbon delivered to the mantle by 2 to 22%. Based on the observed correlations, we suggest that distribution and composition of the subsurface bacterial community are probably affected by deep tectonic processes across the Costa Rican convergent margin and that, by sequestering carbon volatilized during subduction, these chemolithoautotrophic communities could in turn impact the geosphere.
Citation Formats
K. M. Fullerton et al., “Effect of tectonic processes on biosphere-geosphere feedbacks across a convergent margin,” pp. 0–0, 2021, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/90708.