[S-CG52] Inter-segment Tectonics: Interdisciplinary Research on Responses to Plate Subduction

[SCG52-03] Influence of subducting fracture zones on arc volcanism

*Valerie Vidal¹, Claudia Maria Adam², Pablo Grosse³, Pamela Kempton², Mie Ichihara⁴ (1.Laboratoire de Physique, Ecole Normale Supérieure de Lyon - CNRS (France), 2.Department of Geology, Kansas State University, Manhattan, KS (USA), 3.CONICET and Fundación Miguel Lillo, Tucumán (Argentina), 4.Earthquake Research Institute, University of Tokyo (Japan))

Keywords:fracture zones, subduction, arc volcanism

The subduction of linear oceanic features plays a major role in the variation of the volume of arc volcanism along the Pacific ring of fire [Adam et al., 2022]. However, if the subduction of volcanic ridges or active mid-oceanic ridges has a clear effect on promoting or inhibiting melt, the impact of fracture zone subduction still remains unclear. As oceanic fracture zones are associated with topographic offsets, they may promote seawater infiltration and, consequently, the hydrothermal alteration of peridotites into serpentinites. Water-rich serpentinite could increase the volume of slab-derived fluids, thus affecting the melt under arc volcanoes and enhance volcanism. This explanation has been proposed by Manea et al. [2014], based on an apparent correlation between an increase in fluid-mobile element geochemistry (in particular the ratio B/Zr) and the alignment of the corresponding arc volcano with a subducting fracture zone. However, the scarcity of the data and the lack of statistical analysis raise questions on the robustness of this interpretation. This work proposes a thorough analysis of the impact of fracture zone subduction on arc volcanism all around the Pacific ring of fire. We combine multidisciplinary and complementary datasets, including a complete fracture zone database [Wessel et al., 2015], bathymetry and volcano morphometry, together with the integration of geochemical data. In the same way as Adam et al. [2022], we account for the geometrical correction of subducting feature trajectory due to the local slab dip angle. The first results show no evidence of arc volcanism enhancement, in contradiction with previous studies (e.g. Manea et al. [2014]). These results highlight the importance of the integration of multidisciplinary datasets and statistical analyses, and further question the role of fracture zones subduction on arc volcanism.

References
--------------------------------------------
Adam, C., Vidal, V., Grosse, P. & Ichihara, M. (2022). Correlations between subduction of linear oceanic features and arc volcanism volume around the Pacific basin. Geochemistry, Geophysics, Geosystems, 23, e2022GC010553.

Manea, V. C., Leeman, W. P., Gerya, T., Manea, M. & Zhu, G. (2014). Subduction of fracture zones controls mantle melting and geochemical signature above slabs. Nature Communications, 5(1), 5095.

Wessel, P., K. J. Matthews, R. D. Müller, A. Mazzoni, J. M. Whittaker, R. Myhill & M. T. Chandler (2015), Semiautomatic fracture zone tracking, Geochem. Geophys. Geosyst., 16, 2462– 2472.