[S-MP21] Oceanic and Continental Subduction Processes: petrologic and geochemical perspective

[SMP21-05] Subduction thermal state, slab metamorphism and seismicity in Makran subduction zone

*Haris Faheem¹, Yingfeng Yi¹, Weiling Zhu¹, Rui Qu¹, Ye Zhu¹, Shoichi Yoshioka² (1.State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China., 2.Research Center for Urban Safety and Security, Kobe University, Kobe, Japan ,Department of Planetology, Graduate School of Science, Kobe University, Kobe, Japan)

Keywords:thermal regime, slab dehydration, earthquake, 3-D model, Makran

The dependence of the subduction regime on 3D slab geometry poses a challenge to achieving an accurate estimation of the evolving thermal structure of megathrusts globally. While slab dips and ages have gained attention, the specific impacts under oblique subduction remain unmeasured. Here we present an integrated thermal model that quantifies how slab morphology can shape the thermal state of megathrusts such as that in the Makran subduction zone. The model considers both slab obliquity and depth variations along the trench. We find a considerable match between the slab petrological dehydration zone and the distribution of historic great interplate earthquakes. We suggest that the accumulation of fluids along the megathrusts by slab metamorphism can foster a more polarized circumstance for the decrease of plate coupling and increased interplate ruptures. It is thus imperative to improve model representation and more realistically represent how slab geometry drivers affect metamorphic transitions and earthquake occurrence at megathrusts.