Influence of lower crustal rheology on orogenic growth modes

Collisional systems mark the end of a Wilson cycle, where after a period of oceanic subduction two continental plates collide. In response to intense crustal deformation, high topographic features are developed and orogens are formed. Orogens can display multiple architectonic styles, shifting between compressional/extensional episodes and transitioning from wedges to plateaus. The large-scale processes that control different orogenic growth modes are greatly influenced by lower crustal rheology, which can enable and promote switches in tectonic modes and allow orogenic plateaus to be formed.In the present study we use geodynamic numerical modelling to investigate the control of lower crustal rheology in different orogenic growth processes, using the geodynamic code LaMEM (Kaus et al., 2016) to perform high-resolution (512 x 128 x 256) 3D buoyancy-driven models. For realistic density variations, we couple LaMEM with the thermodynamic code MAGEMin (Riel et al., 2022). Using this modelling setup, we specifically assess the role of different continental crust rheological configurations in determining the dynamic feedbacks that control orogenic growth and architecture (for ca. 50 Myr).Here, we obtain the P-T-t paths in our models and compare them to those recorded in different natural orogenic settings. We attempt to establish a correlation between different orogenic growth modes and natural analogues that record similar burial and exhumation patterns. In this sense, we seek to constrain which geodynamic scenarios can better produce the P-T-t paths observed in natural orogenic settings.References:Kaus, B., et al., 2016. Forward and inverse modelling of lithospheric deformation on geological timescales. In: Proceedings of the NIC Symposium, (John von Neumann Institute for Computing (NIC), NIC Series vol. 48.Riel, N., Kaus, B. J. P., Green, E. C. R., & Berlie, N. (2022). MAGEMin, an Efficient Gibbs Energy Minimizer: Application to Igneous Systems. Geochemistry, Geophysics, Geosystems, 23(7). https://doi.org/10.1029/2022GC010427 This work is supported by FCT, I.P./MCTES through national funds (PIDDAC): LA/P/0068/2020 - https://doi.org/10.54499/LA/P/0068/2020 , UID/50019/2025, https://doi.org/10.54499/UID/PRR/50019/2025, UID/PRR2/50019/2025