How Subduction Evolution and Tectonic Stability Drive Sediment-Hosted Mineralization Along Craton Edges.

This model is based on the plate model by Cao et al. (2024). Relative plate motions are identical, and plate topologies are close to identical, with the exception of a small number of subduction zones that were moved slightly further away from continental outlines to comply with the method described in Müller et al. (2022) to reconstruct the extended outlines of continents in deep time. The mantle reference frame was derived using the optimisation approach as described in Müller et al. (2022). For a given iteration, the approach starts with perturbing an initial absolute Euler rotation (pole latitude, pole longitude and angle magnitude) for a given reference continent or plate, and then calculates a series of fit metrics with selected constraining data using objective (or cost) functions. This process continues until a global minimum is found. We use continental Africa as the reference. We calculate fit metrics computed from evaluating (1) net lithospheric rotation rate (NR), (2) trench migration rate (TM), and (3) the fit of present-day hotspots to the major age-progressive hotspot tracks for the period of 0-80 Ma only (HS). We also compute a fourth constraining criterion: (4) median global continental absolute plate velocity (PV). We introduce continental absolute plate velocities as additional criterion to prevent mean oceanic plate velocities based on synthetic plates from potentially inducing unreasonably high continental speeds globally, as the deep-time reconstructions used here include large swathes of the reconstructed ocean floor that is now subducted, based on a variety of indirect pieces of geological evidence (Merdith et al., 2021). The constraining criteria are applied to the absolute plate motion model optimization with the following assumptions/bounds: (1) rates of net lithospheric rotation (NR) are minimized but non-zero, (2) global trench migration velocities are minimized, favouring trench retreat over trench advance, (3) spatio-temporal misfit between plate motion model and present-day hotspot chains is minimized, and (4) global continental median plate speed remains < 60 mm/yr. The contribution of individual optimization parameters to the overall inversion are initially scaled by relative magnitude and then weighted by empirically determined weights. For times older than 80 Ma, NR=1, TM=0.5, PV=0.5, HS=0 (0-80 Ma, NR=TM=PV=HS=1. To estimate the original boundaries of preserved outlines of continents reconstructed to their past positions given a rotation model we apply a continent contouring algorithm to create continental outlines, using the code in this github repository: https://github.com/EarthByte/continent-contouring. The algorithm is based on marching squares, a 2D adaptation of the Marching Cubes algorithm applied to the surface of a sphere. The continental outlines are expanded by a user-specified buffer distance.