3D-time slab deconstruction and ore deposit localization in South America

This is the authors' abstract. We don't add key points for this paper.

Here we present a 3D-time reconstruction of the tectonic evolution of the Nazca and South American plates. The geometry of subducted slabs was modelled down to a depth of ~1950km using UU-P07 global tomographic model. Our approach integrated geochronological records, geological history, and seismotectonic data. Furthermore, our proposed slab models incorporated both velocity and temperature gradients to determine the mid-slab surface accurately. To reconstruct these slabs with minimal distortion back to the Earth's surface, we employed a reverse engineering method. The positions of potential tears in the subducted slabs can then be recognized by the induced distortions. We identified at least three down-dip tears, which significantly influence subduction behaviour. We then integrated the floated or pre-subducted slabs into a 2D-time tectonic reconstruction and tracked the subduction interface over time. Our reconstruction reveals that the pre-subducted slabs accurately mimic the shape of the Andes during the Oligocene-Miocene boundary. However, the remnants of slabs subducted before that time are no longer connected to the entire slab. To the north of the Nazca tear, which coincides spatially with the Nazca fracture zone, the continuous slab has subducted to a depth of ~1950km. To the south, the downgoing slab has been segmented into three distinct zones, with tears localized along the two arms of the extrapolated Juan de Fernández ridge and the inferred Challenger fracture zone. Moving from north to south, the slab in these zones detached at some point after 22Ma, 15Ma, and 12Ma, respectively. Each slab segment exhibits variations in geometry, with flat slab and steep slab portions, as well as differences in penetration depth. Notably, the location of the Nazca down-dip tear coincides with the initial location of the eastward spanning of the Cu belts.