The Role of Lithospheric-Deep Mantle Interactions in the Evolution and Subduction Dynamics of Arc-Continent Collision settings
No Preview Available
Citations
Altmetric:
Altmetric::
Download
Associated Records
File Licence
Editors
Date
2023-03
Source Title
Journal Title
Journal ISSN
Volume Title
Publisher
Melbourne Authors
Affiliation
School of Geography, Earth and Atmospheric Sciences
Document Type
PhD thesis
Subject Code
Citation
Access Status
Open Access
DOI
Access URL
Open Access URL
Open Access at PMC
Linked Resource URL
NHMRC Grant Code
ARC Grant Code
Description
© 2023 ANDRES FELIPE RODRIGUEZ CORCHO
Abstract
Arc-continent collision is the fundamental process that controls the growth of the continental crust and allows the preservation of critical minerals and energy resources. Conceptual models of arc-continent collision show that collision causes orogenic growth and basin formation, which often occur simultaneously. However, these conceptual models account for the processes occurring on the crust-lithosphere, and not the interactions between the lithosphere and the mantle, hereafter called lithospheric-deep mantle interactions. This thesis aims to understand the effect of lithospheric-deep mantle interactions in the evolution of arc-continent collision by using numerical modelling. The mechanical models presented here explore the effect of material properties such as density/rheology, and geometric boundary conditions, such as angle of collision, in the stress evolution, the mantle flow, and the topography evolution of arc-continent collisional orogens and their associated sedimentary basins. To gain this theoretical insight, I use numerical models of subduction in both two and three dimensions, which couple the dynamics of the lithosphere and the mantle with the landscape evolution at the surface. Modelling results show that a buoyancy contrast of 3% between the arc and the margin controls the style of collision, and that arc buoyancy causes gravitational spreading. This gravitational flow applies a body (buoyancy) force to the adjacent subducting and overriding plates, which decreases the stress transmission (mechanical coupling) from the subducting to the overriding plate, causing lithospheric extension in the continental plate and basin formation/infilling and triggers topography decay in the orogen. Slab-folding and slab-steepening within the mantle, cause episodes of increased compression/shortening in the basin above, poloidal mantle flow, and mechanical coupling in the trench. Increased compression opposes arc body forces and triggers topographic growth in the orogen (0.008-0.310 mm/yr), which increases the sediment supply to the basin in the continental plate. However, the results show that this effect is modulated by the erosion (up to 0.2 mm/yr) and sedimentation (0.03-0.3 mm/yr) rates in the orogen and the basin. The angle of collision triggers a toroidal component in the mantle flow by increasing shortening in the leading edge, which increases the magnitude of body forces and counteracts the poloidal flow. This toroidal flow causes rotation and arcuate geometries in the subducting plate, and is larger in simulations with less acute angles of collision (65-85 degrees). The results of our numerical modelling highlight the competition between arc buoyancy forces and the increased tectonic forces caused by slab-folding in the evolution of arc-continent collision; and how this competition is modulated by erosion in the orogen and sedimentation in the basin. These findings have implications for the formation and preservation of critical energy and mineral resources essential for the transition to a green economy.
Notes
Terms of Use
Keywords
arc-continent collision, numerical modelling, buonyancy contrasts, slab-folding, gravitational spreading, oblique collision, arcuate slabs , surface processes, coupled models, collisional orogens, back-orogen basins