Preprints
https://doi.org/10.5194/egusphere-2023-2518
https://doi.org/10.5194/egusphere-2023-2518
14 Nov 2023
 | 14 Nov 2023

Geodynamic controls on clastic-dominated base metal deposits

Anne Cathelijn Glerum, Sascha Brune, Joseph Michael Magnall, Philipp Weis, and Sarah A. Gleeson

Abstract. To meet the growing global demand for metal resources, new ore deposit discoveries are required. However, finding new, high-grade deposits, particularly those not exposed at the Earth’s surface, is very challenging. Therefore, understanding the geodynamic controls on the mineralizing processes can help identify new areas for exploration. Here we focus on clastic-dominated Zn-Pb deposits, the largest global resource of zinc and lead, which formed in sedimentary basins of extensional systems. Using numerical modelling of lithospheric extension coupled with surface erosion and sedimentation, we determine the geodynamic conditions required to generate the rare spatiotemporal window where potential metal source rocks, transport pathways and host sequences are present. We show that the largest potential metal endowment can be expected in narrow asymmetric rifts. This rift type is characterized by rift migration – a process that successively generates hyper-extended crust through sequential faulting, resulting in one wide and one narrow conjugate margin. Rift migration also leads to 1) a sufficient life-span of the migration-side border fault to accommodate a thick submarine package of sediments, including coarse (permeable) continental sediments that can act as source rock; 2) rising asthenosphere beneath the thinned lithosphere/crust resulting in elevated temperatures in these overlying sediments that are favourable to leaching metals from the source rock; 3) the deposition of organic-rich sediments that form the host rock at shallower burial depths and lower temperatures; and 4) the generation of smaller faults that cut the major basin created by the border fault and provide additional fluid pathways from source to host rock. Wide rifts with rift migration can have similarly favourable configurations, but these occur less frequently and less potential source rock is produced, thereby limiting potential metal endowment. In simulations of narrow symmetric rifts, the potential for ore formation mechanisms is low. Based on these insights, exploration programs should prioritize the narrow margins formed in asymmetric rift systems; in particular those regions within several tens of kilometres from the paleo-shoreline, where we predict the highest-value deposits to have formed.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Anne Cathelijn Glerum, Sascha Brune, Joseph Michael Magnall, Philipp Weis, and Sarah A. Gleeson

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Reveiwer comment on "Geodynamic controls on clastic-dominated base metal deposits"', Mark Hoggard, 03 Jan 2024
  • RC2: 'Comment on egusphere-2023-2518', Tim Jones, 06 Apr 2024
  • EC1: 'Comment on egusphere-2023-2518', Simone Pilia, 07 Apr 2024
    • AC3: 'Reply on EC1', Anne Glerum, 10 May 2024
Anne Cathelijn Glerum, Sascha Brune, Joseph Michael Magnall, Philipp Weis, and Sarah A. Gleeson

Data sets

ASPECT input and output files and postprocessing scripts A. C. Glerum https://doi.org/10.5281/ZENODO.10048075

Model code and software

ASPECT and FastScape source code A. C. Glerum (and all other developers of the codes) https://doi.org/10.5281/ZENODO.10048075

Anne Cathelijn Glerum, Sascha Brune, Joseph Michael Magnall, Philipp Weis, and Sarah A. Gleeson

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Short summary
Known high-value lead-zinc deposits formed in sedimentary basins created when tectonic plates rifted apart. We use computer simulations of rifting and the associated erosion and deposition of sediments to understand why they formed in some basins, but not in others. We find that conditions for deposit formation can briefly occur in both narrow and wide rifts for at most 3 My. Our models predict that the largest and the most deposits form in narrow margins of plates that rift asymmetrically.