Earth

Geodynamic mantle flow model explains deformation of continental crustal blocks in northern China

Crustal structure and reconstruction of deforming plates in Northeast Asia and the Western Pacific. Credit: Nature Geoscience (2024). DOI: 10.1038/s41561-024-01513-2

Cratons are fascinating but mysterious geological formations. Cratons, known as relatively stable parts of Earth’s continental crust, have remained largely unchanged for billions of years. Although cratons have survived many geological events, some are undergoing decratonization, a process characterized by deformation and eventual destruction.

For example, the North China Craton (NCC), an ancient continental crustal block, underwent extensive decratonization during the Mesozoic, primarily due to tectonic and geochemical changes and destabilization of its base (or “keel”). It is known that it started. However, explaining the mechanisms behind these complex geological changes has proven difficult with existing technology and current understanding.

In a recent study published in Nature Geoscience, a research team led by Professor Shaofeng Liu from the China University of Geosciences (Beijing) used extensive geological, geophysical, and empirical geochemical data to explain the puzzling phenomenon. We have successfully addressed this knowledge gap by developing a computational model backed by . Variant of NCC.

Specifically, the developed model focuses on the subduction of the Izanagi plate beneath the Eurasian plate on which the NCC is located as the underlying reason for the observed decratonization.

Credit: Nature Geoscience (2024). DOI: 10.1038/s41561-024-01513-2

The researchers compared several possible subducting plate geometries using earthquake seismicity and basin stratigraphic evidence to narrow down possible reconstructions. Finally, we used a geodynamic mantle flow model to simulate the full range of subduction processes and empirically validate our predictions.

Their analysis describes the decratonization of NCC in three stages. First, the Izanagi plate underwent initial subduction and slipped beneath the Eurasian plate. But instead of moving downward, the Izanagi plate flattened and began moving parallel to the Eurasian plate in a process called flat slab subduction. Fluids from the subducting plate altered the keel of the upper NCC and initiated its destruction. Additionally, compressive forces caused other deformations such as extrusion, craton thickening, and surface uplift.

Interestingly, a rollback process then occurs, as a result of which the subducted plate becomes steeper again and travels deeper beneath the Eurasian plate, reaching the upper and lower mantle interface and moving into the mantle transition zone. I experienced horizontal subsidence. This rollback caused extensional deformation, resulting in the formation of a rift zone with thinning of the lithosphere and lowering of the craton’s surface topography.

In addition, a large region of upper mantle material known as a “large mantle wedge” develops between the advancing slab and the craton, causing convection and intense metasomatism with heating and erosion at the base of the submarine. May cause melting. -The same goes for cratons and magma activity.

Professor Liu said: “We have successfully developed a new mantle flow model that incorporates a flat slab and rollback subduction, which is consistent with the geological evolution of the Earth’s surface and the current mantle-slab structure. .”

“Interestingly, our validated model is able to effectively describe the spatiotemporal dynamics and topographic response of long-term mantle slab subduction.”

Understanding the life cycle of cratons is important from both academic and practical perspectives, given that cratons contain deposits of minerals and rare earth elements that are of immense value for technological applications. Building on these insights, further investigation into Earth’s geological history could lead to a deeper understanding of geological processes such as decratonization, revealing a path to a more sustainable future. It is expected.

Further information: Shaofeng Liu et al., Craton deformation due to flat slab subduction and rollback, Nature Geoscience (2024). DOI: 10.1038/s41561-024-01513-2

Provided by China University of Geosciences

Citation: Geodynamic mantle flow model explains deformation of continental crust block in northern China (November 3, 2024) https://phys.org/news/2024-11-geodynamic-mantle-deformation-continental-crust Retrieved November 3, 2024 from.html

This document is subject to copyright. No part may be reproduced without written permission, except in fair dealing for personal study or research purposes. Content is provided for informational purposes only.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button