China University of Geosciences (Beijing) Unveils Clues to an Enigmatic Geological Process

Using advanced computational models, researchers explain how the North China Craton, an ancient and stable geological structure, is falling apart

BEIJING, Nov. 1, 2024 /PRNewswire/ -- Cratons are fascinating yet enigmatic geological formations. Known to be relatively stable portions of the Earth's continental crust, cratons have remained largely unchanged for billions of years. Although cratons have survived many geological events, some are undergoing decratonization—a process characterized by their deformation and eventual destruction. For example, the North China Craton (NCC), an ancient continental crust block, is known to have begun extensive decratonization during the Mesozoic era, largely due to tectonic and geochemical modifications and destabilization of its base (or 'keel'). However, explaining the mechanisms behind these complex geological transformations has proven difficult.

In a recent study published in volume 17 of Nature Geoscience on September 6, 2024, a research team led by Professor Shaofeng Liu from China University of Geosciences (Beijing) successfully addressed this knowledge gap. The researchers developed a computational model supported by extensive geological, geophysical, and empirical geochemical data that explains the puzzling deformation of the NCC. For a better understanding of the mechanism, an animated video illustrating the model's dynamics and implications is available here: https://youtu.be/E8MVveD4VMY.

The model focuses on the subduction of the Izanagi plate beneath the Eurasian plate, where the NCC is located. By comparing possible subducted plate geometries using earthquake seismicity and basin stratigraphy evidence, the team narrowed down potential reconstructions. Their geodynamic mantle-flow model simulated the full extent of the subduction process, validating predictions empirically.

The analysis reveals that the NCC's decratonization occurred through the subduction of the Izanagi plate, which initially flattened and moved parallel to the Eurasian plate, causing fluid alterations and deformations. A subsequent rollback process led to extensional deformation, thinning the lithosphere and forming rift basins.

Prof. Liu says, "We successfully developed a new mantle-flow model incorporating flat-slab and rollback subduction, which aligns with surface geological evolution and the present-day mantle slab structure. Interestingly, our validated model can effectively describe the space–time dynamics and topographic response of mantle slab subduction over time."

Given that cratons contain mineral and rare-earth element deposits with immense value for technological applications, understanding the life cycle of cratons is important from both an academic and a practical standpoint. Here's hoping that further research will deepen our understanding of geological processes like decratonization, revealing paths towards a more sustainable future.

Reference
Title of original paper: Craton deformation from flat-slab subduction and rollback

Journal: Nature Geoscience

DOI: https://doi.org/10.1038/s41561-024-01513-2

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SOURCE China University of Geosciences