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Explained: Why North China Craton Undergoing Decratonization

A team of researchers at China University of Geosciences Beijing have come out with clues on why cartons, like North China Craton (NCC), are undergoing decratonization

Sunday November 3, 2024 9:40 PM, ummid.com News Network

Beijing: A team of researchers at China University of Geosciences Beijing have come out with clues on why cartons, like North China Craton (NCC), are undergoing decratonization.

Cratons are fascinating yet enigmatic geological formations. Known to be relatively stable portions of the Earth's continental crust, cratons have survived many geological events and remained largely unchanged for billions of years.

However some, like the North China Craton (NCC), are undergoing decratonization.

What is decratonization?

Decratonization is a process characterized by the deformation and eventual destruction of cartons.

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').

Explaining the mechanisms behind these complex geological transformations has proven difficult. However, 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. The model focuses on the subduction of the Izanagi plate beneath the Eurasian plate, where the NCC is located, according to a study published in Nature Geoscience September 2024.

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.

"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", Professor Liu said.

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 researchers said.

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", the research team said.

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.

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