The Earth Science Team of HKU put forward a new theory on the formation of crustal plates and published the results in academic journals

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Written by: Ma Weijie

2020-07-19 18:13

Earth science scholars have not been sure about the cause of the earth plate structure. Associate Professor of the Department of Earth Sciences at the University of Hong Kong and Alexander Webb of the Earth and Planetary Science and Space Research Laboratory, and international research partners proposed new answers to the origin and causes of plate motion; Dr. Webb and his team proposed that the formation of the earth plate is due to the early shell of the earth It heats up, causing thermal expansion to produce cracks. The cracks continue to expand and merge to form a global network, subdividing the earth’s early crust into multiple plates.

The results of the study have just been published in the authoritative academic journal Nature Communications, and the new theories help to unravel how the earth changed from a hot sphere into a planet with plate tectonics today.

All along, scientists have not been sure about the cause of plate tectonics. Alexander Webb, an associate professor in the Department of Earth Sciences of the University of Hong Kong and the Earth and Planetary Science and Space Research Laboratory, recently proposed new answers with international research partners and published in an academic journal " Published in Nature Communications.

Webb and his team proposed that the formation of the earth's plate is because the earth's early shell became hot, causing thermal expansion to produce cracks. These cracks continued to expand and merge to form a global network, subdividing the early earth's shell into multiple plates.

Study simulates the earth's crust undergoing thermal expansion

The team used the fracture mechanics code developed by Professor Tang Chunan of Dalian University of Technology as the first author of the paper to verify this statement through a series of numerical simulations. Each simulation recorded the stresses and deformations experienced by a thermally expanding Earth's crust, and the earth's crust was subjected to a thermal expansion distance of more than 1 km that would normally be tolerated, causing cracks to form and quickly forming a global crack network.

The new theory model diagram shows a developing global crack network (late stage). Black/shadow indicates fracture, while the color display represents stress (pink indicates tensile stress, blue indicates compressive stress) (Photo of Hong Kong University)

In simple terms, the principle of this new model is that the earth's crust becomes hot, expands, and then ruptures. The cause of geothermal expansion is because the hot materials deep in the earth warm the lithosphere on the surface through heat conduction, and the new model shows that if the solid lithosphere of the earth has enough thermal expansion, it will break and form cracks very quickly. The network divides the lithosphere of the earth into plates.

Webb and the research team will continue to integrate methods of field investigation, analysis, and theoretical research to explore the early development of the Earth and other planets and satellites in the solar system. Their theoretical research, simulating various earth dynamics, helps to unravel how the earth changed from a hot sphere into a plate-structured planet today.

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