A new study led by Dr. Ziyi Zhu, a Research Fellow at Monash University, has uncovered the extensive loss of continental crust into the Earth’s mantle during the formation of major mountain ranges.
Published in ‘Earth and Planetary Science Letters’, the research focuses on the crustal dynamics of collision zones like the Himalayan-Tibetan Plateau and highlights their crucial role in Earth’s geological evolution.
Using a mass and volume balance model, the study analyzed how crustal thickening, erosion, and displacement occurred during mountain formation. The researchers found that up to 30% of the continental crust in these regions was destroyed, sinking into the mantle through processes such as subduction and delamination.
Dr. Zhu compared the phenomenon to compressing a soft material, explaining that parts of the crust are pushed beneath the surface and lost rather than remaining visible. This process, known as delamination, involves the sinking of denser lithospheric material into the mantle. This not only changes the mantle’s composition but also generates rock types with geochemical signatures resembling mantle material.
The study also links these processes to the rapid uplift of the Himalayas around 22 million years ago, which intensified monsoon rainfall in the region.
Similar patterns were identified in other mountain systems, such as the European Alps and the Zagros Mountains. The research estimated that nearly 50% of the Alps’ crust and 64% of the Zagros Mountains’ crust were lost during their formation.
The findings have significant implications for understanding Earth’s long-term geological evolution. By showing how crustal recycling alters the mantle over billions of years, the study highlights the deep connections between tectonic activity, surface changes, and climate.
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