In a study published in Earth and Planetary Science Letters, researchers quantify the significant loss of continental crust to the mantle during the formation of major mountain ranges, including the Himalayan Tibetan Plateau. Dr Xie Zhu, a research fellow at Monash University, and colleagues analyzed crustal dynamics, revealing that up to 30% of the crust could be destroyed in collision zones, with implications for Earth’s geological evolution. The results were compared with other mountain systems such as the European Alps and the Zagros Mountains.

Massive crystal loss during collisions

According to studythe team developed a mass and volume balance model to measure the amount of continental crust that underwent subduction or delamination during collision. By estimating crustal thickening, lateral exhumation, and erosion, an asymmetry was identified, suggesting that a substantial portion of the crust was subducted into the mantle. Dr. Zhu told Phys.org that the process can be likened to the pressing of soft materials, where the displaced parts disappear beneath the surface rather than being preserved at the ground surface.

Mechanisms behind crystal recycling

The study highlighted delamination as the primary mechanism driving crustal recycling, particularly during the formation of the Himalayan Tibetan Plateau. This process, marked by the subduction of dense lithospheric material, was linked to the generation of specific rock types with geochemical markers indicative of mantle influence. Evidence also links these events to the rapid uplift of the Himalayas and the resulting climatic changes, including heavy monsoon rains about 22 million years ago.

Implications for Mountain Systems

In other regions, such as the European Alps and the Zagros Mountains, similar processes were reported. About 50% of the crustal volume of the Alps and up to 64% of the crust of the Zagros Mountains were lost during their formation periods. Research shows that such losses have occurred throughout Earth’s history, affecting the composition of the mantle over billions of years.

The research highlights the interplay between deep Earth processes and surface changes, providing insight into how crustal dynamics shape the planet.