Since the initial collision between the Indian and Eurasian plates more than 50 million years ago, their convergence has continued to the present day. This has led to widespread intra-plate deformation and the uplift of the Tibetan Plateau. Traditional plate tectonic theory posits that continental lithosphere is relatively buoyant and unlikely to subduct into the mantle, suggesting that continental collisions cannot be sustained for long periods. Consequently, the driving mechanism behind the prolonged convergence of the Indian and Eurasian plates has been a subject of extensive debate, posing significant challenges to our understanding of plate tectonics and continental dynamics.

Numerous studies have explored potential drivers of this convergence, including basal shear at the base of the lithosphere, slab pull from Indian continental subduction, slab pull from the subduction of the Indo-Australian oceanic plate at the Sumatra-Java trench, and ridge push from the Central and Southeast Indian Ridge (Figure 1). However, previous numerical or analog models, due to simplified model settings, have not been able to systematically quantify all driving forces within a unified framework, leading to ongoing debate about their relative importance.

The key to resolving this issue lies in accurately quantifying plate boundary forces and basal shear within models that realistically represent Earth’s internal structure. In particular, analyzing the driving and resisting forces of plate motions in subduction zones requires high-resolution and detailed nonlinear rheology in global models, which presents a significant challenge in addressing this scientific problem.

A research team led by Associate Professor Jiashun Hu from the Department of Earth and Space Sciences at the Southern University of Science and Technology (SUSTech) has addressed this challenge by employing high-resolution 3D global numerical simulations, combined with various geophysical observational data, to quantitatively assess the driving forces within the lithosphere-mantle coupled convection system. Their study elucidates the multiplicity of solutions for the driving mechanism under single velocity observation constraints. However, when intraplate stress is used as an additional constraint, the primary driving force of the India-Eurasia collision can be fully determined.

The results indicate that the current India-Eurasia convergence is mainly driven by the Sumatra-Java slab pull. This mechanism not only explains the current convergence between the two plates but also applies to the continued convergence process since the initial collision. The orogenic process dominated by slab pull from the surrounding subduction zone also implies that the uplift of the Tibetan Plateau may be a unique event in Earth’s history.

Their paper, titled “Ongoing India-Eurasia collision predominantly driven by Sumatra-Java slab pull,” has been published in Nature Geoscience.

Figure 1. Geodynamic setting of the India-Eurasia collision zone and the neighboring regions

The researchers developed high-resolution three-dimensional lithosphere-mantle coupling models. These models feature a detailed subduction channel and slab structure using adaptive mesh refinement with the finest resolution of ∼ 1 km, along with complex nonlinear rheology, enabling them to fully capture various driving and resisting forces in current plate motions. Based on this framework, they conducted a quantitative analysis of the driving forces behind the India-Eurasia convergence from the perspective of the Indo-Australian plate, including plate boundary forces, basal shear, and ridge push forces.

Figure 2. Model results of plate motions, plate boundary forces, and basal shear

Based on the aforementioned simulation method, the team first fitted the current global plate velocities (Figure 2). The results show that multiple combinations of driving forces can reproduce the current plate velocity of the Indo-Australian plate, demonstrating that there is a multiplicity of solutions for the driving mechanism under a single observational constraint. However, when stress and strain observational data are used as additional constraints, the primary driving force can be accurately determined (Figure 3a).

The study found that the position of the stress-orientation-transition interface within the Indo-Australian plate is highly sensitive to the relative strength of plate boundary forces (Figure 3). When simultaneously fitting both plate motion and the position of the stress-orientation-transition interface, the slab pull from the Sumatra-Java subduction zone was identified as the predominant driving force behind the current India-Eurasia convergence. In contrast, the continental collision acts as an impediment to the northward movement of the Indian plate. While basal shear forces vary in influence across different regions, they generally play a secondary role and do not constitute the main driving force (Figure 2a).

Figure 3. Comparison of the observed and predicted orientations of the most compressive horizontal principal stresses

The driving forces behind the Indian plate motion must be reconciled with the large-scale subduction dynamics of the global plate network. The Eocene plate reorganization within the broader India-Eurasia-Australia system is closely related to changes in the dynamics of the India-Asia collision zone. Previous studies, which provided precise constraints on ultrahigh-pressure exhumation in the NW Himalaya, suggest that a shift in the driving force of the India-Asia collision occurred in the middle Eocene. Therefore, the team proposes that the driving mechanism has dominated the India-Eurasia convergence since that time.

This study not only provides answers to specific scientific questions but also highlights the significance of its research approach and methodology. By focusing on regional tectonics within a high-resolution global three-dimensional framework and integrating various factors into a unified coupled system for comprehensive assessment, this work determines the relative importance of each driving force and provides quantitative force calculations (Figure 4). This approach could potentially offer a more effective framework for future geodynamic studies.

Figure 4. Quantitative calculation results of plate boundary forces, basal shear, and ridge push, along with a comparison between predicted and observed stress

Senior research scholar Qunfan Zheng from Jiashun Hu’s group is the first author of the paper, with Associate Professor Jiashun Hu serving as the corresponding author. SUSTech is the primary affiliated institution. Other collaborators include Professor Michael Gurnis from the California Institute of Technology, Researcher Ling Chen from the Institute of Geology and Geophysics at the Chinese Academy of Sciences, Professor Yaolin Shi from the University of the Chinese Academy of Sciences, as well as Assistant Professor Xueyang Bao and Professor Yingjie Yang from SUSTech.

Paper link: https://www.nature.com/articles/s41561-025-01771-8

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