Tectonic evolution of the Sumatran Fault: synthesis and perspective

Abstract: [Objective]Oblique convergence between the Indo-Australian Plate and the Eurasian Plate produced a ~1,900-km-long dextral strike-slip fault—the Sumatran Fault—within the overriding plate. While previous studies have extensively examined its geometry, kinematics, and seismicity, the tectonic evolution of the fault remains poorly constrained. [Methods] This study integrates multidisciplinary evidence from structural geology, geomorphology, seismicity analysis, geodesy (GPS), low-temperature thermochronology (apatite/zircon (U-Th)/He dating), and volcanic distribution mapping. We systematically synthesize data on fault segmentation, slip rates, cumulative displacement, magmatic-tectonic relationships, and regional geodynamic models to evaluate the fault’s spatiotemporal evolution. [Results] The Sumatran Fault is a highly segmented dextral strike-slip system, currently can be divided into 19 segments by geometric complexities and seismic activities. Slip rates along the fault are relatively uniform from south to north, with an average rate around ~15 mm/yr, and a total cumulative displacement estimated at approximately 20–25 km. Regionally, the distribution of active arc magmatism closely aligns with the trace of the fault, indicating a dynamic interaction between faulting and magmatism: while magma-induced crustal weakening facilitates fault development, extensional zones associated with normal faulting in turn influence the volcanic activity. Despite its tectonic significance, low-temperature thermochronological studies on the Sumatran Fault remain limited. Existing thermochronological data reveal a period of rapid uplift at ~2 Ma, likely driven by dip-slip motion along the fault. [Conclusion] A three-stage model is proposed. From an earlier period up to 2 Ma, oblique convergence accommodated primarily by the forearc faults (e.g., Mentawai Fault) and shear zones. Around 2 Ma, the Sumatran Fault initiated, coevally with the Mentawai Fault, manifesting strain localization in the overriding plate. At present, the Sumatran Fault accommodates the majority of the strain, while strike-slip motion on the Mentawai Fault has significantly diminished. The uplift phase correlates with the initial timing of the Sumatran Fault inferred from present-day slip rates and cumulative offsets, suggesting that the current throughgoing structure of the fault and the modern tectonic framework were established at the same time. [Significance] To better understand the dynamics of large strike-slip faults at obliquely convergent margins, comprehensive geochronological and structural investigations—particularly focused on fault segmentation and deformation timing—are essential. It helps to provide a paradigm for understanding strain partitioning and the genesis of trench-parallel strike-slip faults at oblique convergent margins globally, with implications for seismic hazard assessment and plate boundary reorganization.