Abstract The orogenic processes along the northeastern margin of the Tibetan Plateau are often regarded as critical evidence of the ongoing Cenozoic collision between the Indian and Asian plates, driving the plateau's progressive northward expansion. However, the mechanisms driving uplift in the Qilian Shan since the mid‐Miocene remain poorly constrained due to limited record directly linking mountain building. Here, we present new stratigraphic and fault activity observations from the fold‐and‐thrust belt along the northern margin of the Qaidam Basin, providing insights into the tectonic context of basin‐mountain development. By integrating high‐resolution magnetostratigraphic data, deep seismic imaging, and field observations from the fold‐and‐thrust belt, we reconstruct a comprehensive history of sedimentation and tectonic activity from 13.5 Ma to 0.5 Ma. Our findings indicate that shifts in paleocurrents/provenance are concurrent with variations in sedimentation rates and stratigraphic tilting (growth strata) due to fault‐propagation‐folding. These observations suggest that the southern Qilian Shan underwent three distinct phases of accelerated uplift and southward expansion during ∼13.5–10 Ma, ∼6–5 Ma, and ∼3.5–2 Ma. Synthesizing these results with prior studies on the timing of deformation, we propose that since the mid‐Miocene, the Qilian Shan have expanded simultaneously in opposite directions along both their northern and southern margins, with eastward growth. This expansion pattern coupled with crustal‐scale pure shear deformation, suggests that gravitational collapse triggered by ongoing internal uplift of the Tibetan Plateau, diffusing outward toward the plateau's margins, may be a key driver of the horizontal compressive stresses along the northeastern Tibetan Plateau.
Wu et al. (Fri,) studied this question.
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