Following a river capture event, a new drainage divide forms between the capture point and the beheaded river, and then migrates toward the beheaded river at a much higher rate than before the capture event. The intersection between the abandoned river channel and the newly-formed drainage divide is called a "wind gap". Sediments around wind gaps are commonly used to infer paleo-drainage pathways and constrain the timing of capture events. However, recent studies suggest that these sediments may primarily originate from ongoing proximal sedimentary processes rather than from ancient great river deposits. Here, we conducted a detailed optically stimulated luminescence chronological analysis of the sediments around the wind gap between the Dadu and Anning Rivers, and further assessed the stability of the Dadu-Anning drainage divide. The results indicate that these sediments are not remnants of the southward-flowing Paleo-Dadu-Anning River, as most of the sediment ages (4-145 ka) are significantly younger than the Dadu-Anning capture event (similar to 0.6-2.4 Ma). Instead, they are post-capture deposits located at the headwaters of the beheaded river, which accelerate the wind-gap migration after the capture event. This study highlights the significance of sedimentation at the headwaters of the beheaded river in shaping landscape dynamics following a river capture event.