Thirty-eight new apatite and zircon fission-track ages from 26 bedrock samples vary from 2.0 ± 0.3 to 12.1 ± 1.2 Ma, and 3.3 ± 0.3 and 13.2 ± 0.7 Ma, respectively, along three transects of the Kurung, Subansiri, and Siyom Rivers, which flow across the major structures of the Arunachal Himalaya. These cooling ages reveal marked variations in millennial-scale (>10⁵ yr) exhumation rates from 0.6 to 3.0 mm/yr. A distinct positive correlation is visible between local topographic relief, hill slopes, channel steepness, and exhumation rates. The cooling ages are younger in the northern antiformal domains and older within the synformal nappe along the mountain front. Thermal modelling and time–temperature paths suggest that zones of rapid exhumation are controlled by structural windows within the Lesser Himalaya that were developed between 8 and 6 Ma over blind Main Himalayan Thrust (MHT). This time of rapid rock uplift and major topographic change led to a two-fold increase in the exhumation rates in the northern antiformal domains than the southern front of Arunachal Himalaya. Variation in cooling ages does not correlate with the present-day precipitation pattern. Tectonics appears to be the leading factor in driving the exhumation rates and landscape evolution in the Arunachal Himalaya.

来自 26 个基岩样品的 38 个新的磷灰石和锆石裂变径迹年龄分别在 2.0 ± 0.3 至 12.1 ± 1.2 Ma 和 3.3 ± 0.3 和 13.2 ± 0.7 Ma 之间变化，沿库隆河、苏班西里河和锡约姆河的三个横断面，它们流经阿鲁纳恰尔喜马拉雅山的主要结构。这些冷却年龄揭示了千禧年尺度 (>10 ⁵yr) 折返率从 0.6 到 3.0 毫米/年。局部地形起伏、山坡、水道陡度和折返率之间明显存在正相关。北部反形式域的冷却年龄较年轻，而沿山前的同形推覆内的冷却年龄较旧。热模型和时间-温度路径表明，快速折返区由小喜马拉雅山脉内的结构窗口控制，这些窗口在 8 到 6 Ma 之间在盲主喜马拉雅逆冲断层 (MHT) 上形成。这次岩石快速隆起和主要地形变化导致北部反形式域的挖掘率比阿鲁纳恰尔喜马拉雅山南部前沿增加了两倍。冷却年龄的变化与当今的降水模式无关。