Abstract The Tibetan Plateau and Indian Plain exhibit the largest altitudinal difference between two geographically contiguous areas on Earth, but the eastern margin of the Plateau has not experienced headward erosion of the Yarlung Zangbo River (YZR) since ~2.5 Ma. In the past, some scientists have argued that moraine dams on Mount Namcha Barwa (in the Eastern Himalayan syntaxis) frequently blocked the YZR, thus keeping the Plateau's margin intact at this point. In this study, three sets of moraines were identified in the Pai Valley alongside Namcha Barwa, and were dated using optically stimulated luminescence (OSL) and 10Be exposure dating. The resultant ages would suggest that three glaciations occurred at ~22.2, 4.7 and 1.3 ka, respectively. Comparison of OSL and 10Be ages for glacial advances with local paleoclimatic proxies would suggest that temperature was the dominant factor controlling glacial change. Because of the paleoglacial advance frequency, coupling with rapid fluvial incision, moraine dams were cut through by the YZR. Thus, any moraine dams that lost their efficacy in impacting upon knickpoint migration. Instead, similarities between rock uplift and fluvial incision, rather than moraine dams, might have been the main control impeding headward erosion of the YZR, thereby keeping this part of the eastern Tibetan Plateau margin intact.

中文翻译：

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喜马拉雅东部构造地末次盛冰期以来南迦巴瓦山冰碛坝的冰川进展和稳定性

摘要 青藏高原和印度平原表现出地球上两个地理上相邻区域之间最大的海拔差异，但高原东缘自~2.5 Ma以来没有经历雅鲁藏布江（YZR）的上游侵蚀。过去，一些科学家认为，Namcha Barwa 山（位于喜马拉雅东部构造界）上的冰碛水坝经常阻塞 YZR，从而在这一点上保持了高原边缘的完整。在这项研究中，在 Pai Valley 与 Namcha Barwa 一起发现了三组冰碛，并使用光学受激发光 (OSL) 和 10Be 曝光测年法测年。由此产生的年龄表明，三个冰川作用分别发生在~22.2、4.7 和 1.3 ka。将冰川进展的 OSL 和 10Be 年龄与当地古气候代理进行比较，表明温度是控制冰川变化的主要因素。由于古冰川的推进频率，加上快速的河流切割，YZR 切断了碛坝。因此，任何在影响拐点迁移方面失去效力的碛坝。相反，岩石隆起和河流切口之间的相似性，而不是碛坝，可能是阻止青藏高原上游侵蚀的主要控制因素，从而保持青藏高原东部边缘的这一部分完整。任何在影响临界点迁移方面失去效力的冰碛坝。相反，岩石隆起和河流切口之间的相似性，而不是碛坝，可能是阻止青藏高原上游侵蚀的主要控制因素，从而保持青藏高原东部边缘的这一部分完整。任何在影响临界点迁移方面失去效力的冰碛坝。相反，岩石隆起和河流切口之间的相似性，而不是碛坝，可能是阻止青藏高原上游侵蚀的主要控制因素，从而保持青藏高原东部边缘的这一部分完整。