金沙江上游特米古滑坡堰塞湖形成与溃决时间讨论

Discussion on formation and outburst time of Temi paleo-landslide dammed lake in the upper Jinsha River

开展古滑坡堰塞湖形成演化过程研究,可以揭示古灾害地质环境效应,重建区域构造历史活动序列和古气候演变特征。特米古滑坡发育于金沙江上游巴塘段,滑坡堆积地貌和堰塞湖相沉积物保存较好,是研究区内古地质环境的良好载体。在遥感解译、无人机测绘、现场调查和地质测年的基础上,结合前人研究成果,分析探讨了特米古滑坡发育特征、堰塞湖形成时间与溃决演化过程。结果表明,特米古滑坡是特大型岩质历史堵江滑坡,滑坡堰塞湖实际形成时间应该远早于2.15 ka BP,历史上曾发生过多次溃决,完全溃决时间大约为1.08 ka BP,堰塞湖稳定保存时间大于1.07 ka。金沙江巴塘段大型堵江滑坡群并非由单次地质事件形成,而是由金沙江断裂带多次强烈地震诱发。

Analyzing the evolution process of the paleo-landslide dammed lake could reveal the geological and environmental effects of ancient disasters, and reconstruct the regional tectonic historical activity sequence and the characteristics of paleoclimate evolution. The Temi paleo-landslide is located at the Batang section of the upper Jinsha River. The landslide accumulation landform and lacustrine deposits are well preserved, which provides a good condition for studying the paleo-geological environment in the study area. Based on remote sensing interpretation, UAV mapping, field investigation and geological dating, combined with previous research results, the development characteristics, formation age, and outburst evolution process of Temi paleo-landslide dammed lake are discussed. The results showed that the Temi paleo-landslide was an extremely large-scale rock landslide, which dammed the Jinsha River for a long time. The real formation time of landslide dammed lake should be earlier than 2.15 ka BP, and the total outburst time was about 1.08 ka BP. The landslide-dammed lake had occurred many times outburst on a massive scale in history, and it completely burst after being stable for at least 1070 years. The large damming landslide group in the Batang section of the Jinsha River was not triggered by a single geological event, but induced by several strong earthquakes in the Jinsha fault zone.