Abstract: Tongzilin and Ertan etc.,are located in the lower reach of the Yalong River,a sequence of less dense sediments in the bottom of the valley named Xigeda Formation (Early Pleistocene) with a thickness of 70m.14C dating indicates an age ranging from 23000-10000 yrs for the lacustrine deposit,suggesting a time spanning Late Pleistocene and Early Holocene for the Tongzilin Formation.Tectonic deformation of the succession leads to a east-dipping sequences,the development of extension-torsion fault and compression fault,and a set of X-shaped jointa,suggesting that this area showed a tendency to uplift rapidly

摘要： 本文根据沉积环境分析和¹⁴C测龄结果,确定沿雅砻江下游河床分布的一套未成岩的河湖相地层的时代为晚更新世晚期-全新世早期,而不是长期以来归之于早更新世的昔格达组,建议称其为桐子林组;并通过该地层变形成因的分析,提出李明久-桐子林断裂带在全新世中期活动显著的认识。