Abstract: Neo-tectonic movements in the northern section of the Yuanmou fault zone, Yunnan Prov. are very well reflected by the modification of landforms and the deformation of the early Pleistocene lacustrine strata.1. A narrow, deep trough-basin (the Yuanmou Basin) formed on the western side of the major Yuanmou fault was at first filled with Q₁ lacustrine deposits of more than 400m thick, and then uplifted into a westward tilting high lake terrace. Subsequently 5 lower and lower river terraces appeared one after another only along the eastern margin of the trough-basin. The Longchuanjiang River, which has carved out the terraces, now runs along the western margin of the basin.2. Jurassic sandstones and shales were thrust westward on Q₁ lacustrine deposits, which was affected by a series of young folds and faults. These folds and faults trend with a sharp angle toward the major Yuanmou fault and constitute some Quaternary tectonic structures of "λ" pattern.3. A series of cross tectonic structures such as downwarp-faulted basins with an arched uplift between them is found in the trough-basin.All the features above mentioned suggest that the northern section of the Yuanmou fault zone forming the middle part of the Sichuan-Yunnan N-S tectonoseismic belt, has been affected not only by vertical, but also horizontal (either sinistral or dextral) multi-cyclic movements.Nevertheless, from the seismo-geological analysis we consider that the risk of a destructive earthquake here would not be so serious as that in the northern and southern terminal areas of the Sichuan-Yunnan N-S tectonoseismic belt.

摘要： 元谋断裂有强烈、复杂和多阶段的新活动,表现西盘先断陷成湖,后回升成阶地,并在东盘水平挤压下时而顺扭、时而反扭,使阶地变形、错位、掀斜,并在湖积中形成轴向或走向与主干断裂成向南或向北锐角相交的新褶皱与断层,构成新“人”字形构造。 此带地处滇西南北带中段,灾害性地震危情不如南、北两端严重。