中文摘要：

南北地震带南西缘的元谋-昔格达断裂新构造特征对认识区域构造地貌形变、强震分布与构造应力场之间的关系、以及其在块体运动中的活动方式和强震趋势意义重大．经开展该构造带地质、地貌、形变及活动性综合研究，表明：（1）元谋-昔格达断裂活动方式总体表现为第四纪早期的逆冲和晚期的左旋走滑兼局部挤压或张剪．（2）断裂切错的地层、地貌形变特点和探槽表明：江边以南，断层最新活动时间在距今6．92±0．70—8．68±0．94ka之间；自20．82±2．12ka以来，断层垂向活动速率约为0．096mm／a，水平滑动速率为1-2mm／a；断裂强活动复发间隔应不小于8．68±0．94ka．江边以北，断裂最新活动时间晚于12．83±1．09ka；晚更新世以来的左旋走滑速率约为1．70mm/a，垂向速率为0．04～0．10mm／a；断裂强活动复发间隔大致为1—1．2万年或更短．（3）前期成果表明断裂带自晚新生代以来主要受早期的NNE—SSW向和晚期的NNW-NWW向水平主压应力场作用，而晚期局部构造应力场表明，下雷弄-江边、化同-秧田井、一平浪-罗川-带倾滑明显，影响和调整了断裂带的晚第四纪活动特点．

英文摘要：

The recent geological activities of the Yuanmou-Xigeda fault, which lies in the southwestern margin of China＇s north-south seismic belt, play an important role in our understanding of the regional tectonic geomorphology deformation and the relation between the distribution of strong earthquakes and the tectonic stress field, as well as the motion features in the block movement, and in risk analysis of future earthquakes. Comprehensive studies of the geology, topography, deformation, and activity of the fault indicate that （1） the activity mode of the Yuanmou-Xigeda fault generally shows thrust motion in the Early Quaternary and sinistral strike-slip motion in the Late Quaternary, with partial extrusion or tensile shear motion. （2） According to the stratigraphic section of the outcrop cut by the fault activity, landform deformation, and related dating of trench samples, the most recent activity of Jiangbian south of the Yuanmou-Xigeda fault occurred 6.92±0.70-8.68±0.94 ka. The vertical slip rate and horizontal strike-slip rate of this fault segment at 20.82±2.12 ka was about 0.096 and 1-2 mm/a, respectively. However, the most recent activity in the northern segment of Jiangbian was later than 12.83±1.09 ka and the vertical slip rate and horizontal strike-slip rate in the areas north of Jiangbian since the Pleistocene were about 0.034-0.10 mm/a and 1.70 mrn/a, respectively. According to the seismic remnant and active characteristics of the fault, the recurrence interval of the tectonic activity was at least 8.68±0.94 ka south of Jiangbian, but 10-12 ka or less north of Jiangbian. （3） Our results show that the principal horizontal stress on the fault was in the NNE-SSW direction during the early period and in the NNW-NWW direction during the later period （after the Yuanmou Motion）. The partial tectonic stress field indicates that the tendency to slide in the Xialeinong-Jiangbian, Huatong-Yangtianjing, and Yipinglang-Luochuan areas affects and modifies the Late Quaternary activity of the fault.