滇西南地区汉母坝—澜沧断裂晚第四纪构造活动的地质地貌证据

Geological and Geomorphological Evidence of Tectonic Activity of Hanmuba--Lancang Fault at Southwestern Yunnan in Late Quaternary

通过对汗母坝-澜沧断裂晚第四纪地质、地貌实地调查与测量，并结合前人研究成果，讨论了该断裂晚第四纪最新构造活动特征。综合分析认为，汗母坝-澜沧断裂为一条以右旋走滑为主的全新世活动断裂，长约120km，整体走向NNW。该断裂活动习性具有明显的分段特征，北段称为汗母坝断裂，是1988年耿马7．2级地震的发震断裂；南段称为澜沧断裂，是1988年澜沧7．6级地震的发震断裂之一。晚第四纪以来其新活动形成了丰富的断错地貌现象，如冲沟和山脊右旋位错、断层沟槽、断层垭口、断层陡坎、断陷凹坑等。根据断裂断错地貌特征的相应资料估计，该断裂晚第四纪右旋走滑速率约为（4．7±0．5）mm／a。

According to field survey and measurement of the geology and landform of the Hanmuba --Lancang fault in late Quaternary, the latest tectonic characteristics of the fault in late Quater- nary were discussed on the basis of previous study. The preliminary analysis was that the fault with length of about 120 km belonged to the Holocene active fault with right-lateral strike-slip. The fault activity had obvious characteristics of segment. The north segment was Hanmuba fault, which was the causative structure of Gengma Ms7.2 earthquake in 1988. The south seg- ment was Lancang fault, which was one of seismogenic faults of Lancang Ms7.6 earthquake in 1988. A variety of dislocation landforms had been formed by new fault activities since the late Quaternary, such as dextral dislocation of gullies and ridges, fault groove, fault pars, fault es- carpment and pit. According to the relevant data, we estimated that the rate of right-lateral strike-slip of the fault in late Quaternary was about （4.7±0.5） mm/a.