【摘要】 九湾溪断裂带位于三峡工程大坝西南 １８ ｋｍ处。利用从断裂带中的断层泥、断裂壁岩和断裂围岩内选出的 磷灰石，进行裂变径迹断代学研究，并对径迹长度的频率分布进行统计测量。研究证实：九湾溪断裂带发生断裂时期 为距今（０． ３３ ± ０． ０４） Ｍａ，与它周边围岩形成时代（２５． ７４±１． ９） Ｍａ截然不同。通过各种绝对年龄结果的对比分析， 均未见到全新世以来有明显的活动迹象，由此确认九湾溪断裂活动性对三峡枢纽工程并不构成威胁。更多还原

【Abstract】 Apatite was separated from fault-clay, fractute-cliff rock and fracture wall rock, which were collected from Gaowanxi and Heilongtan fracture north to Jiuwanxi lying 18 km southwest to Three-Gorges Dam Project- Sandouping dam. The fission tract characters and their length variations of apatite show that Jiuwanxi fracture belt was formed at (0. 33 ± 0. 04) Ma, but its wall rock at (25. 74 ± 1. 9) Ma. This result and previous studies show that no activity has happened since the Holocene, and the Three-Gorges Dam Project is not affected by activity of Jiuwanxi fracture belt.更多还原