中文摘要：

青藏高原内部的近东西向伸展变形在藏南地区形成了一系列近南北向裂谷带，对其中最东端的错那-沃卡裂谷带南段错那-拿日雍错地堑调查结果表明，它是第四纪活动明显的半地堑式断陷盆地。控制该盆地发育的主边界断裂带是近南北走向、倾向东侧和长80—110km左右的盆地西缘正断层，是区域内N90°-92°E方向伸展变形的产物。断裂活动速率的多种估算结果表明，该断裂带百万年时间尺度的平均垂直活动速率介于0．2—0．9mm／a之间；MIS 8和MIS 6以来的断裂平均活动速率的合理估计值是0．6±0．2mm／a；但末次冰期盛冰阶以来的断裂平均活动速率明显增加，介于1．0—2．1mm／a之间，合理的估计值为1．3±0．3mm／a，末次冰盛期以来断裂垂直活动速率的增加极可能是该断裂带进入地震丛集期的反映。该地堑近于严格的南北走向及其与当雄-羊八井地堑相似的活动强度，指示了下地壳物质侧向流动所产生的纵向拉张作用最有利于该区近南北向裂谷带的形成。

英文摘要：

The Cona-Nariyong Co graben, forming the southern section of the NNE trending Cona-Woka rift zone which is the only rift located at the east of the Yadong-Gulu rift zone in Southern Tibet,is a north-trending extensional basin in eastern Himalaya Mountains. The basin is about 80km long and 1 - 10km wide and contains three small paleodammed lakes called Nariyong Co,Yang Co,and Yaba Co from north to south respectively. There are 4 sets of tills and fluvioglacial deposits, corresponding to the Nyanyxungla Ice Age, Jilongshi Ice Age, Ronbushi Ice Age, and Holocene glaciations respectively from oldest to youngest. Eight samples of calcareous sands and coats for U-series and coarse-fine grained sands for TL datings respectively were collected from natural and digging exposures either within or associated with the moraines and fluvioglacial deposits. The dating results show that the first（oldest）set of tills was formed before marine isotope stage MIS 6 ; the second set of tills was formed during MIS 6, and the third and fourth moraines were formed during the last glacial maximum and the Holocene glaciations respectively. Based on remote images and field survey, the main boundary fault of the graben is found to be located at the western margin of the Cona-Nariyong Co Basin. It is a N-trending and east dipping normal fault and about 110km long extending from 15km south of Bangla pass to 15km north of Wushankou pass of Cona County,and is the seismogenic fault of 1806 M 7.5 Cona earthquake. It extends in the Tethyan Himalya Block to the north and cuts the south Tibetan Detachment into the High Himalaya Block to the south. In that region,the fault prominent offset Tethyan foldthrust belt containing Triassic-Cretaceous sedimentary rocks, and the 80km long central segment of normal fault offset Quaternary deposits showing obvious activity during Quaternary or Late Quaternary. Based on restoration of geological structure and paleo-topography and measurement of fault scarp offset moraine platform and fluviaoglacial terrace