Abstract: The Eastern Kunlun Fault zone in northern Tibetan Plateau is one of the largest active fault zones in the world,demonstrated by a composite surface rupture zone of more than 700km long. However,the quantitative studies of the fault zone have remained scarce until recently mostly due to the difficulties of carrying out field investigation in this area. In this paper,we analyze offset values along the fault and their relevant TL and 14 C dating samples collected during our field investigation,from which we estimate the Holocene horizontal slip rates and earthquake recurrence intervals along the fault segment between the Toson Hu Lake and Kendingna (east Maqen). It is found that roughly along the Maji peak of the A'nyemaqen Mountains,the eastern Kunlun Fault section can be subdivided geometrically into two discontinuous segments:the Huashixia segment (from the Toson Hu Lake to the Maji Peak) and the Maqen segments (from the east of the Maji Peak to east of Kendingna). These two segments have significantly different Holocene slip rates and paleo-earthquake activities,with increased activity on the Huashixia segment. The Holocene horizontal sinistral slip rate on the Huashixia segment is estimated to be 11.5?1.1mm/a from five offset locations,while that of Maqen segment to be 7.0?0.6mm/a from study of four offset measurements. Furthermore,the vertical differential rising rates caused by the fault are estimated to be 2 1?0 3mm/a for the Huashixia segment since 4ka BP,and about 0.55mm/a for the Maqen segment since 10ka BP. These significant differences in the slip rates between the two segments indicate strongly some behavioral changes for the eastern Kunlun Fault striding over the Maji peak of the A'nyemaqen Mountains; meanwhile,the relatively large vertical differential rising rates may support a rapid Holocene rising of this region.

Key words: Kunlun Fault, Holocene slip rate, river terrace, fault displacement

摘要： 文中通过对东昆仑活动断裂带托索湖至玛曲段的实际野外测量,获得了该段上的1组断裂位错实测数据和¹⁴C及TL测年样品。通过室内分析研究,发现大体以阿尼玛卿山玛积主峰为界,东昆仑活动断裂带托索湖至玛曲段可再分为花石峡段和玛沁段2个在几何上不连续的段落,花石峡段的全新世水平滑动速率(11.5±1.1)mm/a明显高于玛沁段(7.0±0.6)mm/a。此外,由于断裂而引起的断裂两侧的差异垂直隆升速率,花石峡段自4kaBP以来约为(2.1±0.3)mm/a,玛沁段自10kaBP以来约为0.55mm/a。这种差异垂直隆升速率的明显变化,一方面反映了东昆仑活动断裂带不同段落上活动的差异,另一方面也可能反映了研究区内全新世以来的快速隆升。

关键词: 东昆仑活动断裂带, 全新世滑动速率, 断错地貌, 河流阶地, 断层位错