中文摘要：

构造地貌学重点关注构造和地表过程对于地形地貌演化的差异化作用,构造活动速率则是评估这种影响的一个重要指标.利用河流阶地数据计算河流下切速率从而约束构造抬升速率是常用的方法,但由于阶地成因复杂,这一方法具有不确定性.对于山前河流地貌序列,基于背斜段与未变形段的阶地拔河高度差以及阶地面形成年龄,计算得到的河流下切速率可在一定程度上消除气候等因素的影响,因此可用于估算背斜自阶地形成以来的平均抬升速率.基于该方法,本文通过研究天山北麓乌鲁木齐河、塔西河、玛纳斯河、金钩河、安集海河及奎屯河等河流在背斜段发育的主要阶地,分析了背斜抬升速率及其时空特征.天山北麓发育3排逆断裂-背斜带,结果表明位于第Ⅱ排逆断裂-背斜带的吐谷鲁背斜自约13ka以来的抬升速率为3.52mm/a,同时期霍尔果斯背斜构造抬升速率为4.8mm/a,玛纳斯背斜东端的抬升速率相对较小,为＜2mm/a；第Ⅲ排构造带中的独山子背斜全新世抬升速率仅为1.2～ 1.9mm/a.这可能表明,自山前向盆地方向晚第四纪背斜抬升速率大致呈减小趋势,与背斜地壳缩短量的空间分布规律基本一致.更多的阶地年龄数据有助于更好地揭示天山北麓晚第四纪背斜构造活动特征.

英文摘要：

Tectonic geomorphology focuses on tectonic and surface processes and their effects on landform evolution,which is generally evaluated by the rate of tectonic activation.It is common to use the data on fluvial terrace （the surface height above the riverbed of a terrace and its formation age） to constrain the rate of river incision and further the rate of tectonic uplift.It is well known that both climate change and tectonic uplift can drive river incision to form the terrace sequence.Given the complexity of terrace formation,the results based on this method are likely incorrect.In the mountain front characterized by thrusting and folding,fluvial terraces preserved within an anticline are generally deformed as a result of fold growth.Beyond this structure,this terrace sequence is seldom affected by folding.Thus,the folded terrace within the anticline can be used to characterize the history of tectonic deformation of this structure and estimate the magnitude and rate of tectonic uplift.As one of the largest and most active mountain ranges in Asia,the Tian Shan exhibits rapid rates of deformation due to north-south convergence driven by the India-Asia collision system during the Cenozoic times.As a consequence,three successive roughly east-west-trending zones of fault-controlled folds have developed in the north piedmont of the Tian Shan,which are Belt Ⅰ （Nan＇anjihai-Nanmanas-Qigu-Changji-Kalazha Anticlines）,Belt Ⅱ （Huoerguos-Manas-Tugulu Anticlines） and Belt Ⅲ （Dushanzi-Hala＇ande-Anjihai Anticlines）,respectively.Subsequently,transverse rivers incise into these anticlines and display well-developed alluvial fans and fluvial terrace sequences.By studying these units,we can better understand the mechanism of river incision and the pattern of tectonic deformation during Late Quaternary in this region.Here,we apply this approach to estimate the uplift rates of the anticlines of the three thrust-and-fold belts in the north piedmont of the Tian Shan based on these river terrace sequences of severa