【作者】 张忱；

【导师】 潘保田；

【作者基本信息】 兰州大学 ， 第四纪地质学， 2012， 硕士

【摘要】 祁连山脉分布于青藏高原东北缘,整体呈北西西-南东东方向,绵延1000多公里,南北宽约400公里。榆木山分布于祁连山中段,位于活跃的仍在生长的祁连山山前地带,是在东北向逆冲的隐伏断层上盘发育的一个生长褶皱。新生代以来榆木山地块内部断裂活动强烈,活动性由南往北逐次变新且活动强度向北逐渐增强。本文提取了榆木山地区的河长坡降指标(SL),面积高度分析(HI)与流域不对称性(AF)地貌指数,分析发现榆木山南坡与北坡的地貌指数存在明显的差异。SLk Z-score参数是地统计方法中预测误差与克里金标准差的比值,在榆木山地区Z-score异常值分布于距断层线250m范围以内,较好的反映了榆木山构造活动(断层活动)。流域不对称性(AF)在榆木山南北坡呈相反分布,可能是由于榆木山北西西-南东东方向的活动背斜所造成的；北坡最西端AF分布可能反映了榆木山背斜在东西向的扩展生长；榆木山北坡HI值明显较南坡高,表明相对南坡北坡在地貌侵蚀阶段上较“年轻”,榆木山南坡侵蚀较弱,而北坡侵蚀较强烈。这是由于该地区在新生代以来断裂的强烈活动所致,这些断裂由南往北逐次变新,强度和规模逐次增强,反映出榆木山背斜下部的祁连山北缘隐伏逆断层由山体向北部盆地逆冲发展的过程。同时,榆木山地区的地貌指数分析说明了在构造变形速率较慢的区域,地貌形态特征也可以有效的指示区域构造活动特征。更多还原

【Abstract】 The Yumushan Mountain is located at the front of the actively growing mountain range of the Qilianshan Mountain, which is trending NWW-SEE for more than1000km at the northeastern margin of the Tibetan Plateau. The Yumu Shan is the topographic expression of the actively growing fault-propagation fold developed in the hanging walls of the reverse fault along the NE margin of the Qilian Shan. The fault is a system of mostly northeast-vergent buried reverse faults which has not yet broken the Quaternary surface. The Yumu Shan block is tectonically active since the Cenozoic, and the acitivity successivly becomes younger from south to north, and the magnitude gradually weaken from south to north.We calculated stream-length gradient (SL), hypsometric curve (HI) and asymmetry factor (AF) along the Yumu Shan, and found that there are significant differences with these indexes between the north and south flanks of the Yumu Shan. SLk analysis shows a strong correlation between the abnormal Z-score and fault distribution. The contrary distribution of AF in northern and southern Yumu Shan probably correspond to growing of the Yumu Shan anticline, whose formation is related to the buried reverse faults along the northern margin of the Qilian Shan. Hypsometric curve analysis and HI values show differences between northern and southern mountain ranges, probably due to tectonic activity intensity and lithologic differences. The tectonic activity in northern flank is stronger than in southern, but the erosion intensity is weaker than in northern. The geomorphic index analysis along Yumu Shan demonstrate that the landform characteristics can effectively indicates the characteristics of regional tectonic activity in the region of slow tectonic deformation rate.更多还原