六盘山东西两侧第四纪以来构造差异隆升速率递变性

REGULARITY OF TECTONIC DIFFERENTIAL UPLIFTING RATES OF BOTH THE EAST AND WEST SIDES OF LIUPANSHAN MOUNTAIN SINCE THE QUATERNARY

河流阶地作为第四纪以来较新的沉积地貌单元，在研究区域构造隆升和区域断裂活动性方面扮演重要角色。本文利用前人对六盘山东西两侧黄河、渭河及泾河地区阶地研究成果，借用古地磁及。14C等方法测定阶地形成年龄和实测阶地拔河高度已有数据，引进构造差异隆升速率（△Ur）参数来反映区域构造隆升强弱。通过对兰州黄河阶地、陇西渭河阶地与泾河阶地的构造差异隆升速率对比研究表明，第四纪以来，兰州黄河阶地与泾河阶地4个期次平均构造差异隆升速率（△UT）分别为76．87mm／ka、42．88mm／ka、421．06mm／ka和1050mm／ka；平均值为397．70mm／ka；陇西渭河阶地与泾河阶地3个期次内（△UT）分别为177．37mm／ka、171．83mm／ka和168．27mm／ka；平均值为172．49mm／ka。说明六盘山西侧总体活动性要强于六盘山东侧，同时六盘山构造带北段较南段活动性强，并有逐渐增强趋势。其主要原因可能是六盘山西侧区域系列NWW、NNW活动构造发育对应力的转换和吸收占据重要位置，而六盘山东侧依附于较稳定的鄂尔多斯地块，对区域应力的转换和吸收不明显。

As a kind of new sedimentary geomorphology since the Quaternary, river terraces are playing an important role in the study of regional tectonic uplift and fault activity. In this article, we collected the previous study achievements of the Yellow River terraces of the east and west Liupanshan Mountain, the Weihe River terrace and the Jinghe River terrace, meanwhile, we incorporated the formation age according to the paleomagnetic and 14C methods, the measurements of tug-of-war and so on. Based on these data, we built a tectonic differential uplifting rate （△UT） model to reflect the regional activity and the intensity of tectonic uplift based on the parameters of terraces in both the east and west sides of Liupanshan Mountain. First of all, we compared the tectonic differential uplifting rates of the Jinghe River with the Lanzhou segment of the Yellow River terraces, the results show that there are four times of △UT, which are 76.87mm/ka, 42.88mm/ka, 421.06mm/ka and 1050mm/ka. The average of the four rates is 397.70mm/ka. Then, we compared the tectonic differential uplifting rates of the Jinghe River with the Weihe River terraces of Longxi segment, the results show that there are three times of AUT, which are 177.37 mm/ka, 171.83mm/ka and 168.27mm/ka, and the average rate of them is 172.49mm/ka. Two sets of date in each time have been shown positive. The result implies that the activity of the west Liupanshan Mountain is stronger than the east, meanwhile, the north section of Liupanshan Mountain tectonic belt is more active than the south section and increasing gradually. The primary reason may be the transformation and absorption of the NWW, NNW structural development to the tectonic stress in the west Liupanshan Mountain, while its east side clings to the stable Ordos block and the stress transformation and absorption is not so obvious.