摘要
温泉盆地西缘断裂在晚第四纪期间经历了多期活动。沿断层至少可以识别出高度分别为0.33～0.62m、4.3～5.2m、6.8～8.3m、10～11.8m、约16m、20～28m、45～50m和65～80m的8套断层崖或断层陡坎,以及与各级断层崖大致对应的河流阶地、洪积扇和泉华台地。地质地貌体的相对时代分析和泉华、河流沉积物中的砾石钙膜、钙质胶结物的U系、ESR测年结果表明,高45～50m、20～28m、约16m、10～11.8m、6.8～8.3m和4.3～5.2m的断层崖可能分别形成于约127kaBP、54kaBP、25kaBP、18kaBP、11kaBP和4kaBP以来或更早。综合分析断裂不同地点的断层崖的高度和时代发现,不同时期的断裂活动强度可能是不同的。其中在约127～25kaBP、25～4kaBP期间,断裂平均的垂直活动速率分别为0.3～0.23mm/a、0.8～0.36mm/a,而约4～1.1kaBP期间的断层最大垂直活动速率可能达1.65mm/a。
Surface observations along the nearly N-S-trending Western Wenquan basin marginal fault in the interior of the Tanggula Mountains show that this fault underwent multi-stage activities during the late Quaternary. Along the fault we may recognize at least eight fault scarps or steep fault slopes whose heights are 0.33-0.62 m, 4.3-5.2 m, 6.8-8.3 m, 10-11.8 m, ～16 m, 20-28 m, 45-50 m and 65-80 m respectively, as well as river terraces, diluvial fans and spring sinter platforms that may largely correspond with these fault scarps. Analysis of the relative ages of geologic-geomorphologic bodies and U-series and ESR dating of calcareous coatings of pebbles and calcareous cements in spring sinters and stream sediments indicate that the fault scarps with heights of 45-50 m, 20-28 m, ～16 m, 10-11.8 m, 6.8-8.3 m and 4.3-5.2 m formed at ～127 ka BP, 54 ka BP, 25 ka BP, 18 ka BP, 11 ka BP and since 4 ka BP. The intensities of faulting were different in different periods. The average rates of vertical movements of the fault during ～127-25 ka BP, 25-4 ka BP and 4-1.1 ka BP were 0.3-0.23 mm/a, 0.8-0.36 mm/a and 1.65 mm/a respectively.
出处
《地质通报》
CAS
CSCD
北大核心
2005年第1期48-57,共10页
Geological Bulletin of China
基金
中国地质调查局项目<青藏铁路沿线活动断层调查与地应力测量>(批准号1212010340302)
<西藏1:25万当雄幅区域地质调查>(批准号DKD9901001)成果。
关键词
青藏高原
温泉地堑
晚第四纪
正断层作用
东西向伸展变形
Qinghai-Tibet plateau
Wenquan graben
late Quaternary
normal faulting
east-west extension
