论文部分内容阅读
格尔木河河谷中发育有四级河流阶地,均形成于末次冰盛期之后。阶地的形成由构造抬升驱动,四级阶地代表的河流下切过程反映了四次阶段性构造抬升。以三岔河和纳赤台为代表的中游河段,四次河流阶段性下切速率分别为16～13kaBP(T4-T3),3.33～9.33mm/a;13～11kaBP(T3-T2),5.5～12mm/a;11～5kaBP(T2-T1),0.33～1mm/a;5kaBP(T1至今),0.6～0.8mm/a,下切速率自T4至T1先增快后减慢。上游小南川河段5kaBP以来的平均下切速率为4mm/a,显著大于三岔河和纳赤台河段,同期河流溯源侵蚀速率也较快,表明小南川局部地区全新世中期抬升强烈,应为西大滩断裂强烈活动所致。受区域性构造活动差异影响,格尔木河河流阶地在局部地区出现变形,其中在三岔河和最老冲积扇扇顶存在两个下切幅度和速度高峰值,而纳赤台河段下切和缓。表明控制昆仑河和野牛沟发育的昆仑河—野牛沟断裂、山前的红石沟断裂自末次冰盛期以来持续活动。其中,昆仑河—野牛沟断裂16～13kaBP活动速率较快,到13～11kaBP达到最快,11kaBP后减慢,与河流中下游整体构造活动趋势一致。
There are four stages of river terrace in the Golmud valley, both formed after the last ice age. The formation of terraces is driven by tectonic uplift and the process of river undercutting, represented by the four terraces, reflects four stages of tectonic uplift. The middle sub-tributaries represented by Sanchahe River and Nachitai River are respectively 16 ~ 13kaBP (T4-T3), 3.33 ~ 9.33mm / a, 13 ~ 11kaBP (T3-T2) (T2-T1), 0.33 ~ 1mm / a; 5kaBP (T1-present), 0.6 ~ 0.8mm / a, and the rate of undercutting increased from T4 to T1 and then slowed down. The mean sub-shear rate since Xiakaichuan reach of 5 kaBP was 4 mm / a, which was significantly higher than that of Sancha and Nachitai rivers. The traceability of the river was also faster during the same period, indicating that the mid-Holocene in Xiao Nanchuan had a strong uplift and should be westward Big Beach fracture caused by intense activity. Affected by the differences in regional tectonic activity, the Golmud River terraces have deformed in some areas. There are two cutting amplitude and velocity peaks at the top of Sanchahe River and the oldest alluvial fan, while the Nachitai River reaches the lower one. Indicating that the Kunlun-Ye Niuogou fault controlled the development of the Kunlun and Ye Niuogou, and that the Hongshigou fault of the Piedmont remained active since the last ice age. Among them, the Kunlun-Ye Niuogou faulted 16 ~ 13kaBP at a faster rate, reaching the fastest at 13 ~ 11kaBP and then slowing down after 11kaBP, consistent with the trend of the whole tectonic activity in the middle and lower reaches of the river.