格尔木河流域河流地貌演化的研究进展

位于柴达木盆地南缘的格尔木河发源于东昆仑山脉,末端注入盆地中东部的察尔汗盐湖,是该盐湖最主要的补给河流,极大地影响着该盐湖的成盐演化过程。格尔木河的主要支流——昆仑河和雪水河都是由冰川融水形成,因此,该流域内的冰川进退对河流径流量变化和谷地填充地层物源有着重要影响。该河流域内主要的填充地层为昆仑河砾岩(河流相)、纳赤台沟组(冲洪积相)和三岔河组(河湖相)。在三岔河组之上,发育了四/五级阶地,除最高的T₅之外,其他均为以三岔河组为基底的内叠基座阶地。根据前人的研究,昆仑河砾岩沉积的年代为1269至1042 ka(ESR年龄)；纳赤台沟组堆积于482至642 ka之间(ESR和TL年龄)；三岔河组形成于355-95 ka(ESR和U系年龄)、90-16 ka(OSL年龄),T₅-T₁阶地基本形成于16- 4.6 ka之间。由于采用的测年方法不同,不同学者对三岔河组的形成时代存在争议,对阶地的划分也有所不同(四级或五级阶地)。但是对T₅-T₁阶地形成时代有较一致的观点,即末次冰消期和全新世早中期。对于格尔木河河流地貌过程的驱动因素,目前尚存在争论,大部分学者认为是气候变化驱动了该区域河流地貌的形成,但也有学者认为构造活动是主导因素。

Research progress of geomorphic evolution of Golmud River, southeastern Qaidam Basin

The Golmud River which located in the northeastern Qinghai-Tibetan PlateauSoriginates from the Kunlun Mountains, and terminates in Qarhan Salt Lakes. It is the biggest feeder of the salt lakes, thus having a great influence to the Qarhan Salt Lakes. The main fill sediments of the Golmud River valley are the Kunlunhe conglomerate (Ca-cemented fluvial gravels sediments), Nachitaigou Formation (alluvial sediments) and Sanchahe Formation (fluvial/lacustrine sediments), and five or four fluvial terraces formed within the Sanchahe Formation which are all base terraces except the T₅. The previous studies show that Kunlunhe conglomerate formed between 1269-1042 ka (ESR ages), Nachitaigou Formation is 482-642 ka (ESR and TL ages) and Sanchahe Formation formed the period of 355-95 ka (ESR and U-series ages), 90-16 ka (OSL ages). The ages of T₅- T₁ are 16-4.6 ka. Because of the different dating methods employed by different researchers, the forming period of Sanchahe Formation is still a controversy. However, for the forming period of T₅- T₁ terraces, there is a consistent agreement among the researchers. The most researchers agued that the palaeocliamte changes were the main genesis of fill strata and fluvial terraces in Golmud River catchment, but others considered that the tectonic uplift of Kunlun Mountain controlled the process of river landform.