格尔木河流域河流地貌演化研究进展

Research Progress of Geomorphic Evolution of Golmud River,Southeastern Qaidam Basin

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的物源有着重要影响。该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4-5级阶地,除最高的T5之外,其它均为以三岔河组为基座的内叠阶地（少部分河段以昆仑河砾岩为基座）。根据前人的研究,昆仑河砾岩沉积的年代为1 269-1 042 ka（ESR年龄）;纳赤台沟组堆积于482-642 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（4级或5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。

The Golmud River is located in the northeastern Qinghai-Tibetan Plateau,it originates from the Kunlun Mountains,and terminates in Qarhan Salt Lakes,thus having a great influence to the lakes. The main filled 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 T_5. The previous studies show that Kunlunhe conglomerate formed between 1 269- 1 042 ka（ESR ages）,Nachitaigou Formation was 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 T_5-T_1 were 16 - 4. 6 ka. The forming period of Sanchahe Formation is still a controversy,but for the T_5-T_1 terraces,there is a consistent agreement among the researchers. Most of researchers proposed that the palaeocliamte changes were the main genesis of fluvial terraces in Golmud River catchment,but others considered tectonic uplift of Kunlun Mountain controlled the process of the river landform.