Abstract: The Aksay and Subei basins are adjacent to Altyn Tagh fault system formed in Miocene and were considered as one basin cut by Altyn Tagh fault system in late Miocene. By analyzing the composition of the sandstones, it was found that the two basins were filled by different sources. The Aksay basin is characterized by quartz and clast with abundant metamorphic fragments. The Subei basin is characterized by quartz and feldspar with abundant volcanic grains. The two basins are of different heavy mineral assemblage. The Subei basin has much more instable minerals, such as epidote and hornblende which reflect the rapid accumulation. These two basins go through different evolution stages, which show that the two basins are not formed as a single basin, but they are all controlled by Altyn Tagh fault system. The Altyn Tagh fault system was displacing in Miocene and controlled the Aksay basin, while in the Subei basin, Altyn Tagh fault system transformed the displacement into the uplift of Danghe Nanshan which controled the deposition of the Subei basin.

Key words: Akasy, Subei, composition of sandstone, heavy mineral, Altyn Tagh fault system

摘要： 阿克塞盆地和肃北盆地分列于阿尔金断裂两侧，形成于中新世，有人认为它们曾是统一的盆地，在中新世末期由于阿尔金断裂的活动而被分割。然而砂岩成分分析表明，这两个盆地具有不同的物源特征：阿克塞盆地主要以石英和岩屑为主，含有大量的变质岩岩屑；肃北盆地主要以石英和长石为主，含有大量的岩浆岩岩屑。这两个盆地也具有不同的重矿物组合，与阿克塞盆地相比，肃北盆地含有较多的不稳定矿物（绿帘石和角闪石）。两个盆地的形成及演化均受控于阿尔金断裂，但它们最初并非为统一的盆地。推断阿尔金断裂在渐新世开始走滑，并造成阿尔金山隆升，控制阿克塞盆地的沉积；阿尔金断裂的走滑运动造成党河南山抬升，形成了肃北盆地。

关键词: 阿克塞, 肃北, 砂岩成分, 重矿物, 阿尔金断裂