青藏高原东北缘武威盆地内部全新世伸展构造特征及其成因机制

武威盆地位于青藏高原东北缘北祁连山与龙首山之间的河西走廊东端，全新世期间处于北东向挤压环境中。野外地质调查发现，武威盆地内部发育有两组走向近于垂直的正断层，即北西西走向和北东走向的正断层。光释光测年结果表明，两组正断层在0.70 ka、0.49~0.18 ka发生了两期构造活动。分析结果认为，北西西走向正断层是由武威盆地内部坟门山隆起持续隆升所产生的垂直于地层层面的差异应力作用所形成；北东走向正断层可能是盆地两侧近东西走向左旋走滑断裂控制下形成的张性破裂（T破裂），也不排除是由在青藏高原北东向挤压作用下，与挤压应力相垂直方向上的伸展作用形成。因此，晚全新世期间武威盆地的构造变形受到青藏高原东北缘构造的控制。 

Characterization of the Holocene extensional structures in the Wuwei Basin, northeastern margin of the Tibetan Plateau, and their formation mechanism

The Wuwei Basin at the eastern end of the Hexi Corridor, between the North Qilian Mountain and the Longshou Mountain in the northeastern margin of the Tibetan Plateau, was in a NE-trending compressional environment during the Holocene. Our field survey results indicate that there are two groups of near-vertical normal faults, namely the NWW-trending and NE-trending faults. The OSL dating results show that the two groups of normal faults experienced two periods of tectonic activity in 0.70 ka and 0.49~0.18 ka. The analysis conclude that the NWW-trending normal faults were formed by the differential stress perpendicular to the stratigraphy, which was produced by the continuous uplift of the Fenmenshan uplift in the Wuwei Basin. The NE-trending normal faults could be the extensional rupture (T rupture) produced by the nearly EW-trending sinistral strike-slip faults on both sides of the Wuwei Basin, or be formed by the extension vertical to the NE-trending compression of the Tibetan Plateau. Therefore, the tectonic deformation in the Wuwei Basin was controlled by the tectonic activities in the northeastern margin of the Tibetan Plateau during the late Holocene.