东北东部虎林盆地的构造特征、成盆机制及敦-密断裂带北东段的形成时代

虎林盆地位于黑龙江省东部，是叠置在佳木斯地块之上的中、新生代断陷-坳陷盆地，其构造变形可以划分为3个构造演化阶段：早白垩世为NW-SE向伸展作用阶段，主要形成一系列各自独立的NE向箕状断陷群；晚白垩世为NW-SE向挤压作用阶段，使部分早期控陷正断层发生反转，形成反转构造，虎林盆地转化为具有多个沉降中心的NE向挤压坳陷盆地群；古近纪-第四纪为NNW-SSE向挤压作用阶段，虎林盆地的构造格局发生了重大变化，不仅使部分早期控陷正断层发生反转作用形成大型反转构造，而且在七虎林河凹陷与中央隆起之间形成NEE向大型逆冲断层（敦-密断裂）和断层传播褶皱，它们共同控制了盆地的形成和沉积作用，虎林盆地转化为具有1个中央隆起和南、北2个坳陷的NEE向挤压坳陷型盆地。东北地区自白垩纪以来始终处于活动大陆边缘的大地构造背景，包括虎林盆地在内的东北东部盆地群的形成与伊泽纳奇板块、太平洋板块向欧亚板块的俯冲作用有关。敦-密断裂带总体上呈NE向展布，具有左行走滑的性质，在靠近虎林盆地的北东段转变为NEE向展布，断层的性质也转变为逆冲断层，敦-密断裂带北东段的逆冲作用很可能与该断裂带的NE向左行走滑作用在NEE向的转换挤压有关。敦-密断裂带自古近纪始新世-渐新世虎林期开始活动，一直持续活动到第四纪。

Structural Features,Formation Mechanism of Hulin Basin and Deformation Time of Northeastern Segment of Dunhua-Mishan Fault Zone in Northeast China

The Hulin basin is a Meso-Cenozoic, down-warped, faulted basin located in the eastern part of Heilongjiang Province, which superimposed on the Jiamusi uplift. The structural evolution can be divided into 3 stages, and the structural characteristics and deformation mechanism for each stage are significantly different. 1)A series of separate NE trending half-graben fault depressions developed at the NW-SE-directed extensional stage in the Early Cretaceous. 2)Some of the early depression-controlling normal faults reversed and formed inversion structures during NW-SE compressional stage in Late Cretaceous, the Hulin basin switched into a depression basin with multi-depocenters under the NW-SE-directed compression depression. 3)The tectonic framework changed significantly at the NNW-SSE-directed compression stage in the Paleogene-Quaternary, not only some of the early depression-controlling normal faults reversed, resulting in large-scale inversion structures, but also the NEE trending large-scale thrust faults (Dunhua-Mishan fault zone) and fault-propagation-related folds between the Qihulinhe depression and the central uplift formed, which together controlled the formation and sedimentation of the basin, and the Hulin basin transformed into a NNE trending, down-warped compressional basin which are composed of the central uplift, the south and the north depressions. The Northeast China has been always in an active continental margin tectonic setting since the Cretaceous. The formation mechanism of Hulin basin, which is included in the eastern basin groups of the Northeast China, is related to the subduction of Izawa Naqi plate, the Pacific plate to the Eurasian plate. The Dunhua-Mishan fault zone are NE trending sinistral strike-slip faults, and the NE segment near the the Hulin basin transform into the NEE trending thrust fault, the thrusting of the NE segment of the Dunhua-Mishan fault zone may be related to the NEE trending transformed compression of the NE trending sinistral strike-slip of the fault. The Dunhua-Mishan fault zone developed at the Hulin period of Eocene-Oligocene, and showed continuously activities from the Hulin period to Quaternary.