| As the western boundary fault of the Songliao Basin and the eastern margin of the Greater Hing'an Mountains,Nenjiang - Balihan Fault Belt is located in the central part of Northeastern China, 1200 km long with NNE trending and going through Heilongjiang, Jilin provinces, Inner Mongolian Autonomous Region to Hebei Province. Its distribution starts from Huma along the Nenjiang River southward to the Molidawa, Qiqihar and Tailai in Heilongjiang province, via Baicheng in Jilin Province to Baiyinnuoer of Eastern Zhaluteqi, Western Naiman, Pingzhuang and Balihan in Inner Mongolia Autonomous Region, then links to the Pingchang - Sangyuan Fault in Hebei Province. As one of important faults with NE-striking in the Northeastern China, and its special tectonic setting in the center of the Heilongjiang Microplates and its main part consisting of the boundary between Hing'an Microplate and Songnen Microplate, it is very important to do the research of this fault belt.Nenjiang-Balihan Fault Belt is considered traditionally to be a huge deep-seated fault with NNE-striking, and it is characterized by a normal fault or detachment fault. This study shows many new recognitions to understand the Nenjiang– Balihan Fault Belt, The detail works are as follows:By the measurement of structural elements in the ductile shear zones in different segment along the Nenjiang - Balihan Fault Belt in the field, we found that all of the ductile shear planes in the different segment are NE-striking with SW-/NE-trending sub-horizontal lineation. S-C fabric and eyeball-shaped textures indicate a sinistral shear direction. Therefore, we suggest that the Nenjiang– Balihan Fault Belt has experienced a sinistral strike-slip developing stage, and we also found that the shear zones developed in each segment along the fault belt are locally NE-striking, which are different from the fault belt as a whole with a regional NNE-striking.The microscopic studies of the ductile deformed rocks from the shear zones in different segments along the Nenjiang - Balihan Fault Belt show that the rocks mainly consist of porphyroclast including feldspar, quartz and mica, and the matrix including quartz, epidote, chloritoid, mica and other matrix components. But the deformations are different in each shear zone. The deformations in the Jixing and Tengke shear zones are relatively strong and develop mylonite-ultra-mylonite with ca. 400-450℃deformation temperature, while the deformations in the Nierji, Lingxia, Xiaochengzi shear zones are relatively weak and develop protomylonite-mylonite with ca. 400℃deformation temperature.The micro-structure studies under microscope show that all the rocks develop mineral undulatory extinction, banded extinction, subgrain, core-mantle texture, dynamic recrystallization, quartz band, rotated porphyroclast, S-C fabric, exsolution texture and so on,which indicate that the dynamic metamorphism developed common in the studied shear zones. The S-C fabrics, rotated porphyroclast, mica fish and domino-textures indicated that all of the ductile shear zones in the study area has undergone sinistral strike-slip deformation. The textures, such as deformed lamellae, undulatory extinction and bending deformation of the feldspar, and single crystal quartz band, in Tengke shear zone suggest relatively stronger ductile shearing than in other shear zones.The finite strain measurement of the ductile deformed rocks with Fry method in the each shear zone and the Flinn diagram projections suggest that the ductile shearing is characterized by flattening shearing strain in Tengke area, which is different from the extensional shearing strain in Nierji, Lingxia and Xiaochengzi area. In Nierji area, ductile deformed rocks is classic L-type with strong mineral elongation, but ductile deformed rocks in Lingxia and Xiaochengzi shear zones is L/L-S type with the K-value close to 1.By the measurement of the dynamically recrystallized quartz grain size we calculated the paleo-stresses which are 23.23Mpa, 18.22 Mpa, 18.87Mpa, 29.2 Mpa and 12.22 Mpa by linear regression process method and 25.79Mpa,20.3 Mpa,22.16 Mpa,41.32 Mpa and 16.57 Mpa by peak value frequency method in Jinxing, Tengke, Nierji, Lingxia and Xiaochengzi respectively.The interpretation of the gravity data in the Northeastern China shows that the Nenjiang - Balihan Fault Belt consists of a series echeloned and parallelled linear anomaly, considering the difference of shear plane strike directions in each shear zones from the general strike direction of the fault belt as a whole, and the differences of ductile deformation, strain type, paleo-stress and evolution in each shear zones, we suggest that the Neijiang-Balihan Fault Belt with NNE-strike is not a simple single fault, but consists of a series of NE-striking echeloned and paralleled faults in Galashan, Jinxing, Tengke, Nierji, Lingxia, Xiaochengzi.The studies on comparing Wolegen Rock Group occurred in both sides of the Nenjiang-Balihan Fault Belt and the Extension of Xar Moron River fault under the Songliao Basin suggest ca. 40-50 km accumulated lateral-slip offset along the Nenjiang-Balihan Fault Belt.Based on the summarizing of the isotopic geochronological data from the Nenjiang-Balihan Fault Belt and the regional tectonic setting studies, we conclude that the Fault Belt have different evolutions in different segment with the time: (1)Extension period in early Early Cretaceous (145-134 Ma), mainly occurred in the Galashan shear zone in the north. (2) Sinistral strike-slip period in middle Early Cretaceous (134-113Ma), as the main deformation stage occurred in Jinxing, Tengke, Nierji, Lingxia and Xiaochengzi shear zones in the middle and south. (3) Extension stage after Early Cretaceous (after 113 Ma), main occurred in the Xiaochengzi shear zone in the south.The dynamic tectonic setting of the Nenjiang-Balihan sinistral strike-slip ductile shearing,and the style which have a small angle between several ductile shear zones'striking and the Nenjiang-Balihan Belt's striking are related to moving direction changing from NWW to NNW of the Western Pacific Izanagi Plate obliquely subducting under the Eurasia Plate with a high-speed of 30 cm/y in 135-127Ma.
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