# Quaternary Segmentation Characteristics of the Hunhe Fault, Northeast China
## 4 Results
### Zhangdang-Nan Zann Segment  
* 1 The fault structure and deformational characteristics of the fault  
Distributed across mountainous and hilly areas, the fault spans a length of 30 km and consists of 3 to 4 main branches, forming a fault zone (Figure 7). It is slightly curved or parallel in shape, with a composite branching structure that is compact and well-connected. The fault extends in a gently undulating and stable manner, with a clear appearance, trending at 70\({}^{\circ}\)-80\({}^{\circ}\). Overall, it has a northern inclination with a steep dip. The most recent movement characteristics indicate a right-lateral strike-slip combined with normal dip-slip, with the primary activity manifested as creeping.
* 2 Transverse faults and obstruction structures  
The western boundary is defined by the NE-trending Dahada fault and the Fushun Basin, while the eastern boundary is marked by the NW-trending Suzihe fault and the Nanzamu Basin. The Hunhe fault is discontinuous on both sides, resulting in fault offsets or structural steps.
* 3 Geological and geomorphological characteristics  
Located in a low mountain and hilly area with exposed bedrock (Figure 8), the fault is characterized by well-developed strip-like gullies and steep slopes or cliffs. However, no fault-related microtopography has been observed on the alluvial fans at the foot of the mountains where the fault passes. There is no development of Quaternary fault basins along the fault, and there are no continuous, complete, or extensive Quaternary deposits. The thickness of the Quaternary sediments in this section is not comparable to those in other segments.  
Figure 7: Detailed structure and seismic tectonic map of the Hunhe fault in the Zhangdang-Nan Zamu segment.  
4 Seismic features  
Located at the boundary of the Tieling-Jingyu uplift, the fault cuts through and controls the crystalline basement and cover layers, with the middle to upper Proterozoic, Mesozoic, and Paleogene strata exhibiting a strip-like distribution along the fault zone. Early intense reverse thrusting formed a north-to-south stepped reverse thrust-and-overthrust belt. This area is characterized by a new structural uplift with a gradual overall rise. There are noticeable differences on both sides of the fault, with the northern side showing a more pronounced uplift. The fault zone is large and structurally complex, showing features such as nylonites, schists, and graphitization. It also exhibits various structural features like cataclastic rocks, lenticular bodies, crushed rocks, and fault gouge. However, the width of the broken zone formed by recent Quaternary activity is relatively small. The crushed rock and fault gouge are loose and unconsolidated. The fault has cut through the base of the Quaternary strata, while the upper layers remain relatively intact. The intensity and frequency of seismic activity along the fault are very low, with no records of destructive earthquakes, and the current minor seismic events are sporadic in distribution.  
Figure 8: Typical fault movement surface of the Hunhe fault zone on Zhangdang-Nan Zamu segment (photo courtesy of [PERSON]). The red arrows shows the fault trace in the photo.  
5 Fault activity  
Multiphase activity is evident, with intense reverse thrusting during the Yanshan period to the Paleogene. In the Neogene, the activity shifted to extensional and torsional movements, with a decrease in intensity. The Quaternary period saw a further significant reduction in inherited extensional activity, with the most recent activity occurring in MIS 2-5, characterized by weak activity levels.