Search Results (4)

The northern segment of the Tanlu fault zone, which encompasses the Dunhua–Mishan and Yilan–Yitong fault zones, plays a critical role in the tectonic framework of Northeast China. This study focuses on the Hunhe fault, part of the Liaoning segment of the Dunhua–Mishan fault zone, which exhibits concealed characteristics and an NE–NEE orientation. We employ remote sensing and field investigations to accurately delineate the Hunhe fault’s location, scale, and tectonic activity. The findings indicate that the Hunhe fault displays significant spatial variability in tectonic activity. Some segments show evidence of late Quaternary activity, contradicting prior research that classified the Hunhe fault as an active fault during the MIS (Marine Isotope Stages) 20-103MIS 20-103- MIS6-19MIS6-19 period and assessed its seismic potential differently. Recent field investigations suggest considerable spatial variability in tectonic activity, indicating segmental characteristics. In this study, the Hunhe fault is divided into segments based on five aspects: the fault structure and movement characteristics of the fault; transverse faults and obstruction structures; geological and geomorphological characteristics; seismic features; and fault activity. The detailed segments are as follows: the Shenyang segment, the Fushun segment, the Zhangdang-Nan Zamu segment, and the Nan Zamu to Ying Emeng East section. These findings aim to enhance the understanding of the seismic hazard potential associated with the Hunhe fault, highlighting the need for ongoing research to address its complexities and implications for regional seismic risk assessment. Full article

Detailed geological and geomorphological evidence has suggested that the Yilan-Yitong fault (YYF), one of the key branches of the Tancheng-Lujiang fault zone in northeastern China, has been an active fault since the Holocene that has extended from Liaoning Province to far-eastern Asia. However, there are no clear fault traces or late Quaternary active features northeast of Tangyuan County. In this study, we carried out shallow seismic reflection exploration, field geological investigation, and trench excavation across the YYF north of Tangyuan. The results revealed that the YYF is composed of two main branches: the west YYF branch is a late Pleistocene active fault, and the east one is a middle-to-early Pleistocene fault. In Heli Town, the west branch of YYF presents fault scarps with heights of ~0.6 m. Across the scarps, we excavated a trench, and we propose that the YYF displaced the late Pleistocene to Holocene deposits, as this was indicated by the geochronological data. The seismic reflection data and sedimentary sequence revealed that the YYF north of Tangyuan is composed of three tectonic belts: the western depression, the central bulge, and the eastern depression. Each tectonic belt is composed of several small folds formed from the end of the Paleogene to the beginning of the Neogene. After the Neogene, different subsidence and uplift events occurred in various parts of the YYF, and after the early Pleistocene, the fault showed a consistent subsidence. Full article

Northeast China is an area with high energy consumption and high carbon emissions, and the utilization of geothermal resources can effectively overcome these problems. However, there are few geothermal manifestations in Northeast China and no systematic method for geothermal exploration at present, which hinders the utilization of geothermal resources. Here, a systematic analysis, including hydrochemistry, petrology, isotopes, controlled source audio magnetotelluric sounding, drilling, and temperature curve of two boreholes was carried out to investigate the genesis of geothermal resources in Tonghe County, Northeast China, along the Yilan-Yitong lithospheric fault (YYF). We found that the geothermal water is alkaline Na-HCO₃ type water, is of local meteoric origin, and is recharged from the hilly area with an elevation of ~280 m around the study area. We established a geothermal water circulation path model: (1) cold water infiltrated along the YYF to a depth of 2–3 km, (2) cold water was heated by mantle heat, and (3) hot water was stored in sandstone/siltstone, forming a sandstone geothermal reservoir with a temperature of ~70 ℃. These results have important guiding significance for the scientific exploration of geothermal resources in Northeast China. Full article

Using global positioning system (GPS) observations of northeastern China and the southeast of the Russian Far East over the period 2012–2017, we derived an ITRF2014-referenced velocity field by fitting GPS time series with a functional model incorporating yearly and semiannual signals, linear trends, and offsets. We subsequently rotated the velocity field into a Eurasia-fixed velocity field and analyzed its spatial characteristics. Taking an improved multiscale spherical wavelet algorithm, we computed strain rate tensors and analyzed their spatial distribution at multiple scales. The derived Eurasia-referenced velocity field shows that northeastern China generally moved southeastward. Extensional deformation was identified at the Yilan–Yitong Fault (YYF) and the Dunhua–Mishan Fault (DMF), with negligible strike–slip rates. The principal strain rates were characterized by NE–SW compression and NW–SE extension. The dilation rates show compressional deformation in the southern segment of the YYF, northern end of the Nenjiang Fault (NJF), and southeast of the Russian Far East. We also investigated the impact of the 2011 Tohoku M_w 9.0 earthquake on the crustal deformation of northeastern China, generated by its post-seismic viscoelastic relaxation. The velocities generated by the post-seismic viscoelastic relaxation of the giant earthquake are generally orientated southeast, with magnitudes inversely proportional with the epicentral distances. The principal strain rates caused by the viscoelastic relaxation were also characterized by NW–SE stretching and NE–SW compression. The dilation rates show that compressional deformation appeared in the southern segment of the DMF and the YYF and southeast of the Russian Far East. Significant maximum shear rates were identified around the southern borderland between northeastern China and the southeast of the Russian Far East. Finally, we compared the multiple strain rates and the seismicity of northeastern China after the 2011 Tohoku earthquake. Our finding shows that the M_L ≥ 4.0 earthquakes were mostly concentrated around the zones of high areal strain rates and shear rates at scales of 4 and 5, in particular, at the DMF and YYF fault zones. Full article