Study On Fault Activity In Jiujiang,Jiangxi Province

Fault activity can lead to tectonic earthquakes and threaten the safety of human life and property.Therefore,the study of fault activity has importantly practical significance.Jiujiang in Jiangxi Province has a good economic development.It has planned and built key national projects such as nuclear power plants and wind power generations.However,from the geotectonic location aspect,Jiujiang is located in the joint of three tectonic plates.It has undergone multi-stage tectonic movements,complicated geological structures,developed faults,and scattered with earthquakes and hot springs.In this paper,I use Landsat-8 and Google Earth remote sensing images to interpret the main fault structures with the features of active faults as remote sensing interpretation markers,and obtain their distribution status.I also analyze the distribution of earthquakes and hot springs.Three groups of fault structures(F3,F4,F5)in Jiujiang area were sampled for fault gouges and surrounding rocks.Mossbauer spectroscopy experiments were carried out to obtain the distribution characteristics of Fe chemical species in fault gouges.Combined with remote sensing interpretation,seismic and hot spring characteristics,the fault activity characteristics in Jiujiang were comprehensively analyzed,and the crustal stability in was evaluated.Research shows that:(1)There are six groups of large-scale fault structures in Jiujiang area,namely Lujiang-Guangji fault zone(F1),Xiangfan-Guangji fault zone(F2),Wuning-Ruichang fault zone(F3),Jiujiang-Jingan fault zone(F4),Tongling-Jiujiang fault zone(F5)and Dongzhi fault zone(F6).(2)Earthquakes in this area are mainly of magnitude less than 3,and Jiujiang area is an earthquake-intensive area.According to historical records,there have been 18 moderate-strong earthquakes with magnitude more than 4,the highest magnitude being 5.7,and no earthquakes with magnitude more than 6 have ever occurred.Generally speaking,the seismicity in Jiujiang area is relatively low.(3)Geothermal resources are well developed in Jiujiang area.The hot springs are mainly of medium and low temperature.Their distribution is corresponding to or similar to the medium and strong earthquake sources with magnitude 4 or above,and there are hot-springs-concentrated areas.(4)F3-1 fault gouge and its surrounding rock are mainly oxidized iron,which is the internal fault or shallow fault in the block;F3-2 fault zone shows reductive environment,indicating that it exchanges with deep underground fluids,and has certain activity nowadays;F4 fault wall rock shows reductive condition,fault gouge is oxidized environment,and fault tends to open: F5 only oxidized iron,showing strong oxidation condition,fault activity is low.(5)Except for the Wuning-Ruichang fault(F3),the activity of the remaining five groups is generally low,and the whole Jiujiang area is in a relatively stable state.F3-1 and F3-2 are the southern and Northern segments of the Wuning-Ruichang fault(F3),The southern segment is relatively stable,and the northern segment has certain activity,which may be the seismogenic fault of the Ruichang earthquake in 2005.The same fault shows different activity,indicating that the fault activity is piecewise.Generally speaking,some faults in Jiujiang area have certain activity,which is the basic reason for the occurrence of small and medium-sized tectonic earthquakes in this area and threatens the construction of major projects.It is suggested that the influence of active faults should be considered in the planning and construction of nuclear power plants and other projects.