吉林省松原地区孤店断裂活动性研究

RESEARCH ON ACTIVITIES OF THE GUDIAN FAULT IN SONGYUAN,JILIN PROVINCE

孤店断裂位于松原市西南、松辽盆地中央凹陷区内。该断裂是通过石油勘探资料解译确认的。在石油勘探资料的基础上,进行了浅层地震勘探、钻孔联合剖面探测、取样测年（OSL）和地貌测量,对其活动性和附近变形带的变形量进行了计算和研究。关于孤店断裂得出以下结论：1）断裂呈弧形,具有逆断裂性质,在T1反射层（下白垩统嫩江组底）破裂总长度66km;2）断裂破裂段中间宽,向外延伸变窄或尖灭,根据T04反射层下白垩统嫩江组4段底界破裂情况,将该断裂分为3段;3）断裂错断上更新统底部的黄色粉土,（33.66±3.27）~50ka BP,其上部的黄褐色粉土层未错动,属于晚更新世活动断裂;4）深井子附近地貌变形9m,变形带两侧上更新统底部垂直落差约20m。另外,1119年松原地区曾发生6级前郭地震,在前人研究其发震构造的基础上,认为孤店断裂可能是该次地震的发震构造。

The Gudian Fault in the southwest of Songyuan is an important fault in the central depression of the Songliao Basin. It was recognized from the petroleum exploration data. Based on the data,we conducted shallow seismic exploration,drilling exploration,age determination（ OSL） and topography measurement. The fault features and its motion characteristics are analyzed with the results of shallow seismic exploration. With stratigraphic correlation and optical stimulated luminescence dating,the latest active age of the fault is determined. The surface relief of the region to the southeast of the drilling site is relatively larger than surrounding places. An 800 m long section across the fault was measured by GPSRTK,and the deformation amount across the zone was calculated. Four conclusions are drawn in this paper：（ 1） The Gudian Fault is arcuate in shape and shows a property of inverse fault with a length of about 66 km in the reflection interface T1（ bottom of the upper Cretaceous Nenjiang Group）.（ 2） The middle part of the fault rupture is wider than the ends,narrowing or dying out outwards. According to this feature and the rupture of the bottom of the fourth segment of the upper Cretaceous Nenjiang Group,the fault can be divided into three segments,e. g. Daliba Village-Gaizijing-Guyang segment,Guyang-Shenjingzi-Julongshan Village segment and Julongshan VillageCaiyuanzi segment.（ 3） The yellow silt layer at the base of the upper Pleistocene series（（ 33. 66±3. 27） ka BP ~ 50 ka BP） is offset by the Gudian Fault,while the upper tawny silt layer is not influenced by the fault. Thus,the fault belongs to late Pleistocene active fault.（ 4） The amount of geomorphic deformation around Shenjingzi is 9m. The depth of the bottom of the upper Pleistocene series is 11 m and the Huangshan Group of the mid Pleistocene series exposes to the southeast of the deformation zone. Therefore,the throw of the bottom of the upper Pleistocene series is about 20 m at the sides of the deformation zone. In addition,the Qianguo M 6 earthquake occurred in Songyuan area in 1119 AD. Though some studies have been done,arguments still exist on the seismogenic structure of the Qianguo M 6 earthquake. Combined with others studies,Gudian Fault is considered as the seismogenic structure of the Qianguo M 6 earthquake.