摘要
基于云南鲁甸MS6.5地震震区的3条"工"字形剖面的重力与GPS观测数据,获得了沿剖面的布格重力异常、剩余密度相关成像和地壳密度分层结构。研究表明,会理—鲁甸—昭通、攀枝花—蒙姑—大井、舍块—汤丹—会泽剖面布格重力变化范围分别为-278^-197×10-5ms-2、-273^-200×10-5ms-2、-280^-254×10-5ms-2,均呈"鞍"形分布,其局部低值均位于小江断裂带附近,且幅度差自北向南逐渐减小。小江断裂带内物质密度低于两侧,低密度体扩展至中下地壳,且其东侧物质密度低于西侧,密度异常体呈正负交迭,地壳稳定性低,鲁甸震区处于该区域内。地壳分层结构显示莫霍面以小江断裂带为中心向上抬升,莫霍面最大深度自北向南从50km抬升至41km,反映了小江断裂带在区域地质构造中的地位——川滇块体与华南块体的分界线。
In this paper,based on three gravity profiles in Yunnan Ludian MS6.5 earthquake and adjacent area,we obtained Bouguer gravity anomaly,residual density correlation image and crustal stratification structure along the profiles.The study shows a saddle-shaped distribution of Bouguer gravity anomalies along the Huili-Ludian-Zhaotong,Panzhihua-Menggu-Dajing and ShekuaiTangdan-Huize profile,with the values ranging-278 ～-197 × 10 ～ 5ms 2,-273 ～-200 × 10 ～ 5ms-2,-280～-254× 10 ～ 5ms-2,respectively; the local low values locate in the Xiaojiang fault zone,the amplitude difference decreases gradually from the north to the south; the density in the Xiaojiang fault zone is lower than that of the sides,the low density zone extends to the middle and lower crust,and the material density in the east is lower than that in the west; positive and negative density anomalies overlap,indicating a poor stability of the lower crust.The Ludian earthquake occurred in this region.Layered crustal structure shows the undulation of Moho surface,with uplift beneath the Xiaojiang fault zone as the center and change of the maximum depth of Moho from 50km up to 41km from north to south.This reflects the position of Xiaojiang Fault in the regional geological structure as block boundary of Sichuan-Yunnan block and South China block.
出处
《地震地质》
EI
CSCD
北大核心
2014年第4期1145-1156,共12页
Seismology and Geology
基金
国家自然科学基金(41204014,41274141)
国家重点基础研究发展规划计划(2013CB733304)
中国地震局行业重大专项(201308011)
中国地震局"云南鲁甸6.5级地震专题研究"项目共同资助
关键词
鲁甸地震
重力剖面
布格异常
地壳结构
Ludian earthquake
gravity profile
Bouguer anomaly
crustal structure
