辽宁兴城钓鱼台—朝阳娘娘庙地区大地电磁探测及地质意义研究

MT detection and geological structure in DiaoyutaiNiangniangmao region

辽宁兴城地区是我国重要的地质教学实习和地球物理方法仪器试验基地.在多年的建设中,对区域地层分布以及矿床成因等方面开展了大量研究,取得了丰富的基础地质资料,但对于深部构造研究的地球物理资料相对较少.在国家深部探测专项九第六项目(SinoProbe-09-06)的支持下,我们在辽宁兴城钓鱼台—朝阳娘娘庙地区开展了约100km的大地电磁(MT)探测工作.测线横跨该区主要断裂构造带以及古老结晶基底、侵入岩和古生代、中新生代地层以及杨家杖子矿床分布区域.通过对大地电磁剖面的数据处理和反演解释,揭示了该区域燕山期花岗岩、古老基底和晚元古白云岩明显的高阻和较高阻特征,而侏罗系火山岩或火山沉积岩和新生代地层相对的低阻特征.较清楚反映了区域花岗岩岩基和其它侵入岩的侵位关系,特别是杨家杖子矿床的形成时空特征与燕山期花岗岩的侵入关系.为探讨结晶岩系的形成时代、构造环境和侵位机制,对比分析不同岩体的岩浆侵入期次和变质—变形序次,以及研究区域地质构造的演化规律提供了重要的地球物理资料.对于揭示该地区深部构造、岩浆侵入以及动力学演化规律,探索区域成矿背景都具有重要意义.

The Xingcheng area of Liaoning province is not only an important practice base for geology education but also a test base for geophysical methods and instrument. There are a lot of geological studies carried out strata distribution, sedimentary characteristic and tectonic evolution in the last few years. Unfortunately, there were few geophysical detection works, especially for the deep geophysical detection is almost not carried out. It is lack of the basic information for deep structure, magrnatic intrusion and dynamic evolution study. Based on the support of SinoProbe-09-06, we carried out the magnetotelluric （MT） detection in the region from seaside of Xingcheng to Niangniang temple. The survey line is along northwest and passed through the ancient crystalline base, intrusive rock, Paleozoic, Mesozoic and Cenozoic strata, as well as important mineral deposits in the area. Through the processing, interpretation and inversion of the magnetotelluric observation data, it reveals regional crystalline basement and granite body with significantly higher resistivity characteristics, Paleozoie and Cenozoic stratigraphy with relative low resistivity. The resistivity inversion image reflects the areas rock foundation and other magmatic intrusions emplacement clearly. Based on the detection of MT, it is provide information on studying the formation of crystalline rock, tectonic setting and emplacement mechanism, also studying different metamorphic-rock during magma intrusion and deformation sequence, and regional tectonic evolution. By more dense detection in Yangjiazhangzi zone, it provides important data to study Yangjiazhangzi deposit formation and the relationships of spatial-temporal characteristics of Yanshanian granite intrusive. So the research on the MT profile is important for continent dynamics, deed structure,magma intrusion and dynamic evolution of Xingcheng-Niangniang Miao.