辽宁抚顺地区铁矿地球物理模型——以毛公堡铁矿为例

GEOPHYSICAL MODEL OF IRON DEPOSITS IN FUSHUN REGION OF LIAONING PROVINCE:A Case Study of Maogongpu Iron Mine

辽宁抚顺地区铁矿十分丰富.它们与著名的鞍本铁矿同属辽东吉南成矿带.成矿地层均为鞍山群,属沉积变质型铁矿,受变质岩系层状控制明显.鞍山-本溪地区为鞍山群的茨沟岩组、樱桃园岩组;抚顺-清源地区为鞍山群的石棚岩组、通什村组.它们具有相似的岩性组分和物性特征.通过开展“深部盲矿体勘查技术研究”科研项目,以抚顺毛公堡铁矿为例,总结分析抚顺地区铁矿的重磁电物性特征,建立了地球物理模型.研究认为,应当打破传统的以磁测为唯一手段的磁铁矿勘查工作模式,开展重、磁、电联合勘查是可取的、有效的.在水平定位技术方面,重力方法有其独特的优势;在垂向定位技术方面可以开展电(磁)测深工作.磁铁矿的极化作用是明显的,应符合低阻高极化.铁矿重磁电特性是高磁、高密度、高极化、低电阻,呈“三高一低”的物性特征,而且品位越高极化率越高.电阻率应不高于2000Ωm,极化率应不低于6%,磁化率不低于100000×10^(-6)SI,密度高于3.00×10^(3) kg/m^(3).

Fushun region of Liaoning Province is rich in iron deposits,which belongs to the eastern Liaoning-southern Jilin metallogenic belt with the famous Anshan-Benxi iron deposits.The ore-forming strata of both are Anshan Group,belonging to sedimentary-metamorphic type and obviously controlled by the stratified metamorphic rock series.The Anshan-Benxi area is developed with Cigou and Yingtaoyuan complexes of Anshan Group,while the Fushun-Qingyuan area with Shipeng and Tongshicun complexes of Anshan Group,and both share similar lithologic compositions and geophysical characteristics.Based on the research project of exploration technology for deep blind orebodies,taking Maogongpu iron mine in Fushun as an example,the paper analyzes the gravity-magnetic-electrical characteristics of iron ores,and establishes the geophysical model.The research shows that the gravity-magnetic-electric integrated exploration is feasible and effective other than the traditional exploration by single magnetic survey.Gravity method has unique advantages in horizontal positioning,while electrical/magnetic sounding works well in vertical.The polarization of magnetite is obvious,presented as low resistance and high polarization.The gravity-magnetic-electrical characteristics of iron ores are high magnetic,high density,high polarization and low resistance.The higher the grade is,the greater the polarizability is.The resistivity should not be higher than 2000Ωm,polarizability no less than 6%,magnetic susceptibility no less than 100000×10^(-6) SI,and the density higher than 3.00×10^(3) kg/m^(3).