内蒙古狼山成矿带深部地质结构特征

内蒙古狼山成矿带由于特殊的构造位置，地层出露较齐全、岩浆活动频繁、构造复杂。受自然条件等因素影响，狼山成矿带的深部地球物理勘查工作较少，对深部地质结构特征的总体研究程度较低，无法深入研究区域深部构造特征。为此，利用两条垂直于主要地质构造走向的大地电磁测深和重磁探测综合地球物理调查剖面成果，结合地质成果资料，深入研究了狼山成矿带的深部地质结构特征。获得以下认识：1共识别9条断裂(F1~F9)，其中F1为乌拉特后旗—化德—赤峰深大断裂带与温都尔庙-西拉木伦河深大断裂带的交会处，为华北地块与西伯利亚板块两大一级单元的缝合带；2发现多处高阻、高磁性体，为岩浆岩或岩浆岩与古生代及元古代、太古代地层的综合反映；3在F7与F4之间、F2与剖面Ⅰ东南端点间及F1与F3之间呈低阻特征，为中、新生代断陷盆地的反映；4深部断裂F4与F5之间为宝音图隆起，隆起两端呈高密度体凸起，反演电阻率呈高阻两侧低阻的特征，宝音图隆起受F4与F5的影响，其内部次生断裂发育，有多期岩浆岩侵入；5在F1两侧出现明显的波浪起伏式密度异常特征，由华北板块与西伯利亚板块接触挤压、在板块缝合带两侧形成的褶皱构造引起；⑥在F1的大于10km深度、F1与F9的大于20km深度位置存在巨大的低阻异常体，呈“上部直立、下部向北倾”，向下可延伸至莫霍面以下，推断为从地幔上涌的岩浆软流体(或岩浆通道)，为岩浆上溢及深部成矿提供了深部地质条件。

Characteristics of deep geological structure of Lang-shan metallogenic belt in Inner Mongolia

The special tectonic position of the Langshan metallogenic belt leads to its completely exposed strata,frequent magma activities,and complex structure. Affected by natural conditions and other factors,there is little deep geophysical exploration in Langshan metallogenic belt. The features of the deep geological structure are less studied generally,and the research on regional deep structural characteristics is not deep. To study the deep geological structure of the Langshan metallogenic belt,this paper utilizes the results of two comprehensive geophysical survey profiles of the magnetotelluric sounding and the gravity and magnetic detection perpendicular to the main geological structure strike. In combination with the geological data,the deep geological structure characteristics of the Langshan region are deeply studied and the following knowledge is obtained. First,nine fractures (F1-F9) are identified. Specifically, F1 is the intersection of the Urad Houqi-Huade-Chifeng deep fault zone and Wendur Temple-Xilamulun River deep fault zone,and it is also the suture zone of the North China plate and Siberia plate. Second,many high-resistance and high-magnetic bodies are found,which are magmatic rocks or the comprehensive reflection of magmatic rocks with Paleozoic,Proterozoic,and Archean strata. Third,it features low resistance between F7 and F4,between F2 and the southeast end of section Ⅰ,and between F1 and F3,which is the reflection of Mesozoic and Cenozoic fault basins. Fourth,Baoyintu uplift is located between deep faults F4 and F5 with high-density bulges at both ends,and the inversion resistivity is characterized by high resistance and low resistance on both sides. Influenced by F4 and F5,Baoyintu uplift has developed internal secondary faults,with multiple magmatic intrusions. Fifth,there are obvious wavy density anomalies on both sides of F1,which are caused by the folding structure formed on both sides of the suture zone between the North China plate and the Siberia plate. Sixth,huge low-resistivity anomalies develop at the depth of more than 10km in F1 and 20 km in F1 and F9. The upper part of these anomalies is upright,and the lower part is inclined to the north and can extend downward below the Moho surface. It is inferred that the low-resistivity anomalies are magma soft fluids (or magma channels) upwelling from the mantle,which provides deep geological conditions for magma overflow and deep mineralization.