内蒙古白云鄂博超大型稀土-铌-铁矿床控矿构造特征及深部找矿方向

对白云鄂博超大型稀土-铌-铁矿田内褶皱及断层构造特征进行了剖析和总结,认为矿区内构造活动演化具有多期性,中元古代—海西期至少发育4期构造活动,包括近东西向控岩断层(F1)、近东西向逆-平移断层(F2)、近东西向褶皱和韧性剪切构造、北东向左行走滑正断层(F3),并将其对成岩成矿的影响及控制作用作了详细分析。认为:①沿白云石碳酸岩与顶底板围岩界线分布的近东西向断层控制了白云石碳酸岩的产出和矿体的形成;②白云石碳酸岩侵位之后,近东西向逆-平移断层对矿体进行了第一次破坏,导致主矿、东矿的深部矿体向东平移,钻孔WK14-01的深部矿体应为主矿深部的矿体平移所致;③成矿期后发育一期近南北向的挤压变形事件对矿体进行了第二次破坏,导致矿区白云鄂博群紧闭褶皱的形成和矿体发生透镜体化;④主矿、东矿之间的北东向左行走滑正断层对矿体进行了第三次破坏,导致主、东矿位置的错动。这些认识将对矿区深部及外围找矿工作具有重要的指导意义。

Ore-controlling structure and deep prospecting of the Bayan Obo large-sized REE-Nb-Fe ore deposit,Inner Mongolia

Analysis on folds and faults of the Bayan Obo REE-Nb-Fe orefield indicates that its structural activities witnessed multistage evolution.There exist at least four periods of structural activities from Mesoproterozoic to Hercynian which control metallogenesis and diagenesis,including the nearly EW-trending litho-controlling fault( F1),the nearly EW-trending strike-slip fault( F2), the nearly EW-trending ductile shear zone and folds and the left lateral strike slip normal fault( F3).Based on a comprehensive analysis it is concluded that: a.The nearly EW-trending fault( F1) distributed along the boundary between dolomite carbonatite and hangingwall or footwall controls the intrusive occurrence and the formation of ore bodies;b.After the emplacement of dolomite carbonatite,the ore body was destroyed by the nearly EW-trending strike-slip faults( F2) for the first time.As a result,the deep ore bodies in the south of the Main and East mines moved from west to east, and the deep orebody encountered by borehole WK14-01 should be caused by the translation of deep orebody in the south of the Main mine;c.The post-ore NS-trending compression destroyed ore body for the second time and brought about tight folding of the Bayan Obo Group strata and lensing of ore body;d. The left lateral strike slip normal fault( F3) distributed between the main mine and east mine destroyed ore bodies for the third time and led to the dislocation of the Main mine and East mine.The above research results and understanding will be of great guiding significance to the prospecting in the deep and periphery of the mine.