安徽芜湖小六房铁矿地质特征及成矿模式

Geological Characteristics and Metallogenic Pattern of Xiaoliufang Iron Mine in Wuhu City,Anhui Province

小六房铁矿床位于雍镇铁矿田内,距芜湖市城西直线距离约13 km。区域地层为由三叠系中统各组(段)地层组成的一个核部位于裕溪口—龙塘沿—下埠圩—汤沟一线的复式背斜,即裕汤复背斜。该复式背斜两翼发育众多的次一级褶皱,该类次一级褶皱大都具有向斜开阔、背斜紧密的特征,呈短轴状分布。小六房铁矿即位于该复式背斜南东翼之次一级褶皱小六房背斜两翼。结合矿区地质工作成果,在分析区域地质背景的基础上,详细讨论了矿区及矿床地质特征,并进一步分析了矿床成因及控矿因素。研究表明:(1)区内共发现铁矿体9个,编号为I~#~IX~#,分布于小六房背斜两翼,铁矿资源储量规模属于中型,其中V#矿体为主要矿体,矿石类型主要有方解石磁铁矿矿石、阳起石磁铁矿矿石及黑云母磁铁矿矿石;(2)矿区有利的成矿层位为三叠系中统黄马青组一段(T_2h^1)以及三叠系中统徐家山组上段(T_2x^2),区内成矿与碳酸盐岩关系密切,成矿规模往往与碳酸盐岩厚度成正比;(3)小六房铁矿床为与岩浆期后热液活动关系密切的以热液充填作用和接触交代作用为主的热液型铁矿床;(4)岩体与地层的接触部位以及岩体隆起形成的凹陷区为成矿有利空间;(5)小六房铁矿的成矿模式主要为岩浆演化中析出的铁质进入到岩浆期后气液中,随着气液上升,交代上部底层,将萃取出的铁质沉积于岩凹或岩浆岩接触带附近的空间中形成矿体。上述分析对于在小六房矿区乃至雍镇铁矿田内进一步开展铁矿勘探找矿工作有一定的参考价值。

The Xiaoliufang iron deposit is located in the Yongzhen iron ore field, and and the straight-line distance of the deposit and the west part of Wuhu City is about 13 km. The regional strata is the duplex anticline that is formed by the Triassic Middle Group （Section） Formations, and the anticlinal core is distributed in Yuxikou-Longtangyan-Xiabuyu-Tanggou area,the duplex anticline can be named as Yutang duplex anticline. Many secondary folds are developed on the both sides of the duplex anticline,most of the secondary folds with broad syncline and closely anticline, and they area distributed with the shapes of short shaft. Xiaoliufang iron deposit is located in the both sides of Xiaoliufang anticline that is the secondary fold and located in the southwest of Yutang duplex anticline. Combing with some related geological working results of Xiaoliufang iron mining area, based on analyzing the regional geological back- ground, geological characteristics of the mining area and deposits are discussed in depth, besides that, the deposit genesis and ore-controlling factors are further analyzed. The study results show that：（1）five iron ore-bodies are found in the mining area, they named as Ⅰ# -Ⅸ#, and the ore-bodies are distributed in the both sides of Xiaoliufang anticline , and with the medium scale of iron resources reverses , among them,Ⅴ# ore-body is the main one in the mining area,the ore types are mainly for calcite magnetite ore,actinolite magnetite ore and biotite magnetite ore;（2）the favorable metallogenic layers in the mining area are the First Section of Huangmaqing Formation of the Middle of Triassic （ T2h1 ） and the Upper Section of Xujiashan Formation of the Middle of Triassic （T2x2） ,the metallogenic in the mining area is closely related to carbonate rocks,the metallogenic scale is proportional to the thickness of carbonate rocks frequently; （3）Xiaoliufang iron deposit is belongs to the hydrothermal type iron deposit that is closely related to hydrothermal activities and mainly for hydrothermal filling effect and contact metasomatism;（4）the favorable metallogenic spaces are the contact area of rock mass and strata and the sag area caused by rock uplift; （5）the metallogenic pattern of Xiaoliufang iron deposit can be described as with the raising of gas and liq- uid,the metasomatism of the upper bottom is conducted by the iron compositions that is coming from the process of magmatic evolution and it is entered into the gas and liquids after magmatic stage, and the iron compositions that is extracted from the upper bottom is deposited on rock sag and the contact area of magmatic rocks to form the iron ore-bodies. The above analysis results related the geological characteristics and metallogenic pattern of Xiaoliufang iron deposit can provide some reference for the further prospecting and exploration work of iron deposit in the mining area and Yongzhen iron ore field.