钟姑矿田姑山、太平山铁矿床成因研究

发布时间：2018-04-29 17:09

本文选题：钟姑矿田 + 太平山　；参考：《合肥工业大学》2015年硕士论文

【摘要】：太平山铁矿床位于长江中下游成矿带宁芜火山岩盆地南段的钟姑矿田北东部。与区域玢岩型铁矿赋矿岩石为闪长玢岩不同的是,太平山铁矿床赋存在二长岩中,对其研究十分薄弱,有关二长岩的形成时代、地球化学特征、成矿意义均不清楚。本文对赋矿二长岩开展LA-ICP-MS锆石U-Pb定年和岩石地球化学特征分析,探讨其成岩成矿地质意义。研究显示,太平山铁矿床中赋矿二长岩的锆石2o6Pb/238U加权平均年龄在129.0±2.0Ma～132.8±1.8Ma之间,属于早白垩世,与钟姑矿田内其它铁矿床的赋矿岩石年龄是一致的,与整个宁芜火山岩盆地内赋矿的闪长质岩浆活动时限也相吻合；二长岩的岩浆起源及演化与钟姑矿田、宁芜火山岩盆地内的赋矿闪长玢岩具有相似的特征,起源于富集的交代岩石圈地幔并受到地壳物质混染,同样具有铁成矿意义；太平山铁矿床的成岩成矿作用应形成于中国东部整体岩石圈减薄的地球动力学背景。姑山矿床是宁芜矿集区最有成因争议的铁矿床。本文在全面认识姑山矿床的区域地质背景和矿床地质特征的基础上,对比研究姑山矿床中岩石地球化学、矿石矿物化学等特征,厘定姑山矿床矿床成因类型,从而进一步明确姑山铁矿石的可能形成过程。对姑山矿床中不同结构构造的铁矿石化学成分分析,野外地质特征如矿石的气孔构造,块状构造等都具有岩浆成因的特点,铁矿石富集重铁元素也说明成矿铁质来源于深部岩浆房,姑山矿床矿石磷灰石稀土元素特征值介于典型的热液矿床和岩浆矿床的磷灰石稀土元素特征值之间等特征,这些研究都表明大部分铁矿石是岩浆成因的,虽然矿床中广泛发育的高岭土化、硅化和碳酸盐化,矿石中许多磁铁矿被赤铁矿交代而呈现假象磁铁矿的结构,这些都说明了矿床形成受热液活动影响,但并不是矿床形成的主要作用。
[Abstract]:The Taipingshan iron deposit is located in the north and east of Zhonggu ore field in the southern section of Ningwu volcanic basin in the middle and lower reaches of the Yangtze River metallogenic belt. Different from the diorite porphyrite hosted by regional porphyrite, the Taipingshan iron deposit is located in the monzonitic rock, and the study on it is very weak. The formation age, geochemical characteristics and metallogenic significance of the monzonite are not clear. In this paper, LA-ICP-MS zircon U-Pb dating and petrogeochemical characteristics of ore-bearing monzonites are analyzed, and the geological significance of their diagenetic mineralization is discussed. The results show that the zircon 2o6Pb/238U weighted average age of the ore-hosting monzonite in the Taipingshan iron deposit is between 129.0 卤2.0Ma~132.8 卤1.8Ma, which belongs to the early Cretaceous and is consistent with that of other ore-hosting rocks in the Zhonggu ore field. The magmatic origin and evolution of the eryanite are similar to those of the ore-bearing diorite porphyrite in the Ningwu volcanic basin, and the ore-bearing diorite porphyrite in the Ningwu volcanic basin is similar to the ore-bearing diorite porphyrite. The metasomatic mantle originated from the enriched metasomatic mantle and mixed by crustal materials has the same significance of iron mineralization. The diagenesis and mineralization of the Taipingshan iron deposit should be formed in the geodynamic background of the whole lithosphere thinning in eastern China. The Gushan deposit is the most controversial ore deposit in Ningwu ore concentration area. On the basis of a comprehensive understanding of the regional geological background and geological characteristics of the Gushan deposit, this paper makes a comparative study of the characteristics of rock geochemistry and ore mineral chemistry in the Gushan deposit, and determines the genetic types of the Gushan deposit. In order to further clarify the Gushan iron ore formation process. Based on the analysis of the chemical composition of iron ore with different structures in the Gushan deposit, the field geological characteristics, such as the pore structure and block structure of the ore, all have the characteristics of magmatic genesis. The enrichment of heavy iron elements by iron ore also shows that the ore-forming iron comes from the deep magma chamber, and the characteristic value of ore apatite rare earth element in Gushan deposit is between the typical hydrothermal deposit and the characteristic value of apatite rare earth element of magmatic deposit. All these studies indicate that most of the iron ore is magmatic in origin. Although kaolin, silicification and carbonization are widely developed in the deposit, many magnetite in the ore are replaced by hematite and present the structure of pseudomagnetite. All these indicate that the formation of ore deposit is affected by hydrothermal activity, but it is not the main role of deposit formation.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.31

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