【作者】 唐卓；

【导师】 杨兴科；

【作者基本信息】 长安大学 ， 构造地质学， 2008， 硕士

【摘要】 张河磁铁矿矿床位于扬子板块北部被动大陆边缘,隶属于南秦岭迭部-旬阳地层分区牛山地层小区。为近年来在陕南地区新勘查发现的磁铁矿矿床,矿床呈东西向带状分布,东西追索长度约20km,南北宽约2km,矿区面积约为40km2。根据野外地质调查,现已发现13条矿体,全铁(TFe)平均品位约为20%,具有较大的科研价值和经济价值。根据野外地质调查和室内综合研究表明,张河磁铁矿矿床赋矿地层为晚古生代中泥盆统石家沟组。中泥盆统石家沟组可划分为三个地层段:D2s1 , D2s2 ,D2s3。其中磁铁矿主要赋存于D2s2 , D2s3地层段之中。各地层段主要岩性如下:D2s1 (中泥盆统石家沟组第三段):灰色绢云千枚岩夹薄层灰岩;D2s2 (中泥盆统石家沟组第二段):灰-灰绿色灰黑色灰岩夹薄层绢云千枚岩,含磁铁矿层;D2s3 (中泥盆统石家沟组第一段):灰黑色钙质板岩夹灰黑色薄层灰岩,含磁铁矿层。通过对野外地质调查、实测剖面、室内测试等已有工作资料进行系统的总结,对区内成矿地质背景、成矿地质条件进行了分析,初步认为张河磁铁矿矿床是产于晚古生代泥盆纪裂谷环境下热水沉积成矿与动力热液改造作用叠加成矿作用形成的铁矿床,热水沉积作用形成的钠长岩和动力热液改造作用形成的磁铁绿泥大理岩是成矿母岩。原岩为含棘屑石灰岩,石灰岩的重结晶是在变质分异和动力热液多种作用参与下进行的。钠长石、磁铁矿、菱铁矿等均是热水沉积作用期间同时形成的,又共同经历了后期变质分异过程和动力热液活动作用。原岩含棘屑石灰岩同磁铁矿、钠长石一起经历了中-低级区域变质和动力的压碎影像。变质过程中既具有重结晶且有多种流体溶液的参与和交代作用。通过对矿体空间分布规律的研究,认为矿体主要受地层因素和构造因素以及变质作用控制,初步认为石家沟组和梅子垭组之间的韧性剥离断层和神河、吕河-茅坪断裂构造与张河磁铁矿矿床成矿具有密切关系。更多还原

【Abstract】 Located on the passive continental margin of the northern part of the Yangtze plate, belonging to Niushan stratum zones , Diebu- Xunyang , South Qinling stratigraphic division , The Zhanghe magnetite deposit is a recently discovered deposit in Xunyang county, Shaanxi province. It extends in a E—W direction, about 20m long in a E—W direction and 45m wide in a S-N direction,and40square kilometers.This paper based on the lastest achievements of 1:50000 regional geological and mineral resources surveys in Xunyang-Baihe from 2006 to 2008.By analysising the Strata structur and Magmatic Rocks of magnetite deposit we can grasp the geological characteristics of the deposit. Then we analyze the ore-controlling factors from three respects: Strata factors and metamorphic factors structure factors. Finally we could discuss the metallogenic regularity and metallogenetic type by studying ore-bearing srtata、rock association characteristics and petrochemistry and trace elements and so on.According to field investigation and indoor comprehensive study,we could draw a conclusion that the Zhanghe magnetite deposit primarily hosted in strata named Shijiagou Formation , Middle Devonian period which including the next three measures section : D2s1 , D2s2 , D2s3.The main lithology in the third measures section of Shijiagou Formation , Middle Devonian is Grey the sericite—phyllite with thin-layer limestone ; the second one of that is grey-celadon - grey black limestone with thin-layer sericite—phyllite Containing magnetite Seam; the first one of that is grey black calcareous slate with grey black thin-layer limestone Containing magnetite Seam.According to the system summary of the past research, we analyzed the geological background of region metallogenic and metallogenic geological conditions. Then we got a conclusion that Zhanghe magnetite deposit formed in rift environment during the middle Devonian period ,early Paleozoic with hydrothermal metasomatism by which forming the mineralization mother rock : marbles and albitites.On the basis of studying the space distribution law of orebodies, we think the Zhanghe magnetite orebodies are mainly controlled by stratigraphic horizon and geological structure factors, especially the ore-bearing strata and fold-fault geological structure. Geological structure-controlling factors include basin margin and tectonic level and structure style .They respectively controlled the shape and Spreading of ore field and deposit and orebody.We preliminarily think Zhanghe magnetite deposit is a type of sedimentary metamorphism with hydrothermal reformation deposit. Its main host rocks is albite- marbles with magnet mineralization formed in rift environment, during the middle Devonian period ,early Paleozoic. Its formation was associated with hydrothermal metasomatism. The original rock was clastic limestone whose recrystallization was associated with hydrothermal activity. Albite- magnetite - Siderite formed in the same period .The late hydrothermal activity of host rocks formed albite, magnetite deposit and chlorite exsiting now. The host rocks (clastic limestone) and magnetite undergone low regional metamorphism with slight crushing image. The metamorphism was associated with recrystallization ,but without hydrothermal metasomatism.更多还原