【作者】 侯通；

【导师】 张招崇；

【作者基本信息】 中国地质大学（北京） ， 矿物学，岩石学，矿床学， 2014， 博士

【摘要】 本文选取四川攀枝花钒钛磁矿，新疆磁海和雅满苏铁矿和安徽姑山铁矿为研究对象，以揭示不同构造环境、不同性质岩浆和不同地质条件下铁质在中-基性岩浆系统中岩浆过程、岩浆-热液转化和热液条件下的超常富集机理。攀枝花苦橄玢岩中高镁橄榄石的识别，表明攀枝花钒钛磁铁矿矿床的形成与二叠纪峨眉山地幔柱导致的高温富铁苦橄质岩浆活动有关。区域地质历史结合富集的He-Ar同位素和Re-Os同位素特征暗示了岩石圈地幔富含榴辉岩相物质，很可能是产生富铁原始岩浆产生的关键。铁钛氧化物早期结晶自富水玄武质岩浆是钒钛磁铁矿成矿的关键控制因素。此外，铁矿层中斜长石边部富An贫Ti，这指示了晶粥层内的粒间熔体不混溶作用。富水-铁的玄武岩中磁铁矿的早期结晶以及粒间不混溶作用共同导致了岩体下部厚层块状矿石的形成。磁海辉绿岩的岩石成因研究表明其为起源自富集岩石圈地幔玄武质岩浆经历贫铁矿物分离结晶而富含挥发分，高侵位形成辉绿岩低压释放流体很可能是磁海铁矿形成的关键控制因素。此外，类似传统矽卡岩型铁矿，多期次的岩浆侵入，碳酸盐岩的围岩与富铁热液的相互作用均为导致热液中铁质大量堆积的关键。对姑山铁矿区闪长玢岩的单斜辉石的系统电子探针分析发现存在铁的突然降低现象，从而为不混溶作用提供了关键的矿物学证据，结合地球化学研究和MELTS模拟，提出不混溶作用是由玄武岩质岩浆在深部发生贫铁矿物(单斜辉石+斜长石)分离结晶形成的富铁闪长岩在上升过程中由于富磷地层的混染结果。LA-ICPMS锆石U-Pb测年的结果表明雅满苏矽卡岩和火山岩是同期形成的，暗示夕卡岩很可能是在下覆活动岩浆房的作用下形成的，成矿热液来自岩浆房释放的富铁流体和海水的混合。玄武岩很可能是主要的铁质来源，富铁流体导致其与灰岩相互作用导致矽卡岩和铁矿。综合4个典型铁矿的形成机制，中基性岩浆系统铁矿形成的关键控制因素存在共同点，包括：1）巨量的岩浆活动是形成铁矿的物质基础；2）分离结晶作用是铁质富集的前提条件，导致了岩浆的演化使得铁质富集，也是液态不混溶作用和高盐度岩浆流体释放的基础；3）压力降低有利于岩浆流体的形成，碳酸盐岩围岩有利于铁质的卸载沉淀富集。更多还原

【Abstract】 In this dissertation, four deposits were selected, including the plutonic PanzhihuaFe-Ti-V oxide ore-bearing layered intrusion in Emeishan Large Igneous Province,Cihai hypabyssal diabase-related Fe skarn deposit in the Beishan region, NW China,Gushan ultra-hypabyssal dioritic porphyry-related Fe deposit, Eastern China andYamansu submarine volcanic-related Fe deposit in Eastern Tianshan, NW China. Onthe basis of the discussion of petrogenesis, some new lights shed on the super efficientenrichment mechanism of iron in the intermediate basic magmatic system includingmagma differentiation, magmatic-hydrothermal transition and hydrothermal fluids.Zircon U-Pb dating on the co-magmatic picritic porphyryin Panzhihua, and thehigh Mg olivine (Fo90) discovered in the latter, indicate the formation of world-classFe-Ti-V oxide deposit is closely related to the high temperature magmatism inducedby the Permian Emeishan mantle plume. The estimated primary magma isferropicritic, combined with the He-Ar and Re-Os isotopes show enriched signatures,implying the lithospheric mantle had been affected by the ancient subduction-relatedmetasomatism and contains an eclogite or pyroxenite component which could interactwith mantle plume and could have produced the parental Fe-rich magma. Plagioclaseshow higher contents of Fe and Ti in the rim which could be explained by interstitialliquid immiscibility. Except this mechansim, several times of the Fe-rich magmareplenishment are also probably key factors to facilitate the formation of massive ores.The petrogenesis studies on the Cihai diabase suggest the parental basaltic magmawas formed by partial melting of the enrich lithospheric mantle and experiencedfractionation of relatively Fe-poor minerals. Moreover, the shallow emplacementdepth are probably the key factor that triggered the release of post-magmatichydrothermal fluids and facilitate Fe skarn mineralization. Mass balance calculationsuggests that the high grade iron ores in Gushan probably were formed from theimmiscible iron-rich liquid which separated from the ferrodioitic magma. The latterwas derived from the enriched lithospheric mantle and MELTS simulation suggeststhe parental magma may experienced fractionation of clinopyroxene and plagioclase,and contamination of P-rich strata. LAICP-MS U-Pb zircon dating of the basalts and skarns at Yamansu yields almost coeval ages, suggesting that the skarn formation isrelated to subaqueous volcanism. The hydrothermal fluids that generated the skarnscould be a mixture of evolved magma-derived fluids and sea water. The Yamansubasalts provided the source of iron for the skarn mineralization.In this study, some common characteristics of key factors were elucidated asfollowed:1) the iron is exlusively from magma, thus large scale magmatism is thebasis of formation of large scale iron deposit;2) Extensive fractional crystallization isone of the requirement for the iron enrichment in the residual magma and possibleliquid immiscibility, and in the high salinity fluids;3) the decompression duringmagma differentiation is favorable for magmatic hydrothermal fluids, and thecarbonate wall rocks is the most favorable environment for the deposition of Fe.更多还原