【作者】 王翠芝；

【导师】 肖荣阁；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2007， 博士

【摘要】 辽东硼矿是我国特有的变质热液交代型硼矿，它发育于我国古元古代的“辽吉古裂谷”中，含硼岩系为经过角闪岩相区域变质作用的辽河群里尔峪组，容矿岩石为镁橄榄岩、橄榄玄武岩和富镁大理岩等镁质岩石。 镁橄榄岩、橄榄玄武岩和富镁大理岩这套特殊组合的镁质岩石为辽东古裂谷发育中期幔源富镁岩浆熔离、水下喷发的产物。三者在空间关系上密切共生，明显出现互相包容及共生现象，呈透镜状、似层状局限分布；都由富镁质矿物组成，具有火山岩的某些结构构造；主量元素具高镁特征，镁橄榄岩显示出地幔橄榄岩残余相的特点，橄榄玄武岩为偏碱性的板内玄武岩，富镁大理岩亦显示出火成岩的某些特点；微量元素具相似性，都显示出火成岩的某些特征；稀土元素具相似的La／Yb比值，镁橄榄岩、橄榄玄武岩显示出相近的玄武岩形成环境(从拉斑玄武岩到碱性玄武岩)，富镁大理岩稀土特征处于球粒陨石和沉积岩之间；碳氧同位素亦表明富镁大理岩为岩浆成因。 镁橄榄岩、橄榄玄武岩和富镁大理岩这套镁质岩石不仅是辽东硼矿的容矿岩石，而且其岩石特性对硼矿的形成有决定性的岩控作用：(1)硼矿体与镁质容矿岩石地层层位上一致，硼矿体的形态受镁质岩石地质产状的制约。(2)硼矿矿石在矿物种类、矿物形态、结构、构造等方面都与镁质岩石有明显的交代继承关系。(3)矿石与容矿镁质岩石及其蚀变岩的主量元素特征具继承性，微量元素特征具相似性，稀土元素演化方面具一致性，尤其是其配分形式显示出硼矿矿石的形成主要受镁质容矿岩石和区域变质混合岩化作用的双重控制。 辽东硼矿的成矿模式可概括为原始矿源层(火山喷发—沉积)中硼元素初始富集和区域变质混合岩化作用过程中的含硼热液交代镁质岩石两个过程，尤其是后一过程促成辽东硼矿的最终形成，在这一过程中区域变质混合岩化过程中产生大量的热流体，热流体促使含硼岩系中的硼质活化从而产生大量含硼热液，含硼热液交代镁质岩石则形成辽东特有的镁硼酸盐型硼矿或交代硅铝岩石形成富电气石的硼硅酸盐岩石。含硼热液对镁质岩石的作用形式有充填、交代两种。更多还原

【Abstract】 East Liaoning borate deposits are special metamorphic-hydrothermal~metasomatic borate deposits and are distributed in "Liaoji paleorift" of Paleoproterozoic of China. Their rocks boron-bearing are Lieryu formation of Liaohe group which went regional metamorphism with amphibolite facies, and their host rocks are magnesian rocks such as magnesium peridotites, olivine basalts and magnesian marbles.The special suite of magnesian rocks (magnesium peridotites, olivine basalts and magnesian marbles) is the product of liquating and erupting of magnesian magma in the intermediate stage of development of "Liaoji paleorift" .The three kinds of magnesian rocks are distributed limitly in lentoid , layer-like , and contained each other. They are maded of magnesian minerals and are of textures and structures of igneous rocks. Their characteristics of major elements are magnesian-rich , magnesium peridotites display characteristics of last phase of mantle peridotites melting partly, olivine basalts display characteristics of weak alkali basalts , and magnesian marbles display some characteristics of magmatic carbonatites . Their trace elements are similar to igneous rocks’ . Ttheir REE elements are of similar La/Yb value, the REE elements of magnesium peridotites and olivine basalts display that their formed setting are similar (from tholeiite to alkali-basalt), and the REE elements of magnesian marbles between the REE elements of chondrite and sedimentary rocks. The composition of C-O isotopes of the magnesian marbles can indicate that the rocks are of characteristics of magmatic origin.The suite of magnesian rocks is not only the host rocks of east Liaoning borate deposits, but also has decisive role on forming of borate deposits:(1)the borate ore bodies and magnesian rocks are same in stratigraphic position, and their shape controlled by attitude of magnesian rocks;(2) ores have relationship of replacement and inheritance with magnesian rocks in composition and shape of minerals, texture, structure ,etc.;(3) major elements are of succession , trace elements are similar and characteristics of evolution of REE elements are accordant between ores and their host rocks, specially, the patterns of REE elements indicate that the formation of ores are depended on magnesian rocks and migmatization.The metallogenic model of east Liaoning borate deposits can be divided into two courses, the one is initial enrichment of boron in original ore-source layer (volcanic eruption— sedimentation) , the other is replacment of hydrotherm boron-bearing on magnesian rocks inregional metamorphism and migmatization, specially, the later one, it favored the final formation of east Liaoning borate deposits, in this course, a large of hydrotherm is formed in regional metamorphism and migmatization , the hydrotherm makes boron activate, and the hydrotherm boron-bearing is formed. As result, the magnesian borate type ores, which are distributed only in east Liaoning borate deposits, are formed with replacing of hydrotherm boron-bearing on magnesian rocks and boron silicate rocks tourmaline-rich are formed with replacing of hydrotherm boron-bearing on aluminous silicate rocks. The formats that the hydroherm boron-bearing act on magnesian rocks are filling and metasomatism.更多还原