河北阜平刚玉的产出特征及成因分析

发布时间：2018-03-13 20:18

  本文选题：刚玉　切入点：寄主岩石　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：刚玉产于富Al贫Si的地球化学背景下,代表了高温矿物的形成环境,在地质学领域很有研究价值。达到宝石级的刚玉可作为红蓝宝石产出,和祖母绿、钻石和猫眼一起并称五大名贵宝石,作为一种很名贵的宝石其经济价值也是不言而喻的。由于全球产宝石级刚玉的矿床并不多,河北阜平刚玉的资料也相对匮乏,前人研究程度不是很深,对于阜平刚玉成因的认识目前也比较混乱,这一系列的问题都亟待解决,因此,对阜平刚玉的产出特征和成因机制开展研究工作是很有必要的,这也可以为今后的刚玉宝石找矿工作提供一定方向。野外观察阜平地区刚玉寄主岩石的岩性主要为花岗质混合岩和夕线石混合岩。刚玉寄主岩石主要由暗色的基体和浅色的脉体组成,暗色基体部分的岩石为粒状变晶结构、片麻状构造(放射状构造),在浅色脉体部分,刚玉和长石呈中粗粒花岗结构、块状构造。刚玉寄主岩石一个显著特点是,长石含量非常高,几乎环绕了整个刚玉晶体,呈眼球状构造。根据岩相学特征以及岩石地球化学特征得知,阜平地区刚玉矿床属于深熔型混合岩化作用成因,即“混合岩型”。刚玉矿床的形成主要经历了区域变质作用、混合岩化作用以及退化变质作用三个阶段,而刚玉的形成主要在前两个阶段。区域变质作用阶段形成的刚玉(世代I)粒度太小,达不到宝石级刚玉粒度。混合岩化作用阶段形成含刚玉晶体(世代II)的浅色脉体,此阶段形成的刚玉的晶体较粗大,达到宝石级粒度的标准。对该区刚玉形成机理进行了探讨,认为其是在片麻岩发生混合岩化过程中,形成富铝质的熔浆结晶而成。但在不同的区域,所形成有成份差异的富铝熔浆是导致矿物组合产生差异的主要原因。桃花村、王家庄村刚玉矿床形成的温度范围为600℃~730℃,压力范围为0.3~1.0GPa。迈岭地区刚玉矿床形成温度范围为484℃~700℃,压力范围为0.1~0.8GPa。均为高角闪岩相-麻粒岩相。通过宝石学特征研究以及质量评价来看,阜平地区的刚玉具备作为宝石开发利用的潜力,然而投入市场价格如何需要进一步的研究与探讨。
[Abstract]:Corundum, which is rich in Al and poor in Si, represents the forming environment of high temperature minerals and is of great value in the field of geology. Corundum of gemstone grade can be used as ruby sapphire and emerald. Diamonds and cat eyes are known as the five most valuable gemstones together. As a very valuable gem, its economic value is also self-evident. Because there are not many deposits of gemstone grade corundum in the world, the data on corundum in Fuping, Hebei Province, is also relatively scarce. The previous studies are not very deep, and the understanding of the origin of Fuping corundum is also confused at present. All these problems need to be solved urgently. Therefore, it is necessary to carry out research work on the production characteristics and genetic mechanism of Fuping corundum. In the field, the lithology of corundum host rocks in Fuping area is mainly composed of granitic migmatite and skirlite migmatite. Corundum host rocks are mainly composed of dark base. Body and light-colored veins, The rocks in the dark matrix are grained and grained, and the lamellar structure (radial structure), in the light vein part, corundum and feldspar are of medium coarse granitic structure and block structure. A prominent feature of corundum host rocks is that, The content of feldspar is very high, it almost encircles the whole corundum crystal and takes on eyeball structure. According to the petrographic and petrogeochemical characteristics, the corundum deposit in Fuping area belongs to the origin of deep-melt mixed lithology. The formation of corundum deposits mainly experienced three stages: regional metamorphism, migmatization and degenerative metamorphism. The formation of corundum is mainly in the first two stages. The grain size of corundum (generation I) formed in the regional metamorphism stage is too small to reach the grain size of gemstone grade corundum. The formation mechanism of corundum in this area is discussed. It is considered that the formation mechanism of corundum is in the process of gneiss migmatization. But in different regions, the main reason for the difference of mineral assemblage is that the aluminum-rich melts formed in different regions. The temperature range of formation of corundum deposits in Taohua Village and Wangjiazhuang Village is 600 鈩，

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