冀北康保红旗营子杂岩的石榴石：矿物化学及成因意义

发布时间：2018-04-10 00:01

本文选题：矿物化学　切入点：成因　出处：《成都理工大学》2017年硕士论文

【摘要】：位于华北克拉通北缘中段的康保红旗营子杂岩,主要集中分布在康保县城东南天津郭一带,被康保—围场断裂和大同—沽源断裂所围限。主要岩性为矽线石榴黑云斜长片麻岩及其内部包含的石榴花岗岩,并含有大理岩、石英脉等透镜体。原康保红旗营子杂岩被划分为两部分,分别为新太古代变质深成岩和古元古代变质侵入岩体。在本次调查中发现其实际为苏计房表壳岩和小淖石榴花岗岩,其中苏计房表壳岩主要为矽线石榴黑云斜长片麻岩,石榴花岗岩分布在天津郭、牛家营一线,即是原来所认为的小淖片麻岩和天津郭片麻岩,调查中发现其仅发生变形,并未发生变质作用。康保—围场断裂带以北的十棚石榴花岗岩主要分布十棚、后淖、芦家营等地,其在晚古生代侵入时代较老的花岗岩体中。苏计房表壳岩在研究区分布范围较广,分布在苏计房、前阿明代、伊胡塞等地,作为主要岩性的矽线石榴黑云斜长片麻岩矿物组合为石英、长石、石榴石、黑云母、矽线石等,石榴石颗粒不等,裂隙发育,多呈集合体产出,在石榴石内部大量出现针状矽线石,在矿物附近存在柱状矽线石,部分石榴石被交代呈孤岛状。石榴石中铁铝榴石、镁铝榴石占据绝对优势,在90%以上,属于铁铝榴石—镁铝榴石系列,明显富MgO、贫MnO,属于变质成因石榴石。小淖石榴花岗岩主要矿物组合包括石英、长石、黑云母、石榴石等,石榴石属于铁铝榴石—镁铝榴石系列。石榴石在地域上表现为牛家营颗粒较粗,矿物定向性明显,天津郭颗粒较细,矿物无明显的定向性,多呈集合体产出,集合体内部可见石英、长石、黑云母等,大多具有裂纹,裂纹大多被黑云母或绢云母等充填;天津郭石榴石具有相对高的MgO、MnO含量以及低的FeO、Ca O含量,牛家营石榴石有相对低的MgO、MnO含量以及高的FeO、CaO含量。康保十棚石榴花岗岩矿物组合主要为石英、长石、白云母、石榴石等,部分白云母中还出现毛发状矽线石,石榴石多为集合体,属于铁铝榴石—锰铝榴石系列,具有高的MgO含量,FeO含量变化不大,为岩浆成因石榴石。苏计房表壳岩和小淖石榴花岗岩石榴石均属于铁铝榴石—镁铝榴石系列,矿物化学成分相当,同时在成因上既有差异又有联系,而两者的寄主岩石在空间分布上紧密相邻,推测应是苏计房表壳岩中石榴石发生部分熔融所造成的小淖两个石榴花岗岩体中石榴石在成分上的略微不同,天津郭石榴石在深融过程中不彻底,保留残留变质石榴石特点,岩浆成因表现不明显;而牛家营石榴石则完全溶解沉淀,岩浆成因特点更加显著。
[Abstract]:The Kangbao Hongqingzi complex located in the middle of the northern margin of the North China Craton is mainly distributed in the area of Tianjin Guo southeast of Kangbao County and is bounded by the Kangbao-Weichang fault and Datong-Guyuan fault.The main lithology is siliceous pomegranate black cloud plagioclase gneiss and its inner pomegranites which contain marble quartz veins and other lens bodies.The Kangbao Hongqiyingzi complex is divided into two parts, NeoArchean metamorphic deep-diagenetic rock and paleoproterozoic metamorphic intrusive rock mass.In this investigation, it was found that it was actually composed of Sujifang epidermal rock and Xiaonao garnet granite, among which the Sujiafang epidermal rocks were mainly siliceous pomegranate black cloud plagioclase gneiss, and the garnet granites were distributed in Tianjin Guo, Niujiaying line.That is, Xiaonao gneiss and Tianjin Guo gneiss, which only deformed and did not metamorphism.The Shipeng garnet granites north of the Kangbao-Weichang fault belt are mainly distributed in Shipeng, Hounao, Lujiaying and other places, which were found in the older granitic bodies of the late Paleozoic intrusions.The surface crust rocks of Sujifang are widely distributed in the study area. They are distributed in Sujifang, Pre-Amin Dynasty, Ihusai and other places. As the main lithology, the mineral assemblages of silicon-line, garnet, garnet, biotite and sillimanite are quartz, feldspar, garnet, biotite, sillimanite, etc.The garnet grain is unequal, the fissure is developed, and most of the garnets occur as aggregates. A large number of acicular sillimanites occur in the interior of garnets, columnar sillimanites are found in the vicinity of the minerals, and some garnets are replaced as isolated islands.Iron-aluminite and magnesia-garnet are the dominant garnet in garnet, which is above 90%. It belongs to the series of iron-aluminite and magnesium-garnet, which is rich in MgO and poor in MNO, so it belongs to metamorphic garnet.The main mineral assemblages of Xiaonao garnet granite include quartz, feldspar, biotite, garnet, etc.On the regional level, garnet is characterized by coarse Niujiaying particles, obvious mineral orientation, fine grain size of Tianjin Guo, no obvious orientability of minerals, most of them are produced by aggregates, quartz, feldspar and biotite are found in the interior of the aggregates, and most of them have cracks.The mineral assemblages of Kangbao Shipeng garnet granite are mainly quartz, feldspar, Muscovite, garnet and so on. Some Muscovite also appear hairlike sillimanite, most of which are aggregates, which belong to the series of iron and aluminium garnet, manganese and garnet.The content of Feo with high MgO content changes little and is magmatic garnet.Both Sujifang epidermal rocks and Xiaonao garnet granites belong to the Iron-Magnesia-Allogite series, with similar mineral chemical composition and genetic differences, and the host rocks are closely adjacent to each other in their spatial distribution.It is supposed that the composition of garnet in the two garnet granites in Xiaonao is slightly different due to the partial melting of garnet in Sujiaofang epidermal rock, and that the garnet in Tianjin Guo garnet is not thorough in the process of deep melting and retains the characteristics of residual metamorphic garnet.The origin of magma is not obvious, but Niujiaying garnet is completely dissolved and precipitated, and the characteristics of magma genesis are more obvious.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P574;P588

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