内蒙古自治区拐子湖一带石炭纪白山组火山岩研究

发布时间：2018-06-01 14:47

本文选题：白山组 + 岩石组合　；参考：《长安大学》2015年硕士论文

【摘要】：内蒙古自治区额济纳旗拐子湖一带位于我国的西北部,属于我国的北山地区,是我国重要的成矿远景区。火山岩的基础性研究对于地质找矿和地质演化具有重要的研究意义。内蒙古拐子湖一带中北部广泛分布着石炭纪白山组火山岩。开展白山组火山岩的研究对于了解该地区的晚古生代的岩浆演化过程有重要意义,也为晚古生代的火山岩的成矿背景提供基础资料。本文以研究区石炭纪白山组火山岩为研究对象,通过岩石学、地球化学等方面的系统研究,总结了白山组的岩石组合、地层层序及变化规律,判断了火山岩的岩石成因和大地构造背景。通过研究取得了以下认识:(1)研究区石炭纪白山组火山岩在石炭纪绿条山组之上,呈整合接触关系,与第四系砂砾滩呈压盖接触关系。(2)研究区白山组火山岩主要由安山岩、英安岩、流纹岩和中酸性碎屑岩组成。(3)研究区白山组火山岩属于钙碱性系列,普遍具有富钠富钾、碱金属含量高、富铝低钛、安第斯型弧的特征。(4)研究区白山组火山岩样品稀土元素球粒陨石标准化配分图显示弱的右倾型。样品显示轻稀土相对富集,重稀土相对亏损,轻重稀土均有不同程度的分馏。稀土总量含量高,岩石样品具有弱的Eu负异常,样品在岩浆的演化过程中存在斜长石的分离结晶作用的存在。研究区火山岩微量元素原始地幔蛛网图明显右倾倾曲线,大离子亲石元素Rb、Ba、U、Pb富集、高场强元素Nb、Ta、Ti相对亏损的特点(5)研究区白山火山岩的岩浆源区并非原始地幔,岩浆源区可能是经过俯冲带流体改造后的富集地幔楔。(6)研究区白山组火山岩为安第斯型大陆边缘弧的构造环境,形成于消减俯冲带,具大陆边缘弧构造环境的特征。
[Abstract]:Guizi Lake, Ejina Banner of Inner Mongolia Autonomous region, is located in the northwest of China and belongs to the Beishan area of China, which is an important metallogenic area in China. The basic study of volcanic rocks is of great significance for geological prospecting and geological evolution. Volcanic rocks of Baishan formation of Carboniferous are widely distributed in the central and northern part of Guizi Lake, Inner Mongolia. The study of volcanic rocks of Baishan formation is of great significance for understanding the magmatic evolution of the late Paleozoic in this area, and also provides basic data for the metallogenic background of the late Paleozoic volcanic rocks. Taking the volcanic rocks of the Baishan formation of Carboniferous in the study area as the research object, the rock assemblage, stratigraphic sequence and variation law of the Baishan formation are summarized through systematic study of petrology and geochemistry. The petrogenesis and tectonic setting of volcanic rocks are judged. Through the study, we have obtained the following understanding: the volcanic rocks of the Baishan formation of the Carboniferous in the study area are in an integrated contact relationship over the Lutiaoshan formation of the Carboniferous, and the volcanic rocks of the Baishan formation in the study area are mainly composed of andesite. The volcanic rocks of Baishan formation in the study area belong to calc-alkaline series, which are generally rich in sodium and potassium, high in alkali metal content, rich in aluminum and low in titanium. The characteristics of Andes arc. 4) the normalized distribution of rare earth element chondrites in volcanic samples of Baishan formation shows a weak right-dip type. The sample shows that the light rare earth is relatively enriched, the heavy rare earth is relatively deficient, and the light and heavy rare earth is fractionated to varying degrees. The total amount of rare earth is high, the rock samples have weak EU negative anomalies, and the samples have the separation and crystallization of plagioclase during the evolution of magma. The trace element cobweb of volcanic rocks in the study area is obviously right-tilted, the large ion lithophile element RbsBaHU UU Pb is enriched, and the characteristics of relative depletion of high field strength element Nbtadao Ti.) the magmatic source region of Baishan volcanic rocks in the study area is not the primitive mantle, and the magmatic source of Baishan volcanic rocks in the study area is not the primitive mantle. The volcanic rocks of Baishan formation in the study area are the tectonic environment of the Andean continental margin arc, formed in subduction zone and characterized by continental margin arc tectonic environment.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P588.14

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