内蒙古贺根山蛇绿岩中铬铁矿的深部矿物组合研究

发布时间：2018-06-23 23:54

本文选题：金刚石 + 深部矿物　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：近年来在西藏罗布莎中生代蛇绿岩和俄罗斯极地乌拉尔早古生代蛇绿岩的铬铁矿中发现了金刚石等超高压和强还原矿物组合,提出铬铁矿深部成因的新认识,引发出了国内外关于蛇绿岩型铬铁矿的成因的讨论。蛇绿岩型铬铁矿分为高铬型和高铝型两类,发现金刚石的西藏和俄罗斯的铬铁矿均属于高铬型铬铁矿。新的问题是,高铝型铬铁矿是否也含类似的深部地幔矿物?即深部地幔矿物在蛇绿岩型铬铁矿中是否普遍存在?我国内蒙古贺根山晚古生代蛇绿岩中的铬铁矿为高铝型。本论文选择内蒙古贺根山蛇绿岩铬铁矿的矿物学为研究目标,以查明其中是否含有金刚石等特殊地幔矿物和铬铁矿的形成机制。内蒙古贺根山蛇绿岩代表了古亚洲洋岩石圈的残余,产在天山-兴安褶皱区的内蒙-大兴安岭褶皱带,北侧为西伯利亚板块,南侧为华北板块。用于本研究的约2000kg铬铁矿石采自内蒙古贺根山蛇绿岩带3756号铬铁矿体。通过人工重砂选矿工作,并在双目镜下进行单矿物的挑选,运用光学性质和拉曼光谱学、能谱测试分析鉴定矿物。在贺根山蛇绿岩铬铁矿中,发现了类似于西藏和俄罗斯北部蛇绿岩报道过的金刚石和碳硅石等多种深部地幔矿物。初步研究表明,该铬铁矿矿石样品中至少有30余种矿物,包括金刚石、自然锰、自然钙、自然铝、自然铬、自然铁等自然元素类;碳硅石、Ni-Mn-Fe、Fe-Ni-Al、Ni-Mn-Co等金属互化物类;方铁矿、赤铁矿、磁铁矿、金红石、锐钛矿、钛铁矿、铬尖晶石、锡石、石英等氧化物类;黄铁矿、白铁矿、方铅矿、辉钼矿等硫化物类;镁橄榄石、顽火辉石、透辉石、锆石、榍石、符山石、绿泥石、蛇纹石、正长石、钙铬榴石、镁铝榴石和普通辉石等硅酸盐类;以及钾盐、菱水碳铝镁石、独居石、钙芒硝和水氯铁镁石等。本次试验表明,金刚石、碳硅石和其他特殊地幔矿物不仅能够在高铬铬铁矿中产出,还能在高铝铬铁矿中产出。中亚造山带晚古生代内蒙古贺根山蛇绿岩带高铝型铬铁矿中发现金刚石等深部地幔矿物表明,需重新评价贺根山蛇绿岩和铬铁矿的成因和地质构造背景。
[Abstract]:In recent years, ultrahigh pressure and strong reduction mineral assemblages such as diamond have been found in chromite of Mesozoic ophiolite and early Paleozoic ophiolite in Lobusa, Tibet, and a new understanding of the deep genesis of chromite has been put forward. The origin of ophiolite chromite is discussed at home and abroad. Ophiolite chromite is divided into two types: high chromium type and high aluminum type. It is found that both Xizang and Russian chromite of diamond belong to high chromium chromite. The new question is whether high alumina chromite also contains similar deep mantle minerals. That is whether the deep mantle minerals are ubiquitous in ophiolite chromite? Chromite in the late Paleozoic ophiolite of Hegan Mountain, Inner Mongolia, is of high aluminum type. In this paper, the mineralogy of the ophiolite chromite in Hegenshan, Inner Mongolia is chosen as the research object to find out whether it contains special mantle minerals such as diamond and the formation mechanism of chromite. The ophiolite represents the remnant of the paleo-Asian oceanic lithosphere in Hegenshan, Inner Mongolia, which occurs in the Inner Mongolia-Daxing 'an fold belt in the Tianshan-Xing 'an fold area, with the Siberian plate to the north and the North China plate to the south. About 2000kg chromite ore was collected from the No. 3756 chromite body in the Helgenshan ophiolite belt, Inner Mongolia. The single mineral was selected under binocular microscope through artificial heavy sand processing. The mineral was identified by optical properties Raman spectroscopy and energy spectrum analysis. Several kinds of deep mantle minerals such as diamond and carbon-silica have been found in the chromite of the ophiolite in Hegenshan, which are similar to those reported in the ophiolite of Tibet and northern Russia. The preliminary study shows that there are at least 30 kinds of minerals in the chromite ore, including natural elements such as diamond, natural manganese, natural calcium, natural aluminum, natural chromium, natural iron, carbonaceous silica, Ni-Mn-Fe Fe Fe Ni Al Ni Ni Ni mn Co, pyrite, hematite, etc. Magnetite, rutile, anatase, ilmenite, chromium-spinel, cassiterite, quartz and other oxides; pyrite, albite, galena, molybdenum and other sulfides; forsterite, pyroxene, diopside, zircon, sphene, amurenite, Silicates such as chlorite, serpentine, orthoclase, calcium chromium garnet, magnesium aluminite and ordinary pyroxene, as well as potassium salts, rhombic aluminite, monazite, glauberite and ferric chloride magnesium. The results show that diamond, carbon-silica and other special mantle minerals can be produced not only in high chromium chromite but also in high aluminum chromite. The discovery of diamond and other deep mantle minerals in the high alumina chromite in the late Paleozoic Helgenshan ophiolite belt of Central Asia orogenic belt indicates that the genesis and geological tectonic background of the ophiolite and chromite in Hegenshan need to be reevaluated.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.3

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