太行山南段西石门铁矿矿床地质特征及成因

发布时间：2018-02-15 20:29

  本文关键词： 矽卡岩型铁矿 地质特征 矿床成因 西石门　出处：《长安大学》2015年硕士论文　论文类型：学位论文

【摘要】：西石门铁矿位于太行山南段,是我国最大的矽卡岩型铁矿矿集区之一,大大小小的矿床现已发现100多处。由于各种因素的影响,矿体的形态比较复杂,矿体的形成时代主要是燕山期,矿体主要赋存在中酸性侵入岩与碳酸盐岩的接触带上,本区的矿石类型比较单一,主要是磁铁矿。本文通过详细的野外地质调查及室内实验研究,包括岩浆岩石学、岩石地球化学特征、岩石微量稀土元素特征、岩体形成年代及成因的研究,建立了西石门铁矿的成矿模式。1.本文通过锆石LA-ICP-MS原位微区U-Pb定年技术,对武安岩体中角闪正长岩进行了定年,获得135.6±1.5Ma的结晶年龄,说明武安杂岩体的形成时间为燕山期,杂岩体的岩石学和地球化学特征表明:(1)杂岩体的岩石类型主要为角闪闪长岩、闪长岩一二长闪长岩和角闪正长岩以及闪长玢岩,闪长岩中发育有环带结构斜长石;(2)武安杂岩体的地球化学特征显示在岩浆演化过程中主要存在橄榄石、单斜辉石、含钛氧化物和磷灰石等矿物的结晶分异,而斜长石结晶分异作用不明显。然而,这样的结晶分异作用很难解释武安杂岩体具有高Mg#、Cr和似EMI的同位素组成特征。所以,武安杂岩体岩浆在演化的过程中势必有地幔物质的加入,其可能是在岩浆的上升过程中也可以岩浆源区。2.蚀变分带在空间上的分布是有规律的,其特点有:(1)蚀变带主要发育于岩体与碳酸岩围岩的接触带附近,蚀变规模很大,特别是垂直方向上自顶板围岩向岩体深部延伸达数百米;(2)各带产物之间一般具有明显的界线;(3)不同带间矿物成分的变化具有突变性。3.西石门铁矿床铁矿石S同位素组成研究显示,铁矿石中硫化物硫值变化范围小,说明硫组成较稳定。地幔或岩浆的δ34S一般变化于0~2‰,硬石膏δ34S=24.0‰~29.1‰,而典型蒸发沉硫δ34S=20‰~24‰。由此可见,邯郸-邢台地区矽卡岩型铁矿床中黄铁矿δ34S值介于地幔硫与沉积硫之间,这说明成矿流体可能来源于岩浆,并在上升的过程中捕获了膏岩地层,使成矿流体δ34S值变大。本区铅同位素模式年龄明显的差异性可能表明,成矿作用的多期次性和成矿岩浆的多类型性。4.通过总结前人研究资料和野外调研,分析了西石门地区矽卡岩型铁矿的控矿因素和成矿规律,指出了找矿标志。
[Abstract]:Xishimen Iron Mine is located in the southern section of Taihang Mountain. It is one of the largest skarn type iron ore deposits in China. More than 100 ore deposits, large and small, have been found. Due to the influence of various factors, the shape of ore bodies is quite complex. The orebody was mainly formed in Yanshanian period, and the orebody mainly occurred in the contact zone between intermediate-acid intrusive rocks and carbonate rocks, and the ore types in this area were relatively simple. Through detailed field geological investigation and laboratory experiments, including magmatic petrology, petrogeochemical characteristics, rock trace rare earth element characteristics, age and origin of rock formation, The metallogenic model of Xishimen iron deposit has been established. The U-Pb dating technique of zircon LA-ICP-MS in situ microzone has been used to dating the hornblende syenite of the Wuan rock body, and the crystallization age of the amphibolite has been obtained at 135.6 卤1.5 Ma, indicating that the formation time of the Wuan complex is Yanshanian period. The petrological and geochemical characteristics of the complex show that the main rock types of the complex are hornblende, diorite, diorite, hornblende and diorite porphyrite. Geochemical characteristics of Wuan complex show that olivine, clinopyroxene, titanium oxide, apatite and other minerals are mainly differentiated during magmatic evolution. The crystallization differentiation of plagioclase is not obvious. However, it is difficult to explain that the Wuan complex has the characteristics of high #mg Cr and EMI like isotopic composition. During the evolution of the Wuan complex magma, the mantle material is bound to be added, which may be the magmatic source region .2. the distribution of the alteration zone in space is regular. The alteration zone is mainly developed near the contact zone between rock mass and carbonatite surrounding rock, and the alteration scale is very large. In particular, vertical direction from the roof surrounding rock to the depth of the rock up to hundreds of meters) the products of the belt generally have a clear boundary between the different zones of mineral composition changes have a mutation .3. Xishimen iron ore iron ore S in the same position. Studies on the composition of elements show that. The sulfur values of sulfides in iron ores vary in a small range, indicating that the sulfur composition is relatively stable. The 未 34s of mantle or magma generally change from 0 to 2 鈥，

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