本文選題：光石溝地區(qū) + 偉晶巖型鈾礦�。� 參考：《東華理工大學(xué)》2015年碩士論文

【摘要】：丹鳳地區(qū)的光石溝鈾礦床是我國(guó)典型的偉晶巖型鈾礦床,該鈾礦床地處北秦嶺加里東褶皺帶,夾持于蔡川斷裂與商丹斷裂構(gòu)造之間。筆者在前人工作及光石溝偉晶巖型鈾礦床區(qū)域地質(zhì)特征、礦床地質(zhì)特征分析的基礎(chǔ)上,重點(diǎn)對(duì)該礦床中的晶質(zhì)鈾礦及與之緊密共生的鋯石和黑云母開(kāi)展了顯微觀察、掃描電鏡和電子探針?lè)治?進(jìn)行了礦物學(xué)特征和化學(xué)成分測(cè)試等系統(tǒng)的礦物學(xué)工作,并據(jù)此初步分析了該區(qū)鈾的遷移演化規(guī)律和鈾沉淀富集機(jī)理。通過(guò)對(duì)光石溝鈾礦床晶質(zhì)鈾礦、鋯石和黑云母的鏡下觀察和電子探針?lè)治?初步得到以下幾點(diǎn)認(rèn)識(shí):(1)光石溝花崗偉晶巖型鈾礦床中的鈾主要以晶質(zhì)鈾礦的形式存在,部分以類(lèi)質(zhì)同像形式賦存于鋯石和獨(dú)居石中。晶質(zhì)鈾礦一般為立方體和八面體為主,晶體顆粒大(200μm左右);分布于石英、長(zhǎng)石、黑云母等脈石礦物內(nèi)部或粒間,與黑云母、鋯石等共生關(guān)系密切。此外,常見(jiàn)綠泥石、黃鐵礦和赤鐵礦與晶質(zhì)鈾礦伴生,晶質(zhì)鈾礦常常被黃鐵礦和綠泥石所包圍,形成黃鐵礦和綠泥石環(huán)邊。(2)晶質(zhì)鈾礦主要成分為UO2、Th O2,其中UO2含量81.62%~89.40%,Th O2含量為1.39%~3.72%,多數(shù)樣品含有不等量的Si O2、Y2O3、Pb O等。晶質(zhì)鈾礦的UO2④號(hào)偉晶巖脈含量高于②號(hào)偉晶巖脈,而小花岔礦體處則相對(duì)較低。此外,本次研究還發(fā)現(xiàn),未發(fā)生后期熱液活動(dòng)、以單個(gè)晶體賦存石英、長(zhǎng)石中晶質(zhì)鈾礦UO2含量最高,為86.75%~89.40%。(3)光石溝花崗偉晶巖型鈾礦床中含礦偉晶巖脈和灰池子巖體中黑云母均具有富鐵、鈦的特征,灰池子黑云母二長(zhǎng)花崗巖中黑云母屬于富鐵云母,含礦偉晶巖脈中黑云母均為鐵葉云母;均具有較低的氧逸度;含礦偉晶巖中黑云母結(jié)晶溫度高于灰池子巖體黑云母二長(zhǎng)花崗巖中黑云母的結(jié)晶溫度;說(shuō)明偉晶巖不是由灰池子黑云母二長(zhǎng)花崗巖分離結(jié)晶而來(lái);(4)總體上,鋯石成分變化較小,部分鋯石具有明顯的環(huán)帶構(gòu)造。根據(jù)上述結(jié)果,初步分析光石溝偉晶巖型鈾礦中鈾礦物成礦過(guò)程大致可以劃分為兩期:巖漿作用期、巖漿期后熱液疊加改造期;主成礦期為巖漿作用期,鈾礦物包括晶質(zhì)鈾礦、釷鈾礦、鈾石等;期后熱液疊加改造期的晶質(zhì)鈾礦遭受擠壓作用,然后巖漿晚期的自交代熱液作用導(dǎo)致晶質(zhì)鈾礦發(fā)生破碎,使部分鈾遷出。隨后發(fā)生熱液活動(dòng),使新形成的黃鐵礦充填在晶質(zhì)鈾礦裂隙中,或包裹晶質(zhì)鈾礦(綠泥石、赤鐵礦等)。最后,由于晶質(zhì)鈾礦等鈾礦物近地表,發(fā)生表面氧化形成硅鈣鈾礦,呈脈狀沿著巖石解理分布。因此,光石溝花崗偉晶巖鈾礦是由原始巖漿的結(jié)晶分異作用、后期熱液的疊加改造作用形成。
[Abstract]:The Guangshigou uranium deposit in Danfeng area is a typical pegmatite type uranium deposit in China. The uranium deposit is located in the Caledonian fold belt of the North Qinling Mountains between the Caichuan and Shangdan faults. Based on the previous work and the analysis of the regional geological characteristics and the geological characteristics of the Guangshigou pegmatite type uranium deposit, the authors have carried out microscopic observation of the crystalline uranium deposit and the zircon and biotite closely associated with the deposit. The mineralogical work of mineralogical characteristics and chemical composition testing system was carried out by scanning electron microscope and electron probe analysis. The migration and evolution law of uranium and the mechanism of uranium precipitation and enrichment in this area were preliminarily analyzed. Based on the microscopic observation and electron probe analysis of crystalline uranium deposits, zircon and biotite in the Guangshigou uranium deposit, it is preliminarily concluded that the uranium in the granitic pegmatite type uranium deposit in Guangshigou granitic pegmatite type uranium deposit is mainly in the form of crystalline uranium deposits. Some of them occur in the middle of zircon and monazite in the form of isomorphism. The crystalline uranium deposits are mainly cubic and octahedron with large crystal size of about 200 渭 m and are distributed in or between grains of gangue minerals such as quartz, feldspar and biotite, which are closely related to biotite and zircon. In addition, common chlorite, pyrite and hematite are associated with crystalline uranium deposits, which are often surrounded by pyrite and chlorite. The main composition of the pyrite and chlorite ring edge is UO _ 2 Th / O _ 2, in which the UO2 content is 81.62 ~ (89.40) and the Th _ 2 _ 2 content is 1.39 ~ 3.72%, and most samples contain different amounts of Sio _ 2o _ 2 Y _ 2O _ 3H _ 2O _ 3Pb _ O and so on. The content of UO24 pegmatite vein in crystalline uranium deposit is higher than that in No. 2 pegmatite vein, but it is relatively low at Xiaohuacha orebody. In addition, this study also found that there was no late hydrothermal activity and that quartz existed in a single crystal, and the UO2 content of uranite in feldspar was the highest. Both the pegmatite vein of the Guangshigou granitic pegmatite type uranium deposit and the biotite in the Huichizi rock mass have the characteristics of rich in iron and titanium. The biotite in the biotite monzonitic granite belongs to ferric mica rich in the ash chizi biotite monzonitic granite, and is rich in iron and mica in the granitic pegmatite type uranium deposit of Guangshigou granitic pegmatite type uranium deposit. The biotite in the pegmatite vein of ore-bearing pegmatite is iron leaf mica with low oxygen fugacity, and the crystallization temperature of biotite in pegmatite is higher than that in biotite monzogranite. The results show that pegmatite is not separated and crystallized from Liqizi biotite monzonitic granite. (4) in general, the change of zircon composition is relatively small, and some zircons have obvious zonal structure. Based on the above results, the metallogenic process of uranium ore in Guanshigou pegmatite type uranium deposit can be roughly divided into two periods: magmatism period, post-magmatic hydrothermal superposition period, main metallogenic period is magmatism period, and uranium ore material includes crystalline uranium deposit. Thorium uranium ore, uranium stone and so on, after the hydrothermal superposition transformation period, the crystalline uranium ore is squeezed, and then the late magma self-metasomatic hydrothermal process results in the breakup of the crystalline uranium deposit, which makes some uranium migrate out. Then hydrothermal activity occurs, which makes the newly formed pyrite fill in the fissure of the crystalline uranium ore or encapsulate the crystalline uranium deposit (chlorite, hematite, etc.) Finally, because the uraninite and other uranium deposits are near the surface of the earth, the surface oxidizes to form the calcium silicate uranium ore, which distributes along the rock cleavage in vein shape. Therefore, the granitic pegmatite uranium deposit in Guanshigou is formed by crystallization differentiation of primitive magma and superposition and transformation of hydrothermal solution.
【學(xué)位授予單位】：東華理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：P619.14

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