本文關(guān)鍵詞： 稀有金屬花崗巖 巖漿演化 流體交代 成礦差異性 華南　出處：《中國(guó)地質(zhì)大學(xué)(北京)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：江西雅山和大吉山成礦巖體都是華南典型稀有金屬花崗巖,均富含W、Sn、Nb、Ta等元素,卻形成不同類型礦床—雅山巖體形成我國(guó)乃至亞洲最大的鉭鈮礦,而大吉山花崗巖雖發(fā)育鉭鈮礦化,但規(guī)模和品位都遠(yuǎn)遠(yuǎn)小于雅山,而以石英脈型鎢礦聞名。探究?jī)深愊∮薪饘倩◢弾r的成礦差異性對(duì)于研究華南花崗巖與成礦的關(guān)系具有重要意義。本文采集兩礦床不同巖性帶中的樣品進(jìn)行巖石學(xué)、地球化學(xué)、鋯石U-Pb年代學(xué)、礦物學(xué)等方面研究,重點(diǎn)研究?jī)傻V床的Nb-Ta和W成礦機(jī)制,探討巖漿演化和流體作用導(dǎo)致不同成礦類型的原因。研究得出如下認(rèn)識(shí):(1)雅山和大吉山花崗巖均具有亞堿、過(guò)鋁、高分異演化特征。SiO2、Al2O3、Li和F等含量較高,稀土總量較低,Eu負(fù)異常和稀土元素四分組效應(yīng)等都指示二者屬于高分異的S型花崗巖。但雅山巖體相對(duì)具有更高的Li、F、P含量,稀土的四分組效應(yīng)更顯著,Eu負(fù)異常更強(qiáng)烈,其Rb/Sr比值更高,Nb/Ta和Zr/Hf比值較低。因此,雅山花崗巖巖漿演化程度相對(duì)更高。(2)隨著巖漿不斷演化,雅山花崗巖云母中的Li、F、Nb、Ta含量逐漸升高,而Fe、Mn等元素含量下降,從相對(duì)富Mg、Fe質(zhì)的黑云母逐漸過(guò)渡到富F、Li的鋰云母,而大吉山花崗巖中云母成分卻相對(duì)單一。另外,相對(duì)于大吉山巖體,雅山巖體晚階段的鋰云母花崗巖中的長(zhǎng)石成分更接近鈉長(zhǎng)石端元組分,且具有更高的P2O5含量,并出現(xiàn)富F礦物(黃玉),是巖漿高度分異演化的結(jié)果。這些礦物學(xué)特征都說(shuō)明雅山巖體比大吉山花崗巖具有更高的巖漿演化程度。(3)雅山二云母花崗巖的成巖年齡為158±1.8 Ma,白云母花崗巖為156±0.4Ma,表明雅山巖體屬于燕山期花崗巖。雅山花崗巖的地球化學(xué)特征、礦物學(xué)特征以及Nb、Ta元素的地球化學(xué)行為均表明Nb、Ta的成礦與花崗巖的高演化密切相關(guān),且在巖漿演化過(guò)程中逐漸富集的F、Li、P等元素,可以增加熔體中的非橋氧數(shù)(NBO),從而進(jìn)一步促進(jìn)鉭、鈮元素的富集成礦。大吉山花崗巖演化程度低于雅山,導(dǎo)致其鉭鈮礦化規(guī)模和品位遠(yuǎn)遠(yuǎn)小于雅山,其鎢礦的形成更多是受到流體作用的影響。熱液流體不僅萃取W、Fe、Mn等元素,而且通過(guò)云英巖化降低氧逸度增加pH值,促進(jìn)W礦的形成。巖漿演化程度的差異和流體交代作用的影響是雅山和大吉山花崗巖具有不同成礦類型的重要原因。
[Abstract]:The Yashan and Dagishan ore-forming bodies in Jiangxi Province are typical rare metal granites in South China. They are rich in elements such as WPS-SnNbTa-Ta, but form different types of deposits-the Yashan ore-body forms the largest tantalum-niobium deposit in China and even in Asia. Although tantalum and niobium mineralization is developed in the Dagishan granite, its scale and grade are far smaller than that in Yashan. It is very important to study the relationship between granites and mineralization in South China. In this paper, samples from different lithologic zones of the two deposits are collected for petrology and geochemistry. Zircon U-Pb geochronology, mineralogy and other aspects are studied, with emphasis on the Nb-Ta and W metallogenic mechanism of the two deposits. The causes of different metallogenic types caused by magmatic evolution and fluid action are discussed. The results show that both the Yashan and Dagishan granites have higher contents of alkali, peraluminite, and high differentiation, such as Al 2O 3 Li and F, etc. The negative anomaly of EU and the four-group effect of rare earth elements indicate that both of them belong to highly differentiated S-type granite. However, the Yashan rock mass has a higher content of Li-FU P, and the four-group effect of rare earth elements is more significant, and the negative anomaly of EU is stronger. The Rb/Sr ratio is higher and the ratios of NB / Ta and Zr/Hf are lower. Therefore, the magmatic evolution degree of Yashan granite is relatively higher. The content of mica in the Dagishan granite is relatively single, in addition, it is relative to the Dagi massif, and the content of the mica in the Dagishanite granite is relatively simple, in addition, the content of the mica in the Daguishan granite is relative to that of the Dagi mountain body. The feldspar composition of the spodolite granite in the late stage of the Yashan rock body is closer to the end component of albite and has higher P _ 2O _ 5 content. These mineralogical characteristics indicate that the Yashan granite has a higher magmatic evolution degree than the Dagishan granite, and the diagenetic age of the Yashan mica granite is higher than that of the Dagishan granite. It is 158 鹵1.8 Ma and 156 鹵0.4 Ma for Muscovite granite and Muscovite granite, indicating that the Yashan granite belongs to Yanshanian granite and the geochemical characteristics of Yashan granite. The mineralogical characteristics and the geochemical behavior of the element NbGTA indicate that the mineralization of NB Ta is closely related to the high evolution of the granite, and the elements such as Fangliang P, which are gradually enriched during the magmatic evolution, are closely related to the mineralization of NbTa-Ta. Thus, the enrichment and mineralization of tantalum and niobium elements can be further promoted. The evolution degree of the Dagishan granite is lower than that of Yashan, resulting in the mineralization scale and grade of tantalum and niobium is much smaller than that in Yashan. The formation of tungsten ore is more affected by fluid action. Hydrothermal fluid not only extracts elements such as WFE mn, but also increases pH value by reducing oxygen fugacity by quartz rock. The difference of magmatic evolution degree and the influence of fluid metasomatism are the important reasons for the different metallogenic types of Yashan and Dagishan granites.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：P618.6

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本文編號(hào)：1544668