本文關(guān)鍵詞： 燕山期 巖石成因 地球化學(xué) 西大明山　出處：《中國地質(zhì)大學(xué)(北京)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：西大明山礦集區(qū)是2015年新探明的具有良好經(jīng)濟(jì)前景的鎢-鋅-銀多金屬礦集區(qū),位于欽杭成礦帶上西南部和西大明山凸起的中西部,與華南地區(qū)燕山晚期的巖漿活動和成礦作用的關(guān)系十分緊密。在前人研究基礎(chǔ)上,本文選擇西大明山礦集區(qū)內(nèi)燕山期巖漿巖為研究對象,開展巖石地球化學(xué)分析、年代學(xué)分析和同位素地球化學(xué)分析;并與丹池成礦帶內(nèi)巖漿巖對比分析,查明西大明山礦集區(qū)燕山期巖漿巖的地球化學(xué)特征和成因,探討了西大明山礦集區(qū)燕山晚期成巖成礦作用。羅維花崗巖巖體與丹池成礦帶上的其他巖體類似,為同碰撞向板內(nèi)構(gòu)造環(huán)境轉(zhuǎn)換的環(huán)境下形成的過鋁質(zhì)堿性A型花崗巖。羅維隱伏巖體的微量元素蛛網(wǎng)圖顯示樣品相對富集Rb、U、Nd、Pb、Th等大離子親石元素,虧損Ba、Sr、Ti等高場強(qiáng)元素;稀土配分模式圖為具明顯負(fù)銪(Eu)異常的右傾的“V”字形配分曲線。鋯石U-Pb測年結(jié)果為94.3±1.9Ma,花崗巖εHf(t)值為-3~-7,顯示其來源于下地殼。那寧山頂出露的石英斑巖蝕變嚴(yán)重,其鋯石U-Pb諧和年齡為93.46±0.46Ma,屬于燕山晚期巖漿巖,與該地區(qū)的成巖成礦年齡一致,并且與礦集區(qū)內(nèi)的成礦作用有密切聯(lián)系。輝綠巖為拉張環(huán)境下形成的堿性大洋環(huán)境玄武巖;樣品微量元素曲線顯示板內(nèi)玄武巖的特征;稀土配分曲線顯示為殼源巖漿的特征的無Eu異常的右傾曲線。輝綠巖鋯石U-Pb年齡中有一期94Ma左右的年齡,與礦集區(qū)內(nèi)酸性巖形成時代相近。輝綠巖中成礦元素(Mn、Cu、Zn、Ni)含量較高,尤其Mn含量最高,可能與礦集區(qū)內(nèi)錳礦的形成有關(guān)。以上研究顯示,西大明山礦集區(qū)內(nèi)燕山期巖漿巖活動時間與華南地區(qū)燕山晚期大規(guī)模巖漿活動時限基本一致。通過搜集前人資料,西大明山礦集區(qū)內(nèi)典型礦床流體包裹體H-O同位素中,δ18O-δD的值顯示礦集區(qū)內(nèi)成礦流體主要為巖漿水。礦石中硫化物的S、Pb同位素顯示其金屬成礦物質(zhì)主要來自巖漿巖,且Pb同位素與羅維隱伏巖體Pb同位素基本一致,表明該地區(qū)燕山晚期巖漿巖與成礦有密切的聯(lián)系。礦集區(qū)內(nèi)礦體空間展布特征、元素地球化學(xué)、同位素組成特征等顯示該區(qū)為一個與深部隱伏巖體密切相關(guān)的巖漿熱液成礦系統(tǒng)。
[Abstract]:In 2015, the West Daming Mountain ore concentration area is a newly proved tungsten, zinc-silver polymetallic area with good economic prospects. It is located in the southwest of the Qinghang metallogenic belt and the central and western part of the West Daming Mountain uplift. It is closely related to the late Yanshanian magmatism and mineralization in South China. On the basis of previous studies, this paper chooses Yanshanian magmatic rocks in the West Daming Mountain ore concentration area as the object of study. Rock geochemistry analysis, geochronology analysis and isotopic geochemical analysis are carried out. The geochemical characteristics and genesis of Yanshanian magmatic rocks in the West Daming Mountain ore concentration area are studied by comparing with the magmatic rocks in the Danchi metallogenic belt. This paper discusses the late Yanshanian diagenesis and mineralization in the West Daming Mountain ore concentration area. The Luowei granite body is similar to other rock bodies in the Danchi metallogenic belt. The trace element cobwebs of the Luowei cryptic rock show that the samples are relatively rich in RbHU Ndndlb Pb, which is formed in the environment of the concollision to the intraplate tectonic environment. Large ion lithophile elements such as Th and depleted high field strength elements such as Ba-Sr-Ti; The REE partition pattern is a "V" zigzag partition curve with obvious negative europium EU) anomaly. The zircon U-Pb dating results are 94.3 鹵1.9 Ma. The 蔚 Hft value of the granite is -3 ~ (-7), indicating that it originated from the lower crust. The quartz porphyry exposed from the top of Nanning is seriously altered, and its zircon U-Pb harmonic age is 93.46 鹵0.46 Ma. It belongs to the late Yanshanian magmatic rock, which is consistent with the diagenetic and metallogenic age of the area, and is closely related to the mineralization in the ore concentration area. The diabase is an alkaline oceanic basalt formed in the extensional environment. The characteristics of trace element curve display basalt in the sample; The REE distribution curve shows the characteristics of crust-derived magma with no EU anomaly and the U-Pb zircon age of diabase is about 94 Ma. It is similar to the formation age of acidic rocks in the ore concentration area. The content of the ore-forming element of diabase is high, especially the mn content is the highest. It may be related to the formation of manganese ore in the ore concentration area. The Yanshanian magmatic activity time in the West Daming Mountain Ore concentration area is basically consistent with that of the late Yanshanian magmatic activities in South China. In the H-O isotopes of fluid inclusions of typical deposits in the West Daming Mountain ore concentration area, the values of 未 18O- 未 D indicate that the ore-forming fluids are mainly magmatic water and S of sulphide in ore. The Pb isotope shows that the metallogenic material mainly comes from magmatic rocks, and the Pb isotopes are basically consistent with the Pb isotopes of the Lowe concealed rock mass. The results show that the late Yanshanian magmatic rocks are closely related to mineralization. The spatial distribution characteristics and element geochemistry of orebodies in the ore concentration area. The isotopic composition features indicate that the area is a magmatic hydrothermal metallogenic system closely related to the deep concealed rock mass.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P612;P588.11
，

本文編號：1486463