本文選題：平川鐵礦　切入點(diǎn)：苦橄玢巖巖床　出處：《中國(guó)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】：作為與大規(guī)模玄武巖噴發(fā)和基性超基性巖侵入有關(guān)的磁鐵礦床,平川鐵礦也是攀西地區(qū)重要的鐵礦床之一。但是,平川鐵礦中苦橄玢巖成因并未引起人們的重視,所以苦橄玢巖的形成以及與平川鐵礦的成因聯(lián)系是我們本次研究的重點(diǎn)。本人選擇四川鹽源平川鐵礦的主礦區(qū)礦山梁子鐵礦為主要研究區(qū)域,運(yùn)用地球化學(xué)及電子探針等方法,對(duì)礦山梁子鐵礦床苦橄玢巖中的橄欖石進(jìn)行深入研究。在巖相學(xué)鏡下觀察觀察的基礎(chǔ)上,通過對(duì)橄欖石、輝石等主要造巖礦物的電子探針成分分析,揭示苦橄玢巖原始巖漿的演化過程及其形成的物理化學(xué)條件。最終得出礦山梁子礦段苦橄玢巖中含有來源各異的橄欖石斑晶,根據(jù)其不同的鏡下特征及地球化學(xué)數(shù)據(jù)分別定名為粗晶橄欖石、微晶橄欖石、包裹體橄欖石及“鬣刺”狀橄欖石。不同類型橄欖石具有不同的成分特征及形成溫度,微晶橄欖石的形成溫度最高,為1335℃。粗晶橄欖石的初始結(jié)晶溫度較低,為1295℃。包裹體橄欖石為1292℃,但橄欖石的結(jié)晶溫度并未發(fā)生變化,說明了其相對(duì)穩(wěn)定的特征�！镑啻獭睜铋蠙焓某跏冀Y(jié)晶溫度相對(duì)較低,為1272℃,但隨著橄欖石結(jié)晶的進(jìn)行,溫度持續(xù)降低,顯示了其連續(xù)結(jié)晶的狀態(tài),說明了只有“鬣刺”狀橄欖石才是苦橄玢巖原始巖漿結(jié)晶的產(chǎn)物。除包裹體橄欖石外,其他三類橄欖石邊部的結(jié)晶溫度相近,說明了其最終在固結(jié)成巖之前經(jīng)過巖漿多期次混合形成我們現(xiàn)今所見的苦橄玢巖時(shí)的溫度。運(yùn)用CSD計(jì)算橄欖石斑晶的體積含量。剔除其他來源的橄欖石斑晶。即粗晶橄欖石、微晶橄欖石及包裹體橄欖石,另外保留“鬣刺”狀橄欖石。剔除橄欖石后可以發(fā)現(xiàn)苦橄玢巖的SiO_2含量為48.41%,故苦橄玢巖的原始巖漿并非苦橄質(zhì)巖漿。由于存在有不同類型橄欖石,苦橄玢巖的形成應(yīng)該是一個(gè)開放環(huán)境。在這個(gè)開放的環(huán)境中,整體未固結(jié)的原始巖漿熔體會(huì)發(fā)生組分的帶入或帶出,這時(shí)含礦流體的加入導(dǎo)致了巖漿房的活化并從其他巖漿房中帶入了其他巖漿房中結(jié)晶出來的橄欖石晶體。之后侵入至近地表后固結(jié)成巖,形成我們現(xiàn)今所見的苦橄玢巖。其作為平川鐵礦的致礦侵入體,且作為鐵礦的屏蔽層更加有利于成礦。
[Abstract]:As a magnetite deposit related to large-scale basalt eruption and basic ultrabasic intrusion, Pingchuan Iron Mine is also one of the important iron ore deposits in Panxi area. However, the genesis of picrite porphyrite in Pingchuan Iron Mine has not attracted much attention. Therefore, the formation of picrite porphyrite and its genetic relationship with Pingchuan Iron Mine are the key points of our research. I have chosen Liangzi Iron Mine, the main mine of Pingchuan Iron Mine in Yanyuan, Sichuan Province, as the main research area, using geochemical and electron probe methods. The olivine in picrite porphyrite of Liangzi iron deposit in mine is studied in depth. Based on the observation of lithofacies, the electron probe analysis of the main rock-forming minerals such as olivine and pyroxene is carried out. The evolution process and physical and chemical conditions of the primitive magma of picrite porphyrite are revealed. Finally, the porphyrite porphyrite from various sources is found in the picrite porphyrite of Liangzi Mine. According to their different microscopic characteristics and geochemical data, they are named as coarse olivine, microcrystalline olivine, inclusion olivine and "iguana" olivine, respectively. Different types of olivine have different composition characteristics and formation temperature. The formation temperature of microcrystalline olivine was 1335 鈩，

本文編號(hào)：1592116