本文選題：花崗閃長(zhǎng)巖 + 二長(zhǎng)花崗巖��； 參考：《合肥工業(yè)大學(xué)》2015年碩士論文

【摘要】：安徽祁門地區(qū)城安復(fù)式巖體位于揚(yáng)子板塊東南緣,江南隆起帶內(nèi)。前人對(duì)城安復(fù)式巖體研究程度薄弱,尤其是內(nèi)部發(fā)育的二長(zhǎng)花崗巖與正長(zhǎng)花崗巖。本文通過該復(fù)式巖體中的巖石學(xué)、同位素年代學(xué)、地球化學(xué)等方面的研究,初步取得以下認(rèn)識(shí)：1、城安復(fù)式巖體主要由花崗閃長(zhǎng)巖體、二長(zhǎng)花崗巖體和正長(zhǎng)花崗巖體組成。主體巖性花崗閃長(zhǎng)巖體內(nèi)部分帶較為明顯。二長(zhǎng)花崗巖體和正長(zhǎng)花崗巖體分別與花崗閃長(zhǎng)巖呈脈動(dòng)侵入接觸關(guān)系。2、高精度鋯石U-Pb年代學(xué)測(cè)試結(jié)果表明,城安花崗閃長(zhǎng)巖、剪刀卡二長(zhǎng)花崗巖、劉家正長(zhǎng)花崗巖的成巖年齡分別在151.0±2.8Ma,131.2±2.0Ma,129.4±1.5Ma。繼承鋯石年齡集中在800Ma左右,說明有大量成巖物質(zhì)可能來源于元古代褶皺基底。結(jié)合前人研究,本文獲得了城安花崗閃長(zhǎng)巖體為皖南地區(qū)燕山期成巖年齡最老的巖體。3、通過電子探針測(cè)試結(jié)果并采用黑云母壓力計(jì)和二長(zhǎng)石溫度計(jì),對(duì)城安復(fù)式巖體形成的溫壓條件進(jìn)行估算：花崗閃長(zhǎng)巖中T=560℃, P=0.22-0.30Gpa,形成深度在5-8 km,二長(zhǎng)花崗巖中,T=580℃, P=0.6Gpa,正長(zhǎng)花崗巖中T=513-520℃, P=0.23-0.24GPa,形成深度在5-8km。由于受到揮發(fā)分的影響,該估算結(jié)果會(huì)低于實(shí)際值。4、花崗閃長(zhǎng)巖體和剪刀卡二長(zhǎng)花崗巖均屬高鉀鈣堿性系列,堿度率較低,具有鈣堿性特征,為過鋁質(zhì)巖石。復(fù)式巖體內(nèi)部,正長(zhǎng)花崗巖體輕重稀土分異作用最弱,花崗閃長(zhǎng)巖體則最為強(qiáng)烈。右傾輕稀土富集模式與下地殼相同。該復(fù)式巖體內(nèi)LILE元素濃度高,HFSE元素濃度低。微量元素原始地幔標(biāo)準(zhǔn)化圖解為右傾型。5、城安花崗閃長(zhǎng)巖體為I型花崗巖的特征,巖漿主要源于地殼,可能混有少量的地幔物質(zhì),在擠壓向拉伸的轉(zhuǎn)折環(huán)境中產(chǎn)生。剪刀卡二長(zhǎng)花崗巖體具有A型花崗巖特點(diǎn),巖漿基本源于地殼,主要形成在轉(zhuǎn)換的動(dòng)力學(xué)背景下產(chǎn)生。城安復(fù)式巖體的形成過程,記錄了皖南地區(qū)燕山期擠壓-轉(zhuǎn)換-伸展的地球動(dòng)力學(xué)演化過程。6、城安復(fù)式巖體演化過程較為完全,可能是源區(qū)部分融熔與分異結(jié)晶共同作用而成。其侵位機(jī)制也較為復(fù)雜,可能為先巖墻擴(kuò)展上侵,隨后發(fā)生頂蝕作用。
[Abstract]:The Chengan complex in Qimen area, Anhui Province is located in the southeast margin of Yangtze plate and in the Jiangnan uplift belt. The previous studies on the Chengan complex are weak, especially the interior-developed monzogranites and syenomorphic granites. Based on the petrology, isotopic chronology and geochemistry of the complex rock mass, the authors have obtained the following preliminary understanding: 1. The Chenan complex rock body is mainly composed of granodiorite, monzogranite and syenite. Part of the main lithologic granodiorite is obvious. The relation between the two granitic bodies and granodiorite is pulsating intrusive contact. The high precision zircon U-Pb geochronology test results show that the Chenan granodiorite, the shisset card monzogranite, the granodiorite, the shisset monzogranite, the granodiorite and the shisset monzodiorite. The diagenetic age of Liujiazheng feldspar granite is 151.0 鹵2.8 Ma, 131.2 鹵2.0 Ma, 129.4 鹵1.5 Ma, respectively. The inherited zircon age is about 800 Ma, indicating that a large amount of diagenetic material may have originated from the Proterozoic fold basement. Combined with previous studies, the authors obtained that the Chengan granodiorite is the oldest rock mass of Yanshanian diagenetic age in southern Anhui. The results were measured by electron probe and biotite pressure gauge and anamite thermometer were used. The temperature and pressure conditions for the formation of Chenan complex granodiorite are estimated as follows: the formation depth of granodiorite is 560 鈩，

本文編號(hào)：2054204