本文選題：卓潘堿性雜巖體 + 電子探針��； 參考：《中國地質(zhì)大學(xué)(北京)》2017年碩士論文

【摘要】：卓潘堿性雜巖體位于瀾滄江斷裂帶東部,是金沙江-哀牢山新生代富堿侵入巖帶的重要組成部分,侵位于蘭坪走滑拉分盆地西部,本文主要從巖石學(xué)、礦物學(xué)與地球化學(xué)角度對(duì)該堿性雜巖體進(jìn)行系統(tǒng)研究,進(jìn)而探討了該雜巖體的成因和就位機(jī)制。卓潘雜巖體主要由輝長巖、輝石巖及正長巖組成,主要含有鈣質(zhì)的輝石、堿性長石、鎂質(zhì)的黑云母等礦物,輝石巖、正長巖風(fēng)化均較為嚴(yán)重,輝石巖、正長巖在野外多呈疏松狀。巖體具有富堿、高鉀低TiO2、高Al2O3的特征,巖石中賦存的輝石為透輝石,屬鈣質(zhì)輝石,鈣質(zhì)輝石出現(xiàn)與該巖體含有高含量的Ca、K有關(guān);輝石的結(jié)晶溫度范圍介于1070-1490℃之間。黑云母高TiO2,結(jié)構(gòu)式中低AlⅥ,反映卓潘雜巖體巖漿體系具有富鐵、高氧逸度的特征。角閃石為韭閃石,具有較高含量的硅、鈣和鎂、低堿性的化學(xué)特征,卓潘雜巖體中的黑云母和輝石均為非堿性暗色礦物。稀土元素地球化學(xué)表明,各類樣品稀土配分模式均為明顯的右傾輕稀土元素富集模式,輕稀土元素總量高于重稀土元素總量,且輕稀土元素相比于重稀土元素分異明顯,無明顯銪異常。微量元素地球化學(xué)特征顯示該巖體相比于原始地幔富集K、Rb、Sr、Ba等大離子親石元素,相比于原始地幔較為虧損高場(chǎng)強(qiáng)元素(Nb、Ta、Ti),表現(xiàn)出該巖體具有殼源的特征,即大離子親石元素更為富集,說明該雜巖體在形成過程中可能受到地殼物質(zhì)的混染。本文通過鋯石U-Pb年齡獲得卓潘雜巖體的成巖年齡應(yīng)在34.88-35.50Ma之間,該成巖年齡與區(qū)域上其他堿性巖體成巖時(shí)間一致,均形成于新生代,屬喜山期構(gòu)造階段。Sr-Nd-Pb同位素比值:87Sr/86Sr介于0.708011-0.709619之間、143Nd/144Nd介于0.512209-0.512297之間、206Pb/204Pb介于18.7248-19.2883之間,207Pb/204Pb介于15.6749-15.7202之間,208Pb/204Pb介于39.0759-40.8077之間。分析表明,卓潘堿性雜巖體的巖漿源區(qū)是EMⅡ型富集地幔,其巖漿源區(qū)可能是經(jīng)歷過殼幔相互作用的富集地幔。利用與黑云母成分相關(guān)的構(gòu)造環(huán)境判別圖解,并結(jié)合地球化學(xué)特征,認(rèn)為卓潘堿性雜巖體應(yīng)形成于后碰撞的擠壓向伸展環(huán)境轉(zhuǎn)換的構(gòu)造背景。卓潘巖體位于金沙江-哀牢山走滑斷裂帶中段,拉伸強(qiáng)度大、斷裂深度大,導(dǎo)致巖漿的起源深度大,進(jìn)而導(dǎo)致該巖體具有與區(qū)域上其他巖體不同的地質(zhì)特征。
[Abstract]:The Zhuopan alkaline complex is located in the eastern part of the Lancang River fault zone. It is an important part of the Cenozoic alkali-rich intrusive rock belt from Jinshajiang to Ailaoshan. It is located in the western part of the Lanping strike-slip pull-apart basin.The mineralogy and geochemistry of the alkaline complex are systematically studied, and the genesis and emplacement mechanism of the complex are discussed.The Zhuopan complex is mainly composed of gabbro, pyroxenite and syenite, mainly containing calcareous pyroxene, alkaline feldspar, magnesia biotite and other minerals, pyroxenite and syenite weathering more seriously.Syenite is loose in the wild.The rock mass is characterized by rich alkali, high potassium and low TIO _ 2, and high Al2O3. The pyroxene in the rock is diopside, which belongs to calcareous pyroxene. The occurrence of calcareous pyroxene is related to the high content of CaOK in the rock mass, and the crystallization temperature range of pyroxene is between 1070-1490 鈩，

本文編號(hào)：1761271