發(fā)布時間：2018-05-07 04:13

  本文選題：城上復(fù)式巖體 + 鋯石U-Pb定年��； 參考：《東華理工大學(xué)》2016年碩士論文

【摘要】：城上復(fù)式巖體位于贛中武功山隆起以東,峽江縣以西約十公里的梅元-羅田一帶,其多期次、多成因的特點(diǎn),對研究區(qū)內(nèi)乃至剖析華南的構(gòu)造-巖漿演化具有重要的指示意義。本文在前人研究成果和野外地質(zhì)調(diào)查的基礎(chǔ)上,通過巖相學(xué)、礦物化學(xué)、LA-ICP-MS鋯石U-Pb定年及元素地球化學(xué)特征分析,探討了其形成物理-化學(xué)條件、巖石成因類型、源區(qū)性質(zhì)、形成構(gòu)造環(huán)境及與成礦的關(guān)系。北部加里東期梅元巖體的中細(xì)粒黑云母花崗閃長巖中的斜長石為中長石,黑云母屬鎂質(zhì)黑云母,成巖年齡為436.2±2.4Ma,結(jié)晶溫度約650~725℃,氧逸度約10-11.4~10-12.2 bar,成巖壓力為68~234MPa,對應(yīng)侵位深度為2.6~8.9km,形成其的巖漿初始溫度約759.5℃;具高鋁、鈣及鎂鐵質(zhì),低硅、磷,弱負(fù)Eu異常,富Rb、Cs、U、Nd、LREE,貧Ba、Nb、Sr、P、Ti,是高鉀鈣堿性、弱過鋁I型花崗巖;主要由較基性的下地殼物質(zhì)部分熔融而來,并在巖漿侵入過程中有少量的地幔巖漿和貧粘土的變質(zhì)雜砂巖物質(zhì)加入,形成于早古生代揚(yáng)子與華夏兩陸塊碰撞造山由擠壓向陸內(nèi)伸展的過渡轉(zhuǎn)變時期,為碰撞晚期花崗巖;除在空間與成因上對新余鐵礦具有破壞改造作用和指示變形時代上限外,與周邊其他礦產(chǎn)不具直接關(guān)系。南部印支期羅田巖體主要經(jīng)歷了3個成巖期次:1成巖年齡為239.0±1.0Ma的中粒二云母花崗巖形成的巖漿初始溫度約682~773℃,為高鉀鈣堿性-堿性系列、強(qiáng)過鋁S型花崗巖,主要由富粘土的長英質(zhì)泥巖部分熔融而來,但可能在巖漿侵入的過程中帶入了部分變質(zhì)雜砂巖物質(zhì)。2大斑中粗粒黑云母二長花崗巖中的斜長石主要為更長石和中長石,肉紅色巨斑晶為較純的正長石,黑云母屬鐵質(zhì)黑云母,成巖年齡為227.0±1.2Ma,結(jié)晶溫度約625~725℃,氧逸度約10-13.8~10-15.1bar,成巖壓力為265~377MPa,對應(yīng)侵位深度為10.0~14.2km,形成其的巖漿初始溫度約745~809℃,為高鉀鈣堿性系列、弱過鋁-強(qiáng)過鋁S型花崗巖,主要由較富粘土的變質(zhì)雜砂巖部分熔融而來,但可能有少量基性和泥質(zhì)成分物質(zhì)的混入。3中斑中細(xì)粒黑云母二長花崗巖中的斜長石主要為鈉長石,個別為更長石,黑云母屬鐵葉云母-鐵質(zhì)黑云母,成巖年齡為222.1±1.1Ma,結(jié)晶溫度約600~650℃,氧逸度約10-15.6~10-16.6bar,成巖壓力為417~559MPa,對應(yīng)侵位深度為15.8~21.1km,形成其的巖漿初始溫度約698~722℃,為高鉀鈣堿性系列、強(qiáng)過鋁S型花崗巖,主要由富粘土的長英質(zhì)泥巖部分熔融而來。在元素地球化學(xué)上這3期花崗巖基本相似,均具高硅、鋁及鉀,低鈣、鎂及磷,強(qiáng)負(fù)Eu異常,富Rb、Cs、U、Nd、LREE,貧Ba、Sr、Ti,結(jié)晶分異程度較高。第1期可能是華南與華北陸塊碰撞造山背景下的產(chǎn)物,為同碰撞花崗巖,但后期應(yīng)受到了武功山伸展構(gòu)造的影響,而第2期和第3期均形成于華南與華北陸塊碰撞造山后的陸內(nèi)伸展環(huán)境,為后碰撞花崗巖。它們與周邊礦產(chǎn)不具時間關(guān)系,但在空間與成因上關(guān)系密切。
[Abstract]:The Chengshangshangcomposite rock body is located in the area of Meiyuan-Luotian, about ten kilometers west of Xiajiang County, to the east of Wukongshan uplift in central Jiangxi Province. Its multi-stage and multi-genetic characteristics are of great significance to the study area and even to the analysis of tectonic-magmatic evolution in South China. On the basis of previous research results and field geological survey, based on the analysis of U-Pb dating and element geochemistry of zircon from petrography and mineral chemistry, the authors have discussed the physical and chemical conditions of their formation, petrogenetic types and source area properties. Forming tectonic environment and its relation with mineralization. The plagioclase of the medium-fine biotite granodiorite of the Meiyuan rock body in the northern Caledonian period is meso-feldspar, and biotite belongs to magnesia-like biotite with a diagenetic age of 436.2 鹵2.4 Ma.The crystallization temperature is about 650 ~ 725 鈩，

本文編號：1855351