本文選題：鋯石U-Pb年齡 + 地球化學特征��； 參考：《地學前緣》2017年06期

【摘要】：光石溝鈾礦床是中國重要的偉晶巖型鈾礦,鈾礦體產(chǎn)在黑云母花崗偉晶巖和黑云斜長片麻巖的接觸帶上。本文對礦區(qū)出露的花崗巖、花崗偉晶巖開展了詳細的年代學和巖石地球化學研究以約束花崗質(zhì)巖石的成因和形成環(huán)境。LA-ICP-MS鋯石U-Pb測年獲得了黑云母花崗閃長巖、黑云母正長花崗巖、產(chǎn)鈾黑云母花崗偉晶巖、非礦黑云母花崗偉晶巖的加權平均年齡,分別為(440.3±2.6)Ma、(420.4±2.7)Ma、(415.1±2.6)Ma和(413.6±2.4)Ma。地球化學數(shù)據(jù)顯示,從礦區(qū)花崗巖到花崗偉晶巖分異程度逐漸升高,富集LILE(Rb、Ba、Sr),虧損HFSE(Nb、Ta、Ti),并且具有I型花崗巖的特征�；◢弬ゾr為具有稀土元素四分組效應(TE1,3=1.06~1.14)的NYF型(NbTa、Y、F)偉晶巖,指示了熔體與出溶的富揮發(fā)分流體間強烈的相互作用。黑云母花崗閃長巖、黑云母正長花崗巖、黑云母花崗偉晶巖的鋯飽和溫度TZr分別為730~765℃、700~723℃和518~640℃。花崗質(zhì)巖漿在深成中等還原(ΔO_x=-0.54~-0.25)的環(huán)境上升侵位,源區(qū)為石榴石和斜長石穩(wěn)定區(qū)。黑云母花崗閃長巖的巖石成因與混入幔源物質(zhì)的加厚下地殼部分熔融有關。伴隨匯聚擠壓作用的減弱,同源母巖漿的緩慢分離結(jié)晶形成了黑云母正長花崗巖-花崗偉晶巖組合。產(chǎn)鈾黑云母花崗偉晶巖中較高含量的FeO~T、MgO、TiO_2、MnO、LILE(Rb、Ba、K)和較低的HFSE(Nb、Ta)是偉晶巖漿和黑云斜長片麻巖發(fā)生化學交換的結(jié)果。偉晶巖漿的同化分離結(jié)晶(AFC)導致了U在接觸帶的飽和,在中等還原的環(huán)境下富集成礦。光石溝花崗巖和花崗偉晶巖形成于北秦嶺同造山-造山晚期。
[Abstract]:The Guangshigou uranium deposit is an important pegmatite type uranium deposit in China. The uranium orebody occurs in the contact zone of biotite granitic pegmatite and biotite plagioclase gneiss. Detailed geochronological and petrogeochemical studies of granite and granitic pegmatite have been carried out in this paper in order to constrain the genesis of granitic rocks and their forming environment. LA-ICP-MS zircon U-Pb dating has obtained biotite granodiorite. The weighted mean ages of biotite syenite, uranium-bearing biotite granipegmatite and non-mineral biotite granitic pegmatite are 420.4 鹵2.7 and 415.1 鹵2.6)Ma and 413.6 鹵2.4 Ma. respectively. Geochemical data show that the differentiation from granitoids to granitic pegmatites in the ore area is gradually increasing, and they are enriched in LILEN RbSU Bajiu Sr ~ (2 +) and depleted HFSE ~ (2 +) NB ~ (+) Tatiao, and have the characteristics of I-type granites. The granitic pegmatite is a pegmatite of the NYF type NbTaOYF with the te1- (31.06- (1.14) effect of REE, indicating the strong interaction between the melt and the dissolved volatile fluid. The zirconium saturation temperature (TZr) of biotite granodiorite, biotite syenite and biotite granitic pegmatite is 730 ~ 765 鈩，

本文編號：1819189