【摘要】：姚沖巖體位于秦嶺-大別山造山帶上,巖體的主要巖性為黑云母花崗巖和花崗斑巖。巖石地球化學分析結果顯示,姚沖巖體SiO_2含量為71.28%~77.24%,K_2O含量為3.81%~5.28%,Na_2O含量為3.76%~5.03%,Al_2O_3含量為11.61%~14.6%,具有高鉀鈣堿性和準鋁質-過鋁質(A/CNK=0.96~1.03)特征。巖石稀土元素總量較低(11.82×10~(-6)~123.65×10~(-6)),輕稀土元素相對富集,重稀土元素相對虧損,具有Eu負異常,巖體富集Rb、U、Hf和Y,虧損Ba、Nb、Ta和Ti,顯示出I型花崗巖的特點。鋯石Hf同位素分析結果表明,姚沖巖體的ε_(Hf)(t)值為-30~-22.8,位于地幔演化線之下,t_(DM2)值變化于2.21~2.60Ga之間,指示其源于揚子板塊北緣的古老地殼,其組成類似于揚子板塊北緣TTG型巖漿巖。結合區(qū)域地質背景,姚沖巖體形成于揚子陸塊與華北陸塊碰撞造山后的陸內(nèi)伸展環(huán)境,對應的地球動力學背景為晚侏羅世—早白堊世地殼從擠壓收縮向區(qū)域性伸展的構造體制大轉換過程。
[Abstract]:The Yaochong rock body is located on the Qinling-Dabie orogenic belt. The main lithology of the rock body is biotite granite and granitic porphyry. The results of petrogeochemical analysis show that the SiO_2 content of the Yaochong rock body is 71.28 and 77.240.The content of K _ 2O is 3.81 and 5.28 and the content of Na _ 2O is 3.760.The content of Al _ 2O _ 2O _ 3 is 11.61 ~ 14.6cm, which is characterized by high potassium calc-alkaline and quasi-aluminum-peraluminous (A/CNK=0.96~1.03). The total amount of rare earth elements in rocks is relatively low (11.82 脳 10 ~ (-6) ~ (123.65) 脳 10 ~ (-6), light rare earth elements are relatively enriched, heavy rare earth elements are relatively depleted, and have negative Eu anomalies. The rock masses are enriched in Rb,U,Hf and Y, and depleted in Ba,Nb,Ta and Ti, show the characteristics of I-type granites. The results of zircon Hf isotopic analysis show that the 蔚 _ (Hf) (t) value of the Yaochong rock body is -30 ~ 22.8, which is located between 2.21~2.60Ga and the mantle evolution line, indicating that it originated from the ancient crust of the northern margin of the Yangtze plate, and its composition is similar to that of the TTG type magmatic rock in the northern margin of the Yangtze plate. Combined with the regional geological background, the Yaochong rock body was formed in the intracontinental extensional environment after the collision orogeny between the Yangtze and North China landmasses. The corresponding geodynamic background is a great transformation process of the tectonic system from the compressional contraction to the regional extension of the crust from late Jurassic to early Cretaceous.
【作者單位】： 中南大學資源與安全工程學院;中南大學有色金屬成礦預測教育部重點實驗室;中南大學地球科學與信息物理學院;河南省有色金屬地質礦產(chǎn)局第七地質大隊;河南省有色金屬地質勘查總院;
【基金】：中國地質調(diào)查局項目《豫南大別山北麓地區(qū)鉬多金屬成礦規(guī)律及找礦方法研究》(編號:12120113091200);中國地質調(diào)查局項目《湖南省花垣-鳳凰鉛鋅礦整裝勘查區(qū)關鍵基礎地質研究》(編號:12120114052201) 湖南省國土資源科研項目《湖南瀏陽-醴陵官莊金礦整裝勘查區(qū)找礦勘查關鍵基礎地質研究》(編號:2016-04)
【分類號】：P588.121

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