本文選題：大別山　切入點(diǎn)：新縣　出處：《地球科學(xué)》2016年08期 　論文類型：期刊論文

【摘要】：新縣巖體位于秦嶺-大別造山帶上,對(duì)其進(jìn)行系統(tǒng)的巖石地球化學(xué)探討有助于加深對(duì)秦嶺-大別造山帶中生代構(gòu)造-巖漿演化及地球動(dòng)力學(xué)背景的認(rèn)識(shí).巖石地球化學(xué)分析結(jié)果顯示,SiO_2含量為74.94%~78.16%,K_2O含量為3.87%~5.86%,Na_2O含量為3.82%~4.24%,Al_2O_3含量為12.38%~13.57%,具有高鉀鈣堿性和過鋁質(zhì)(A/CNK=1.05~1.11)特征.巖石稀土總量較低(42.67×10~(-6)~110.45×10~(-6)),輕稀土元素相對(duì)富集,重稀土元素相對(duì)虧損,具有Eu的負(fù)異常,巖體富集Rb、U、Hf和Y,虧損Ba、Nb、Ta和Ti,顯示出I型高分異花崗巖的特點(diǎn).3個(gè)期次巖石的U-Pb年齡分別為153.4±1.1Ma、146.4±1.6Ma和131.6±1.8Ma.鋯石Hf同位素分析結(jié)果表明,新縣巖體的ε_(tái)(Hf)(t)值為-24.5~-20.3,位于地幔演化線之下,t_(DM2)值為2.68~2.93Ga,指示其源于揚(yáng)子板塊北緣的古老地殼,其組成類似于揚(yáng)子板塊北緣TTG型巖漿巖.結(jié)合區(qū)域地質(zhì)背景,新縣巖體形成于揚(yáng)子陸塊與華北陸塊碰撞造山后的陸內(nèi)伸展環(huán)境,對(duì)應(yīng)的地球動(dòng)力學(xué)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(gòu)造體制大轉(zhuǎn)換過程和大規(guī)模的地殼伸展和巖石圈減薄時(shí)期.
[Abstract]:The Xinxian rock body is located on the Qinling-Dabie orogenic belt. The systematic petrogeochemical study is helpful to the understanding of the Mesozoic tectonic-magmatic evolution and geodynamic background of the Qinling Dabie orogenic belt. The results of petrogeochemical analysis show that the content of SiO-2 is 74.94g / 78.16K _ 2O in Qinling Dabie orogenic belt. The content of Na _ 2O is 3.82%, and the content of Al _ 2O _ 2O _ 3 is 12.38 ~ 13.57, which is characterized by high potassium calc-alkalinity and peraluminous content A / CNK ~ (1.11). The total amount of rare earth elements in rock is relatively low (42.67 脳 10110.-6110.45 脳 10 ~ (-6)), and the content of light rare earth elements is relatively rich. The heavy rare earth elements are relatively depleted and have negative EU anomalies. The rock bodies are enriched in RbPU Hf and Y, and depleted in Baqian NbPU Ta and Ti. the U-Pb ages of the three stages are 153.4 鹵1.1 Ma 146.4 鹵1.6 Ma and 131.6 鹵1.8 MaA, respectively. The results of zircon HF isotopic analysis show that: 1) the U-Pb age of the rocks is 153.4 鹵1.1 Ma, 146.4 鹵1.6 Ma and 131.6 鹵1.8 MaA, respectively. The 蔚 ~ (-1) value of the Xinxian rock mass is -24.5 ~ (-20.3), and the value is 2.68 ~ 2.93Gabeneath 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, which is combined with the regional geological background, and its composition is similar to that of the TTG type magmatic rock in the northern margin of the Yangtze plate. The Xinxian rock mass was formed in the intracontinental extensional environment after collision orogeny between the Yangtze and North China landmasses. The corresponding geodynamic background is the large transition process of tectonic system from compressional contraction to regional extension in the crust of late Jurassic-early Cretaceous and the period of large-scale crustal extension and lithospheric thinning.
【作者單位】： 中南大學(xué)有色金屬成礦預(yù)測(cè)與地質(zhì)環(huán)境監(jiān)測(cè)教育部重點(diǎn)實(shí)驗(yàn)室;中南大學(xué)地球科學(xué)與信息物理學(xué)院;河南省有色金屬地質(zhì)勘查總院;河南省有色金屬地質(zhì)礦產(chǎn)局第七地質(zhì)大隊(duì);
【基金】：中國地質(zhì)調(diào)查局地質(zhì)礦產(chǎn)調(diào)查評(píng)價(jià)專項(xiàng)(No.12120113091200) 中南大學(xué)創(chuàng)新驅(qū)動(dòng)計(jì)劃項(xiàng)目(No.2015CX008)
【分類號(hào)】：P59;P584

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