(1. 中南大學(xué) 有色金屬成礦預(yù)測與地質(zhì)環(huán)境監(jiān)測教育部重點(diǎn)實(shí)驗(yàn)室，長沙 410083；
2. 中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長沙 410083；
3. 河南省有色金屬地質(zhì)礦產(chǎn)局第七地質(zhì)大隊(duì)， 鄭州 450016；
4. 河南省有色金屬礦產(chǎn)探測工程技術(shù)研究中心，鄭州 450016)
摘 要: 蒿坪溝巖體位于華北陸塊南緣沙溝-蒿坪溝銀鉛礦區(qū)內(nèi)，主要巖性為黑云母花崗斑巖和花崗斑巖。LA-ICP-MS鋯石U-Pb定年結(jié)果顯示，黑云母花崗斑巖加權(quán)平均年齡為(128±1) Ma，花崗斑巖加權(quán)平均年齡為(110±1)~(112±1) Ma，表明巖體為燕山期多期次巖漿作用的產(chǎn)物。巖石地球化學(xué)研究表明，兩期巖體為鉀玄巖-高鉀鈣堿性系列，A/CNK值為1.03~1.09，屬弱過鋁質(zhì)花崗巖類；輕重稀土元素分餾顯著，具中等-弱的負(fù)Eu異常，均為I型花崗巖。鋯石Hf同位素研究表明，εHf(t)變化范圍為-22.9~-2.1，均為負(fù)值，tDM2為2617~1304 Ma。鋯石Hf同位素組成以及蒿坪溝巖體中出現(xiàn)的繼承鋯石，表明其源區(qū)物質(zhì)主要來源于前寒武紀(jì)變質(zhì)基底巖石，在侵位過程中可能受到了上地殼的混染。結(jié)合區(qū)域地質(zhì)背景，蒿坪溝巖體形成于揚(yáng)子陸塊與華北陸塊碰撞造山后的陸內(nèi)伸展環(huán)境。
關(guān)鍵字: 蒿坪溝巖體；豫西；巖石地球化學(xué)；鋯石U-Pb年齡；Hf同位素
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitor Ministry of Education, Central South University, Changsha 410083, China？
2. School of Geosciences and Info physics, Central South University, Changsha 410083, China？
3. No. 7 Geological Team, Bureau of Nonferrous Metals Geology and Mineral Resources of Henan Province, Zhengzhou 450016, China;
4. Non-Ferrous Mineral Exploration Engineering Research Center of Henan Province, Zhengzhou 450016, China）
Abstract:The Haopinggou pluton occurred in the southern margin of the North China Craton, Shagou-Haopinggou Ag-Pb deposits, which includes biotite granite porphyry and granite porphyry. LA-ICP-MS zircon dating yields U-Pb age shows that the weighted average ages of biotite granite porphyry and granite porphyry are (128±1) Ma, (110±1)-(112±1) Ma, indicating that the Haopinggou pluton which formed in Yanshanian is the product of two cycles of magmatic activities at least. The compositions of these two period pluton fall into shoshonite and High-K calc-alkaline series, with an A/CNK ratio of 1.03-1.09. They have significant fractionation between LREE and HREE, with medium-weak negative Eu anomalies, which are all belonging to I-type granite. Zircon eHf(t) values of the pluton are negative(-22.9－-2.1), and two-stage Hf model ages (tDM2) range from 1304 Ma to 2617 Ma. Zircon Hf isotope data, along with the presence of the inherited zircons, indicating that the Haopinggou pluton might be generated by partial melting of Precambrian metamorphic basement rocks of coupled with assimilation of the wall rocks of the upper crust. The Haopinggou pluton was emplaced after the major collisional period of the North China block and Yangtze block, in the post-collisional tectonic setting under the regional extension mechanism.
Key words: Haopinggou pluton; Western Henan province; petrogeochemistry; zircon U-Pb ages; Hf isotope
