| 辽东岫岩地区早白垩世侵入岩的年代学、地球化学及地质意义 |
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| 引用本文： | 刘杰勋,郭巍,朱凯.辽东岫岩地区早白垩世侵入岩的年代学、地球化学及地质意义[J].岩石学报,2016,32(9):2889-2900. |
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| 作者姓名： | 刘杰勋 郭巍 朱凯 |
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| 作者单位： | 吉林大学地球科学学院, 长春 130061,吉林大学地球科学学院, 长春 130061,吉林大学地球科学学院, 长春 130061 |
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| 基金项目： | 本文受国家自然科学基金项目（41272223、41340024）和中国地质调查局项目（12120113098500）联合资助. |
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| 摘 要： | 本文对辽东岫岩地区帽盔山二长花岗岩、荒地花岗闪长岩和朝阳苏长辉长岩进行了岩相学、地球化学、LA-ICP-MS U-Pb定年。帽盔山二长花岗岩主量元素具有富Si、Al、K,贫Fe、Mg、Ca的特征;微量元素亏损Sr、P、Eu、Ti,富集K、Rb、Th等不相容元素,元素地球化学特征表明岩体为铝质A型花岗岩(A/CNK=1.03~1.06,A/NK=1.11~1.12)。荒地花岗闪长岩的SiO_2含量为64.1%~70.8%,K_2O/Na_2O的比值为0.87~1.08,含铝指数A/CNK和A/NK分别为0.98~1.02和1.31~1.55,微量元素富集K、Rb、Sr、Ba等大离子亲石元素,亏损Nb、P、Ti等高场强元素,轻重稀土分馏强烈,(La/Yb)N值为13.41~68.2,属于准铝质到过铝质I型花岗岩。朝阳苏长辉长岩的SiO_2含量为54.8%~58.3%,K_2O/Na_2O的比值为0.57~0.78,微量元素富集K、Ba、Sr等大离子亲石元素,亏损Nb、U、P、Ti等高场强元素,富集La、Ce、Pr、Nd等轻稀土元素。测年结果显示帽盔山二长花岗岩的锆石年龄为137Ma,荒地花岗闪长岩的锆石年龄为139Ma,朝阳苏长辉长岩的锆石年龄为139Ma,均形成于早白垩世。结合构造背景图解,帽盔山二长花岗岩、荒地花岗闪长岩和朝阳苏长辉长岩均为伸展构造环境下的岩浆活动产物。结合三个岩体的时空特点,表明在早白垩世时期,辽东岫岩地区处于非造山的伸展环境,且岩石圈减薄及伸展活动的发展有自深部至浅部的特点,是华北板块东部伸展地球动力学背景的具体体现。
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| 关 键 词： | 早白垩世侵入岩 地球化学 锆石U-Pb测年 岩石圈减薄 伸展环境 辽东岫岩地区 |
| 收稿时间： | 4/9/2016 12:00:00 AM |
| 修稿时间： | 2016/7/25 0:00:00 |
Geochronology, geochemistry and geological significance of the Early Cretaceous intrusive rocks from Xiuyan area, eastern Liaoning Province |
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| LIU JieXun,GUO Wei and ZHU Kai.Geochronology, geochemistry and geological significance of the Early Cretaceous intrusive rocks from Xiuyan area, eastern Liaoning Province[J].Acta Petrologica Sinica,2016,32(9):2889-2900. |
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| Authors: | LIU JieXun GUO Wei and ZHU Kai |
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| Institution: | College of Earth Science, Jilin University, Changchun 130061, China,College of Earth Science, Jilin University, Changchun 130061, China and College of Earth Science, Jilin University, Changchun 130061, China |
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| Abstract: | Petrography, geochemical data and LA-ICP-MS zircon U-Pb dating have been obtained for Maokuishan monzogranites, Huangdi granodiorites and Chaoyang norite gabbro in Xiuyan area, eastern Liaoning Province. The major elements of Maokuishan mozogranites are high in Si, Al and K, and low in Fe, Mg, Ca and Ti. Trace elements are enriched in incompatible elements such as K, Rb, Th, and depleted in Sr, P, Eu, and Ti, geochemical features indicate that granitoids are aluminum A-type granites (A/CNK=0.98~1.03, A/NK=1.11~1.12). Huangdi granodiorite, with the content of SiO2 are 64.1%~70.8%, K2O/Na2O is 0.87~1.08, and the aluminium index are A/CNK=0.98~1.02, A/NK=1.31~1.55, are enriched in LILEs, such as K, Rb, Sr and Ba, depleted in HFSEs as Nb, P and Ti, and high field strength elements, (La/Yb)N=13.41~68.2, belong to metaluminous-peraluminous I-type granitoids. Chaoyang norite gabbro with thecontent of SiO2 are 54.8%~58.3%, K2O/Na2O is 0.57~0.78, are enriched in LILEs, as K, Ba, Sr, and LREEs as La, Ce, Pr, Nd, depleted in HFSEs, as Nb, U, P, Ti. LA-ICP-MS zircon U-Pb age data of Maokuishan monzogranite, Huangdi granodiorite and Chaoyang norite gabbro are 137Ma, 139Ma and 139Ma, respectively, indicate that intrusive rocks were formed in Early Cretaceous. Combined with structure background graphic, Maokuishan monzogranites, Huangdi granodiorites and Chaoyang norite gabbro are all the products of magmatism in the extensional tectonic setting. Combined with spatial and temporal characteristics of the three plutons show in the Early Cretaceous period, Xiuyan area of eastern Liaoning Province in a non-orogenic extension environment, and the development of lithospheric thinning and stretching activities are characteristic from deep to shallow, is the eastern North China Plate stretch geodynamic setting concrete manifestation. |
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| Keywords: | Early Cretaceous intrusive rocks Geochemistry Zircon U-Pb dating Lithospheric Extensional tectonic environment Xiuyan area eastern Liaoning Province |
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