| 华北克拉通孔兹岩带古元古代凉城石榴石花岗岩成因机制及其岩石学意义 |
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| 引用本文： | 王洛娟,郭敬辉,彭澎.华北克拉通孔兹岩带古元古代凉城石榴石花岗岩成因机制及其岩石学意义[J].岩石学报,2021,37(2):375-390. |
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| 作者姓名： | 王洛娟 郭敬辉 彭澎 |
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| 作者单位： | 中国地质科学院, 北京 100037;中国科学院地质与地球物理研究所, 岩石圈演化国家重点实验室, 北京 100029;中国科学院大学地球与行星科学学院, 北京 100049 |
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| 基金项目： | 本文受国家自然科学基金项目（41602197）、中国地质科学院基本科研业务费专项（JKY202011）、国家重点研发计划项目（2018YFC0603700）联合资助. |
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| 摘 要： | 在华北克拉通孔兹岩带东段凉城地区分布有大规模古元古代石榴石花岗岩。凉城石榴石花岗岩是产于麻粒岩相变沉积岩中的原地-半原地花岗岩,伴生有徐武家岩体为代表的辉长苏长岩小侵入体群。凉城石榴石花岗岩富含石榴子石(5%~15%,局部可达25%),常见紫苏辉石,推测形成于高温(>850~900℃)、高压(8~10kbar)条件下,不同于典型的S型花岗岩。地球化学特征上,石榴石花岗岩具有强过铝的地球化学属性(A/CNK=1.1~1.6),显示低SiO2(55%~75%)和富MgO+FeOT(5%~14%)的特征,已经偏离了正常S型花岗岩的成分范围。凉城石榴石花岗岩低硅富镁铁的成分特征很可能是由残留体(石榴石岩)带入和辉长苏长岩物质添加造成,残留体和辉长苏长岩的物质贡献比例约占20%~40%。年代学研究表明凉城石榴石花岗岩形成时代为1.93~1.92Ga,与辉长苏长岩形成时代(1.93Ga)和变质沉积岩记录的超高温变质作用时代(1.92Ga)一致,指示凉城石榴石花岗岩是幔源基性岩浆侵入麻粒岩相变质沉积岩中引起变沉积岩在高温-超高温条件下大规模部分熔融的产物。大规模出露的高温石榴石花岗岩及多点分布的超高温麻粒岩共同反映了集宁-凉城区域上超高温的特点。
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| 关 键 词： | 石榴石花岗岩 S型花岗岩 地壳深熔 岩浆混合 壳幔相互作用 华北克拉通 |
| 收稿时间： | 2020/10/23 0:00:00 |
| 修稿时间： | 2020/12/23 0:00:00 |
Petrogenesis of Paleoproterozoic Liangcheng garnet granitoids in the Khondalite Belt, North China Craton |
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| WANG LuoJuan,GUO JingHui,PENG Peng.Petrogenesis of Paleoproterozoic Liangcheng garnet granitoids in the Khondalite Belt, North China Craton[J].Acta Petrologica Sinica,2021,37(2):375-390. |
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| Authors: | WANG LuoJuan GUO JingHui PENG Peng |
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| Institution: | Chinese Academy of Geological Sciences, Beijing 100037, China;State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | The voluminous garnet granitoids are distributed in the Liangcheng area of eastern Khondalite Belt,North China Craton.The Liangcheng garnet granitoids are parautochthonous granites that occur within granulite-facies metasediments,accompanied by Xuwujia gabbronorites.They are characterized by high modal proportion of garnet(5%~15%,locally up to 25%)and the presence of orthopyroxene.The Liangcheng garnet granitoids were formed at high temperature(>850~900℃)and high pressure(8~10 kbar),which is different from typical S-type granite.They are strongly peraluminous S-type granites(A/CNK=1.1~1.6)with lower SiO2(55%~75%)and higher MgO+FeOT(5%~14%)contents than typical S-type granites.The addition of 20%~40%restites(garnetites)and gabbronorites to the anatectic melts could be responsible for the more mafic composition of the garnet granitoids.The Liangcheng garnet granitoids were formed at 1.93~1.92 Ga,which are consistent with the emplacement of gabbronorites(1.93 Ga)and the ultra-high temperature(UHT)metamorphism(1.92 Ga)in the area,suggesting that garnet granitoids were produced by large-scale melting of metasedimentary rocks under UHT condition as a result of the mafic underplating.The voluminous high-temperature granitic magmas and UHT granulites reflect the UHT characteristic in the Jining-Liangcheng area. |
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| Keywords: | Garnet granitoid S-type granite Crustal anatexis Magma hybridization Crust-mantle interaction North China Craton |
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