| 二连—贺根山缝合带晚石炭世埃达克岩的发现及古亚洲洋洋内俯冲作用 |
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| 引用本文： | 王金芳,李英杰,李红阳,董培培.二连—贺根山缝合带晚石炭世埃达克岩的发现及古亚洲洋洋内俯冲作用[J].中国地质,2021,48(2):520-535. |
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| 作者姓名： | 王金芳 李英杰 李红阳 董培培 |
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| 作者单位： | 河北地质大学地球科学学院, 河北 石家庄 050031 |
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| 基金项目： | 国家自然科学基金“内蒙古迪彦庙蛇绿岩带前弧玄武岩组合及其成因”（41972061）和中国地质调查局“内蒙古1：5万高力罕牧场三连等四幅区调”（1212011120711）、“内蒙古1：5万沙日勒昭等四幅区调”（1212011120701）项目联合资助。 |
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| 摘 要： | 内蒙古二连—贺根山缝合带额很傲包图英云闪长岩体,出露于西乌旗梅劳特乌拉SSZ型蛇绿岩带北侧。为了确定该岩体的岩石成因类型,探讨其构造环境及古亚洲洋俯冲消亡过程,对该岩体进行了岩石学、地球化学和LAICP-MS锆石U-Pb年代学研究。额很傲包图英云闪长岩高硅富铝,富钠贫钾,高锶低钇,富集Rb、Ba、Sr等大离子亲石元素和LREE,亏损Nb、Ta、Ti、P等高场强元素和HREE,无明显Eu异常。岩石学和岩石地球化学特征表明,该英云闪长岩体为高Si埃达克岩(HSA),形成于岛弧环境,具有洋内俯冲洋壳+俯冲深积物部分熔融并与上覆地幔楔橄榄岩反应成因特征。锆石LA-ICP-MS U-Pb测年表明,额很傲包图英云闪长岩体的侵位年龄为(305.6±1.5)Ma,形成时代为晚石炭世。结合二连—贺根山缝合带石炭纪蛇绿岩、石炭纪—二叠纪岛弧型岩浆岩的时空分布与演化特征,认为古亚洲洋二连—贺根山洋盆在石炭纪—早二叠世处于以洋内俯冲为特征的大洋俯冲消亡过程中。
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| 关 键 词： | 英云闪长岩 埃达克岩 洋内俯冲作用 晚石炭世 二连—贺根山缝合带 地质调查工程 |
| 收稿时间： | 2018/5/8 0:00:00 |
| 修稿时间： | 2020/7/2 0:00:00 |
Discovery of the Late Carboniferous adakite in the Erenhot-Hegenshan suture zone and intra-oceanic subduction of the Paleo-Asian Ocean |
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| WANG Jinfang,LI Yingjie,LI Hongyang,DONG Peipei.Discovery of the Late Carboniferous adakite in the Erenhot-Hegenshan suture zone and intra-oceanic subduction of the Paleo-Asian Ocean[J].Chinese Geology,2021,48(2):520-535. |
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| Authors: | WANG Jinfang LI Yingjie LI Hongyang DONG Peipei |
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| Institution: | College of Earth Sciences, Hebei GeoUniversity, Shijiazhuang, 050031, Hebei, China |
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| Abstract: | The Ehenaobaotu tonalite is outcropped in the northern part of the Meilaotewula SSZ-type ophiolite of the Erenhot-Hegenshan suture zone in Xi Ujimqin Banner of Inner Mongolia. Based on the study of petrology, geochemistry and zircon LA-ICP-MS U-Pb geochronology, the genetic type and tectonic setting of the tonalite were determined, and the final closure time and subduction process of the Erenhot-Hegenshan ocean basin of the Paleo-Asian Ocean were discussed. The tonalite is characterized by high SiO2, Al2O3, Na2O, Sr and low K2O, Y contents, enrichment of Rb, Ba, Sr large ion lithophile elements and LREE, and depletion of Nb, Ta, Ti, P high field strength elements and HREE. There is no pronounced Eu anomaly. The lithological and geochemical characteristics show that the Ehenaobaotu pluton is a high Si adakite (HSA) formed in island arc, and was derived from patial melting of the intra-oceanic subductingd oceanic crust and sediment and subsequently reaction with overlying mantle wedge peridotite. Its U-Pb LA-ICP-MS dating yields (305.6±1.5) Ma and suggests that the Ehenaobaotu pluton was formed during Late Carboniferous. Combined with the study of spatio-temporal evloution of the Carboniferous ophiolites and Carboniferous-Permian island arc magmatic rocks in the Erenhot-Hegenshan suture, it is assumed that the Erenhot-Hegenshan oceanic basin of the Paleo-Asian Ocean was in the process of oceanic subduction characterized by intra-oceanic subduction during the Carboniferous-Early Permian. |
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| Keywords: | tonalite adakite intra-oceanic subduction Late Carboniferous Erenhot-Hegenshan suture zone geological survey engineering |
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