| 刘锦宏,袁海潮,杨 科.北阿尔金拉配泉地区岩浆岩组合的岩石地球化学特征、 年代学及构造演化[J].甘肃地质,2026,35(1):1-16 |
| 北阿尔金拉配泉地区岩浆岩组合的岩石地球化学特征、 年代学及构造演化 |
| GEOCHEMISTRY AND GEOCHRONOLOGY OF IGNEOUS ROCKS ASSOCIATIONS IN LAPEIQUAN, NORTHALTYN TAGH AND ITS TECTONIC EVOLUTION |
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| DOI：10.27027/j.cnki.ISSN2097-6704.2026.01.001 |
| 中文关键词: 火成岩 地球化学 年代学 构造演化 北阿尔金拉配泉地区 |
| 英文关键词:igneous rocks geochemistry geochronology tectonic evolution Lapeiquan area |
| 基金项目:国家自然科学基金项目（编号41430209、41421002）；?西北大学大陆动力学国家重点实验室自主研究重点课题联合资助； |
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| 中文摘要: |
| 北阿尔金拉配泉地区出露一套岩浆岩组合，主要由辉绿岩、枕状玄武岩、辉长岩、安山质火山角砾岩等组成。本文通过详细的岩相学、地球化学、年代学研究，反演了拉配泉地区岩浆作用时期的大地构造背景，初步探讨了区内洋盆的演化历史。本文获得安山质火山角砾岩的形成时代为（480.5±7.1）Ma，辉绿岩的形成时代为（481.9±2.5）Ma。地球化学分析结果显示拉配泉地区安山质火山角砾岩和辉绿岩具有与岛弧相关的地球化学特征，而枕状玄武岩和辉绿岩的Sr-Nd-Pb同位素分析结果显示其源区具有EMII和HIMU富集地幔端元的特征，暗示其源区受到了俯冲洋壳物质的混染，表明其应形成于洋壳俯冲过程中的岛弧环境，从而进一步得出在482 Ma拉配泉地区已经进入洋壳俯冲阶段。此外，拉配泉钾长花岗岩具有非造山A型花岗岩的特点，表明其应形成于洋盆闭合、陆陆碰撞后的伸展环境。锆石年代学研究结果显示其形成时代为（468±15）Ma，表明拉配泉洋盆在此之前已经关闭。梳理拉配泉地区火成岩的组合、年代学、成因机制，结合区内高压岩石、蛇绿岩等的研究成果，初探北阿尔金拉配泉地区洋盆的构造演化阶段：517 Ma前洋盆已经打开；在482～475 Ma发生了洋壳俯冲并在南侧拉张形成弧后盆地；在468 Ma前洋盆已经关闭，并演化至陆—陆碰撞后的伸展环境。 |
| 英文摘要: |
| A suite of igneous rocks is exposed in the Lapeiquan area of the North Altyn Tagh, mainly consisting of diabase, pillow basalt, gabbro and andesitic volcanic breccia. Through detailed petrographic,geochemical, and chronological studies, this paper reconstructs the tectonic evolution during the magmatic period
in the Lapeiquan area and preliminarily explores the evolution history of the ocean basin. The formation age of the andesitic volcanic breccia is determined to be 480.5 ± 7.1 Ma, and that of the diabase is 481.9 ± 2.5 Ma.Geochemical analysis indicates that the andesitic volcanic breccia and diabase in the Lapeiquan area have geochemical characteristics related to island arcs. The Sr -Nd -Pb isotopic analysis of the pillow basalt and
diabase shows that their source regions are enriched with EMII and HIMU mantle endmembers, suggesting that they were contaminated by subducted oceanic crust materials. This implies that they should have formed in an island arc environment during the oceanic crust subduction process, further indicating that the Lapeiquan area had entered the oceanic crust subduction stage by 482 Ma. Additionally, the moyite in the Lapeiquan area exhibit
the characteristics of non -orogenic A -type granite, suggesting that they should have formed in an extensional environment after the closure of the ocean basin and the collision of continents. Zircon chronology studies show that their formation age is 468 ± 15 Ma, indicating that the Lapeiquan ocean basin had closed before this time.By summarizing the assemblage, chronology, and genetic mechanisms of the igneous rocks in the Lapeiquan area,and combining the research results of high-pressure rocks and ophiolites within the region, the tectonic evolution stages of the Lapeiquan ocean basin in the North Altyn Tagh are initially explored: the ocean basin opened before 517 Ma; oceanic crust subduction occurred between 482 Ma and 475 Ma, and an extensional back -arc basin formed on the southern side; the ocean basin closed before 468 Ma and evolved into an extensional environment
after the continental collision. |
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