| 韩荣文,何鹏,赵子军,蒋园,杨圣坤,朵兴芳,徐方.大兴安岭中南段都兰地区满克头鄂博组火山岩年代学、地球化学及成因研究[J].地质找矿论丛,2025,40(4):524-532 |
| 大兴安岭中南段都兰地区满克头鄂博组火山岩年代学、地球化学及成因研究 |
| Geochronology, Geochemistry and Genesis of Volcanic Rocks from the Manketouebo Formation in the Dulan Area, the Middle and Southern Sections of the Greater Khingan Range |
| 投稿时间：2025-09-06 修订日期：2025-11-17 |
| DOI：10.6053/j.issn.1001-1412.2025.04.009 |
| 中文关键词: 锆石U-Pb年代学 地球化学 岩石成因 满克头鄂博组 都兰 大兴安岭中南段 |
| 英文关键词:zircon U-Pb chronology geochemistry petrogenesis Manketouebo Formation Dulan Area the middle and southern sections of the Greater Khingan Range |
| 基金项目:中国地质调查局项目“燕山-太行成矿带区域地质调查”（〔2025〕01-023/DD202401023）资助。 |
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| 中文摘要: |
| 大兴安岭地区中生代火山岩形成时所处的构造环境是地质学者关注的焦点地质问题，之前研究对象多集中于早白垩世火山岩，对晚侏罗世火山岩研究程度偏低。本文选取内蒙古东部都兰地区晚侏罗世火山岩为研究对象，为查明该套火山岩的形成时代、岩浆源区属性及构造背景，开展了系统的岩石地球化学测试、锆石 U-Pb年代学分析与岩石成因探讨，以期为区域中生代火山岩形成背景提供新的地质资料与依据。通过开展LA-ICP-MS锆石U-Pb定年，获得都兰地区晚侏罗世火山岩年龄值为153.9±1.5 Ma，明确了该地区满克头鄂博组火山岩的精确形成时代，表明大兴安岭南段在晚侏罗世存在一次火山岩成岩高峰期。都兰地区满克头鄂博组火山岩以流纹岩、流纹质凝灰岩等中酸性火山岩为主，岩石地球化学分析数据显示，该组火山岩具有鲜明的物质组成特征，岩石类型属于高钾钙碱性系列流纹岩，主量元素表现出高硅、富碱、高钾的特点；稀土元素图解表现为右倾的铲式特征，指示轻稀土元素富集、重稀土元素相对亏损，呈现显著负Eu异常；火山岩微量元素数据显示，大离子亲石元素（Rb、Th、U等）含量较高，而高场强元素（Nb、P、Ti等）则含量较低。结合区域构造演化，岩石学及地球化学数据显示该套火山岩形成于造山后伸展环境，岩浆来源于地壳岩石的部分熔融，岩浆演化与蒙古-鄂霍茨克洋闭合后的伸展构造背景有关。 |
| 英文摘要: |
| The tectonic setting during the formation of Mesozoic volcanic rocks in the Greater Khingan Range has long been a focal issue of concern to geologists. Previous studies have primarily focused on Early Cretaceous volcanic rocks, with relatively little research on Late Jurassic volcanic rocks. In this paper, Late Jurassic volcanic rocks in the Dulan area of eastern Inner Mongolia are selected as the research object. To clarify the formation age, magmatic source characteristics, and tectonic setting of this suite of volcanic rocks, systematic petrogeochemical analyses, zircon U-Pb geochronological analyses, and petrogenetic discussions were carried out, aiming to provide new geological data and evidence for studying the formation background of regional Mesozoic volcanic rocks. Through LA-ICP-MS zircon U-Pb dating, the age of Late Jurassic volcanic rocks in the Dulan area is determined to be 153.9±1.5 Ma, which clarifies the precise formation age of volcanic rocks in the Manketouebo Formation in this area, indicating that there was a peak period of volcanic rock formation in the southern segment of the Greater Khingan Range during the Late Jurassic. Volcanic rocks of the Manketouebo Formation in the Dulan area are dominated by intermediate- to acidic volcanic rocks, such as rhyolite and rhyolitic tuff. Petrogeochemical analysis data show that this suite of volcanic rocks has distinct compositional characteristics: they belong to the high-K calc-alkaline series rhyolites, with major elements characterized by high silica, alkali-rich, and high potassium contents. Rare earth element (REE) patterns exhibit a right-inclined shovel-like feature, indicating enrichment of light rare earth elements (LREEs) and relative depletion of heavy rare earth elements (HREEs), with significant negative Eu anomalies. Trace element data of the volcanic rocks show high concentrations of large-ion lithophile elements (LILEs, such as Rb, Th, U) and low concentrations of high-field-strength elements (HFSEs, such as Nb, P, Ti). In combination with the regional tectonic evolution, petrological and geochemical data indicate that this suite of volcanic rocks formed in a post-orogenic extensional setting. The magma was derived from the partial melting of crustal rocks, and the magmatic evolution was related to the extensional tectonic background after the closure of the Mongol-Okhotsk Ocean. |
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