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现代地质 ›› 2025, Vol. 39 ›› Issue (01): 62-82.DOI: 10.19657/j.geoscience.1000-8527.2023.087

• 岩浆岩岩石学 • 上一篇    下一篇

大兴安岭北段呼玛地区晚石炭世花岗岩年代学和地球化学特征:对古亚洲洋构造演化的制约

张国宾1,2(), 孔金贵2,3, 王翠彭3, 史宏江3, 鞠楠4, 何云龙2   

  1. 1.山西工程技术学院地球科学与工程系,山西 阳泉 045000
    2.辽宁工程技术大学矿业学院,辽宁 阜新 123000
    3.山东省核工业二七三地质大队,山东 烟台 264000
    4.中国地质调查局沈阳地质调查中心,辽宁 沈阳 110034
  • 出版日期:2025-02-10 发布日期:2025-02-20
  • 作者简介:张国宾,男,副教授,1983年出生,矿产普查与勘探专业,主要从事矿床学与矿产勘查方向的科研与教学。Email: zhangguobin85@163.com
  • 基金资助:
    中国地质调查局项目(1212011120342);辽宁省科技厅面上基金项目(201601370);辽宁省教育厅面上基金项目(LJ2019JL027);山西工程技术学院科研启动基金项目(2024QD-15);山西省来晋博士后科研启动经费项目(2024PT-03)

Geochronology and Geochemical Characteristics of Late Carboniferous Granites in the Huma Area, Northern Greater Khingan Mountains: Insights into the Tectonic Evolution of the Paleo-Asian Ocean

ZHANG Guobin1,2(), KONG Jingui2,3, WANG Cuipeng3, SHI Hongjiang3, JU Nan4, HE Yunlong2   

  1. 1. Department of Earth Science and Engineering, Shanxi Institute of Technology, Yangquan, Shanxi 045000, China
    2. School of Mines, Liaoning Technical University, Fuxin, Liaoning 123000, China
    3. Shandong Province Nuclear Industry Geological Group 273, Yantai, Shandong 264000, China
    4. Shenyang Center of China Geological Survey, Shenyang, Liaoning 110034, China
  • Published:2025-02-10 Online:2025-02-20

摘要:

大兴安岭位于中亚造山带东段,由额尔古纳地块、兴安地块、松嫩地块及其间缝合带拼接形成,各地块间的拼合时间、位置及演化过程一直是地学研究的热点问题。本文以呼玛地区晚石炭世中细粒二长花岗岩和中细粒花岗闪长岩为研究对象,开展LA-ICP-MS锆石U-Pb定年和岩石地球化学研究,探讨其岩石成因、岩浆源区特征及成岩构造环境,并尝试限定古亚洲洋闭合时限。研究表明,中细粒二长花岗岩和中细粒花岗闪长岩的锆石U-Pb加权平均年龄分别为(310.3±2.6) Ma和(313.4±2.5) Ma,成岩时代为晚石炭世。两类岩体表现出富硅、弱过铝质、高钾钙碱性系列岩石的特征,富集Rb、K、Th、U等大离子亲石元素,亏损Nb、Ta、P、Ti等高场强元素,稀土配分模式显示轻稀土富集、重稀土亏损及明显负铕异常,具有典型I型花岗岩地球化学特征。结合区域锆石Hf同位素组成特征,认为岩浆来源于新元古代晚期—显生宙新增生下地壳角闪岩相物质的部分熔融源区,并经历了分离结晶作用。综合年代学、地球化学特征及区域构造背景,推测大兴安岭北段晚石炭世花岗岩形成于兴安地块与松嫩地块碰撞拼合后的后造山构造环境,代表了区域从挤压向伸展体制转变的地质响应。

关键词: 大兴安岭北段, 晚石炭世, 花岗岩, 锆石U-Pb定年, 岩石地球化学, 构造背景

Abstract:

The Greater Khingan Mountain, located in the eastern part of the Central Asian orogenic belt, is composed of Erguna block, Xing’an block, Songnen block, and their suture zones. However, the timing, locations, and evolutionary processes of the amalgamation of these blocks have been key scientific issues of controversy within the geological community. In this paper, the Late Carboniferous medium fine grained monzonitic and medium fine grained granodiorite in the Huma area, northern Greater Hinggan Mountains are studied, conduct LA-ICP-MS zircon U-Pb geochronology and whole-rock elemental composition studies, investigate rock genesis and magma source regions, analyze the tectonic setting of petrogenesis, and attempt to constrain the timing of the closure of the ancient Paleo-Asian Ocean. The research results shows that the age of the medium fine grained monzonitic and medium fine grained granodiorite are (310.3±2.6)Ma and (313.4±2.5)Ma, respectively. Both types of rock formations share characteristics of high silicon, high aluminum, high alkali, low calcium, low magnesium, and weakly peraluminous. They belong to high potassium calc alkaline series rocks, rich in Rb, K, Th, U and other elements, and depleted in Nb, Ta, P, Ti. The content of P2O5 and Al2O3 decreases with the increase of SiO2, and the content of Th and Y increases with the increase of Rb, showing the characteristics of I-type granite. In conjunction with the regional magmatic zircon Hf isotope composition features, it indicates that the magma originated from the partial melting of basic rocks of amphibolite facies in the late Neoproterozoic-Phanerozoic neoaccretionary crust, and experienced a certain degree of fractional crystallization. Integrating geochronology, geochemistry characteristics and regional tectonic evolution, it is suggested that the Late Carboniferous granites in the northern Greater Khingan Mountains were formed in the post-collision environment after the collision of the Xing’an block and the Songnen block.

Key words: Northern Greater Khingan Mountain, Late Carboniferous, granite, zircon U-Pb age, petrogeochemistry, tectonic setting

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