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高校地质学报 ›› 2026, Vol. 32 ›› Issue (05): 605-623.DOI: 10.16108/j.issn1006-7493.2025050

• •    下一篇

东昆仑东段洪水河地区印支期花岗岩锆石U-Pb年代学、地球化学特征及构造意义

何振凯1，李瑞保1, 2*，裴先治1, 2，李玉龙3，李佐臣1, 2，周 晓1，裴 磊1，陈有炘1，王 盟1，刘成军1
  

  1. 1. 长安大学 地球科学与资源学院，西安 710054；
    2. 西部矿产资源与地质工程教育部重点实验室，西安 710054；
    3. 青海省地质调查院，西宁 810012
  • 出版日期:2026-10-20 发布日期:2026-10-20

U-Pb Chronology, Geochemical Characteristics and Tectonic Significance of Indosinian Granite in the Hongshuihe Area of the Eastern Part of East Kunlun Orogen

HE Zhenkai1，LI Ruibao1,2*，PEI Xianzhi1,2，LI Yulong3，LI Zuochen1，ZHOU Xiao1，PEI Lei1，CHEN Youxin1，WANG Meng1，LIU Chengjun1#br#   

  1. 1. School of Earth Sciences and Resources, Chang’an University, Xi’an 710054, China；
    2. Key Laboratory of Mineral Resources and Geological Engineering in Western China, Ministry of Education, Xi’an 710054, China;
    3. Qinghai Geological Survey Institute, Xining 810012, China
  • Online:2026-10-20 Published:2026-10-20

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摘要： 东昆仑造山带东段洪水河地区出露一套晚三叠世花岗岩，其具有典型的埃达克质花岗岩特征，对研究冈瓦纳大陆北
缘古特提斯洋关闭过程及时限具有重要意义。该文章对研究区花岗岩进行了详细的岩石学、锆石U-Pb年代学和地球化学研究。结果表明，该地区花岗闪长岩及闪长质包体的加权平均年龄为225±1 Ma和223±1 Ma，时代为晚三叠世。地球化学分析表明该花岗闪长岩SiO2含量为63.85％~65.87％，Na2O/K2O的值为0.99~1.42，Mg#为42.76~49.15，A/CNK的值为0.90~1.03，具准铝质、高钾钙碱性花岗岩特征。岩石的轻、重稀土分馏明显，具有轻稀土富集，重稀土亏损的特征。微量元素具有高Sr（360.10×10-6~483×10-6），低Y（8.54×10-6~14.3×10-6）、Yb（0.97×10-6~1.23×10-6），高Sr/Y（27.05~36.65）特征，Eu为微弱的正异常或无异常，具典型的埃达克质花岗岩特征；闪长质包体SiO2的含量为59.15％~61.80％，Na2O/K2O的值平均为1.84，Mg#为46.12~48.02，A/CNK为 0.85~0.92。闪长质包体亦具有轻稀土元素富集和重稀土元素亏损的右倾特征，其微量元素同样具有高Sr（447.30×10-6~482.70×10-6）、低Y（8.54×10-6~10.36×10-6）、Yb（0.67×10-6~0.78×10-6）以及高Sr/Y（43.18~56.52）的埃达克质岩特征。岩石成因研究表明东昆仑东段洪水河地区花岗岩起源于加厚下地壳角闪岩的部分熔融，幔源岩浆对其进行了一定程度的混染。结合区域地质资料，文章认为洪水河花岗岩体形成于碰撞构造环境，东昆仑造山带古特提斯洋于晚三叠世之前已经完全关闭并进入碰撞造山阶段，从而产生了区域上的富铝花岗岩和埃达克质花岗岩。

关键词: 东昆仑造山带, 埃达克质花岗岩, 地球化学, 古特提斯, 印支期, 洪水河

Abstract: A set of Late Triassic granite is exposed in the Hongshuihe area of the eastern section of the East Kunlun Orogenic
Belt, which has typical adakite granite characteristics and is of great significance for the study of the time constraint on the closure process of the Paleo-Tethys Ocean on the northern margin of the Gondwana continent. A detailed petrology, zircon U-Pb chronology, and geochemical study of the granite in the area was carried out in this study. The results show that the weighted average ages of granodiorite and diorite inclusions in this area are 225±1 Ma and 223±1 Ma, indicating a Late Triassic age. Geochemical analysis shows that the SiO2 content of the granodiorite is 63.85%-65.87%, the value of Na2O/K2O is 0.99-1.42, the value of Mg# is 42.76-49.15, and the value of A/CNK is 0.90-1.03. The fractionation of light and heavy rare earths in rocks is obvious, and it has the characteristics of enrichment in light rare earths and loss of heavy rare earths. The trace elements show high Sr (360.10×10-6-483×10-6), low Y (8.54×10-6-14.3×10-6), Yb (0.97×10-6-1.23×10-6), high Sr/Y (27.05-36.65) ratio, and weak positive or no Eu anomaly, with the characteristics of adakitic granite. The content of diorite inclusions in SiO2 was
59.15%-61.80%, the average value of Na2O/K2O was 1.84, the value of Mg# was 46.12-48.02, and the value of A/CNK was 0.85- 0.92. The diorite inclusions also show the right-dipping characteristics of light rare earth element enrichment and heavy rare earth element loss, and their trace elements also display the characteristics of high Sr (447.30×10-6-482.70×10-6), low Y (8.54×10-6 - 10.36×10-6), low Yb (0.67×10-6-0.78×10-6) and high Sr/Y (43.18-56.52). Petrogenetic studies indicate that the granodiorite in the Hongshuihe area of the eastern East Kunlun Orogen originated from partial melting of amphibolite in the thickened lower crust, with subsequent contamination by mantle-derived magmas. Combined with the regional data and the discriminant diagrams of tectonic environments, it is believed that the Hongshuihe granodiorite mass was formed in the post-collisional tectonic
environment, which further indicates that the East Kunlun orogenic belt had entered the post-collisional tectonic evolution stage in the Late Triassic. 

Key words: East Kunlun Orogenic Belt, adakitic granite, geochemistry, Paleo Tethys, Indosinian, Hongshuihe

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