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首页 > 过刊浏览>2025年第71卷第3期 >2025030005-2025030005. DOI:10.16509/j.georeview.2025.05.045
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青藏高原东北缘乌兰地区早古生代A型片麻状花岗岩的发现及地质意义——来自LA- ICP- MS锆石U- Pb年龄、地球化学和Hf同位素特征
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本文为青海省科技援青合作专项项目“柴北缘全吉地块沉积变质型铁矿成矿环境与找矿方向研究”（编号：20230202QYC0048）和青海省级财政资金地勘项目“青海省天峻县贡卡休玛地区1∶25万区域地质矿产调查”（编号：2019048095KC037）、“青海省天峻县茶卡北山地区锂稀有稀土金属矿预查”（编号：2018353008kc002）的成果


Discovery and geologyical significance of Early Paleozoic A- type granites in Wulan area on northeastern margin of Xizang(Tibet) Plateau——LA- ICP- MS U- Pb ages,geochemistry,and Hf isotopic characteristics of the zircons
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  • 1) 青海省青藏高原北部地质过程与矿产资源重点实验室,西宁 810012；2) 青海省地质调查院, 西宁, 810012;3) 青海省遥感大数据工程技术中心, 西宁,810012    
  • 1) 青海省青藏高原北部地质过程与矿产资源重点实验室,西宁 810012；2) 青海省地质调查院, 西宁, 810012;3) 青海省遥感大数据工程技术中心, 西宁,810012    
  • 1) 青海省青藏高原北部地质过程与矿产资源重点实验室,西宁 810012；2) 青海省地质调查院, 西宁, 810012    
  • 1) 青海省青藏高原北部地质过程与矿产资源重点实验室,西宁 810012；2) 青海省地质调查院, 西宁, 810012;3) 青海省遥感大数据工程技术中心, 西宁,810012    
  • 1) 青海省青藏高原北部地质过程与矿产资源重点实验室,西宁 810012；2) 青海省地质调查院, 西宁, 810012    
  • 1) 青海省青藏高原北部地质过程与矿产资源重点实验室,西宁 810012；2) 青海省地质调查院, 西宁, 810012    
  • 1) 青海省青藏高原北部地质过程与矿产资源重点实验室,西宁 810012；2) 青海省地质调查院, 西宁, 810012    
  • 1) 青海省青藏高原北部地质过程与矿产资源重点实验室,西宁 810012；2) 青海省地质调查院, 西宁, 810012    
  • 1) 青海省青藏高原北部地质过程与矿产资源重点实验室,西宁 810012；2) 青海省地质调查院, 西宁, 810012    
  • 1) Qinghai Provincial Key Laboratory of Geological Processes and Mineral Resources of Northern Qinghai—Xizang(Tibet) Plateau Xining, 810012；2) Qinghai Geological Survey Institute, Xining, 810012；3) Qinghai Remote Sensing Big Data Engineering Technology Ceter, Xining, 810012    
  • 1) Qinghai Provincial Key Laboratory of Geological Processes and Mineral Resources of Northern Qinghai—Xizang(Tibet) Plateau Xining, 810012；2) Qinghai Geological Survey Institute, Xining, 810012；3) Qinghai Remote Sensing Big Data Engineering Technology Ceter, Xining, 810012    
  • 1) Qinghai Provincial Key Laboratory of Geological Processes and Mineral Resources of Northern Qinghai—Xizang(Tibet) Plateau Xining, 810012；2) Qinghai Geological Survey Institute, Xining, 810012    
  • 1) Qinghai Provincial Key Laboratory of Geological Processes and Mineral Resources of Northern Qinghai—Xizang(Tibet) Plateau Xining, 810012；2) Qinghai Geological Survey Institute, Xining, 810012；3) Qinghai Remote Sensing Big Data Engineering Technology Ceter, Xining, 810012    
  • 1) Qinghai Provincial Key Laboratory of Geological Processes and Mineral Resources of Northern Qinghai—Xizang(Tibet) Plateau Xining, 810012；2) Qinghai Geological Survey Institute, Xining, 810012    
  • 1) Qinghai Provincial Key Laboratory of Geological Processes and Mineral Resources of Northern Qinghai—Xizang(Tibet) Plateau Xining, 810012；2) Qinghai Geological Survey Institute, Xining, 810012    
  • 1) Qinghai Provincial Key Laboratory of Geological Processes and Mineral Resources of Northern Qinghai—Xizang(Tibet) Plateau Xining, 810012；2) Qinghai Geological Survey Institute, Xining, 810012    
  • 1) Qinghai Provincial Key Laboratory of Geological Processes and Mineral Resources of Northern Qinghai—Xizang(Tibet) Plateau Xining, 810012；2) Qinghai Geological Survey Institute, Xining, 810012    
  • 1) Qinghai Provincial Key Laboratory of Geological Processes and Mineral Resources of Northern Qinghai—Xizang(Tibet) Plateau Xining, 810012；2) Qinghai Geological Survey Institute, Xining, 810012    
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    摘要:

    宗务隆山构造带处于青藏高原东北缘，是衔接东昆仑造山带和南祁连造山带的重要地质构造单元。近年来，该地区开展的1∶25 000区域地质矿产调查，在锂铍矿方面取得了重大突破性进展，极大提升了基础地质研究和找矿空间。本文采用岩石学、矿物学、全岩地球化学、LA- ICP- MS锆石年代学和Lu—Hf同位素方法对片麻状二长花岗岩开展研究。结果显示，29颗锆石中共识别出3期不同的年龄值:（1）有8个测点n（206Pb）/n（238U）谐和年龄数据介于563. 4±9. 7～1116. 6±11. 0Ma之间，代表岩体上侵过程中捕获的围岩或继承早期的岩浆结晶锆石。（2）有4个测点，为捕获或继承的早期锆石年龄，锆石的n（206Pb）n（238U）谐和年龄介于521. 1±8. 7～534. 6±4. 4 Ma，代表早古生代早期的岩浆事件。（3）有16个分析点n（206Pb）/n（238U）谐和年龄值为512. 9±1. 2Ma（MSWD=0. 80，n=16)，为岩体的结晶年龄，代表岩体侵位时代为中寒武世。Hf同位素结果表明εHf(t)在-3. 03～-18. 03区间变化，平均值为-9. 61，二阶段模式年龄（TDMC）介于1678～2617Ma之间，推测该花岗岩源于古老地壳的重融。岩石轻稀土相对富集而重稀土相对亏损，岩体具有高Si、Y，富Na2O+K2O，贫Ca、低Fe、Mg，而强烈亏损Sr、Eu、P、Ti的特征，属典型的A型花岗岩。综合区域地质背景分析，我们认为本区片麻状二长花岗岩形成于原特提斯洋向南俯冲的活动大陆边缘弧伸展环境，这一发现对于反演宗务隆构造带早古生代构造演化具有重要意义。

    Abstract:

    The Zongwulongshan tectonic belt is located on the northeast edge of the Qinghai Tibet Plateau and is an important geological structural unit that connects the East Kunlun orogenic belt and the South Qilian orogenic belt.The results show that in recent years, the 1∶25000 regional geological and mineral surveys conducted in the region have made significant breakthroughs in lithium beryllium deposits, greatly enhancing basic geological research and exploration space.This article uses petrology, mineralogy, whole rock geochemistry, LA- ICP- MS zircon geochronology, and Lu—Hf isotope methods to study gneiss like diorite.The results showed that a total of 29 zircons identified 3 different age values:(1)There are eight measurement points with n(206Pb) /n(238U) concordant age data ranging from 563.4 ± 9.7Ma to 1116.6 ±11.0 Ma, representing the captured surrounding rocks or inherited early magmatic crystalline zircons during the intrusion process of the rock mass.(2) There are four measurement points,which represent the early magmatic events of the Early Paleozoic era. The n（206Pb）/n（238U）concordant age of zircons ranges from 521.1 ± 8.7 Ma to 534.6 ± 4.4 Ma, representing the captured or inherited early zircon ages.(3) There are sixteen analysis points with a concordant age value of n(206Pb）/n(238U）, which is 512.9 ± 1.2Ma (MSWD)=0.80,n=16), indicating the crystallization age of the rock mass and representing the intrusion age of the rock mass in the Middle Cambrian. The Hf isotope results indicate that εHf(t) varies between -3.03 and -18.03, with an average value of -9.61. The two- stage model age (TDMC) ranges from 1678 Ma to 2617 Ma, suggesting that the granite originated from the remelting of ancient crust. The rock is relatively enriched in light rare earth elements and relatively depleted in heavy rare earth elements. The rock mass is characterized by high Si and Y, rich in Na2O+K2O, poor in Ca, low in Fe and Mg, and strong depletion of Sr, Eu, P and Ti, belonging to a typical A- type granite. Based on the comprehensive analysis of regional geological background, we believe that the gneiss like diorite in this area was formed in an active continental margin arc extensional environment where the original Tethys Ocean subducted southward. This discovery is of great significance for inverting the early Paleozoic tectonic evolution of the Zongwulong structural belt.

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王国良,许海全,曹锦山,李善平,缑明亮,郑英,袁锦鹏,封建平,徐尚平.2025.青藏高原东北缘乌兰地区早古生代A型片麻状花岗岩的发现及地质意义——来自LA- ICP- MS锆石U- Pb年龄、地球化学和Hf同位素特征[J].地质论评,71(3):2025030005,[DOI].
WANG Guoliang, XU Haiquan, CAO Jinshan, LI Shanping, GOU Mingliang, ZHENG Ying, YUAN Jinpeng, FENG Jianping, XU Shangping.2025. Discovery and geologyical significance of Early Paleozoic A- type granites in Wulan area on northeastern margin of Xizang(Tibet) Plateau——LA- ICP- MS U- Pb ages, geochemistry, and Hf isotopic characteristics of the zircons[J]. Geological Review,71(3):2025030005.

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  • 收稿日期:2024-12-14
  • 最后修改日期:2025-04-24
  • 在线发布日期: 2024-05-19
  • 出版日期: 2025-05-15
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