| 四川盐源地区晚二叠纪双峰式火山岩的厘定及其地质意义 |
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| 引用本文： | 程建康,孙宝伟,霍加庆,肖亮,王彬,朱凯宁.四川盐源地区晚二叠纪双峰式火山岩的厘定及其地质意义[J].地质论评,2024,70(1):2024010013-2024010013. |
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| 作者姓名： | 程建康 孙宝伟 霍加庆 肖亮 王彬 朱凯宁 |
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| 作者单位： | 四川省地质矿产勘查开发局四〇五地质队，成都， 611830 |
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| 基金项目： | 本文为四川省地质矿产勘查开发局四〇五地质队创新基金资助项目（编号：KJCX- 2022- 015）的成果 |
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| 摘 要： | 四川省盐源县柏林山一带广泛分布着一套基性岩、酸性岩的火山岩组合，两类火山岩在时空上紧密伴生，二者之间缺失中性火山岩，构成典型的双峰式火山岩组合。通过对区内双峰式火山岩的空间分布调查，基性岩主要为致密块状玄武岩、斑状玄武岩，酸性火山岩主要为碱流岩，碱流岩位于玄武岩顶部，为晚二叠纪峨眉山大火成岩省的组成部分。在地质背景、岩石学、地球化学等方面研究的基础上，对区内双峰式火山岩的成因和形成环境进行了探讨，表明玄武岩的原始岩浆来自富集型地幔源区，为地幔橄榄岩小程度部分熔融的产物，形成于洋岛构造环境，碱流岩主要为玄武岩浆极度分离结晶后的酸性残余岩浆形成，形成于陆内拉张构造环境。柏林山地区晚二叠纪双峰式火山岩的发现和厘定为峨眉山玄武岩的演化提供了新的线索和依据，为区域成矿研究以及稀有稀土找矿提供了新的启示。
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| 关 键 词： | 双峰式火山岩 峨眉山玄武岩 碱流岩 地幔柱 盐源 |
| 收稿时间： | 2023/7/31 0:00:00 |
| 修稿时间： | 2024/1/12 0:00:00 |
Definitionof Late Permian bimodal volcanic rocks in Yanyuan area of Sichuan Province and its geological significance |
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| CHENG Jiankang,SUN Baowei,HUO Jiaqing,XIAO Liang,WANG Bin,ZHU Kaining.Definitionof Late Permian bimodal volcanic rocks in Yanyuan area of Sichuan Province and its geological significance[J].Geological Review,2024,70(1):2024010013-2024010013. |
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| Authors: | CHENG Jiankang SUN Baowei HUO Jiaqing XIAO Liang WANG Bin ZHU Kaining |
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| Institution: | No. 405 Geological Team of Sichuan Bureau of Geology & Mineral Resources,Chengdu,611830 |
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| Abstract: | This paper focuses on the study of petrology and geochemistry of the newly discovered bimodal volcanic rock assemblage in Mount Bailin area,Yanyuan County,Sichuan Province, and discusses its petrogenesis and tectonic geological background,which provides new clues and geological basis for further research on the formation mechanism,tectonic evolution and mineralization of Emeishan large igneous province.Methods:On the basis of field investigation,representative samples of basic and acid volcanic rocks were collected,and the bimodal volcanic rocks were studied by microscopic observation,analysis of major elements,trace elements and rare earth elements,and the petrogenesis and tectonic environment of the bimodal volcanic rocks were discussed.Results:A bimodal volcanic rock composed of alkali- rich high- titanium basalt and pantellerite was newly discovered in Mount Bailin area of Yanyuan County,Sichuan Province.It belongs to a part of the Emeishan large igneous province and was formed in the late Permian.Both basalt and pantellerite are characterized by light rare earth enrichment.The rare earth content and fractionation degree in pantellerite are significantly higher than those in basalt,and pantellerite shows obvious negative Eu anomaly.The basalts are relatively enriched in high field strength elements such as U,Th,Nb and Ta, and relatively depleted in large ion lithophile elements such as Rb,K and Sr.The pantellerite are significantly enriched in high field strength elements such as U,Th,Nb,Ta,Zr and Hf, and severely depleted in Ba,K,Sr,P,Ti,Ni and Cr.Basalt is the product of partial melting of mantle peridotite to a small extent.Pantellerite is mainly formed by acidic residual magma after extreme separation and crystallization of basaltic magma.The basalt were formed in the oceanic island environment,and the pantellerite were formed in the intracontinental extensional environment.The tectonic environment is related to the activity of the Emeishan mantle plume and the intracontinental rift extension by it.Conclusions:The definition of the late Permian bimodal volcanic rocks in Mount Bailin area,Yanyuan County,Sichuan Province is of great significance for the study of regional tectonic evolution and mineralization and the expansion of prospecting ideas. |
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| Keywords: | bimodal volcanic rocks Emeishan basalt pantellerite mantle plume Yanyuan |
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