摘要
Phia Bioc花岗岩体位于老挝-越南长山褶皱带北西部马江缝合带与哀牢山-斯雷博河缝合带之间,镜下显微鉴定岩石类型为似斑状角闪黑云二长花岗岩。锆石阴极发光图上具有典型的震荡环带,锆石的稀土元素配分模式表现为轻稀土元素亏损,重稀土元素富集的左倾曲线,具有强烈正Ce异常和中等负Eu异常,其Th/U比值均大于0.1,表明所测锆石为典型的壳源岩浆锆石。锆石LA-ICP-MS U-Pb同位素分析结果显示,Phia Bioc岩体的年龄为(244.4±1.2)Ma,属于中三叠世安尼期岩浆活动的产物。对长山褶皱带印支期的区域地质背景、岩浆活动以及思茅-彭世洛陆块-东印支陆块-越北-华南陆块间的构造演化关系的综合分析表明,Phia Bioc花岗岩体是印支早期东印支陆块与越北-华南陆块沿马江缝合带同碰撞造山期挤压剪切环境的产物。
The Phia Bioc granite is located in the northwestern Truong Son fold belt from Laos-Vietnam, between Song Ma suture zone and Ailaoshan-Sre Pok suture zone. The rock type is regarded as porphyritic hornblende-biotite monzonitic granite after microscopic identification by microscope. There are typical oscillatory zones on the cathode luminescence （CL） images. REE patterns of the analyzed zircons which are characterized by depleted light rare earth elements （LREE） and enriched heavy rare earth elements （HREE） give a left-leaning curve, obviously positive Ce anomaly and moderately negative Eu anomaly. In addition, all of the Th/U ratio is more than 0.1. These characteristics suggest a crust source magmatic genesis of the analyzed zircons. The LA-ICP-MS U-Pb isotopic analysis results of the zircons show that the age of the Phia Bioc granite is （244.4±1.2）Ma, which belongs to the product of Anisian of Middle Trias- sic. According to the comprehensive analysis of regional geological background and magmatic activity of Truong Son belt in Indosinian and the tectonic evolution relationship among Simao-Phisanulok block, East Indo-China block and North Vietnam-South China block, we consider that the Phia Bioc granite is the product of orogenic extrusion shearing environment inducing by the syn-collisional period between East In- do-China and North Vietnam-South China along Song Ma suture zone in Early Indosinian.
出处
《地质科技情报》
CAS
CSCD
北大核心
2014年第5期66-74,共9页
Geological Science and Technology Information
基金
国土资源大调查项目"老挝-越南长山成矿带成矿规律及勘察选区研究"(1212011120337)
国外矿产资源风险勘查专项资金项目"东南亚地区重要成矿带成矿规律与优势矿产资源潜力评价研究"([2011]D3-03)
