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东昆仑那更晚三叠世流纹岩地球化学特征、成因及构造环境

Geochemical Characteristics, Petrogenesis and Structural Setting of Late Triassic Epoch Rhyolite in Nageng Area, East Kunlun

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【作者】 窦光源赵伟王振东李华毛建业

【Author】 DOU Guangyuan;ZHAO Wei;WANG Zhendong;LI Hua;MAO Jianye;Qinghai Geological Survey;

【机构】 青海省地质调查局

【摘要】 岩石地球化学分析显示,那更流纹岩SiO2含量为70.69%~73.21%,全碱(Na2O+K2O)含量7.54%~8.38%,且Na2O>K2O,Al2O3=11.94%~13.11%,A/ANK>1.1,岩石属于高钾钙碱性准铝质系列;岩石轻、重稀土元素存在一定的分馏,负铕异常明显(δEu=0.19~0.34),相对富集Rb、Ba、Th、U等元素,亏损Sr、Ta、Nb等元素。其与伸展构造背景下地壳物质部分熔融的产物特征一致。206Pb/204Pb=18.182~18.191,207Pb/204Pb=15.572~15.585,208Pb/204Pb=38.451~38.512,表明岩浆来源于下地壳,为地壳下部岩浆经历了早期结晶分异作用的产物。

【Abstract】 Rock geochemistry shows us that Nageng rhyolite is characterized by SiO2 content of 70.69%~73.21%, alkali(Na2O+K2O) 7.54%~8.38% and Na2O>K2O, Al2O3 = 11.94%~13.11%, A/ANK>1.1. The rock belongs to the high potassium and calc-alkaline quasi-aluminum series. It is enriched in LREE and Rb, Ba, Th, U and depleted in Sr, Ta, Nb with negative Eu anomalies(δEu=0.19~0.34). The characteristics is the same as in partially-fused crust of the context of extensional tectonics. We know about 206Pb/204Pb=18.182~18.191, 207Pb/204Pb=15.572~15.585, 208Pb/204Pb=38.451~38.512. All show that magma comes from the lower crust and it experiences the early crystallization differentiation.

【基金】 青海省地质勘查基金项目(2016020077kc039)
  • 【文献出处】 中国锰业 ,China’s Manganese Industry , 编辑部邮箱 ,2019年01期
  • 【分类号】P534.51;P588.141;P59
  • 【被引频次】3
  • 【下载频次】81
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