| 定量估算造山带地壳厚度的岩石地球化学方法:综述与实例 |
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| 引用本文： | 官文慧,汪洋.定量估算造山带地壳厚度的岩石地球化学方法:综述与实例[J].延边大学理工学报,2017,0(2):214-224. |
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| 作者姓名： | 官文慧 汪洋 |
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| 作者单位： | 中国地质大学(北京) 地球科学与资源学院，北京 100083 |
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| 摘 要： | 应用岩石地球化学数据定量、半定量估算岩浆弧地壳厚度的方法包括:钙碱性岩套K2O含量、w(Sr)/w(Y)值、w(La)N/w(Yb)N值，玄武质岩石Na2O含量、CaO含量、w(Ce)/w(Y)值等。目前提出的定量公式对厚度在20~45 km范围内的俯冲造山带地壳厚度反演结果可靠性较高。中酸性岩w(Dy)/w(Yb)值可以指示造山带是否存在加厚的地壳。应用岩石地球化学数据定量、半定量反演造山带地壳厚度的公式要求:明确其适用条件与应用范围；有足够数量的样本；进行数据筛选并且剔除离群值。藏南冈底斯弧的实例研究表明，w(La)N/w(Yb)N值能够估算碰撞造山带古地壳厚度，印度板块与亚洲大陆碰撞引起的地壳显著增厚导致冈底斯地体中酸性岩浆岩w(Sr)/w(Y)值、w(La)N/w(Yb)N值在40 Ma以来明显跃升。三江地区三叠纪义敦岛弧地壳厚度为60 km；福建长乐—南澳构造带早白垩世时期岩浆弧的地壳厚度为42 km；辽西地区中侏罗世—早白垩世时期火山岩地壳厚度为50~65 km。
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| 关 键 词： | 地壳厚度 地球化学 岩浆弧 造山带 冈底斯弧 义敦岛弧 福建 辽宁 |
Petrogeochemical Methods for Quantitative Estimation of the Crustal Thickness of Orogenic Belt: Overview and Case Studies |
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| GUAN Wen-hui,WANG Yang.Petrogeochemical Methods for Quantitative Estimation of the Crustal Thickness of Orogenic Belt: Overview and Case Studies[J].Journal of Yanbian University (Natural Science),2017,0(2):214-224. |
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| Authors: | GUAN Wen-hui WANG Yang |
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| Affiliation: | School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China |
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| Abstract: | The petrogeochemical data, which include K2O content, w(Sr)/w(Y) and w(La)N/w(Yb)N of calc-alkaline suite, and Na2O and CaO contents and w(Ce)/w(Y) of basaltic rocks, can be used to quantitatively or semi-quantitatively estimate the crustal thickness of magmatic arc. The quantitative formulas are reliable to calculate the crustal thickness (20-45 km) of subduction orogenic belt. w(Dy)/w(Yb) of intermediate-acidic rocks can constrain the thick crust with more than 50 km. The proper application for quantitatively or semi-quantitatively estimating the crustal thickness of orogenic belt requires that obeying the conditions and scopes of the method, gathering a dataset for analysis as large as possible, and doing data screen and outlier elimination. For the case of Gangdese in the southern Tibet, it concludes that w(La)N/w(Yb)N can be used to estimate the thickness of crustal thickness in the post-collisional environment. The remarkable jump of w(Sr)/w(Y) and w(La)N/w(Yb)N of intermediate magmatic rocks in Gangdese terrane since 40 Ma is due to the crust thickening caused by the collision between India plate and Asia continent. The crustal thickness of Triassic Yidun island arc in Sanjiang area is 60 km; that of Early Cretaceous magmatic arc in Changle-Nan’ao tectonic zone of Fujian is 42 km; that of Middle Jurassic-Early Cretaceous volcanic rocks in the western Liaoning is 50-65 km. |
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| Keywords: | crustal thickness geochemistry magmatic arc orogenic belt Gangdese arc Yidun island arc Fujian Liaoning |
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