| 辽西白塔地区侏罗纪火山岩岩石学、同位素年代学与地球化学特征 |
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| 引用本文： | 宋旸,徐学纯,郑常青,林波,孟兆海,徐久磊.辽西白塔地区侏罗纪火山岩岩石学、同位素年代学与地球化学特征[J].世界地质,2018,37(1):70-87. |
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| 作者姓名： | 宋旸 徐学纯 郑常青 林波 孟兆海 徐久磊 |
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| 作者单位： | 1. 吉林大学地球科学学院, 长春 130061;2. 天津航海仪器研究所, 天津 300131 |
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| 基金项目： | 国土资源部公益性行业科研专项经费项目（201311197）. |
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| 摘 要： | 出露于辽西白塔地区的侏罗纪中酸性火山岩及火山碎屑岩组合,主要是由粗安岩、流纹质岩屑晶屑熔结凝灰岩、粗面英安岩和流纹岩组成。通过系统的LA-ICPMS锆石的U-Pb同位素年代学研究,研究区火山岩形成年代为165~149 Ma。岩石地球化学特征显示,酸性火山岩属于钙碱性火山岩系,中性火山岩分别属于碱性火山岩系和中-高钾钙碱性火山岩系,中性岩具有埃达克质岩的地球化学特征,SiO_2≥56.20%、Al_2O_3≥15.09%、MgO≤2.89%、Sr≥561×10~(-6)、Y≤13.15×10~(-6)、Yb≤1.47×10~(-6)和无明显Eu异常。研究区火山岩普遍具有富集大离子亲石元素(Rb、K、Ba、Sr、Pb)和轻稀土元素,亏损高场强元素(Ti、Nb、Ta、P)的特征。其原始岩浆来源于基性下地壳物质的部分熔融,形成于古太平洋板块俯冲影响下板内挤压造山的构造环境。
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| 关 键 词： | 辽西 火山岩 锆石年龄 地球化学 |
| 收稿时间： | 2017-09-12 |
| 修稿时间： | 2018-01-18 |
Petrology,isotopic geochronology and geochemistry of Jurassic volcanic rocks in Baita area,western Liaoning |
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| SONG Yang,XU Xue-chun,ZHENG Chang-qing,LIN Bo,MENG Zhao-hai,XU Jiu-lei.Petrology,isotopic geochronology and geochemistry of Jurassic volcanic rocks in Baita area,western Liaoning[J].World Geology,2018,37(1):70-87. |
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| Authors: | SONG Yang XU Xue-chun ZHENG Chang-qing LIN Bo MENG Zhao-hai XU Jiu-lei |
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| Institution: | 1. College of Earth Sciences, Jilin University, Changchun 130061, China;2. Tianjin Navigation Instrument Research Institute, Tianjin 300131, China |
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| Abstract: | Intermediate-acidic volcanic rocks and pyroclastic rocks exposed in the Baita area of western Liaoning are mainly composed of trachyandesite, rhyolitic breccia ignimbrite, trachydacite and rhyolite. Geochronology studies via zircon LA-ICPMS U-Pb isotopic dating show that volcanic rocks of the research area formed from 149 to 165 Ma. The geochemical study indicates that the acidic volcanic rocks belong to the calc-alkaline series, while the intermediate volcanic rocks belong to alkaline series and mid-high K calc-alkaline series. The intermediate rocks geochemically belong to adakitic rocks, with SiO2 ≥ 56.20%, Al2O3 ≥ 15.09%, MgO ≤ 2.89%, Sr ≥ 561×10-6, Y ≤ 13.15×10-6, Yb ≤ 1.47×10-6 and no obvious Eu anomaly. The volcanic rocks in the study area are generally enriched in LILE(Rb, K, Ba, Sr and Pb)and LREE, and depleted in HFSE (Ti, Nb, Ta and P). The original magma was derived from partial melting of the basic materials of lower crust, in the intraplate compressive orogenic background under the influence of the Paleo-Pacific plate subduction. |
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| Keywords: | western Liaoning volcanic rocks LA-ICP-MS zircon U-Pb dating geochemistry |
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