| 谈乐,杨本昭,李大磊,崔小齐,刘小朋.陕西省红阳地区火山岩地球化学、锆石U-Pb年龄及其地质意义[J].地质找矿论丛,2023,38(3):358-366 |
| 陕西省红阳地区火山岩地球化学、锆石U-Pb年龄及其地质意义 |
| Geochemistry and zircon U-Pb age of volcanics in Hongyang area, Shaanxi province and the geological significance |
| 投稿时间：2022-10-27 |
| DOI：10.6053/j.issn.1001-1412.2023.03.012 |
| 中文关键词: 火山岩 晚奥陶世 锆石U-Pb测年 地球化学特征 红阳地区 陕西省 |
| 英文关键词:Volcanics Late Ordovician U-Pb age geochemical characteristics Hongyang area Shaanxi province |
| 基金项目:陕西省2020年地勘基金项目“陕西省镇坪县红岩萤石矿预查”(编号:61202211365)资助。 |
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| 中文摘要: |
| 通过对陕西省镇坪县红阳地区火山岩锆石U-Pb测年与岩石地球化学特征研究,结果表明:火山岩锆石U-Pb年龄为450.2 Ma±3.7 Ma,时代为晚奥陶世。火山岩具有富硅、碱,贫钙、镁特征,为过碱性-碱性系列。微量元素大离子亲石元素Rb和LREE相对富集,并且Rb、Nb、Zr等富集成峰;高场强元素分布范围较大,分异较明显,Sr、Ti、Ba相对亏损明显,呈现低谷形态,显示了大陆裂谷环境岩浆活动的特征;w(Ti)/w(Zr)值平均为3.53,与地幔岩浆的范围(<20)一致,反映了其源区为地幔部分熔融。稀土元素球粒陨石标准化配分曲线总体表现为右倾,负Eu异常(δEu=0.40~0.55)的"海鸥式"模型;w(Th)/w(Yb)值平均为3.81,w(Ta)/w(Yb)值平均为2.05,判别图解均落在板内玄武岩区。基于该火山岩的岩石化学、微量稀土元素地球化学特征,并结合已有的区域地质研究资料,综合分析认为本区火山岩应为北大巴山早古生代裂谷环境的产物。 |
| 英文摘要: |
| This paper deals with zircon U-Pb age and geochemical characteristics of volcanics in Hongyang area, Zhenping county, Shaanxi province. Zircon U-Pb age is 450.2 Ma±3.7 Ma corresponding to Late Ordovician Epoch. The volcanics is characterized by enrichment of Si, alkais and depletion of Ca and Mg belonging to peraalkaline-alkaline rock series. Trace element of the volcanics is characterized by large ion Lithophilic element enrichment with Rb, Nb and Zr peak values, relative REE enrichment, wide distribution range, evident differentiation and trough distribution pattern of high field strength element with relative Sr, Ti and Ba depletion implying that the magmatic activity take place in continental rift environment. Average value of w(Ti)/w(Zr) is 3.53 coinsided with those (<20) of mantle magmatic rock indicating that the volcanics come from partial melting of the mantle material. The chondrite-normalized REE values of the volcanics take shape of a right leaning seagull pattern with negative Eu anomaly (δEu=0.40~0.55). The average w(Th)/w(Yb) value is 3.81, the everage w(Ta)/w(Zr) 2.05 and all the values fall in the field of the Intra-plate basalt in discrimination diagram. Based on petrochemical and trace element geochemical characteristics of the volcanics and regional geological data abailable. We comprehensively consider that the volcanics should be product of Early Palaeozoic rift in the North Dabashan area. |
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