沂沭断裂带中生代青山群火山岩地球化学特征及其岩石成因

发布时间：2018-03-22 16:02

  本文选题：沂沭断裂带　切入点：中生代　出处：《地学前缘》2017年06期 　论文类型：期刊论文

【摘要】：以沂沭断裂带安丘地区中生代青山群火山岩为研究对象,在进行系统的元素-同位素分析的基础上,探讨其岩浆源区和岩石成因。安丘火山岩SiO2含量变化于56.5%~65.8%,主要为高钾钙碱性系列岩石,岩石组合为英安岩和粗面安山岩;安丘火山岩富集大离子亲石元素和轻稀土元素,亏损高场强元素,显示富集但变化范围较大的Sr-Nd同位素组成((~(87)Sr/~(86)Sr)t=0.708 7~0.710 7,εNd(t)=-13.7~-5.93)。综合分析表明,安丘火山岩为大陆下地壳物质经拆沉作用于地幔环境中发生部分熔融作用,与上地幔岩石发生交代作用后进入地表形成,且其源区中可能有软流圈物质的加入。
[Abstract]:The volcanic rocks of Mesozoic Qingshan group in Anqiu area of Yishu fault zone were studied. Based on systematic element-isotope analysis, the volcanic rocks of Qingshan Group in the Anqiu area of Yishu fault zone were studied. The SiO2 content of Anqiu volcanic rocks varies from 56.5 to 65.8, mainly composed of high-potassium calc-alkaline series rocks, the rock assemblages of dolomite and coarse-faced andesite, and the anqiu volcanic rocks are enriched in large ion lithophile elements and light rare earth elements. The loss of elements in high field strength indicates that the Sr-Nd isotopic composition, which is enriched but with a large range of variations, is 0.708 ~ (-87) ~ (-0.708) -0.710 ~ (7), 蔚 -Ndndltti-13.7 ~ (7) ~ (-5.93) ~ 3.The comprehensive analysis shows that the volcanic rocks of Anqiu occur partial melting in the mantle environment due to the delamination of continental lower crustal material. After metasomatism with the upper mantle rocks, it is formed on the surface, and there may be the addition of asthenospheric material in its source region.
【作者单位】： 中国地质调查局天津地质调查中心;中国地质大学(武汉)地球科学学院;中国地质调查局武汉地质调查中心;
【基金】：国家自然科学基金委员会创新研究群体科学基金项目(40521001)
【分类号】：P588.14
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本文编号：1649367