北黄海盆地中上侏罗统火山岩岩石地球化学特征及构造背景
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摘要：对北黄海盆地 X 井钻遇中—上侏罗统暗色岩组进行研究。研究结果表明：北黄海盆地 X 井钻遇中—上侏 罗统暗色岩组中有 2 层火山岩，以夹层产出；火山岩为钙碱性系列，且两层火山岩 Na2O 含量差别较大，下层是 钠质流纹岩，上层是钾质流纹岩−英安岩；2 层火山岩的微量元素、稀土元素地球化学特征相似；稀土元素配分型 式为轻稀土富集的右倾型，轻、重稀土分馏不明显，具微弱铕异常；Rb，Sr，Ba 和 K 等不相容的大离子亲石元 素以及和 Hf 和 Zr 等不相容的高场强元素富集，Ti，Nb 和 Yb 等难溶元素呈现较强亏损，且(w(Rb)/w(Yb))N＞1， 岩浆具有地壳物质属性； Nb 和 Ta 相对亏损， Ba 相对富集，岩石具有火山弧火山岩地球化学特征；结合 w(Ti)/w(Zr)−w(Ti)/w(Y)岩石成因以及 w(Nb)−w(Y)和 w(Rb)−w(Y+Nb)构造环境判别图，认为研究区火山岩形成于 与俯冲有关的火山弧或弧后伸展环境。下层火山岩岩浆是盆地裂陷较深时深部地壳部分熔融的产物，源区受幔源 物质混染，Na2O 质量分数高；上层火山岩岩浆是盆地裂陷较浅时浅部地壳部分熔融的产物，Na2O 质量分数低。 关键词：北黄海盆地；中—上侏罗统；火山岩；地球化学；岩石成因；构造背景 中图分类号：P595 文献标志码：A 文章编号：1672−7207(2013)01−0223−10
第 44 卷第 1 期 2013 年 1 月
中南大学学报(自然科学版) Journal of Central South University (Science a3
北黄海盆地中—上侏罗统火山岩岩石地球 化学特征及构造背景
王嘹亮 1，沈艳杰 2，程日辉 2，许中杰 2 (1. 广州海洋地质调查局，广东 广州，510075； 2. 吉林大学 地球科学学院，吉林 长春，130061)
收稿日期：2012−01−13；修回日期：2012−03−18 基金项目：国家自然科学基金资助项目(40972074，41030853)；国家重点基础研究发展规划(“973”计划)项目(2009CB219306) 通信作者：沈艳杰(1981−)，女，黑龙江望奎人，博士，讲师，从事矿产普查与勘探研究；电话：0431-88502620；E-mail: shenyj@
Geochemistry and tectonic background of Middle—Upper Jurassic volcanic rocks in the North Yellow Sea basin
WANG Liaoliang1, SHEN Yanjie2, CHENG Rihui2, XU Zhongjie2
(1. Guangzhou Marine Geological Survey, Guangzhou 510075, China; 2. College of Earth Science, Jilin university, Changchun 130061, China) Abstract: Middle-Upper Jurassic Dark sandstone and mudstone rocks was studied. The results show that there are two layers of volcanic rocks interbeded in Middle-Upper Jurassic Dark sandstone and mudstone rocks revealed by Well X in the North Yellow Sea basin. The volcanic rocks are Calc-alkaline series and acidic rocks.The lower layer is the sodic rhyolite while the upper layer is potassium rhyolite-dacite based on the contents of Na2O and K2O. Geochemistry characteristics of trace and rare earth elements of these volcanic rocks are similar: Light REE elements are rich，and light and heavy REE elements are not singificantly fractionated. Chondrite normalized REE distribution patterns are the Right Type with weak Eu abnormality. Incompatible large ion lithophile elements such as Rb, Sr, Ba and K and incompatible high field strength elements such as Hf, Zr are enriched, but the hardly contain elements such as Ti, Nb and Yb have large loss with (w(Rb)/w(Yb))N＞1, which suggests the source magma comes from crustal materials. Clear relative losses of Nb and Ta, and relatively rich of Ba indicate that these volcanic rocks have a typical characteristics of the volcanic arc. Petrogenesis analysis of w(Ti)/w(Zr)−w(Ti)/w(Y) and tectonic discrimination diagram analysis of w(Ti)/w(Zr)−w(Ti)/w(Y),
第 44 卷第 1 期 2013 年 1 月
中南大学学报(自然科学版) Journal of Central South University (Science a3
北黄海盆地中—上侏罗统火山岩岩石地球 化学特征及构造背景
王嘹亮 1，沈艳杰 2，程日辉 2，许中杰 2 (1. 广州海洋地质调查局，广东 广州，510075； 2. 吉林大学 地球科学学院，吉林 长春，130061)
收稿日期：2012−01−13；修回日期：2012−03−18 基金项目：国家自然科学基金资助项目(40972074，41030853)；国家重点基础研究发展规划(“973”计划)项目(2009CB219306) 通信作者：沈艳杰(1981−)，女，黑龙江望奎人，博士，讲师，从事矿产普查与勘探研究；电话：0431-88502620；E-mail: shenyj@
Geochemistry and tectonic background of Middle—Upper Jurassic volcanic rocks in the North Yellow Sea basin
WANG Liaoliang1, SHEN Yanjie2, CHENG Rihui2, XU Zhongjie2
(1. Guangzhou Marine Geological Survey, Guangzhou 510075, China; 2. College of Earth Science, Jilin university, Changchun 130061, China) Abstract: Middle-Upper Jurassic Dark sandstone and mudstone rocks was studied. The results show that there are two layers of volcanic rocks interbeded in Middle-Upper Jurassic Dark sandstone and mudstone rocks revealed by Well X in the North Yellow Sea basin. The volcanic rocks are Calc-alkaline series and acidic rocks.The lower layer is the sodic rhyolite while the upper layer is potassium rhyolite-dacite based on the contents of Na2O and K2O. Geochemistry characteristics of trace and rare earth elements of these volcanic rocks are similar: Light REE elements are rich，and light and heavy REE elements are not singificantly fractionated. Chondrite normalized REE distribution patterns are the Right Type with weak Eu abnormality. Incompatible large ion lithophile elements such as Rb, Sr, Ba and K and incompatible high field strength elements such as Hf, Zr are enriched, but the hardly contain elements such as Ti, Nb and Yb have large loss with (w(Rb)/w(Yb))N＞1, which suggests the source magma comes from crustal materials. Clear relative losses of Nb and Ta, and relatively rich of Ba indicate that these volcanic rocks have a typical characteristics of the volcanic arc. Petrogenesis analysis of w(Ti)/w(Zr)−w(Ti)/w(Y) and tectonic discrimination diagram analysis of w(Ti)/w(Zr)−w(Ti)/w(Y),