| 新疆卡拉麦里姜巴斯套组火山岩地球化学特征与构造意义 |
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| 引用本文： | 汪帮耀,姜常义,李永军,吴宏恩.新疆卡拉麦里姜巴斯套组火山岩地球化学特征与构造意义[J].西安地质学院学报,2011(3):237-245. |
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| 作者姓名： | 汪帮耀 姜常义 李永军 吴宏恩 |
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| 作者单位： | [1]长安大学地球科学与资源学院,陕西西安710054 [2]长安大学西部矿产资源与地质工程教育部重点实验室,陕西西安710054 [3]新疆维吾尔自治区有色地质矿产勘查院,新疆乌鲁木齐830000 |
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| 基金项目： | 中国地质调查局项目（QD200508） |
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| 摘 要： | 通过对新疆卡拉麦里姜巴斯套组火山岩野外地质特征、岩石学和高精度同位素年代学的研究,发现姜巴斯套组火山岩具典型双峰式组合,岩石类型包括玄武岩-酸性火山碎屑岩-玄武粗面安山岩;得到玄武粗面安山岩LA-ICP-MS锆石U-Pb年龄为（319.8±2）Ma（加权均方偏差值为3）,表明姜巴斯套组火山岩形成于早石炭世谢尔普霍夫阶。对火山岩地球化学特征的研究表明,姜巴斯套组火山岩钙碱性系列、高钾钙碱性系列和钾玄岩系列岩石兼而有之,岩石的稀土元素配分曲线均为轻稀土元素富集型,无明显Eu异常,玄武岩和玄武粗面安山岩具有K正异常和Sr负异常,酸性火山碎屑岩表现出Nb、Ta和Ti显著亏损。总体来说,姜巴斯套组火山岩富集大离子亲石元素,相对亏损高场强元素。玄武岩和玄武粗面安山岩表现出大陆裂谷（大陆板内拉张区域）岩石特征;酸性火山碎屑岩表现出岛弧或者活动大陆边缘岩石属性。总之,姜巴斯套组火山岩形成于卡拉麦里洋盆闭合碰撞造山后的拉张伸展环境,卡拉麦里地区在早石炭世末期就进入了碰撞后的陆内伸展拉伸阶段。
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| 关 键 词： | 火山岩 大陆裂谷 岩石地球化学 谢尔普霍夫阶 姜巴斯套组 卡拉麦里 新疆 |
Geochemical Characteristics and Tectonic Implications of Karamaili Jiangbasitao Formation Volcanic Rock in Xinjiang |
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| Authors: | WANG Bang-yao JIANG Chang-yi LI Yong-jun WU Hong-en |
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| Institution: | 1.School of Earth Sciences and Resources,Chang＇an University,Xi＇an 710054,Shaanxi,China; 2.Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education,Chang＇an University,Xi＇an 710054,Shaanxi,China;3.Xinjiang Institute of Geological Exploration for Nonferrous Resources,Urumqi 830000,Xingjiang,China) |
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| Abstract: | Geochemical characteristic and the chart of tectonic of volcanic rocks and dating of high-precision geochronology in Karamaili Jiangbasitao Formation of Xinjiang were studied.The results showed that there were typical bimodal volcanic rocks of Jiangbasitao Formation,which included basalt-acid volcanolastic rock-basaltic trachyte andesite;LA-ICP-MS U-Pb zircon age of basaltic trachyte andesite was（319.8±2）Ma（weighted mean square deviation was 3）,and indicated that the volcanic rocks of Jiangbasitao Formation formed in Serpukhovian Stage of Early Carboniferous.The study on geochemical characteristic of volcanic rocks showed that the rocks of Jiangbasitao Formation were composed of calc-alkaline series,high-K calc-alkaline series and shoshonite series;light rare earth element（REE） enriched patterns in chondrite-normalized REE diagram with no exception of Eu was shown in rocks;basalt and basaltic trachyte andesite were positive K anomaly and negative Sr anomaly,and acid volcanolastic rock were depleted in Nb,Ta and Ti.On the whole,the volcanic rocks of Jiangbasitao Formation were enriched in large ion lithophile elements,and depleted in high field strength element.Characteristics of basalt and basaltic trachyte andesite was continental rift valley（continental extension zone）;characteristic of acid volcanolastic rock was arc or active continental margins.In general,the volcanic rocks of Jiangbasitao Formation formed in the post-collisional extension setting after Karamaili ocean basin closed,and there was post-collisional continent extension setting at the late stage of Early Carboniferous in Karamaili Region. |
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| Keywords: | volcanic rock continental rift lithogeochemical Serpukhovian Stage Jiangbasitao Formation Karamaili Xinjiang |
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