| 摘要: |
| 笔者在综合分析最近十多年来的Sr、Nd、Pb同位素资料基础上,重点研究了青藏高原及邻区新生代火山岩岩浆源区在时空上的变化规律。结果表明:①冈底斯中段火山岩的岩浆源区逐渐从普通地幔向EMⅡ方向演化;西段晚期火山岩源区的演化方向为俯冲带壳幔混合源→造山带上地壳源→下地壳源。②西羌塘岩浆源区主要为不具富集或亏损的幔源物质;囊谦盆地、大理海东火山岩源区较深,为大洋型软流圈地幔+消减组分混合源;藏北羊湖、雄鹰台鲸鱼湖、西昆仑以及北羌塘巴毛穷宗火山岩的岩浆源区为EMⅡ;鱼鳞山超钾质火山岩为经历了大陆地壳物质强烈交代作用的EMⅡ型岩浆源区;西秦岭火山岩源于亏损地幔,腾冲新生代火山岩源区为受到地壳物质交代的EMⅡ。③西羌塘、可可西里、西昆仑和腾冲新生代火山岩具两种演化趋势——鱼鳞山、普鲁、雄鹰台鲸鱼湖岩区和腾冲火山群向EMⅡ方向演化,而泉水沟、黑石北湖、阿什库勒则分别沿0Ma的地幔上地壳混合线方向演化。④青藏高原及邻区新生代火山岩至少存在4种不同的岩浆源区。 |
| 关键词: 多元同位素示踪 岩浆源区 演化趋势 新生代火山岩 青藏高原及邻区 |
| DOI： |
| 附件 |
| 投稿时间：2003-07-14 |
| 基金项目:973项目“印度与亚洲大陆主碰撞成矿带作用”(2002CB412600)下属课题“成功潜力评估与战略新区预测”;中国地质调查局青藏高原地质研究综合项目“青藏高原地质构造及资源环境效应研究”(200113900069);“青藏高原南部空白区基础地质调查与研究”实施项目(1212010310102)资助。 |
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| Sr-Nd-Pb isotopic variations of the Cenozoic volcanic rocks from the Qinghai-Xizang Plateau and its adjacent areas |
| ZHU Di-cheng, PAN Gui-tang, MO Xuan-xue, DUAN Li-ping, LIAO Zhong-li, WANG Li-quan |
(1. Chengdu Institute of Geology and Mineral Resources, Chengdu 610082, Sichuan, China;
2. China University of Geosciences, Beijing 100083, China) |
| Abstract: |
| The highlights in the present paper are placed on the spatio-temporal evolution of the Cenozoic volcanic rocks from the Qinghai-Xizang Plateau and its adjacent areas in the light of Sr, Nd and Pb isotopic data issued in recent years. The results of research are generalized as follows. (1) There are gradations from PREMA to EMⅡ for the magmatic sources of the volcanic rocks in central Gangdise, and from the mixed crust-mantle sources in subduction zones through upper crust sources in orogenic zones to lower crust sources in western Gangdise. (2) The magmatic sources in western Qiangtang are represented by depleted mantle-derived rocks. The Nangqian Basin and volcanic sources in Haidong, Dali are relatively deeper, suggesting a mixed source of oceanic asthenospheric mantle and subduction components. The magmatic sources of northern Xizang, western Kunlun and northern Qiangtang are represented by EMⅡ-type enrichment mantle; The Yulinshan ultrapotassic volcanic rocks represent the EMⅡ-type magmatic sources that have been subjected to intense metasomatism of the continental crustal matter. The western Qinling volcanic rocks are derived from the depleted mantle. The Tengchong Cenozoic volcanic rocks occur in the EMⅡ-type enrichment mantle source areas. (3) There are two evolutionary trends for the Cenozoic volcanic rocks from western Qiangtang, Hoh Xil, western Kunlun and Tengchong:towards the EMⅡ type for the Yulinshan, Pulu, Xiongyingtai-Jingyuhu and Tengchong volcanic rocks, and along the 0 Ma mantle-upper crust line for the Quanshuigou, Heishibeihu and Ashikule volcanic rocks. (4) At least four types of magmatic sources may be recognized for the Cenozoic volcanic rocks on the Qinghai-Xizang Plateau and its adjacent areas. |
| Key words: multivaricate isotope tracing magmatic source evolutionary trend Cenozoic volcanic rock Qinghai-Xizang Plateau and its adjacent areas |
