| 大兴安岭中段突泉盆地高Mg#火山岩激光全熔~(40)Ar/~(39)Ar测年与地球化学特征 |
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| 引用本文： | 李永飞,孙守亮,郜晓勇.大兴安岭中段突泉盆地高Mg#火山岩激光全熔~(40)Ar/~(39)Ar测年与地球化学特征[J].地质与资源,2013,22(4):264-272. |
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| 作者姓名： | 李永飞 孙守亮 郜晓勇 |
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| 作者单位： | 沈阳地质矿产研究所/中国地质调查局 沈阳地质调查中心, 辽宁 沈阳 110034 |
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| 基金项目： | 中国地质调查项目"东北地区晚古生代以来构造演化特征综合研究"，"古亚洲洋构造体制与滨太平洋构造体制叠加转变综合调查和研究"，"松辽外围中新生代盆地群油气基础地质调查" |
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| 摘 要： | 对大兴安岭中段突泉盆地中出露的高Mg#火山岩进行了详细的岩石学、激光全熔40Ar/39Ar测年及地球化学研究,讨论了该组火山岩成因、岩石物质来源及其地质意义.突泉盆地高Mg#火山岩为一套中酸性岩石,化学成分显示其主要为安山岩与英安岩.岩石激光全熔40Ar/39Ar测年结果显示火山岩年龄为136.0±2.0 Ma,形成于早白垩世早期.火山岩地球化学特征总体表现出了埃达克质岩石的地球化学特征:SiO2≥57.50%,A12O3≥16.66%,MgO<3.31%,Mg#>45,贫Y(平均值17.53×10-6),贫Yb(平均值1.84×10-6),高S(r>534×10-6),高Ba(789×10-6925×10-6);Sr/Y=22.71925×10-6);Sr/Y=22.7173.54,Y/Yb=8.9573.54,Y/Yb=8.9511.32;REE分异明显,富集LREE,亏损HREE;无明显Eu异常(平均Eu/Eu*=0.94).该套高Mg#火山岩可能是加厚基性下地壳发生部分熔融并与底侵的基性岩浆混合的产物.结合大兴安岭中生代盆岭构造演化的特点,突泉盆地早白垩世高Mg#的埃达克质火山岩形成于蒙古-鄂霍茨克洋(古太平洋)闭合造山阶段碰撞构造背景,岩浆源区性质主要归因于增厚的造山带下地壳部分熔融作用.
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| 关 键 词： | 大兴安岭中段 突泉盆地 高Mg#火山岩 激光全熔40Ar/39Ar测年 埃达克质岩 |
| 收稿时间： | 2012-11-21 |
LASER 40Ar/39Ar DATING AND GEOCHEMISTRY OF THE HIGH-Mg# VOLCANIC ROCKS FROM THE TUQUAN BASIN IN CENTRAL DAXINGANLING |
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| LI Yong-fei
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SUN Shou-liang
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GAO Xiao-yong.LASER 40Ar/39Ar DATING AND GEOCHEMISTRY OF THE HIGH-Mg# VOLCANIC ROCKS FROM THE TUQUAN BASIN IN CENTRAL DAXINGANLING[J].Geology and Resources,2013,22(4):264-272. |
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| Authors: | LI Yong-fei SUN Shou-liang GAO Xiao-yong |
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| Institution: | Shenyang Institute of Geology and Mineral Resources, CGS, Shenyang 110034, China |
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| Abstract: | A detailed study is carried out on petrology, laser 40Ar/39Ar dating and geochemistry of the high-Mg# volcanic rocks from Tuquan Basin in Central Daxinganling region on the ground of their genesis, magmatic origin and geological implication. It is concluded that the volcanic rocks comprise a series of the acid-medium rocks （namely, andesite and dacite） with the age of 136.0 ～2.0 Ma by the method of laser 40Ar/39Ar dating, identical to early Early-Cretaceous. Geochemically, these rocks show a close affinity to adakitic rocks, with SiO2≥57.50%, high A1203 （≥ 16.66% ）, MgO〈 3.31%, Mg#〉45, low Y （averagely 17.53×10-6, 〈18×10-6） and Yb （averagely 1.84×10-6, 〈l.90×l0-6）, high Sr （〉534×10-6） and Ba （789×10-6 - 925×10-6）, Sr/Y=22.71 - 73.54, Y/Yb=8.32 - 11.32, enriched LREE, depleted HREE and without significant Eu anomaly （average Eu/Eu＊ =0.94）. The features listed above imply that the original magma for the studied rocks is most likely resulted from partial melting of the thickened lower crust and in turn contaminated by the basaltic magma. Combined with the tectonic evolution characteristics in this region in Mesozoic, the volcanics from the Tuquan Basin should be derived from partial melting of the thickened lower crust as the result of the collision of Mongol-Okhotsk （Paleo-Pacific） orogenic belt. |
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| Keywords: | Central Daxinganling Tuquan Basin high-Mg# volcanic rock laser 40Ar/39Ar dating adakitic rock |
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