大兴安岭海拉尔地区北秋叶山岩体的锆石U-Pb年龄及其地质意义
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摘要
大兴安岭中生代花岗岩成因和构造背景的确定对讨论东北地区中生代构造-岩浆演化具有重要意义。笔者对大兴安岭中北段海拉尔盆地北缘的北秋叶山石英闪长岩岩体进行了锆石LA-ICP-MS U-Pb定年研究。结果显示:锆石具有清晰的生长振荡环带,其Th/U比值为0.64～1.16,属于典型的岩浆成因锆石;获得的~(206)Pb/~(238)U加权平均年龄为(227.6±1.2)Ma(n=25,MSWD=1.08),代表了北秋叶山岩体的结晶年龄,岩体的时代为晚三叠世,该岩体的形成可能与该区西侧的蒙古—鄂霍茨克洋演化相关。
The determination of the genesis and tectonic setting of Mesozoic granites in the Great Hinggan Mountains is of great significance to the discussion of Mesozoic tectonics-magmatic evolution in Northeast China. Zircon LA-ICP-MS U-Pb dating of the north Qiuyeshan quartz diorite pluton in the northern margin of Hailar Basin in the middle and northern part of Daxing'an Mountains is studied. The results showed that Zircon has clear growth oscillation zones. The Th/U ratio is 0.64-1.16.It belongs to the typical magmatic zircon. The weighted average age of ~(206)Pb/~(238)U was(227.6±1.2) Ma(n=25, MSWD=1.08). It represents the crystallization age of the Beiqiushan pluton. The age of the rock mass is Late Triassic. The formation of the intrusion may be related to the evolution of the Mongolian-Okhotsk Ocean on the western side of the area.
The determination of the genesis and tectonic setting of Mesozoic granites in the Great Hinggan Mountains is of great significance to the discussion of Mesozoic tectonics-magmatic evolution in Northeast China. Zircon LA-ICP-MS U-Pb dating of the north Qiuyeshan quartz diorite pluton in the northern margin of Hailar Basin in the middle and northern part of Daxing'an Mountains is studied. The results showed that Zircon has clear growth oscillation zones. The Th/U ratio is 0.64-1.16.It belongs to the typical magmatic zircon. The weighted average age of ~(206)Pb/~(238)U was(227.6±1.2) Ma(n=25, MSWD=1.08). It represents the crystallization age of the Beiqiushan pluton. The age of the rock mass is Late Triassic. The formation of the intrusion may be related to the evolution of the Mongolian-Okhotsk Ocean on the western side of the area.
引文
[1]王建国,和钟铧,许文良,等.大兴安岭南部钠闪石流纹岩的岩石成因:年代学和地球化学证据[J].岩石学报,2013,29(03):853-863.
[2]孟恩,许文良,杨德彬,等.满洲里地区灵泉盆地中生代火山岩的锆石U-Pb年代学、地球化学及其地质意义[J].岩石学报,2011.27(04):1209-1226.
[3]许文良,王枫,裴福萍,等.中国东北中生代构造体制与区域成矿背景:来自中生代火山岩组合时空变化的制约[J].岩石学报,2013.29(02):339-353.
[4]佘宏全,李进文,向安平,等.大兴安岭中北段原岩锆石U-Pb测年及其与区域构造演化关系[J].岩石学报,2012.28(02):571-594.
[2]孟恩,许文良,杨德彬,等.满洲里地区灵泉盆地中生代火山岩的锆石U-Pb年代学、地球化学及其地质意义[J].岩石学报,2011.27(04):1209-1226.
[3]许文良,王枫,裴福萍,等.中国东北中生代构造体制与区域成矿背景:来自中生代火山岩组合时空变化的制约[J].岩石学报,2013.29(02):339-353.
[4]佘宏全,李进文,向安平,等.大兴安岭中北段原岩锆石U-Pb测年及其与区域构造演化关系[J].岩石学报,2012.28(02):571-594.