内蒙古阿巴嘎旗白音图嘎地区晚石炭世花岗岩地球化学特征、锆石U-Pb定年及其地质意义
发布时间：2018-08-28 15:47
【摘要】：内蒙古白音图嘎地区位于西伯利亚板块东南缘晚古生代陆缘增生带,地处二连—贺根山板块对接带西北侧,该区发育大量晚古生代花岗岩,主要岩石类型为斑状二长花岗岩和碱长花岗岩。本文对该区花岗岩进行了LA-ICP-MS锆石U-Pb测年和岩石地球化学测试。结果表明:斑状二长花岗岩和碱长花岗岩锆石U-Pb年龄分别为302.8±1.3Ma(MSWD=1.4)和301.1±0.6 Ma(MSWD=0.84),属于晚石炭世;岩石地球化学数据显示,岩体属钾玄岩系,具有高硅(SiO_2=70.83%~75.01%),富碱(Na_2O+K_2O=11.58%~13.20%),贫钙(CaO=0.50%~1.22%)和镁(MgO=0.11%~0.33%)特征。铝饱和指数A/CNK=0.81~1.01,为准铝—弱过铝质花岗岩。岩体整体富集Rb、Th、U等大离子亲石元素(LILEs),亏损Ba、Sr以及高场强元素(HFSEs)Nb、Ta、P、Ti;LERR富集,HERR相对亏损,具有明显的负Eu异常(δEu=0.11~0.43)。初始岩浆温度(759.33℃~801.81℃)和岩石地球化学分析表明,白音图嘎花岗岩具有A型花岗岩特征。同时,低的Nb/Ta(7.38~19.50)、Zr/Hf(29.61~35.26)和Sm/Nd(0.22~0.32)比值指示其源岩为壳源。综合研究表明,白音图嘎花岗岩为陆壳变杂砂岩部分熔融的产物,形成于晚石炭世早期西伯利亚板块和华北板块后碰撞作用的板内伸展环境,为兴蒙造山带晚古生代构造岩浆演化及古亚洲洋闭合的时限提供了新的约束和佐证实例。
[Abstract]:The Baiyintuga area of Inner Mongolia is located in the late Paleozoic continental margin accretive zone of the southeastern edge of the Siberian plate, located in the west and north of the Erlian-Hegenshan plate docking belt. A large number of late Paleozoic granites were developed in this area. The main rock types are porphyry monzogranite and alkali feldspar granite. In this paper, LA-ICP-MS zircon U-Pb dating and geochemistry of the granite in this area have been carried out. The results show that the zircon U-Pb ages of porphyry monzogranites and alkali feldspar granites are 302.8 卤1.3Ma (MSWD=1.4) and 301.1 卤0.6 Ma (MSWD=0.84), respectively, which belong to late Carboniferous, and the petrogeochemical data show that the rock bodies belong to kalmonite series, with high SiO_2=70.83%~75.01%, high Na_2O K _ 2O _ 2O _ (11.58)%, poor CaO=0.50%~1.22% and magnesium (MgO=0.11%~0.33%). The aluminum saturation index (A / CNK = 0.81) is quasi aluminum-weakly peraluminous granite. The large ion lithophile elements such as Rb,Th,U and (LILEs), depleted Ba,Sr are enriched in the whole rock mass, and the high field strength element (HFSEs) Nb,Ta,P,Ti;LERR is enriched with the relative depletion of Herr, which has obvious negative Eu anomaly (未 Eu=0.11~0.43). The initial magmatic temperature (759.33 鈩，
本文编号：2209866
[Abstract]:The Baiyintuga area of Inner Mongolia is located in the late Paleozoic continental margin accretive zone of the southeastern edge of the Siberian plate, located in the west and north of the Erlian-Hegenshan plate docking belt. A large number of late Paleozoic granites were developed in this area. The main rock types are porphyry monzogranite and alkali feldspar granite. In this paper, LA-ICP-MS zircon U-Pb dating and geochemistry of the granite in this area have been carried out. The results show that the zircon U-Pb ages of porphyry monzogranites and alkali feldspar granites are 302.8 卤1.3Ma (MSWD=1.4) and 301.1 卤0.6 Ma (MSWD=0.84), respectively, which belong to late Carboniferous, and the petrogeochemical data show that the rock bodies belong to kalmonite series, with high SiO_2=70.83%~75.01%, high Na_2O K _ 2O _ 2O _ (11.58)%, poor CaO=0.50%~1.22% and magnesium (MgO=0.11%~0.33%). The aluminum saturation index (A / CNK = 0.81) is quasi aluminum-weakly peraluminous granite. The large ion lithophile elements such as Rb,Th,U and (LILEs), depleted Ba,Sr are enriched in the whole rock mass, and the high field strength element (HFSEs) Nb,Ta,P,Ti;LERR is enriched with the relative depletion of Herr, which has obvious negative Eu anomaly (未 Eu=0.11~0.43). The initial magmatic temperature (759.33 鈩，
本文编号：2209866
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