【摘要】：內蒙古白音圖嘎地區(qū)位于西伯利亞板塊東南緣晚古生代陸緣增生帶,地處二連—賀根山板塊對接帶西北側,該區(qū)發(fā)育大量晚古生代花崗巖,主要巖石類型為斑狀二長花崗巖和堿長花崗巖。本文對該區(qū)花崗巖進行了LA-ICP-MS鋯石U-Pb測年和巖石地球化學測試。結果表明:斑狀二長花崗巖和堿長花崗巖鋯石U-Pb年齡分別為302.8±1.3Ma(MSWD=1.4)和301.1±0.6 Ma(MSWD=0.84),屬于晚石炭世;巖石地球化學數據顯示,巖體屬鉀玄巖系,具有高硅(SiO_2=70.83%~75.01%),富堿(Na_2O+K_2O=11.58%~13.20%),貧鈣(CaO=0.50%~1.22%)和鎂(MgO=0.11%~0.33%)特征。鋁飽和指數A/CNK=0.81~1.01,為準鋁—弱過鋁質花崗巖。巖體整體富集Rb、Th、U等大離子親石元素(LILEs),虧損Ba、Sr以及高場強元素(HFSEs)Nb、Ta、P、Ti;LERR富集,HERR相對虧損,具有明顯的負Eu異常(δEu=0.11~0.43)。初始巖漿溫度(759.33℃~801.81℃)和巖石地球化學分析表明,白音圖嘎花崗巖具有A型花崗巖特征。同時,低的Nb/Ta(7.38~19.50)、Zr/Hf(29.61~35.26)和Sm/Nd(0.22~0.32)比值指示其源巖為殼源。綜合研究表明,白音圖嘎花崗巖為陸殼變雜砂巖部分熔融的產物,形成于晚石炭世早期西伯利亞板塊和華北板塊后碰撞作用的板內伸展環(huán)境,為興蒙造山帶晚古生代構造巖漿演化及古亞洲洋閉合的時限提供了新的約束和佐證實例。
[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 鹵1.3Ma (MSWD=1.4) and 301.1 鹵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，

本文編號：2209866