大兴安岭中段晚三叠世四分组效应花岗岩的厘定及其地质意义

发布时间：2018-02-26 23:10

本文关键词： 布敦化四分组效应稀有金属矿晚三叠世大兴安岭　出处：《岩石学报》2016年09期 　论文类型：期刊论文

【摘要】：布敦化岩体位于中亚造山带东段大兴安岭地区的科尔沁右翼中旗,该岩体由中细粒二云母花岗岩和斑状中细粒白云母花岗岩组成。LA-MC-ICP-MS锆石U-Pb同位素年龄测试显示布敦化岩体形成于晚三叠世早期。地球化学分析表明,该岩体为弱过铝质-过铝质、高钾钙碱性系列,主量元素表现出高硅(73.73%~78.33%)、富碱(Na2O+K2O=7.07%~9.06%)、低钙(Ca O=0.01%~0.87%)、贫镁(Mg O=0.12%~0.52%)的特征;稀土元素具有明显的Eu负异常和M型四分组效应配分型式。岩石学和地球化学特征显示布敦化岩体为高分异I型花岗岩。Lu-Hf同位素研究显示其εHf(t)值为7.0~12.4,二阶段Hf模式年龄(tDM2)为812~473Ma。结合邻区晚三叠世地质资料可知,布敦化岩体是在古亚洲洋闭合造山后伸展的构造背景下产生的,是晚元古代-早古生代地壳物质熔融的产物。布敦化地区的四分组效应花岗岩的稀土元素总量高、岩浆侵位后经历了强烈的分异演化,暗示布敦化地区可能具有较好的稀有金属矿的找矿前景。
[Abstract]:The BuDunhua rock body is located in the central flag of Horqin right-wing in the Daxing'anling area of the eastern part of the Central Asian orogenic belt. The U-Pb isotopic dating test of zircon from the granites and porphyry mesomorphic Muscovite shows that the Budenghua rock body was formed in the early late Triassic. Geochemical analysis shows that the rock body is weakly peraluminous and peraluminous. The main elements of high potassium calc-alkaline series show the characteristics of high silicon 73.73 and 78.33, alkali-rich Na 2O K 2O 7.07 and 9.06, low calcium Ca O 0. 01 and 0.87, and poor magnesium mg O + 0. 12 + 0. 52); The REE has obvious EU negative anomaly and M-type four-grouping effect partition pattern. The petrological and geochemical characteristics show that the Buduhua granite is a highly differentiated I-type granite. Lu-Hf isotopic study shows that the 蔚 Hfft) value is 7.0 ~ 12.4, and the two-stage HF model. The age of TDM _ 2 is 812 ~ 473Ma. combined with the geological data of the late Triassic in the adjacent area, it can be seen that, The Budenghua rock mass was formed in the tectonic setting of the extension after the closed orogenic of the Paleo-Asian Ocean and was the product of the late Proterozoic and early Paleozoic crustal material melting. The total amount of rare earth elements of the four-group effect granites in the Buduhua area is high. The magmatic emplacement has undergone a strong differentiation and evolution, suggesting that there may be a better prospecting prospect for rare metal deposits in the Buduhua area.
【作者单位】：吉林大学地球科学学院;中国地质调查局沈阳地质调查中心;东北师范大学地理科学学院;
【基金】：国家自然科学基金项目(41340024、41272223) 中国地质调查局项目(1212011121085、1212011085473)联合资助
【分类号】：P588.121

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