东准噶尔卡拉麦里石炭系火山岩地球化学特征及构造意义  

Geochemistry and Tectonic Settings of Carboniferous Volcanic Rocks from Karamaili, Eastern Junggar

作　　者：樊海龙 郭建明[2] 张生银[2] 张顺存[2] 郭晖[1,2,3] 刘翔 FAN Hai-long;GUO Jian-ming;ZHANG Sheng-yin;ZHANG Shun-cun;GUO Hui;LIU Xiang(Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;Key Laboratory of Petroleum Resources,Gansu Province/Key Laboratory of Petroleum Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院西北生态环境资源研究院,兰州730000 [2]甘肃省油气资源研究重点实验室/中国科学院油气资源研究重点实验室,兰州730000 [3]中国科学院大学,北京100049

出　　处：《矿物岩石地球化学通报》2019年第5期998-1008,共11页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(41503048);甘肃省重点实验室建设项目(1309RTSA041)

摘　　要：东准噶尔卡拉麦里构造带两侧广泛发育区域性石炭系火山岩,为探讨其形成的构造环境,对构造带西南侧白碱沟、帐篷沟、火福公路的火山岩进行了岩石学、地球化学研究。结果表明,该火山岩以钙碱性为主,随着SiO2含量的增加,其TFe2O3、TiO2、P2O5、MgO、MnO、TiO2含量明显下降。流纹岩具高的SiO2(68.24%~74.15%)、K2O+Na2O(8.71%~9.89%),低CaO(0.19%~0.60%)、MgO(0.03%~0.06%)、TiO2(0.19%~0.21%);安山岩具高TFe2O3(3.63%~12.58%);玄武岩具高CaO(13.00%~16.84%)、MgO(3.72%~4.33%)、TiO2(1.28%~1.51%),低K2O(0.42%~0.74%)。中基性火山岩球粒陨石标准化图呈较为平坦的右倾分布型式,具微弱的δEu负异常(0.753~1.042,均值为0.894)和δCe正异常(1.021~1.070);流纹岩显示明显的δEu负异常(均值为0.251)。εNd(t)值(4.73~7.22)、同位素和微量元素特征均表明有碰撞前岛弧岩浆组分加入到亏损地幔源区。综合磨拉石建造、前人年代学及同位素数据认为,晚石炭世是东准噶尔构造体制转换的过渡期,卡拉麦里地区石炭系火山岩形成于后碰撞伸展背景。Eastern Junggar in the Central Asian Orogenic Belt is characterized by voluminous Carboniferous volcanic rocks(rhyolite, andesite, hyalopsite and basalt) with minor tuff. Element and isotope analyses of volcanic rocks in the southern Karamaili of Eastern Junggar were carried out to investigate their tectonic setting in the Carboniferous. Rhyolite samples have relatively high SiO2, K2O+Na2O and low CaO, MgO, TiO2 contents while andesite have a high content of TFe2O3. Chondrite-normalized REE patterns of rhyolite, diorite porphyrite, hyalopsite and shows LREE enrichment with obvious Eu negative anomalies. Andesite display weak Ce anomalies. These samples are enriched in LILE but relatively depleted in HFSE, with high LaN/YbN, Zr-Zr/Y, Th/Nb-Ce/Nb, Zr-Zr/Y diagrams and the positive εNd(t)(4.73~7.22) values, indicating the depleted mantle source with the addition of island-arc materials. Integrating the previous data, the Carboniferous volcanic rocks in Karamaili are related to the post-collisional extension and the research provide reliable evidence for tectonic evolution.

关 键 词：地球化学 构造环境 火山岩 后碰撞期 卡拉麦里 东准噶尔 

分 类 号：P588.14[天文地球—岩石学]