大兴安岭中生代玄武岩的地球化学特征: 壳幔相互作用的证据  

Geochemical characteristics of the Mesozoic basalts in Da Hinggan Ling: Evidence of the mantle crust interaction

作　　者：葛文春[1,2] 林强[2] 孙德有[2] 吴福元[2] 元钟宽[3] 李文远 陈明植 尹成孝[5] 

机构地区：[1]中国科学院广州地球化学研究所,广州510640 [2]长春科技大学地球与行星科学系,长春130061 [3]江原大学校自然科学大学地质学科 [4]韩国资源研究所 [5]釜山大学校师范大学地球科学科

出　　处：《岩石学报》1999年第3期396-407,共12页Acta Petrologica Sinica

基　　金：国家自然科学基金;(中-韩国际合作)项目

摘　　要：大兴安岭中生代玄武岩类由北区碱性系列岩石和南区亚碱性系列岩石组成， 主要活动时期为晚侏罗世至早白垩世， 在时间、空间上显示大体呈北北东向展布的环状 “热向斜构造”。北区碱性系列岩石高度富集轻稀土元素和大离子亲石元素， 其丰度类似于板内碱性玄武岩， 但明显亏损高场强元素这一特点又类似于火山弧钙碱性玄武岩。南区亚碱性系列岩石强烈亏损高场强元素的特征类似于火山弧钙碱性玄武岩， 但轻稀土元素和大离子亲石元素富集程度又类似于洋中脊拉斑玄武岩和岛弧拉斑玄武岩。显然， 大兴安岭中生代玄武岩系列显示地球化学双重性， 也就是既有板内特征又有火山弧特征， 既有富集特征又有亏损特征。这种地球化学双重性表明， 大兴安岭地区存在若干不同性质的地幔源： 富集性的、亏损性的、过渡性的地幔源。解释一个地区存在多元地幔源区模式的最佳方案是地幔柱。这种包含富集成分和亏损成分的地幔柱源区的形成是与古生代地质时期古亚洲域闭合过程中俯冲洋壳与亏损地幔相互作用的动力学、地球化学过程有关。The Mesozoic basalts in Da Hinggan Ling is constituted by alkaline series in north and sub alkaline series in the south,The volcanic activity is mainly from late Jurassic to early Cretaceous The spatial distribution of volcanic rocks is in a NNE extending circular “thermal synclinal structure” The alkaline rocks in the north are highly enriched in LILE, of which the contents are similar to those of intraplate alkaline basalts However, they resemble volcanic arc calc alkaline basalts in the obvious depletion of the HFSE The sub alkaline rocks in the south are similar to volcanic arc strongly depleted in HFSE, however, they resemble MORB and volcanic arc tholeiite in the degree of LREE and LILE enrichment Therefore, the Mesozoic basalts in Da Hinggan Ling area are two folds in geochemical features In other words, they show both intraplate and volcanic arc characteristics, being either enriched or depleted It can be suggested that there are several mantle sources with different features existing around Da Hinggan Ling area The formation of mantle plume source regions with enriched and depleted components is related to the dynamic and geochemical process of subducted oceanic crust depleted mantle interaction during the closure of Old Asian Ocean in the period of Paleozoic

关 键 词：壳幔作用 微量元素 地幔柱 玄武岩 地球化学 

分 类 号：P588.145[天文地球—岩石学]