渤海周边中、新生代火山作用及其深部过程意义  

MESOZOIC-CENOZOIC VOLCANISM AND THE SIGNIFI CANCE OF DEEP PROCESSES IN THE BOHAI REGION

作　　者：谷俐[1] 戴塔根[1] 范蔚茗[2] 

机构地区：[1]中南工业大学资源环境与建筑工程学院,湖南长沙410083 [2]中国科学院长沙大地构造研究所,湖南长沙410013

出　　处：《大地构造与成矿学》2000年第1期9-17,共9页Geotectonica et Metallogenia

基　　金：国家自然科学基金!(No.49252001)项目

摘　　要：根据渤海周边的三大主要盆地中、新生代火山岩的岩石学、岩石化学、微量元素地球化学和同位素地球化学的综合分析研究表明 :1.本区中、新生代有三大火山作用时期即早中生代 (228～226.9Ma)、晚中生代 (136.0～66.3Ma)和新生代 (61.0～29.7Ma) ;2.早中生代英安岩为偏钾质酸性钠质玄武岩 ,它们均发生结晶分离作用 ;3.晚中生代火山岩微量元素分配形式和Sr、Nd同位素表明其来源于富集的岩石圈地幔 ,新生代玄武岩与OIB相似的微量元素分配模式以及亏损的Sr、Nd同位素组成 ,暗示其来源于软流圈 ;4.岩石圈 -软流圈界面在中 -新生代发生上升、回落 ,岩石圈经历拉伸和减薄过程。Based on data from petrochemistry,trace element geochemistry and isotopic compositions of Mesozoic-Cenozoic volcanic rocks in three basins in the Bohai region,some conclusions can be drawn.In the region,there are three major volcanic eruption stages with corresponding volcanic rocks in the Mesozoic-Cenozoic,i.e.,early Mesozoic dacite(228.8～226.9 Ma),late Mesozoic basaltic-trachy-andesite,lamprophyre and rhyolite(136.0～90.9 Ma),and Cenozoic basalt(61.0～29.7 Ma).All the volcanics have undergone different fractional crystallization.Trace elements and isotopic compositions characteristics of the Cenozoic volcanics suggest that they are derived from the asthenosphere,and those of the Mesozoic volcanics show that they are derived from the enriched lithosphere.A model is proposed indicating that the lithosphere-asthenosphere boundary was uplifted,then fell back in the Mesozoic-Cenozoic with the thinning of lithosphere.

关 键 词：火山作用 中-新生代 岩石圈 深部过程 渤海地区 

分 类 号：P542.5[天文地球—构造地质学] P588.14[天文地球—地质学]