大同地区早中生代煌斑岩-碳酸岩岩墙群  

Early Mesozoic dike swarms of carbonatites and lamprophyres in Datong area

作　　者：邵济安[1] 张永北[2] 张履桥 牟保磊[1] 王佩瑛[1] 郭峰[4] 

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]中国科学院地质地球物理研究所,北京100029 [3]内蒙古地质研究所,呼和浩特010020 [4]中国科学院长沙大地构造研究所,长沙410013

出　　处：《岩石学报》2003年第1期93-104,共12页Acta Petrologica Sinica

基　　金：国家自然科学基金(批准号49872079;40072073);中科院知识创新工程项目(KZCX1-07)

摘　　要：大同地区密集分布的岩墙群由基性-超基性煌斑岩和碳酸岩组成,侵入于石炭-二叠纪煤层中。与地层的接触关系和Rb-Sr、K-Ar同位素年代学数据表明岩墙群的侵位于晚三叠世。Sr、Nd同位素比值显示,碳酸岩和煌斑岩都来源于壳幔混合型岩浆源区。稳定元素比值和相容、不相容元素同等富集则表明它们是碳酸岩和硅酸盐混合的原始母岩浆液态不混熔的产物。岩墙群形成的地质条件和构造背景表明,它们是在伸展构造背景下,受到不同级别的构造控制。大同岩墙群的研究对进一步认识华北早中生代岩石圈演化有重要的意义。In the Carboniferous-Permian coal formations in Datong area lots of basic dike warms occur. They are mainly carbonatites and basic-ultrabasic lamprophyres. The strata, relationships as well as Rb-Sr and K-Ar isotopic chronology show that the dike swarms were formed at Late Triassic (229Ma). The Sr,Nd isotopic ratios and Rb/Sr ratios of carbonatites and lamprophyres indicate that they were originated from a crustal-mantle mixing type reservoir. The stable element ratio of compatible and incompatible elements implies that they are liquid immiscible congeners coming from a primitive magma consisting of mixed carbonatites and silicates. Examination of the conditions reveals that they were formed in extensional tectonic sittings and controlled by structures at different levels. Study on Datong dike swarms will play an important role in further understanding the evolution of the Early Mesozoic lithosphere in North China.

关 键 词：大同地区 早中生代 岩墙群 煌斑岩 碳酸岩 基性岩 超基性岩 

分 类 号：P588.12[天文地球—岩石学] P588.245[天文地球—地质学]