中文摘要：

中生代是全球岩浆活动的高峰期,也是最近研究的热点,但在我国西南的康滇地区,鲜有报道.近年来,通过野外地质填图和综合研究工作,在康滇地区中部,云南省东川地区识别出一系列燕山期基性岩脉,SHRIMP锆石U-Pb年龄为128.2±1.5 Ma（MSWD=2.0,n=16）,与长江中下游、华北地区早白垩世大规模岩浆活动及同期全球性太平洋超级地幔热柱事件高度一致.基性岩脉岩石化学显示为低SiO3（44.3％～47.28％,平均值为45.68％）、高MgO含量（6.8％～9.64％,平均值为7.99％）和高Mg#值（65.3～70.4,平均值为67.9）,Na2O/K2O＞1,总体上与拉斑玄武岩的岩石化学相似.原始岩浆为石榴子石二辉橄榄岩较低部分熔融（～2.2％）与尖晶石二辉橄榄岩较高部分熔融（15％～20％）混合形成,岩浆演化过程中发生过轻度的橄榄石、斜方辉石和铬铁矿结晶分异.基性岩脉的轻/重稀土元素分异不明显,原始地幔标准化配分模式呈向右平缓倾斜的曲线;微量元素地球化学参数与OIB相似,MORB标准化配分模式图中没有明显的高场强元素,如Nb、Ta、Zr和Hf的异常,但Ba、K相对富集.基性岩脉具有较高的（87Sr/86Sr）i初始比值,且变化较明显,为0.71003～0.71499,可能为后期较强的热液蚀变作用所致,根据锆石年龄计算出来的εNd（t）值为-1.5～3.1（均值为2.4）,反映了其初始岩浆的同位素组成.原始岩浆演化过程中没有明显的岩石圈物质混染,但可能有较多相对亏损的软流圈地幔物质加入,导致较高的εNd（t）值和平缓的稀土元素配分模式.康滇中部地区白垩纪基性岩脉的成因可能与大尺度的岩石圈减薄无关,可能是白垩纪全球性太平洋超级地幔柱的分支（幔枝构造-地幔柱的第三级或更高级构造单元）.由于其规模较小,且岩石圈较厚,未能形成大规模的大陆溢流玄武岩,仅能选择构造薄弱部位快速侵位冷却,形成具有独特细晶结构?

英文摘要：

Mesozoic era is the period during which intensive magmatic activities occurred,and has become the research focus for years.But few had been reported in Kangdian area,Southwest of China.Through geological mapping in field and laboratory test in central Kangdian area in recent years,a series of Yanshanian mafic dykes were identified in the Dongchuan area,Yunnan Province.The SHRIMP U-Pb age for zircons is 128.2±1.5 Ma （MSWD =2.0,n =16）,which are highly in accordance with the large scale magmatic activities in the middle and lower reaches of Yangtze River,north China craton,and the global pacific superplume events for early Cretaceous.The petrochemistry of Cretaceous mafic dykes are characterized by low SiO2 （44.3%～47.28%,mean value for 45.68%） and high MgO （6.8%～9.64%,average for 7.99%） contents,and high values of Mg# （65.3～70.4,average for 67.9）,and Na3O/K3O〉1,which are similar to the petrochemistry of tholeiitic basalts.The primitive magma reprresents small melt fractions（～2.2%） from garnet-facies combined with large melt fractions（15%～20%） from spinelfacies,and experienced slightly crystallization and differentiation of olivine,orthopyroxene and chromite during the evolution.The differentiation of LREE and HREE is not obviously,and the primitive mantle normalized patterns exhibit gently right-dipping curves.The geochemical parameters of trace elements are similar to that of the OIB,and the MORB normalized patterns have no obviously anomaly of high fieldstrength elements,such as Nb,Ta,Zr,and Hf except the enrichment of Ba and K.The mafic dykes have relatively highly and frequently variational initial （87 Sr/86 Sr）i ratio （0.71003 ～0.71499） which may be resulted from the relatively intensively hydrothermal alteration,and the εNdt values calculated according to the U-Pb Age vary from-1.5 to 3.1 （average for 2.4） reflecting the actually isotopic composition of primitive magma.The original magma may be contaminated without significant lithospheric material,but probab