中文摘要：

马泉新生代碱性玄武岩出露在青藏高原东北缘，岩石SiO2介于40．40％～41．84％之间，TiO2含量高（3．73％～4．57％），K2O（0．37％～3．24％）和Na2O（0．57％～2．59％）含量高且变化范围较宽，K2O／Na2O为0．46～1．92，属于典型的幔源高钛-极高钛大陆溢流碱性玄武岩类。岩石微量及稀土元素具板内火山岩特征，Th、Rb等元素呈较明显的富集状态。岩石^87Sr／^86Sr（0．704090～0．704668），^143Nd／^144Nd（0．512770～0．512869），^206Pb／^204Pb（18．363698～18．866220），^207Pb／^204Pb（15．495292～15．602144），^208Pb／^204Pb（38．092958～39．399417）等同住素变化特征以及岩石高Mg（Mg#=60．7—65．9），高Sm/Yb值，（Ce／Yb）N在29．37—35．82，表明马泉碱性玄武岩的岩浆源区深度较大，应来源于软流圈地幔石榴石二辉橄榄岩的局部熔融。

英文摘要：

The Cenozoic alkaline basalt from the Maquan area located at the northeastern margin of the Tibetan plateau. The rock exhibits SiO2 between 40.40% to 41.84% , high TiO2 （3.73% - 4.57% ）, K2O （0.37% 3.24% ）, Na2O （0.57% - 2.59% ） , and K2O/Na2O being 0.46 - 1.92, belonging to an association of the typical mantle generation high/ultr-high titanium continental flood alkaline basalt. The trace and rare earth elements show geochemical characteristics of the within plate volcanism. The Th and Rb are enrichment. Isotopic compositions of this group rock have radiogenic Sr, Nd and Pb （^87Sr/^86Sr = 0. 704 090 -0. 704 668, ^143Nd/^144Nd = 0.512 770 - 0.512 869,^ 206Pb/^204Pb = 18. 363 698 = 18. 866 220, ^207Pb/^204Pb = 15. 495 292 - 15. 602 144, ^208Pb/^204Pb - 38. 092 958 -39. 399 417）. The Sr-Nd-Pb isotopic compositions and the characteristic chemistry compositions of Mg （ Mg# = 60.7 - 65.9） and （Ce/Yb） N （29.37 - 35.82） suggest that the basalt should be derived from a asthenosphere garent-lherzolite mantle reservoir.