黑龙江鸡西盆地新生代玄武岩大地构造环境探讨

鸡西盆地新生代玄武岩的岩石学、岩石化学和地球化学研究表明，岩石中发育橄榄石包裹体，且造岩矿物中也多含橄榄石晶体；δEu=0.87~0.94（大于0.7），具基性岩浆分异特征.微量元素Nb^*值为0.91（接近1）、K^*值为1.09，略大于1，表明岩浆与消减作用相关不大，且有非地壳物质加入.总体分析，岩浆来源于上地幔，上升过程中遭受了壳源物质的混染.鸡西地区新生代玄武岩岩浆来源于上地幔，是裂谷作用的产物，为大陆裂谷型玄武岩，其形成与敦密断裂在上新世的拉张活动有关.

TECTONIC ENVIRONMENT OF THE CENOZOIC BASALTS IN JIXI BASIN,HEILONGJIANG PROVINCE

Study on the petrology,petrochemistry and geochemistry for the Cenozoic basalt in Jixi basin,Heilongjiang Province shows that olivine inclusions are developed in the rock.The olivine crystals are common among the rock-forming minerals.The δEu values of the basalt range from 0.87 to 0.94(greater than 0.7),showing the characteristics of basic magmatic differentiation.The trace element Nb* value(2NbN /KN+LaN])is 0.91(close to 1)and K* value(2KN/TaN+ LaN])is 1.09(slightly larger than 1),indicating that the magma is not closely related to the subduction,but with addition of non-crustal materials.In general,the magma originates from the upper mantle,with contamination of crustal materials in the process of uplifting.The Jixi Cenozoic basalt magma is the product of rifting,derived from upper mantle,belonging to continental rift basalts.Its forming is related to the extension of the Dun-Mi fault in Pliocene.