吉林东部汪清新生代玄武岩中地幔包体的矿物化学：对该地区岩石圈地幔形成过程的启示

Mineral chemistry of mantle xenoliths in Cenozoic basalts from Wangqing,eastern Jilin:Implications for formation of newly accreted sub-continental mantle

在对吉林汪清新生代玄武岩中橄榄岩包体进行全岩主、微量元素分析的基础上，重点分析了矿物的主、微量元素含量，讨论了华北克拉通东北缘与兴蒙造山带结合部位陆下岩石圈地幔所经历的部分熔融作用和地幔交代作用。橄榄石的Fo、单斜辉石以及尖晶石的Mg#和Cr#均表明该地区陆下岩石圈地幔相对饱满。对地幔橄榄岩透辉石微量元素模拟计算证实，汪清陆下岩石圈地幔经历了1％～3％的部分熔融作用，并遭受后期硅酸盐熔体交代作用。这些地幔特征与中国东部其他地区新生代主体岩石固相似。研究结果证明，吉林汪清中、新生代以来岩石圈性质的转变是在汇聚板块构造体制下通过“拆沉作用”实现的。

In addition to analyses of bulk-rock major and minor element composition of mantle peridotite xenoliths in Cenozoic basalt at Wangqing, Jilin Province, we further analyzed the major and trace elements of minerals, and discussed the partial melting and metasomatism of SCLM at the joint area between North Cbina Craton and Mongolia-Hinggan Orogen. Mineral compositions as evidenced by Fo in olivine, Mg# and Cr# in both elinopyroxene and spinel suggest that the SCLM beneath Wangqing is relatively fertile. Simulated calculation of trace elements for diopside in mantle peridotites proves that the SCLM beneath Wangqing has undergone 1 %- 3% partial melting followed by silicate melt metasomatism. These mantle features are similar to Cenozoic SCI.M beneath other areas of eastern China. Our results suggest that the transformation of SCLM nature was realized through delamination under a ＂multiple＂ convergent plate tectonic domain.