六合—仪征第三纪大陆碱性玄武岩微量元素地球化学

本文报道了六合-仪征第三纪大陆碱性玄武岩十八个样品的REE、Rb、Ba、Sr、Nb、Zr、Ni、Cr、V、Sc、Y、Ga、Zn、Cu等痕量元素含量,讨论了该岩套的成因及其地幔源区的特征。石榴石橄榄岩型地幔源区经较小程度部分熔融形成了基性原始岩浆;其后经过橄榄石和单斜辉石为主的结晶分异作用,演化后的岩浆喷出地表形成玄武岩套。本区碱性玄武岩的地幔源区曾受近期富集作用影响,具有富集LREE等不相容元素的特征。

TRACE ELEMENT GEOCHEMISTRY OF TERTIARY CONTINENTAL ALKALIC BASALT FROM LIUHEYIZHENG, JIANGSU PROVINCE, CHINA

The chemical compositions and trace elements(REE, Ba, Rb, Sr, Nb, Zr, Ni, Cr, V, Ga, Y, Sc, Zn, Cu etc.) abundances of Tertiary continental alkalic basalt from Liuhe-Yizheng, Jiangsu Province, China are reported and interpreted. The olivine basalt, aklalic olivine basalt and basanite all are derived from evolved melts that are affected by crystal fractionation of olivine and clinopyroxene(1:2)under high pressure. The primitive melts are derived from garnet lherzolite mantle source by low degree partial melting. The mantle source is affected by recent mantle enrichment (e, g, mantle metasomatism) with the enrichment characteristics of incompatible trace elements.