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南秦岭扬子克拉通北缘,中～晚元古代陨西群、耀岭河群、西乡群及碧口群火山岩系具有大陆裂谷火山岩或大陆溢流玄武岩特征,是大陆板内拉张构造环境下形成的,火山岩富集不相容元素及高ε_(Nd)和低～中等~(87)Sr/~(86)Sr值等特点,表明其来源于软流圈地幔柱.在较强烈的岩石圈拉张作用下,地幔柱上隆并快速减压熔融形成岩浆.这种拉张作用在晚元古代发展为大陆裂解并形成洋盆.中～晚元古代火山作用是南秦岭前寒武纪大陆裂解的先兆.
The northern margin of the Yangtze craton, the Middle ~ Late Proterozoic meteorological western group, the Yaolinghe Group, the Xixiang Group and the Bikou Group volcanic rocks are characterized by continental rift volcanic rocks or continental overflow basalts, (87) Sr / ~ (86) Sr and other characteristics of volcanic rocks enriched in incompatible elements and high ε Nd and low ~ moderate 87 Sr / ~ 86 Sr values suggest that they are derived from asthenospheric mantle plume. Of the lithosphere stretching, the mantle plume uplifted and rapidly depressurized and melted to form magma, which developed during the Late Proterozoic to continental rupture and the formation of oceanic basins. The Middle-Late Proterozoic volcanism was the pre-Qinling The premonition of the cracking down of the Wu-Ji continent.