The Late-Proterozoic-Cambrian Active Continental Rift Volcanism in Northern Qilian Mountains
北祁连山元古宙末－寒武纪主动大陆裂谷火山作用

The Late- Proterozoic- Cambrian continental rift volcanic rock series display a bimodal suite, which consist of basic and acidic volcanic rocks. The basic rocks, which belong to alkali and tholeiitic magma series, enriched in LREE and LIL. The magmatic source of basic volcanic rocks was enrichment mantle being analogous to oceanic island basalts sources. The asthenospheric plume ascended and impacted with the lithosphere and led the lithospheric mantle partial melting. The plume-derived melts mixed the lithospheric mantle-derived melts and formed the primary basic magma, which characterized by middle ENd values and middle (87Sr/86Sr), values. The basic magma ascened into continental crust and induced anatexis of the crust which produced felsic magma. The mantle plume upwelling may promote the continental extention, then the Late-Proterozoic-Cambrian continental rift in Northern Qilian mountains was formed.