Geochemical characteristics and petrogenesis of the lamprophyres in Liuquan area of northern Jiangsu Province

The Liuquan area is the concentrated distribution area of lamprophyres in northern Jiangsu, accompanied by kimberlites, olivine basaltic porphyrites and so on. By studying the petrology and lithogeochemical characteristics of lamprophyres in the area, the petrogenesis and tectonic setting are discussed further in this paper. The results show that the lamprophyres are the product of comagmatic evolution, belonging to potassium alkaline series, characterized by low Si and rich Fe, Mg, Ca and Ti, enrichment of LILEs and LREEs, and depletion of HSFEs and HREEs generally. They are formed under the background of Meso-Cenozoic Pacific plate subduction and lithospheric thinning, originating from the enriched lithospheric mantle source formed by subducted sediments at a depth of about 75～100 km, with the nature of low-degree partial melting of amphibole garnet-bearing lherzolite intruding into the shallow crust along the tectonic weak zones.