The volcanic rock characteristics and magmatic evolution of the Xingshan Volcano Group in the Jingpo Lake area
Volcanic field in Jingpo Lake area is an important window for the study of intra-continental Cenozoic basalts.Previous studies on the Xingshan Volcano Group located in the southeast of this area have rarely been conducted and the possibility of magma assimilation and mixing in this area has been denied.The basalts of the Xingshan Volcano Group have been systematically studied in terms of petrology,petrochemistry and Sr—Nd—Pb isotopes.It is believed that the basalts of the Xingshan Volcano Group are mainly basanites and trachy-basalts.The fractionation of olivine and clinopyroxene occurred during the ascent of the primary magma,and the assimilation and mixing occurred in the upper crust,with weak AFC effect.The comparison between the basalts of the Xingshan Volcano Group and the Jingbohu basalts during the same eruption shows that the basalts in both areas are derived from the partial melting of garnet peridotite,and the partial melting degree of the Xingshan Volcano Group is slightly lower than that of Jingbohu basalts.In terms of magmatic source region,the Xingshan Volcano Group is the mixing source of PREMA and BSE end-member.The heterogeneity of magma source area and the assimilation and mixing during magma evolution are the main influencing factors that cause the difference between the lithologic features of the Xingshan Volcano Group and Jingpohu Volcano Group.
Xingshan Volcano GroupMiocene—Pleistocene basaltpetrochemistryassimilation and mixingmantle source region
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