Immiscibility of magma recorded in melt inclusion within corundum megacryst from alkali basalt

摘要

The corundum megacrysts sampled from Cenozoic alkaline basaltic rocks,Changle district, Shandong province, are closely associated with lherzolite xenolith and other mantle megacrysts, such as anorthoclase, spinel, pyroxene etc. The studied area is located in the northeast segment of the basaltic zone in southeast of China, and the Cenozoic alkaline volcanisms taken place in this area were controlled by Yi-Shu fault, which is part of Tanlu big fault. The host basalt is typical high alkaline basalt, with characteristic of high concentration of (K_2O+Na_2O)( 4.46 %～4.92 %), Al_2O_3 (13.05 %～14.15 %) and TiO_2(1.75 %～3.75 %), and low concentration of SiO_2 (43.62 %～47.70 %) (Dong et al, 1999).