A geochemical comparison between the Emeishan and Siberian large igneous provinces and its petrogenetic implications

The Emeishan and the Siberian large igneous provinces (LIP) represent two major magmatic events close to the Permian-Triassic boundary. They are characterized by similar major element,microelement,and Sr, Nd and Pb isotopic compositions. However, the variation ranges of the incompatible element ratios and isotopic ratios are much narrower in the Emeishan LIP than in the Siberian LIP. Compared with the Siberian LIP,the Emeishan basalts have somewhat higher Fe_8,and Sm/Yb ratios,suggesting a relatively greater depth and a lower degree of melting. Their source regions are garnet lherzolite. Based on the Nd isotopic characteristics, the Nd value of Emeishan and Siberian plume is estimated to be approximately 2, close to that of the primitive mantle. In combination with other geochemical characteristics, it is proposed that the two LIPs might have originated from the same super-plume derived from the core-mantle boundary.