Geochemistry Features And Dynamics Fingerprints Of Emeishan Large Igneous Province

Emeishan continental floor basalts province (ECFB )is one and only LIP in China which is approbatory by international academe. It has peculiar geochemistry features and complete magma evolutionary series, so is widely paying attention to geologists, but the degree of study on it is quiet low. Recently, through studies on ELIP advancing, four important things will be needed to researched: (1) to compare the geochemistry features with each rocky areas of ELIP; (2) to study the evolutionary trend and geochemistry features respectively; (3) to research more evidences about the mantle plume dynamic origin of ELIP; (4) to analyze the geochemistry reserves and geodynamic fingerprints of ELIP magma. So this paper researched and discussed systematacially ELIP from rock-, PGE-, isotope- and dynamic- geochemistry etc.Except that analyzing the problem of ECFB/ELIP magma as follows: basalts magma activity period of time, S- unsaturated character, three evolutionary trends and it's fO₂, two evolutionary series, high-Mg magmas etc., this paper established some new trace element-, PGE-, porosity dynamic melting modeling diagrams, furthermore made modeling with porosity-dynamic melting model on REE- and Spider Web-patterns. I have studied the proportions of DM and EM of ELIP magma by means of some Sr-Nd-Pb isotope models. The quantitative modeling in this paper show ELIP magma origined from the mixture source 0.3-l%Outer Core + 50%DM + 49.7% PM, which is imply Emeishan traps resulted from deep mantle plume.The modeling in this paper show that the melting source zone of western ELIP is within Gt peridotite mantle to Sp lherzolite mantle (the melting pressure is 3.0～ 1.8GPa) , the degree of partial melting is 2 — 8%, partially <2%; the one of Middle ELIP is within Gt-Sp lherzolite mantle (3.0—2.5GPa), the degree of partial melting is mainly <2%; the one of Eastern ELIP is within Gt-Sp lherzolite mantle( 2.9～2.4GPa), the degree of partial melting is <1%. So I think that up-laying lithosphere become thick from western thin paleotethys oceanic lid to eastern thicker Yangtze craton lid, this setting change caused the melting pressure/depth increased and the average degree of partial melting reduced, which accord with melting surface map inferred...