Studies On Geochemistry Of The Permian Basalts In Shangri-La County YunNan Province

To limit the extent of The ELIP.This research aim at the basaltsthat are located in Songba village of Shangri-La County.The hand specimen of basalt are grey-green,black-gray with strong alteration.Basalt shows porphyritic and/or amygdaloidal structures.The normalized contents of Si O2 are within42.14~48.58%,while contents of Ti O2 within 3.79~4.49%,contensts of Mg O within 9.18~14.27%,and values of Mg# vary from 53.9 to 62.2.Additionally,two samples collected in the same place with the basalt are recognized as picrite based on their high contents of Mg O.All the samplesshow high TFe2O3,Ti O2,Cr,Ni,so all the sample belong to ferrobasalt.The basalt is rich in LREE and poor in HREE and no obvious Eu abnomalies.the primitive mantle normalized diagrams of the basalts showdeficit in K,Sr.(87Sr/86Sr)iratios range from 0.703672 to 0.706893,and ?Nd(t)(t=260 Ma)ranges from +2.77 to +5.54.The basalts have occurred fractional crystallization of Mg-Fe mineral and display a Fenner trend of differentiation,But didn't have undergone crustal contamination.The ferrobasalt comes from ferropicrite.The bulk-rock major and trace element show the sources of the basalts is garnet-pyroxenite with a high melting temperature.The petrogeness is partical melting of eclogite produces Si O2-rich melts that react with garnet-lherzolite and generate garnet pyroxenite source.We calculated primary magmas of Dashibao basalts and Gangdagai basalts using PRIMELT2 and PETROLOG software.The results show that the Dashibao basalts' mantle temperature is higher than ELIP' east edga zone,that the Gangdagai basalts' mantle temperature is similarity to east edga zone.So we speculate that in the west part of Shangri-La County,SGT,Zhongza block have Emei Shan basalt.So we belive that the Emeishan plume head is bigger than that estimated before.