四川华蓥偏岩子晚二叠世玄武岩地球化学特征及其与峨眉山大火成岩省的成因关系

四川华蓥偏岩子地区位于四川盆地中东部,新发现的晚二叠世玄武岩介于茅口组(下伏)和龙潭组(上覆)之间,可与峨眉山玄武岩进行对比.矿物学和地球化学研究表明,偏岩子玄武岩属于高钛亲碱性系列,具有OIB型的稀土元素和微量元素配分模式.偏岩子玄武岩基本未遭受地壳混染,单斜辉石的结晶温度为1405～1439℃,指示源区存在异常高温...

Geochemical characteristics of the Late Permian basalts in Pianyanzi, Huaying, Sichuan and their genetic relationship with Emeishan Large Igneous Province

Huaying Pianyanzi area is located in the middle-east of Sichuan Basin.The newly discovered Pianyanzi Late Permian basalt is between Maokou Formation(underlying)and Longtan Formation(overlying),which can be compared with Emeishan basalt.The study of petrology,mineralogy and geochemistry suggests that Pianyanzi basalts belong to the high-Ti alkaline series,and the rare earth element(REE)and trace element patterns are similar to those typically found in ocean island basalts(OIB).The basalts have not undergone any significant crustal contamination.The crystallization temperature of clinopyroxene is estimated to be 1405~1439℃,suggesting anomalously thermal inputs from a mantle source and a possible plume-head origin.The REE simulation result su-ggests that Pianyanzi basalts were produced by small degree of partial melting of Emeishan mantle plume within the garnet-spinel transition region.In general,the Pianyanzi Late Permian basalt is very similar to the Emeishan basalt,especially the basalt in the east of Emeishan Large Igneous Province(ELIP),which is an integral part of ELIP.