Geochemical Characteristics and Analysis of Tectonic Setting of Hannuoba Basalts from Chifeng Region, Inner Mongolia

Abstract

The Hannuoba basalts from Chifeng region, Inner Mongolia, are continental flood basalt, produced by fissure-t type volcanism in the Miocene. The basalts chemically belong to the tholeiitic series. On the whole, the petrologic compositions are homogeneous. The basalts is characterized by Al2O3 = 11.5%~13.0%, Na2O> K2O and TiO2=1.93~3.29%, chemically belong to the calc-alkaline series with low K2O, which are the agpaitic type; The total amounts of REE of Hannuoba basalts are lower and rich in LREE. There is a weak Eu negative anomaly and weak Ce negative anomaly. The basalts are obviously enriched in incompatible elements (K, Rb, Sr, Zr, Ba, LREE etc.), and depleted in high field-strength element (U,HREE) as well as compatible elements (Co, Ni, Cr etc.).Comprehensive studies have shown that Hannuoba basalts erupted in a stable setting within continental plate and controlled by deep fracture crossed mantle, belonging to continental rift basalt.