TAN Tao, XIAO Yuan-fu^*, LIN Kun, LI Meng, YANG Ya-min, YUAN Hao-wei

(School of Geoscience, Chengdu University of Technology, Chengdu 610059, China)

Abstract: This paper studied mineralogy and geochemical characteristics of Emeishan basalt in Makou area, northeastern Yunnan, this paper gives a reasonable explanation for petrogensis of these rocks and the origin of parent magma. The content of basalt SiO2 is 48.88% ~ 52.80%, which is basic lava. In the TAS diagram, most of the samples fall into alkaline basalt series, and a small part is subalkaline basalt series. The content of Mg# average value of 0.45%, which is lower than that of the original magma (Mg# 0.67%－0.70%). This indicates that the original magma undergoes some differentiation. The LREE/HREE ratio is 6.69－8.07, and the light and heavy rare earths are slightly differentiated, showing a slight negative Europium anomaly. (Delta Eu=0.72－0.93); K, P, Sr and other elements are depleted to varying degrees in the spidergrams map. The ratio of Ti/Y (Ti/Y content is 490.06－627.77) indicates that the basalt belongs to high-Ti basalt. The results show that the basalts in this area are partial melting products of lower mantle garnet mantle peridotite, formed in the continental intra-plate extensional tectonic setting and related to mantle activity. During diagenesis, they are contaminated by crustal materials, and olivine and plagioclase are separated and crystallized.

Keywords: geochemical characteristics; petrogensis; Emeishan basalt; Makou area, northeastern Yunnan

ACTA MINERALOGICA SINICA Vol. 39, No.6, 2019, page 627-636