Correlation of oxygen fugacity in the mantle lithosphere between Ce+4 / Ce+3 relation of zircons and petrological buffer FMQ

The paper presents variations of Ce+4/Ce+3 and Eu+3/Eu+2 in zircons from different mantle rocks of the lithosphere. The ratio Ce+4/Ce+3 reflects the "oxidation" degree of the zircon (and rock) formation and Eu+3/Eu+2 – "reducing" properties of the source which allows one to control the level of the oxygen fugacity. A correlation of the ratio Ce+4/Ce+3 in zircons ("geochemical buffer" – "CeB") and petrological buffer FMQ of rocks in the lithosphere vertical section has been performed. This allows one to determine the boundaries of the "upper" and "lower" parts of the lithosphere and reveal the similarity of the variation range of the oxygen fugacity in the upper lithosphere and analogous parameters of the crustal rocks of different age. Besides it helps to establish unique reducing parameters for oxygen in the foot part of the lithosphere.