Zircon U-Pb geochronology, geochemical characteristics and geological significance of the pluton in the Shaoguoyingzi gold ore deposit in Jianping, western Liaoning

The Shaoguoyingzi intrusion is located in the Chifeng-Chaoyang gold concentration area on the northern margin of the North China Craton, surrounded by Shaoguoyingzi and Zhuanshanzi gold deposits or gold ore spots. The lithology of the intrusion is monzogranite which shares the same source with the gold deposits. The zircon U-Pb age data obtained by using laser ablation ICPMS technique are 159.1±1.5 Ma, 160.2±4.4 Ma and 160.1±1.1 Ma, which indicate that the Shaoguoyingzi intrusion was formed in Late Jurassic and the gold deposits were formed at the same time or a little later. The major and rare elements are characterized by high Si, low Al, medium alkali, poor Mg and Ca, rich Th, Zr, Nd, Rb and K and comparatively low Ba, Sr, P and Ti, with obvious negative Eu(δ Eu=0.08-0.60)and Sr anomalies; which indicates that the Shaoguoyingzi intrution is a high-K calc-alkaline I-type granite that has experienced a high degree of crystallization and differentiation. The depth of the source is about 30km, as shown by the characteristics of Sr-Yb-Y. This area was a tectonic transition period in late Jurassic, and the intrusion was formed by back-arc extension in the Pacific plate subduction environment, as shown by an analysis of the regional tectonic environment.