Zircon U–Pb Geochronology, Elemental Geochemistry and Geological Implications of the Andesite of the Yixian Formation in the Tiejiangyingzi Basin in Southeastern Chifeng, China

Abstract The Early Cretaceous andesite of the Yixian Formation is an ore‐host rock in the Tiejiangyingzi basin in southeastern Chifeng, China, and bears several meso‐epithermal Au deposits, such as the Nalingou and Yaogou Au deposits. The geochronology and elemental geochemistry of the Yixian Formation were investigated to reveal its metallogenic context, petrogenesis, and mineralization contribution. The 206 Pb/ 238 U ages of zircons reveals that the andesite formed at 125.5 ± 0.9 Ma. This rock belongs to calc‐alkali rock series according to its elemental geochemical analysis results (i.e., SiO 2 = 63.63%–67.27%, MgO = 1.17%–1.43%, K 2 O = 4.07%–4.67%, Mg # = 35–41, Al 2 O 3 = 17.16%–18.63%, Na 2 O = 3.35%–4.08%, Sr = (240.1–585.6) × 10 ‐6 , Yb = (1.83–2.22) × 10 ‐6 , Y = (13.9–23.36) × 10 ‐6 , Na 2 O/K 2 O = 0.7–0.9, Eu/Eu* = (0.75–0.79) × 10 ‐6 , Sr/Y = 13–27, La N /Yb N = 11–19 ). The chondrite‐normalized trace element plot shows that the andesite is enriched in light rare earth elements (LREEs) and Yb. Thus, the residual phase of andesite volcanic rocks is a granulite suite that contains amphibole and little remaining garnet in the Tiejiangyingzi basin. It can be concluded that andesite volcanic rocks distributed in the Tiejiangyingzi basin were formed in an extensional tectonic environment during the Mesozoic orogen, and the lower crust had experienced extensive high‐temperature metamorphism and melting. This gold‐bearing lower crust is closely related to mineralization. Therefore, the conclusions of this research have an important implication for further prospecting in southeastern Chifeng, China.