Zircon Age and Geochemical Constraints on the Correlation of Early Cretaceous Volcanic Successions in the Wangfu Fault Depression

Volcanic intervals with comparable lithologies or stratigraphic labels may contain different zircon age populations, complicating interwell comparison in the Wangfu Fault Depression, southern Songliao Basin, northeastern China. Using formation and member assignments from the field well records, we integrate lithological records and well logs from three wells with zircon U–Pb ages, trace elements, and cathodoluminescence observations from four samples, together with Lu–Hf isotope data for C64 and C14. C64 and C14 yield weighted-mean zircon ages of 116.10 ± 1.01 and 117.14 ± 1.07 Ma, respectively, whereas C90 yields 111.61 ± 1.07 Ma; quoted uncertainties are internal 2σ. The less precise C98 estimate overlaps C90. Zircon textures, Th/U ratios, and rare-earth-element patterns support magmatic crystallization. C64 and C14 have positive εHf(t) values of +5.0 to +11.4 and +5.2 to +8.5, consistent with juvenile contributions but not diagnostic of unique magma sources. In the adopted well framework, C64 and C14 have overlapping zircon ages across different formation assignments, while C14 and the C9 samples assigned to Huoshiling Member 1 record different age groups. These are differences in zircon crystallization ages among sampled materials; they do not directly establish differences in eruption or depositional ages, given the breccia lithology of C64 and unresolved emplacement mode of the C9 rhyolites.