Dating of the volcanic rocks from the Shuzhugang Hill, Guangzhou: age constraints on the Late Cretaceous strata in the Sanshui and Zhujiangkou basins

Well-developed Cretaceous-Paleogene strata are exposed in the Guangzhou-Foshan area. Owing to limited volcanic activity, isotopically datable material is scarce, and the chronology of these strata relies primarily on biostratigraphic correlations. The Baihedong Formation has been generally regarded as a sedimentary sequence deposited during the late Early Cretaceous, although robust chronological constraints are lacking. In the Shuzhugang Hill area, located south of Guangzhou, a suite of volcanic rocks is exposed and is generally assigned to the upper part of the Baihedong Formation, though some scholars attribute it to the Paleogene. Zircon U-Pb dating conducted in this study yielded an absolute age of 83.5 ± 0.7 Ma for these volcanic rocks, thereby constraining the deposition of the Baihedong Formation to the Late Cretaceous. This study provides a crucial chronological reference for defining the Cretaceous-Paleogene stratigraphic chronology framework across the Sanshui and Zhujiangkou basins.