The database of global zircon ages shows a marked age gap at 2.45–2.2 Ga, which was postulated associated with the global magmatic and plate tectonic “shutdown” or “slowdown”. But in recent years, a great deal of ∼ 2.3 Ga magmatism has been identified in the North China Craton (NCC). Nevertheless, tectonic evolutionary scenario of the NCC during early Paleoproterozoic is still in hot debate. This study focuses on the gabbroic diorites and biotite granites in the Xiaoshan area, southern margin of the NCC. They were emplaced at ∼ 2.32 Ga. The gabbroic diorites have low SiO2, high Mg#, Cr, Ni values, and characterized by LREE-enriched, HREE-depleted trends, slightly positive Eu anomalies with pronounced negative Nb-Ta anomalies. Meanwhile, the samples have low-δ18O value of 2.05–5.35 ‰, they show negative zircon εHf (t) (−5.8 to − 4.1) and whole-rock εNd (t) (−2.36 to − 1.77) values, with TDM1 ages of 2.81–2.88 Ga and 2.80–2.86 Ga respectively, and crustal assimilation was limited during magma ascent, indicating a lithospheric mantle (CLM) source, which has been refertilized by metasomatic processes. The biotite granites have low 10000 Ga/Al ratios, Zr, Zr + Nb + Ce + Y concentrations, and calculated zircon saturation temperature (697–776 °C), belonging to metaluminous I-type granite. Their highly fractionated REE patterns, high Sr/Y and La/Yb ratios, low Dy/Yb and Gd/Yb ratios indicating that they were derived from partial melting of a lower crust source with both garnet and amphibole in the residue. Besides, they have δ18O values ranging from 2.41 ‰ to 5.11 ‰, variable zircon εHf (t) (−1.1 to + 1.4) and whole-rock εNd (t) (−0.76 to + 0.29) values, implying they were formed mainly by reworking of the pre-existing ancient crust, which was probably triggered by underplated mantle-derived mafic magmas. In combination with previous studies on the great diversity 2.45–2.2 Ga mafic-felsic rock assemblages and their geochemical features, we prefer that the extensional tectonic regime, which can result in thermal anomaly to account for the lithospheric mantle and crustal melting, is reasonable in the early Paleoproterozoic Era, at least for the southern NCC.