Amphibolite-facies metamorphism, displaying varied geothermal gradients and clockwise pressure-temperature (P-T) paths, is observed in Archean supracrustal belts between and rafts within granitoid (tonalite-trondhjemite-granodiorite, TTG) gneiss domes. However, its tectonic regimes remain controversial. This paper presents a systematic study of the metamorphic evolution and tectonic regime of the Luanxian supracrustal sequence, a belt situated between TTG gneiss domes in the East Hebei Terrane of the North China Craton. Three samples were selected: two of garnet-biotite gneiss and one of amphibolite. Two (J1745 and J1753) record clockwise P-T paths that involve the prepeak prograde stage from low P/T (27−38 °C/km) to medium P/T (20−21 °C/km) in the peak stage (∼11 kbar and 770−800 °C), followed by decompression to low P/T (28−38 °C/km) at 5.5−7.5 kbar and 750−760 °C. However, a cordierite-bearing garnet-biotite gneiss (sample J1748) seems to record a cooling process from 830−850 °C, 5−6 kbar, registering a low−P/T geothermal gradient (∼40 °C/km). Zircon dating yields metamorphic ages of ca. 2.50 Ga. The amphibolite-facies metamorphism is coeval with the ultrahigh-temperature metamorphism observed in supracrustal rafts within TTG domes, which is characterized by counterclockwise P-T paths and a low−P/T geothermal gradient. This juxtaposition of different metamorphic grades, P/T types, and the coexistence of clockwise and counterclockwise P-T paths can be addressed with a vertical sagduction model. That is, a supracrustal sequence may first sink into the underlying TTGs relative to the neighboring diapiric uprising, coupled with a prograde metamorphic process characterized by increasing P-T leading to the peak stage. Then, the sunken supracrustal sequence is exhumed due to further granitoid doming, forming the keel between the TTG domes, and along with the postpeak decompression. In these processes, the supracrustal rocks tend to record clockwise P-T paths. In contrast, supracrustal rafts within TTG domes that were first heated and then dropped may record ultrahigh-temperature conditions with counterclockwise P-T paths.

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